Journal Articles

A new LC-MS/MS method for the clinical determination of reduced and oxidized glutathione from whole blood. Journal of chromatography. B, Analytical technologies in the biomedical and life sciences Moore, T., Le, A., Niemi, A., Kwan, T., Cusmano-Ozog, K., Enns, G. M., Cowan, T. M. 2013; 929: 51-55
Abstract

Reduced levels of glutathione (?-glutamylcysteinylglycine, GSH) and the ratio of GSH to glutathione disulfide (GSSG) can serve as important indicators of oxidative stress and disease risk. Measured concentrations of GSH and GSSG vary widely between laboratories, largely due to the instability of GSH during sample handling and variables arising from different analytical methods. We have developed a simple and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for measuring whole blood GSH and GSSG that minimizes preanalytic and analytic variability, reliably eliminates interference from ion suppression, and can easily be implemented in clinical laboratories. Samples were deproteinized with sulfosalicylic acid (SSA) and derivatized with N-ethylmaleimide (NEM) in a single preparative step, and the resulting supernatants combined with stable-isotope internal standards (GSH-(13)C, (15)N-NEM and GSSG-(13)C,(15)N), subjected to chromatographic separation using a Hypercarb column, and analyzed by MS/MS in the positive-ion mode. Results showed excellent linearity for both GSH and GSSG over the ranges of physiologic normal, with inter- and intra-assay CV's of 3.1-4.3% and accuracy between 95% and 101%. The lower limits of detection (LLOD) were 0.4?M for GSH and 0.1?M for GSSG and the lower limits of quantitation (LLOQ) were 1.5?M for GSH and 0.1?M for GSSG. Derivatized samples are stable for at least 3 years when stored at -80�C, and underivatized samples for at least 24h at either 4�C or room temperature. Reference intervals were determined for 59 control samples, and were (mean�SD): GSH 900�140?M; GSSG 1.17�0.43?M; GSH/GSSG 880�370.

View details for DOI 10.1016/j.jchromb.2013.04.004

View details for PubMedID 23660247
Brain uptake of Tc99m-HMPAO correlates with clinical response to the novel redox modulating agent EPI-743 in patients with mitochondrial disease MOLECULAR GENETICS AND METABOLISM Blankenberg, F. G., Kinsman, S. L., Cohen, B. H., Goris, M. L., Spicer, K. M., Perlman, S. L., Krane, E. J., Kheifets, V., Thoolen, M., Miller, G., Enns, G. M. 2012; 107 (4): 690-699
Abstract

While decreased ATP production and redox imbalance are central to mitochondrial disease pathogenesis, efforts to develop effective treatments have been hampered by the lack of imaging markers of oxidative stress. In this study we wished to determine if Tc99m-HMPAO, a SPECT imaging marker of cerebral blood flow and glutathione/protein thiol content, could be used to monitor the effect(s) of EPI-743, an oral redox modulating, para-benzoquinone based therapeutic for mitochondrial disease. We hypothesized that treatment changes in HMPAO uptake would be inversely proportional to changes in oxidative stress within the brain and directly correlate to clinical response to EPI-743 therapy. Twenty-two patients with mitochondrial disease were treated with EPI-743. Each underwent baseline and 3-month Tc99m-HMPAO SPECT scanning along with clinical/neurologic evaluations. Diseases treated were: Leigh syndrome (n=7), polymerase ? deficiency (n=5), MELAS (n=5), Friedreich ataxia (n=2), Kearns-Sayre syndrome, Pearson syndrome, and mtDNA depletion syndrome. Neuro-anatomic uptake analyses of HMPAO were performed with NeuroGam? (Segami Corp.) statistical software and clinical response was assessed by the Newcastle Paediatric Mitochondrial Disease Scale or Newcastle Mitochondrial Disease Adult Scale depending on patient age. For all 22 patients there was a significant linear correlation between the change in cerebellar uptake of HMPAO and the improvement in Newcastle score (r=0.623, **p=0.00161). The MELAS subgroup showed a significant relationship of whole brain uptake (n=5, r=0.917, *p=0.028) to improvement in Newcastle score. We conclude that Tc99m-HMPAO SPECT scanning has promise as a general marker of the oxidative state of the brain and its response to redox modulating therapies. Further studies will be needed to confirm these findings in a more homogenous study population.

View details for DOI 10.1016/j.ymgme.2012.09.023

View details for Web of Science ID 000311816200010

View details for PubMedID 23084792
Leigh syndrome caused by a novel m.4296G > A mutation in mitochondrial tRNA isoleucine MITOCHONDRION Cox, R., Platt, J., Chen, L. C., Tang, S., Wong, L., Enns, G. M. 2012; 12 (2): 258-261
Abstract

Leigh syndrome is a severe neurodegenerative disease with heterogeneous genetic etiology. We report a novel m.4296G>A variant in the mitochondrial tRNA isoleucine gene in a child with Leigh syndrome, mitochondrial proliferation, lactic acidosis, and abnormal respiratory chain enzymology. The variant is present at >75% heteroplasmy in blood and cultured fibroblasts from the proband, <5% in asymptomatic maternal relatives, and is absent in 3000 controls. It is located in the highly conserved anticodon region of tRNA(Ile) where three other pathogenic changes have been described. We conclude that there is strong evidence to classify m.4296G>A as a pathogenic mutation causing Leigh syndrome.

View details for DOI 10.1016/j.mito.2011.09.006

View details for Web of Science ID 000301906600011

View details for PubMedID 21982779
Initial experience in the treatment of inherited mitochondrial disease with EPI-743 MOLECULAR GENETICS AND METABOLISM Enns, G. M., Kinsman, S. L., Perlman, S. L., Spicer, K. M., Abdenur, J. E., Cohen, B. H., Amagata, A., Barnes, A., Kheifets, V., Shrader, W. D., Thoolen, M., Blankenberg, F., Miller, G. 2012; 105 (1): 91-102
Abstract

Inherited mitochondrial respiratory chain disorders are progressive, life-threatening conditions for which there are limited supportive treatment options and no approved drugs. Because of this unmet medical need, as well as the implication of mitochondrial dysfunction as a contributor to more common age-related and neurodegenerative disorders, mitochondrial diseases represent an important therapeutic target. Thirteen children and one adult with genetically-confirmed mitochondrial disease (polymerase ? deficiency, n=4; Leigh syndrome, n=4; MELAS, n=3; mtDNA deletion syndrome, n=2; Friedreich ataxia, n=1) at risk for progressing to end-of-life care within 90 days were treated with EPI-743, a novel para-benzoquinone therapeutic, in a subject controlled, open-label study. Serial measures of safety and efficacy were obtained that included biochemical, neurological, quality-of-life, and brain redox assessments using technetium-99m-hexamethylpropyleneamine oxime (HMPAO) single photon emission computed tomography (SPECT) radionuclide imaging. Twelve patients treated with EPI-743 have survived; one polymerase ? deficiency patient died after developing pneumonia and one patient with Surf-1 deficiency died after completion of the protocol. Of the 12 survivors, 11 demonstrated clinical improvement, with 3 showing partial relapse, and 10 of the survivors also had an improvement in quality-of-life scores at the end of the 13-week emergency treatment protocol. HMPAO SPECT scans correlated with clinical response; increased regional and whole brain HMPAO uptake was noted in the clinical responders and the one subject who did not respond clinically had decreased regional and whole brain HMPAO uptake. EPI-743 has modified disease progression in >90% of patients in this open-label study as assessed by clinical, quality-of-life, and non-invasive brain imaging parameters. Data obtained herein suggest that EPI-743 may represent a new drug for the treatment of inherited mitochondrial respiratory chain disorders. Prospective controlled trials will be undertaken to substantiate these initial promising observations. Furthermore, HMPAO SPECT imaging may be a valuable tool for the detection of central nervous system redox defects and for monitoring response to treatments directed at modulating abnormal redox.

View details for DOI 10.1016/j.ymgme.2011.10.009

View details for Web of Science ID 000299363800014

View details for PubMedID 22115768
High-quality DNA sequence capture of 524 disease candidate genes PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Shen, P., Wang, W., Krishnakumar, S., Palm, C., Chi, A., Enns, G. M., Davis, R. W., Speed, T. P., Mindrinos, M. N., Scharfe, C. 2011; 108 (16): 6549-6554
Abstract

The accurate and complete selection of candidate genomic regions from a DNA sample before sequencing is critical in molecular diagnostics. Several recently developed technologies await substantial improvements in performance, cost, and multiplex sample processing. Here we present the utility of long padlock probes (LPPs) for targeted exon capture followed by array-based sequencing. We found that on average 92% of 5,471 exons from 524 nuclear-encoded mitochondrial genes were successfully amplified from genomic DNA from 63 individuals. Only 144 exons did not amplify in any sample due to high GC content. One LPP was sufficient to capture sequences from <100-500 bp in length and only a single-tube capture reaction and one microarray was required per sample. Our approach was highly reproducible and quick (<8 h) and detected DNA variants at high accuracy (false discovery rate 1%, false negative rate 3%) on the basis of known sample SNPs and Sanger sequence verification. In a patient with clinical and biochemical presentation of ornithine transcarbamylase (OTC) deficiency, we identified copy-number differences in the OTC gene at exon-level resolution. This shows the ability of LPPs to accurately preserve a sample's genome information and provides a cost-effective strategy to identify both single nucleotide changes and structural variants in targeted resequencing.

View details for DOI 10.1073/pnas.1018981108

View details for Web of Science ID 000289680400046

View details for PubMedID 21467225
Novel Deoxyguanosine Kinase Gene Mutations and Viral Infection Predispose Apparently Healthy Children to Fulminant Liver Failure JOURNAL OF PEDIATRIC GASTROENTEROLOGY AND NUTRITION Shieh, J. T., Berquist, W. E., Zhang, Q., Chou, P., Wong, L. C., Enns, G. M. 2009; 49 (1): 130-132
View details for Web of Science ID 000267383400019

View details for PubMedID 19502998
Mapping Gene Associations in Human Mitochondria using Clinical Disease Phenotypes PLOS COMPUTATIONAL BIOLOGY Scharfe, C., Lu, H. H., Neuenburg, J. K., Allen, E. A., Li, G., Klopstock, T., Cowan, T. M., Enns, G. M., Davis, R. W. 2009; 5 (4)
Abstract

Nuclear genes encode most mitochondrial proteins, and their mutations cause diverse and debilitating clinical disorders. To date, 1,200 of these mitochondrial genes have been recorded, while no standardized catalog exists of the associated clinical phenotypes. Such a catalog would be useful to develop methods to analyze human phenotypic data, to determine genotype-phenotype relations among many genes and diseases, and to support the clinical diagnosis of mitochondrial disorders. Here we establish a clinical phenotype catalog of 174 mitochondrial disease genes and study associations of diseases and genes. Phenotypic features such as clinical signs and symptoms were manually annotated from full-text medical articles and classified based on the hierarchical MeSH ontology. This classification of phenotypic features of each gene allowed for the comparison of diseases between different genes. In turn, we were then able to measure the phenotypic associations of disease genes for which we calculated a quantitative value that is based on their shared phenotypic features. The results showed that genes sharing more similar phenotypes have a stronger tendency for functional interactions, proving the usefulness of phenotype similarity values in disease gene network analysis. We then constructed a functional network of mitochondrial genes and discovered a higher connectivity for non-disease than for disease genes, and a tendency of disease genes to interact with each other. Utilizing these differences, we propose 168 candidate genes that resemble the characteristic interaction patterns of mitochondrial disease genes. Through their network associations, the candidates are further prioritized for the study of specific disorders such as optic neuropathies and Parkinson disease. Most mitochondrial disease phenotypes involve several clinical categories including neurologic, metabolic, and gastrointestinal disorders, which might indicate the effects of gene defects within the mitochondrial system. The accompanying knowledgebase (http://www.mitophenome.org/) supports the study of clinical diseases and associated genes.

View details for DOI 10.1371/journal.pcbi.1000374

View details for Web of Science ID 000266214200033

View details for PubMedID 19390613
Inherited disorders affecting mitochondrial function are associated with glutathione deficiency and hypocitrullinemia PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Atkuri, K. R., Cowan, T. M., Kwan, T., Ng, A., Herzenberg, L. A., Herzenberg, L. A., Enns, G. M. 2009; 106 (10): 3941-3945
Abstract

Disorders affecting mitochondria, including those that directly affect the respiratory chain function or result from abnormalities in branched amino acid metabolism (organic acidemias), have been shown to be associated with impaired redox balance. Almost all of the evidence underlying this conclusion has been obtained from studies on patient biopsies or animal models. Since the glutathione (iGSH) system provides the main protection against oxidative damage, we hypothesized that untreated oxidative stress in individuals with mitochondrial dysfunction would result in chronic iGSH deficiency. We confirm this hypothesis here in studies using high-dimensional flow cytometry (Hi-D FACS) and biochemical analysis of freshly obtained blood samples from patients with mitochondrial disorders or organic acidemias. T lymphocyte subsets, monocytes and neutrophils from organic acidemia and mitochondrial patients who were not on antioxidant supplements showed low iGSH levels, whereas similar subjects on antioxidant supplements showed normal iGSH. Measures of iROS levels in blood were insufficient to reveal the chronic oxidative stress in untreated patients. Patients with organic acidemias showed elevated plasma protein carbonyls, while plasma samples from all patients tested showed hypocitrullinemia. These findings indicate that measurements of iGSH in leukocytes may be a particularly useful biomarker to detect redox imbalance in mitochondrial disorders and organic acidemias, thus providing a relatively non-invasive means to monitor disease status and response to therapies. Furthermore, studies here suggest that antioxidant therapy may be useful for relieving the chronic oxidative stress that otherwise occurs in patients with mitochondrial dysfunction.

View details for DOI 10.1073/pnas.0813409106

View details for Web of Science ID 000264036900054

View details for PubMedID 19223582
Survival after treatment with phenylacetate and benzoate for urea-cycle disorders NEW ENGLAND JOURNAL OF MEDICINE Enns, G. M., Berry, S. A., Berry, G. T., Rhead, W. J., Brusilow, S. W., Hamosh, A. 2007; 356 (22): 2282-2292
Abstract

The combination of intravenous sodium phenylacetate and sodium benzoate has been shown to lower plasma ammonium levels and improve survival in small cohorts of patients with historically lethal urea-cycle enzyme defects.We report the results of a 25-year, open-label, uncontrolled study of sodium phenylacetate and sodium benzoate therapy (Ammonul, Ucyclyd Pharma) in 299 patients with urea-cycle disorders in whom there were 1181 episodes of acute hyperammonemia.Overall survival was 84% (250 of 299 patients). Ninety-six percent of the patients survived episodes of hyperammonemia (1132 of 1181 episodes). Patients over 30 days of age were more likely than neonates to survive an episode (98% vs. 73%, P<0.001). Patients 12 or more years of age (93 patients), who had 437 episodes, were more likely than all younger patients to survive (99%, P<0.001). Eighty-one percent of patients who were comatose at admission survived. Patients less than 30 days of age with a peak ammonium level above 1000 micromol per liter (1804 microg per deciliter) were least likely to survive a hyperammonemic episode (38%, P<0.001). Dialysis was also used in 56 neonates during 60% of episodes and in 80 patients 30 days of age or older during 7% of episodes.Prompt recognition of a urea-cycle disorder and treatment with both sodium phenylacetate and sodium benzoate, in conjunction with other therapies, such as intravenous arginine hydrochloride and the provision of adequate calories to prevent catabolism, effectively lower plasma ammonium levels and result in survival in the majority of patients. Hemodialysis may also be needed to control hyperammonemia, especially in neonates and older patients who do not have a response to intravenous sodium phenylacetate and sodium benzoate.

View details for Web of Science ID 000246816500007

View details for PubMedID 17538087
Molecular-clinical correlations in a family with variable tissue mitochondrial DNA T8993G mutant load MOLECULAR GENETICS AND METABOLISM Enns, G. M., Bai, R., Beck, A. E., Wong, L. 2006; 88 (4): 364-371
Abstract

Unlike many pathogenic mitochondrial DNA mutations, the T8993G mutation associated with Leigh syndrome (LS) and neurogenic muscle weakness, ataxia, retinitis pigmentosa (NARP) typically shows little variation in mutant load between different tissue types. We describe the molecular and clinical findings in a family with variable disease severity and tissue T8993G mutant loads. Real-time ARMS qPCR testing showed that two brothers with features of NARP and LS had high mutant loads (>90%) in all tissues tested, similar to previously reported cases. Their sister, who has mild speech delay but attends normal school, was found to have a relatively high mutant load (mean 93%) in tissues derived from endoderm (buccal mucosa) and mesoderm (blood and skin fibroblasts). However, in tissue derived from ectoderm (hair bulbs), she carried a considerably lower proportion of mutant mtDNA. Because both surface ectoderm, which gives rise to outer epithelia and hair, and neuroectoderm, which gives rise to the central nervous system, are derived from ectoderm, it is tempting to speculate that the mutant load detected in the oligosymptomatic sister's hair bulbs is a reflection of the brain mutant load. We conclude that significant variation in tissue mutant load may occur in at least some individuals that harbor the T8993G mutation. This adds additional complexity to genetic counseling and prenatal diagnosis in such instances. Given the shared embryonic origin of hair bulbs and brain, we recommend performing hair bulb mtDNA analysis in asymptomatic or oligosymptomatic individuals that have high blood mutant loads in order to understand better the genotype-phenotype correlations related to the T8993G mutation.

View details for DOI 10.1016/j.ymgme.2006.02.001

View details for Web of Science ID 000240029700010

View details for PubMedID 16546428
Relationship of primary mitochondrial respiratory chain dysfunction to fiber type abnormalities in skeletal muscle CLINICAL GENETICS Enns, G. M., Hoppel, C. L., DeArmond, S. J., Schelley, S., Bass, N., Weisiger, K., Horoupian, D., Packman, S. 2005; 68 (4): 337-348
Abstract

Variation in the size and relative proportion of type 1 and type 2 muscle fibers can occur in a number of conditions, including structural myopathies, neuropathies, and various syndromes. In most cases, the pathogenesis of such fiber type changes is unknown and the etiology is heterogeneous. Skeletal muscle mitochondrial respiratory chain analysis was performed in 10 children aged 3 weeks to 5 years with abnormalities in muscle fiber type, size, and proportion. Five children were classified as having definite, four as probable, and one as possible mitochondrial disease. Type 1 fiber predominance was the most common histological finding (six of 10). On light microscopy, four cases had subtle concomitants of a mitochondriopathy, including mildly increased glycogen, lipid, and/or succinate dehydrogenase staining, and one case had more prominent evidence of underlying mitochondrial disease with marked subsarcolemmal staining. Most cases (nine of 10) had abnormal mitochondrial morphology on electron microscopy. All were found to have mitochondrial electron transport chain (ETC) abnormalities and met diagnostic criteria for mitochondrial disease. We did not ascertain any patients who had isolated fiber type abnormalities and normal respiratory chain analysis during the period of study. We conclude that mitochondrial ETC disorders may represent an etiology of at least a subset of muscle fiber type abnormalities. To establish an etiologic diagnosis and to determine the frequency of such changes in mitochondrial disease, we suggest analysis of ETC function in individuals with fiber type changes in skeletal muscle, even in the absence of light histological features suggestive of mitochondrial disorders.

View details for DOI 10.1111/j.1399-0004.2005.00499.x

View details for Web of Science ID 000231621900008

View details for PubMedID 16143021
The contribution of mitochondria to common disorders MOLECULAR GENETICS AND METABOLISM Enns, G. M. 2003; 80 (1-2): 11-26
Abstract

Mitochondrial dysfunction secondary to mitochondrial and nuclear DNA mutations has been associated with energy deficiency in multiple organ systems and a variety of severe, often fatal, clinical syndromes. Although the production of energy is indeed the primary function of mitochondria, attention has also been directed toward their role producing reactive oxygen and nitrogen species and the subsequent widespread deleterious effects of these intermediates. The generation of toxic reactive intermediates has been implicated in a number of relatively common disorders, including neurodegenerative diseases, diabetes, and cancer. Understanding the role mitochondrial dysfunction plays in the pathogenesis of common disorders has provided unique insights into a number of diseases and offers hope for potential new therapies.

View details for DOI 10.1016/j.ymgme.2003.08.009

View details for Web of Science ID 000186304600002

View details for PubMedID 14567954
Mitochondrial respiratory chain complex I deficiency with clinical and biochemical features of long-chain 3-hydroxyacyl-coenzyme A dehydrogenase deficiency JOURNAL OF PEDIATRICS Enns, G. M., Bennett, M. J., Hoppel, C. L., Goodman, S. I., Weisiger, K., Ohnstad, C., Golabi, M., Packman, S. 2000; 136 (2): 251-254
Abstract

The mitochondrial respiratory chain and the fatty acid oxidation cycle are theoretically interdependent on each other for normal function. We describe a patient with complex I deficiency who had clinical and biochemical features of long-chain 3-hydroxyacyl-coenzyme A dehydrogenase deficiency including liver failure, cardiomyopathy, and consistent urine organic acid pattern. Patients with features of either a respiratory chain or fatty acid oxidation disorder should have the defect characterized biochemically because of the implications with respect to potential therapy and genetic counseling.

View details for Web of Science ID 000085289400026

View details for PubMedID 10657835
Liver transplantation for urea cycle disorders in pediatric patients: A single-center experience PEDIATRIC TRANSPLANTATION Kim, I. K., Niemi, A., Krueger, C., Bonham, C. A., Concepcion, W., Cowan, T. M., Enns, G. M., Esquivel, C. O. 2013; 17 (2): 158-167
Abstract

LT has emerged as a surgical treatment for UCDs. We hypothesize that LT can be safely and broadly utilized in the pediatric population to effectively prevent hyperammonemic crises and potentially improve neurocognitive outcomes. To determine the long-term outcomes of LT for UCDs, charts of children with UCD who underwent LT were retrospectively reviewed at an academic institution between July 2001 and May 2012. A total of 23 patients with UCD underwent LT at a mean age of 3.4 yr. Fifteen (65%) patients received a whole-liver graft, seven patients (30%) received a reduced-size graft, and one patient received a living donor graft. Mean five-yr patient survival was 100%, and allograft survival was 96%. Mean peak blood ammonia (NH(3) ) at presentation was 772 ?mol/L (median 500, range 178-2969, normal <30-50). After transplantation, there were no episodes of hyperammonemia. Eleven patients were diagnosed with some degree of developmental delay before transplantation, which remained stable or improved after transplantation. Patients without developmental delay before transplantation maintained their cognitive abilities at long-term follow-up. LT was associated with the eradication of hyperammonemia, removal of dietary restrictions, and potentially improved neurocognitive development. Long-term follow-up is underway to evaluate whether LT at an early age (<1 yr) will attain improved neurodevelopmental outcomes.

View details for DOI 10.1111/petr.12041

View details for Web of Science ID 000315467000017

View details for PubMedID 23347504
Atypical Amyoplasia Congenita in an Infant With Leigh Syndrome: A Mitochondrial Cause of Severe Contractures? AMERICAN JOURNAL OF MEDICAL GENETICS PART A Wilnai, Y., Seaver, L. H., Enns, G. M. 2012; 158A (9): 2353-2357
Abstract

Amyoplasia congenita is a distinct form of arthrogryposis with characteristic features including internally rotated and adducted shoulders, extended elbows, flexion, and ulnar deviation of the wrists, and adducted thumbs. Fetal hypokinesia, secondary to a variety of genetic conditions, neuromuscular disorders, and environmental agents, is associated with contractures. In order to increase our understanding of the phenotypic spectrum associated with SURF 1 deficiency, a common cause of mitochondrial respiratory chain complex IV deficiency and Leigh syndrome, we describe a now 6-year-old boy who presented in the neonatal period with amyoplasia congenita. His development was normal until age 10.5 months, at which time he developed severe hypotonia and choreoathetosis following an episode of viral gastroenteritis. Following the onset of neurological symptoms, he gradually developed severe kyphosis and lower limb contractures. Blood and cerebrospinal fluid lactate levels were elevated and head imaging showed characteristic features of Leigh syndrome. He was found to harbor two pathogenic heterozygous mutations in the SURF 1 gene. In this case, mitochondrial dysfunction and the resultant energy deficiency may have played a role in causing abnormal neuronal development during embryogenesis, causing arthrogryposis. A variety of mitochondrial respiratory chain complex deficiencies have been associated with contractures of varying severity. Therefore, mitochondrial disorders should be considered in the differential diagnosis of neonatal arthrogryposis, especially if other characteristic findings such as lactic acidemia or basal ganglia abnormalities are present.

View details for DOI 10.1002/ajmg.a.35533

View details for Web of Science ID 000310068700041

View details for PubMedID 22887355
Propionic acidemia: To liver transplant or not to liver transplant? PEDIATRIC TRANSPLANTATION Chapman, K. A., Summar, M. L., Enns, G. M. 2012; 16 (3): 209-210
View details for DOI 10.1111/j.1399-3046.2012.01649.x

View details for Web of Science ID 000302619500008

View details for PubMedID 22332632
Natural history of propionic acidemia MOLECULAR GENETICS AND METABOLISM Pena, L., Franks, J., Chapman, K. A., Gropman, A., Mew, N. A., Chakrapani, A., Island, E., MacLeod, E., Matern, D., Smith, B., Stagni, K., Sutton, V. R., Ueda, K., Urv, T., Venditti, C., Enns, G. M., Summar, M. L. 2012; 105 (1): 5-9
Abstract

Propionic acidemia is an organic acidemia that can lead to metabolic acidosis, coma and death, if not treated appropriately in the acute setting. Recent advancements in treatment have allowed patients with propionic acidemia to live beyond the neonatal period and acute presentation. The natural history of the disease is just beginning to be elucidated as individuals reach older ages. Recent studies have identified the genomic mutations in the genes PCCA and PCCB. However, as of yet no clear genotype-phenotype correlations are known. As patients age, the natural progression of propionic acidemia illuminates intellectual difficulties, increased risk for neurological complications, including stroke-like episodes, cardiac complications, and gastrointestinal difficulties, as well as a number of other complications. This article reviews the available literature for the natural history of propionic acidemia.

View details for DOI 10.1016/j.ymgme.2011.09.022

View details for Web of Science ID 000299363800003

View details for PubMedID 21986446
Length of prenatal exposure to selective serotonin reuptake inhibitor (SSRI) antidepressants: effects on neonatal adaptation and psychomotor development PSYCHOPHARMACOLOGY Casper, R. C., Gilles, A. A., Fleisher, B. E., Baran, J., Enns, G., Lazzeroni, L. C. 2011; 217 (2): 211-219
Abstract

This study evaluated the question whether length of in utero exposure to selective serotonin reuptake inhibitor (SSRI) antidepressants might affect neonatal outcome and psychomotor development in infancy.Birth outcome was determined in the offspring of 55 women with major depressive disorder who used SSRI medication for different durations during their pregnancies. At an average age of 14�months, children underwent a pediatric examination and an evaluation with the Bayley Scales of Infant Development (BSID-II).Duration of in utero exposure to SSRIs was negatively associated with total Apgar scores, specifically the activity subscale. Odds ratios for a low score (<2) on this scale were 3.8 and 6.0 at 1 and 5�min, respectively. Newborns with longer exposure were more often admitted to the Neonatal Intensive Care Unit (p?
View details for DOI 10.1007/s00213-011-2270-z

View details for Web of Science ID 000294224800006

View details for PubMedID 21499702
alpha-Tocotrienol quinone modulates oxidative stress response and the biochemistry of aging BIOORGANIC & MEDICINAL CHEMISTRY LETTERS Shrader, W. D., Amagata, A., Barnes, A., Enns, G. M., Hinman, A., Jankowski, O., Kheifets, V., Komatsuzaki, R., Lee, E., Mollard, P., Murase, K., Sadun, A. A., Thoolen, M., Wesson, K., Miller, G. 2011; 21 (12): 3693-3698
Abstract

We report that ?-tocotrienol quinone (ATQ3) is a metabolite of ?-tocotrienol, and that ATQ3 is a potent cellular protectant against oxidative stress and aging. ATQ3 is orally bioavailable, crosses the blood-brain barrier, and has demonstrated clinical response in inherited mitochondrial disease in open label studies. ATQ3 activity is dependent upon reversible 2e-redox-cycling. ATQ3 may represent a broader class of unappreciated dietary-derived phytomolecular redox motifs that digitally encode biochemical data using redox state as a means to sense and transfer information essential for cellular function.

View details for DOI 10.1016/j.bmcl.2011.04.085

View details for Web of Science ID 000291145900038

View details for PubMedID 21600768
Suboptimal outcomes in patients with PKU treated early with diet alone: Revisiting the evidence MOLECULAR GENETICS AND METABOLISM Enns, G. M., Koch, R., Brumm, V., Blakely, E., Suter, R., Jurecki, E. 2010; 101 (2-3): 99-109
Abstract

The National Institute of Health (NIH) published a Consensus Statement on the screening and management of Phenylketonuria (PKU) in 2000. The panel involved in the development of this consensus statement acknowledged the lack of data regarding the potential for more subtle suboptimal outcomes and the need for further research into treatment options. In subsequent years, the approval of new treatment options for PKU and outcome data for patients treated from the newborn period by dietary therapy alone have become available. We hypothesized that a review of the PKU literature since 2000 would provide further evidence related to neurocognitive, psychosocial, and physical outcomes that could serve as a basis for reassessment of the 2000 NIH Consensus Statement.A systematic review of literature residing in PubMed, Scopus and PsychInfo was performed in order to assess the outcome data over the last decade in diet-alone early-treated PKU patients to assess the need for new recommendations and validity of older recommendations in light of new evidence.The majority of publications (140/150) that contained primary outcome data presented at least one suboptimal outcome compared to control groups or standardized norms/reference values in at least one of the following areas: neurocognitive/psychosocial (N=60; 58 reporting suboptimal outcomes); quality of life (N=6; 4 reporting suboptimal outcomes); brain pathology (N=32; 30 reporting suboptimal outcomes); growth/nutrition (N=34; 29 reporting suboptimal outcomes); bone pathology (N=9; 9 reporting suboptimal outcomes); and/or maternal PKU (N=19; 19 reporting suboptimal outcomes).Despite the remarkable success of public health programs that have instituted newborn screening and early introduction of dietary therapy for PKU, there is a growing body of evidence that suggests that neurocognitive, psychosocial, quality of life, growth, nutrition, bone pathology and maternal PKU outcomes are suboptimal. The time may be right for revisiting the 2000 NIH Consensus Statement in order to address a number of important issues related to PKU management, including treatment advancements for metabolic control in PKU, blood Phe variability, neurocognitive and psychological assessments, routine screening measures for nutritional biomarkers, and bone pathology.

View details for DOI 10.1016/j.ymgme.2010.05.017

View details for Web of Science ID 000283609600003

View details for PubMedID 20678948
Long-term outcome following pediatric liver transplantation for metabolic disorders PEDIATRIC TRANSPLANTATION Stevenson, T., Millan, M. T., Wayman, K., Berquist, W. E., Sarwal, M., Johnston, E. E., Esquivel, C. O., Enns, G. M. 2010; 14 (2): 268-275
Abstract

In order to determine long-term outcome, including survival, growth and development, following liver transplantation in children with metabolic disorders, we retrospectively reviewed charts of 54 children with metabolic disorders evaluated from 1989-2005 for presenting symptoms, transplantation timing and indications, survival, metabolic parameters, growth, and development. Thirty-three patients underwent liver transplantation (12 received combined liver-kidney transplants) at a median age of 21 months. At a median follow-up of 3.6 yr, patient survival was 100%, and liver and kidney allograft survival was 92%, and 100%, respectively. For the group as a whole, weight Z scores improved and body mass index at follow-up was in the normal range. Two yr post-transplantation, psychomotor development improved significantly (p < 0.01), but mental skills did not; however, both indices were in the low-normal range of development. When compared to patients with biliary atresia, children with metabolic disorders showed significantly lower mental developmental scores at one and two yr post-transplantation (p < 0.05), but psychomotor developmental scores were not significantly different. We conclude that, in patients with metabolic disorders meeting indications for transplantation, liver transplantation or combined liver-kidney transplantation (for those with accompanying renal failure) is associated with excellent long-term survival, improved growth, and improved psychomotor development.

View details for DOI 10.1111/j.1399-3046.2009.01228.x

View details for Web of Science ID 000274389600020

View details for PubMedID 19671092
Pathological evidence of Wolman's disease following hematopoietic stem cell transplantation despite correction of lysosomal acid lipase activity BONE MARROW TRANSPLANTATION Gramatges, M. M., Dvorak, C. C., Regula, D. P., Enns, G. M., Weinberg, K., Agarwal, R. 2009; 44 (7): 449-450
View details for DOI 10.1038/bmt.2009.57

View details for Web of Science ID 000270933000007

View details for PubMedID 19308038
Hypoplastic Glomerulocystic Kidney Disease and Hepatoblastoma A Potential Association not Caused by Mutations in Hepatocyte Nuclear Factor 1 beta JOURNAL OF PEDIATRIC HEMATOLOGY ONCOLOGY Abdul-Rahman, O. A., Edghill, E. L., Kwan, A., Enns, G. M., Hattersley, A. T. 2009; 31 (7): 527-529
Abstract

Hypoplastic glomerulocystic kidney disease is an autosomal dominant disorder caused by mutations in hepatocyte nuclear factor-1beta. Hepatoblastoma is a sporadic occurring tumor of embryonal origin that has been associated with the several overgrowth syndromes. We report a case of concomitant hypoplastic glomerulocystic kidney disease and hepatoblastoma. Review of the literature identified 4 other patients with a similar association. We propose that hypoplastic glomerulocystic kidney disease and hepatoblastoma represent a possible association, and we excluded mutations in hepatocyte nuclear factor-1beta in our patient as causative of this putative association.

View details for Web of Science ID 000267567800014

View details for PubMedID 19564751
A novel homozygous SCO2 mutation, p.G193S, causing fatal infantile cardioencephalomyopathy CLINICAL NEUROPATHOLOGY Mobley, B. C., Enns, G. M., Wong, L., Vogel, H. 2009; 28 (2): 143-149
Abstract

Cytochrome c oxidase (COX) deficiency is a frequent cause of mitochondrial disease in infants. Mutations in the COX assembly gene SCO2 cause fatal infantile cardioencephalomyopathy. All patients reported to date with SCO2 deficiency share a common p.E140K mutation in at least 1 allele. In order to further the understanding of the genotype-phenotype spectrum associated with fatal infantile cardioencephalomyopathy, we describe a novel homozygous SCO2 mutation p.G193S in a patient with fatal infantile cardioencephalomyopathy born to consanguineous parents of Indian ancestry.

View details for Web of Science ID 000264437100011

View details for PubMedID 19353847
Successful pregnancy and cesarean delivery via noninvasive ventilation in mitochondrial myopathy JOURNAL OF PERINATOLOGY Yuan, N., El-Sayed, Y. Y., Ruoss, S. J., Riley, E., Enns, G. M., Robinson, T. E. 2009; 29 (2): 166-167
Abstract

We report a case study of a 22-year-old woman with mitochondrial thymidine kinase 2 deficiency and chronic respiratory failure due to severe neuromuscular weakness requiring noninvasive positive pressure ventilation (NIPPV) since 12 years of age. During pregnancy and cesarean delivery, she was successfully supported with NIPPV. A multidisciplinary team approach should be used in pregnant patients with these disorders with specific attention to management of pulmonary complications, selection of route of delivery, anesthesia, and analgesia.

View details for DOI 10.1038/jp.2008.178

View details for Web of Science ID 000263492700016

View details for PubMedID 19177045
Neurologic Damage and Neurocognitive Dysfunction in Urea Cycle Disorders SEMINARS IN PEDIATRIC NEUROLOGY Enns, G. M. 2008; 15 (3): 132-139
Abstract

Although the survival of patients who have urea cycle disorders has improved with the use of modalities such as alternative pathway therapy and hemodialysis, neurologic outcome is suboptimal. Patients often manifest with a variety of neurologic abnormalities, including cerebral edema, seizures, cognitive impairment, and psychiatric illness. Current hypotheses of the pathogenesis underlying brain dysfunction in these patients have focused on several lines of investigation, including the role of glutamine in causing cerebral edema, mitochondrial dysfunction leading to energy failure and the production of free radicals, and altered neurotransmitter metabolism. Advances in understanding the pathogenetic mechanisms underlying brain impairment in urea cycle disorders may lead to the development of therapies designed to interfere with the molecular cascade that ultimately leads to cerebral edema and other brain pathological findings.

View details for DOI 10.1016/j.spen.2008.05.007

View details for Web of Science ID 000207789700006

View details for PubMedID 18708004
Cell-based therapies for metabolic liver disease MOLECULAR GENETICS AND METABOLISM Enns, G. M., Millan, M. T. 2008; 95 (1-2): 3-10
Abstract

Liver transplantation is an important therapeutic option for many individuals with metabolic liver disease. Nevertheless, the invasive nature of surgery and limitations of donor organ availability have led to the search for alternatives to whole-organ transplantation. Cell-based therapies have been a particularly active area of investigation in recent years. Hepatocyte transplantations have been performed for a variety of indications, including acute liver failure, end-stage liver disease, and inborn errors of metabolism. Individuals with inborn errors of metabolism who have undergone hepatocyte transplantation have shown clinical improvement and partial correction of the underlying metabolic defect. In most cases, sustained benefits have not been observed. This may be related to inadequate cell dose, variations in the quality of hepatocyte preparations, rejection of the transplanted cells, or senescence of transplanted hepatocytes. Though initial proof of concept with hepatocyte transplantation has been demonstrated by a number of investigators, wide application of this technology has been hindered by the inability to secure a reliable and well-characterized cell source(s) for transplantation and by the challenges of sustained engraftment and expansion of transplanted cells in vivo. Cell-based therapies, including those based on stem cells or more differentiated progenitor cells, may represent the future of cell transplantation for treatment of metabolic liver disease.

View details for DOI 10.1016/j.ymgme.2008.06.001

View details for Web of Science ID 000259941000002

View details for PubMedID 18640065
Central nervous system therapy for lysosomal storage disorders NEUROSURGICAL FOCUS Enns, G. M., Huhn, S. L. 2008; 24 (3-4)
Abstract

Most lysosomal storage disorders are characterized by progressive central nervous system impairment, with or without systemic involvement. Affected individuals have an array of symptoms related to brain dysfunction, the most devastating of which is neurodegeneration following a period of normal development. The blood-brain barrier has represented a significant impediment to developing therapeutic approaches to treat brain disease, but novel approaches-including enzyme replacement, small-molecule, gene, and cell-based therapies-have given children afflicted by these conditions and those who care for them hope for the future.

View details for DOI 10.3171/FOC/2008/24/3-4/E11

View details for Web of Science ID 000256374100012

View details for PubMedID 18341388
Glutaric acidemia type I: a neurosurgical perspective JOURNAL OF NEUROSURGERY Hou, L. C., Veeravagu, A., Hsu, A. R., Enns, G. M., Huhn, S. L. 2007; 107 (2): 167-172
Abstract

Glutaric acidemia type I (GA-I) is a rare, autosomal recessive metabolic disorder that leads to severe dystonia, basal ganglia degeneration, and bilaterally enlarged anterior middle cranial fossae. The current management of this disease includes early diagnosis with newborn screening, prevention of catabolism, carnitine supplementation, and a strict dietary protein restriction. Neurosurgical evaluation and intervention may be necessary in patients with structural lesions associated with this disease. In this report, the authors present two pediatric patients with GA-I and discuss the neurosurgical aspects of this rare medical disorder.

View details for DOI 10.3171/PED-07/08/167

View details for Web of Science ID 000248626600016

View details for PubMedID 18459892
Systemic hyalinosis: A distinctive early childhood-onset disorder characterized by mutations in the anthrax toxin receptor 2 gene (ANTRX2) PEDIATRICS Shieh, J. T., Swidler, P., Martignetti, J. A., Ramirez, M. C., Balboni, I., Kaplan, J., Kennedy, J., Abdul-Rahman, O., Enns, G. M., Sandborg, C., Slavotinek, A., Hoyme, H. E. 2006; 118 (5): E1485-E1492
Abstract

We sought to further characterize the phenotype and facilitate clinical recognition of systemic hyalinosis in children who present with chronic pain and progressive contractures in early childhood.We report on 3 children who presented in infancy with symptoms and signs that initially were not recognized to be those of systemic hyalinosis. Although the children were evaluated for a variety of problems, including lysosomal storage disorders and nonaccidental trauma, all eventually underwent genetic analysis of the anthrax toxin receptor 2 gene (ANTRX2) and were diagnosed as having systemic hyalinosis.We describe the recognizable but variable clinical phenotype of systemic hyalinosis and associated mutations in ANTRX2. Affected individuals presented in early infancy with severe pain and progressive contractures. Initial diagnostic evaluations were unrevealing; however, hyperpigmented skin over bony prominences, skin nodules, and fleshy perianal masses suggested a diagnosis of systemic hyalinosis. ANTRX2 analysis confirmed the diagnosis in each case. Although 2 of the children died in infancy as a result of complications of chronic diarrhea, the third child has survived into midchildhood. These data suggest that some ANTRX2 mutations, such as that identified in the long-term survivor, may be associated with a less severe course of disease.Although some aspects of systemic hyalinosis may resemble lysosomal storage disorders, the clinical features of systemic hyalinosis are distinctive, and detection of an ANTRX2 mutation can confirm the diagnosis. Early recognition of affected individuals should allow for aggressive pain control and expectant management of the multiple associated problems, including gastrointestinal dysfunction.

View details for DOI 10.1542/peds.2006-0824

View details for Web of Science ID 000241731700101

View details for PubMedID 17043134
Genitopatellar syndrome: Expanding the phenotype and excluding mutations in LMX1B and TBX4 AMERICAN JOURNAL OF MEDICAL GENETICS PART A Abdul-Rahman, O. A., La, T. H., Kwan, A., Schlaubitz, S., Barsh, G. S., Enns, G. M., Hudgins, L. 2006; 140A (14): 1567-1572
Abstract

Genitopatellar syndrome is a newly described disorder characterized by absent/hypoplastic patellae, lower extremity contractures, urogenital anomalies, dysmorphic features, skeletal anomalies, and agenesis of the corpus callosum. More recently, cardiac anomalies and ectodermal dysplasia have been suggested as additional features of this syndrome. We report on two additional patients with genitopatellar syndrome and expand the spectrum of anomalies to include radio-ulnar synostosis. Since there exists significant overlap in the skeletal phenotype between genitopatellar syndrome and both the nail-patella and short patella syndromes, mutation screening of their causative genes, LMX1B and TBX4, was performed. Although there still does not appear to be an identifiable molecular etiology in genitopatellar syndrome, mutations in these two candidate genes have been excluded in our patients. Since both LMX1B and TBX4 are involved in a common molecular pathway, it is likely that the causative gene of genitopatellar syndrome functions within the same developmental process.

View details for DOI 10.1002/ajmg.a.31258

View details for Web of Science ID 000238799900011
Glutaryl-CoA dehydrogenase deficiency and newborn screening: Retrospective analysis of a low excretor provides further evidence that some cases may be missed MOLECULAR GENETICS AND METABOLISM Gallagher, R. C., Cowan, T. M., Goodman, S. I., Enns, G. A. 2005; 86 (3): 417-420
Abstract

Glutaryl-CoA dehydrogenase deficiency (GA-I) is associated with the onset of irreversible, disabling dystonia between 3 and 18 months of age. Presymptomatic identification and treatment can prevent the devastating disability associated with this disorder. We report the retrospective analysis of the newborn blood spot of an affected child with a low excretor phenotype. The level of glutarylcarnitine was below the newborn screening program cut-off. This suggests that some cases of GA-I may be missed by newborn screening by tandem mass spectrometry.

View details for DOI 10.1016/j.ymgme.2005.08.005

View details for Web of Science ID 000233327600012

View details for PubMedID 16183314
Management of methylmalonic acidaemia by combined liver-kidney transplantation JOURNAL OF INHERITED METABOLIC DISEASE Nagarajan, S., Enns, G. M., Millan, M. T., Winter, S., Sarwal, M. M. 2005; 28 (4): 517-524
Abstract

Methylmalonic acidaemia (MMA) is a rare autosomal recessive inborn error of metabolism that typically presents in infancy with recurrent episodes of metabolic acidosis, developmental delay and failure to thrive. The disease course is complicated by the development of chronic tubulointerstitial nephritis progressing to end-stage renal disease in adolescence. We describe two adolescents with cobalamin-nonresponsive MMA (mut0) who developed polyuria, chronic tubulointerstitial nephritis, dystonia but normal synthetic liver function. Both patients received combined liver-kidney transplantation (CLKT), preceded by a single pretransplant haemodialysis for clearance of methylmalonic acid. Post CLKT there was 95-97% reduction in serum and urine methylmalonic acid, leading to significant liberalization of dietary protein intake and a consequent increase in body mass index, muscle strength and energy. In addition, renal function normalized and clinical neurological status stabilized. We propose that CLKT be considered as a therapeutic option early in the course of cobalamin-nonresponsive MMA. Progressive tubulointerstitial nephritis with disabling polyuria is a confounder in patient management even in the absence of end-stage renal disease. Successful CLKT restores methylmalonyl-CoA mutase enzyme levels in the liver and kidney, improves clearance of methylmalonic acid with resultant dietary protein liberalization, and offers excellent graft and patient outcomes with improvement in quality of life.

View details for DOI 10.1007/s10545-005-0517-8

View details for Web of Science ID 000229220200008

View details for PubMedID 15902554
Postpartum "psychosis" in mild argininosuccinate synthetase deficiency OBSTETRICS AND GYNECOLOGY Enns, G. M., O'Brien, W. E., Kobayashi, K., Shinzawa, H., Pellegrino, J. E. 2005; 105 (5): 1244-1246
Abstract

Urea cycle disorders are relatively rare but well-established causes of postpartum coma and death. Such clinical presentations have been reported previously in ornithine transcarbamylase and carbamyl phosphate synthetase deficiencies.We describe a woman, without prior symptoms of metabolic disease, who presented with hyperammonemia and psychiatric symptoms in the postpartum period. Initial diagnoses included acute fatty liver of pregnancy and postpartum psychosis. She was later found to have argininosuccinate synthetase deficiency after further metabolic investigations. Rare heterozygous mutations in the argininosuccinate synthetase gene were identified.Urea cycle disorders may present initially with postpartum psychiatric symptoms and may represent an underrecognized cause of "postpartum psychosis." We recommend obtaining metabolic studies in women with neurologic or severe psychiatric symptoms in the postpartum period.

View details for DOI 10.1097/01.AOG.0000157769.90230.24

View details for Web of Science ID 000228842600028

View details for PubMedID 15863597
Identification of three novel mutations in the dihydropyrimidine dehydrogenase gene associated with altered pre-mRNA splicing or protein function BIOLOGICAL CHEMISTRY van Kuilenburg, A. B., Meinsma, R., Beke, E., Bobba, B., Boffi, P., Enns, G. M., Witt, D. R., Dobritzsch, D. 2005; 386 (4): 319-324
Abstract

Dihydropyrimidine dehydrogenase (DPD) is the initial and rate-limiting enzyme in the catabolism of the pyrimidine bases uracil and thymine, as well as of the widely used chemotherapeutic drug 5-fluorouracil (5FU). Analysis of the DPD gene ( DPYD ) in two patients presenting with complete DPD deficiency and the parents of an affected child showed the presence of three novel mutations, including one splice site mutation IVS11 + 1G-->T and the missense mutations 731A-->C (E244V) and 1651G-->A (A551T). The G-->T mutation in the invariant GT splice donor site flanking exon 11 (IVS11 + 1G-->T) created a cryptic splice site within exon 11. As a consequence, a 141-bp fragment encoding the aminoacid residues 400-446 of the primary sequence of the DPD protein was missing in the mature DPD mRNA. Analysis of the crystal structure of pig DPD suggested that the E244V mutation might interfere with the electron flow between NADPH and the pyrimidine binding site of DPD. The A551T point mutation might prevent binding of the prosthetic group FMN and affect folding of the DPD protein. The identification of these novel mutations in DPYD will allow the identification of patients with an increased risk of developing severe 5FU-associated toxicity.

View details for DOI 10.1515/BC.2005.038

View details for Web of Science ID 000228817700002

View details for PubMedID 15899693
Mild developmental delay in terminal chromosome 6p deletion AMERICAN JOURNAL OF MEDICAL GENETICS PART A Chen, K. M., Cherry, A. M., Hahn, J. S., Enns, G. M. 2004; 129A (2): 201-205
Abstract

Deletions involving the short arm of chromosome 6 are relatively rare. Although features of this condition are variable, common findings include developmental delay, ocular abnormalities, hearing loss, and cardiac defects. In an effort to define further the clinical variability of this condition, we report a 6-year-old female with a de novo terminal deletion of chromosome 6 at band 6p24, with mild gross motor delays and normal cognition.

View details for DOI 10.1002/ajmg.a.30127

View details for Web of Science ID 000223478900020

View details for PubMedID 15316977
Terminal 22q deletion syndrome: A newly recognized cause of speech and language disability in the autism spectrum PEDIATRICS Manning, M. A., Cassidy, S. B., Clericuzio, C., Cherry, A. M., Schwartz, S., Hudgins, L., Enns, G. M., Hoyme, H. E. 2004; 114 (2): 451-457
Abstract

Cryptic subtelomeric chromosome rearrangements account for 6% to 10% of idiopathic mental retardation. As cytogenetic and molecular techniques have become more sophisticated, the number of genetic syndromes attributed to these microdeletions has increased. To date, 64 patients have been described in the literature with a more recently recognized microdeletion syndrome, del 22q13.3. The purpose of this study is to present 11 new cases of this recently described syndrome to delineate further the phenotype and to alert the clinician to another genetic condition that should be considered in the differential diagnosis of early hypotonia, delayed speech acquisition, and autistic behavior.Eleven patients were evaluated in 3 academic institutions. Clinical features and results of cytogenetic testing were recorded and tabulated. Reasons for referral for genetic evaluation included developmental delay, severe expressive speech and language delay, and dysmorphic features.Age of presentation ranged from 5 months to 46 years. There were 10 female patients and 1 male patient. All of the patients exhibited delayed motor development, some degree of hypotonia, and severe expressive speech and language delay. Dysmorphic facial features included epicanthal folds, large cupped ears, underdeveloped philtrum, loss of cupid's bow, and full supraorbital ridges. Six patients exhibited autistic-like behaviors. Microscopically visible chromosome deletions were observed in 6 patients. In the remainder, the deletion was detected with the use of fluorescence in situ hybridization.Hypotonia and developmental delay are nonspecific findings observed in many malformation and genetic syndromes. However, in association with severe speech and language delay and autistic-like behavior, this phenotype may be a significant indication to consider the 22q13 deletion syndrome as a potential cause.

View details for Web of Science ID 000223040000017

View details for PubMedID 15286229
Head imaging abnormalities in dihydropyrimidine dehydrogenase deficiency JOURNAL OF INHERITED METABOLIC DISEASE Enns, G. M., Barkovich, A. J., van Kuilenburg, A. B., Manning, M., Sanger, T., Witt, D. R., Van Gennip, A. H. 2004; 27 (4): 513-522
Abstract

Dihydropyrimidine dehydrogenase (DPD) deficiency is a rare autosomal recessive disorder of pyrimidine metabolism. Patients may present with a wide range of neurological symptoms during the first years of life. Head imaging abnormalities have been reported only rarely and include diffuse cerebral atrophy and white-matter hyperintensity. The pathogenesis of the white-matter abnormalities is unknown, although environmental factors and altered energy metabolism may be involved. To further understanding of the spectrum of brain abnormalities associated with DPD deficiency, we report a 17-month-old girl, born to a consanguineous Pakistani couple, who had a history of encephalopathy, prolonged hypoventilation, developmental delay and failure to thrive. Head MRI showed prominent sulci and abnormal T2 prolongation in the cerebral white matter and brainstem. Thus, DPD deficiency may feature prominent brain abnormalities involving the cerebral white matter and brainstem. Anoxic stress may have contributed to the clinical presentation and brain findings in this case. In order to define more clearly the contribution of DPD deficiency to the pathogenesis of these MRI abnormalities, we recommend performing detailed analysis of urine pyrimidine metabolites in patients who have such findings.

View details for Web of Science ID 000223177000010

View details for PubMedID 15303009
Methotrexate/misoprostol embryopathy: Report of four cases resulting from failed medical abortion AMERICAN JOURNAL OF MEDICAL GENETICS PART A Adam, M. P., Manning, M. A., Beck, A. E., Kwan, A., Enns, G. M., Clericuzio, C., Hoyme, H. E. 2003; 123A (1): 72-78
Abstract

Methotrexate, a methyl derivative of aminopterin, is a folic acid antagonist and a known human teratogen; misoprostol is a synthetic prostaglandin E1 analog that causes uterine contractions. Recently, there has been resurgence in the use of methotrexate in combination with misoprostol or of methotrexate alone for the treatment of unwanted or ectopic pregnancies, respectively. This report documents the findings in four infants who were exposed prenatally to methotrexate alone or in combination with misoprostol in a failed attempt at medical abortion or treatment of ectopic pregnancy. All patients demonstrated growth deficiency, with growth parameters <10th centile, and all displayed features consistent with methotrexate and/or misoprostol embryopathy. Since an increasing number of medical abortions are being performed, it is important for physicians to recognize the associated teratogenic effects of these abortifacients. Data from the patients herein described should prompt obstetricians and other health care practitioners who prescribe these medications to counsel their patients regarding these risks, especially if the treatment regimen fails to induce an abortion.

View details for DOI 10.1002/ajmg.a.20503

View details for Web of Science ID 000186239400010

View details for PubMedID 14556250
Compensatory amplification of mtDNA in a patient with a novel deletion/duplication and high mutant load JOURNAL OF MEDICAL GENETICS Wong, L. J., Perng, C. L., Hsu, C. H., Bai, R. K., Schelley, S., Vladutiu, G. D., Vogel, H., Enns, G. M. 2003; 40 (11)
View details for Web of Science ID 000186682000022

View details for PubMedID 14627692
Congenital disorder of glycosylation Ic in patients of Indian origin MOLECULAR GENETICS AND METABOLISM Newell, J. W., Seo, N. S., Enns, G. M., McCraken, M., Mantovani, J. F., Freeze, H. H. 2003; 79 (3): 221-228
Abstract

Congenital disorder of glycosylation type Ic (CDG-Ic) is caused by mutations in ALG6, encoding an alpha 1,3-glucosyltransferase. The most frequent mutation found in this gene (C998T resulting in an A333V substitution) has until now been found only in patients of European origin. Here we describe the first occurrence of this CDG-Ic mutation in patients of Indian origin. Of three Indian patients described in this study, patient 1 was homozygous and patient 2 heterozygous for the A333V mutation. In patient 2 we also found a new mutation, IVS3+2_3insT, just 3bp away from the previously described IVS3+5G>A substitution; both mutations resulted in exon 3 skipping. We screened a panel of >350 genomic DNA samples from an ethnically diverse American population to determine the frequency of the A333V mutation. None of the samples carried this mutation, indicating the frequency of patients carrying this homozygous mutation should be <1 in 5x10(5). The discovery of the common CDG-Ic mutation A333V in an Indian population raises questions as to its ethnic origin.

View details for DOI 10.1016/S1096-7192(03)00089-1

View details for Web of Science ID 000184304300010

View details for PubMedID 12855228
Clinical and molecular features of congenital disorder of glycosylation in patients with type 1 sialotransferrin pattern and diverse ethnic origins JOURNAL OF PEDIATRICS Enns, G. M., Steiner, R. D., Buist, N., Cowan, C., Leppig, K. A., McCracken, M. F., Westphal, V., Freeze, H. H., O'Brien, J. F., Jaeken, J., Matthijs, G., Behera, S., Hudgins, L. 2002; 141 (5): 695-700
Abstract

To increase awareness of congenital disorders of glycosylation (CDG), we report the features of patients with a variety of clinical presentations ranging from mild hypotonia and strabismus to severe neurologic impairment.Nine North American patients with CDG type I and different ethnic origins were studied.All patients had transferrin isoelectric focusing studies with a type 1 sialotransferrin pattern. Molecular analysis showed the previously described R141H, V231M, and T237M PMM2 mutations in four patients as well as 3 rare mutations (DeltaC389, L104V, and IVS1 -1 G-->A) in the PMM2 gene in two Asian patients.The clinical features of these patients with diverse ethnic backgrounds confirm the variable course of CDG type I. Screening for CDG should be considered in children with relatively mild neurologic impairment, especially if they have suggestive findings such as cerebellar hypoplasia and abnormal fat distribution.

View details for DOI 10.1067/mpd.2002.128658

View details for Web of Science ID 000179182300025

View details for PubMedID 12410200
The adolescent with an inborn error of metabolism: medical issues and transition to adulthood. Adolescent medicine (Philadelphia, Pa.) Enns, G. M., Packman, W. 2002; 13 (2): 315-?
Abstract

As patients with inborn errors of metabolism survive longer, understanding of potential medical and psychiatric complications adolescence and adulthood has increased. In general, detailed therapeutic guidelines for specific metabolic disorders are not available, and medical management must be tailored to the individual patient. Close interaction between the biochemical genetics clinic staff, primary care physician, mental health professional, and other specialists is necessary to formulate an integrated care plan. The education of the patient and family is a critical function of the biochemical genetics clinic, and transition from dependence on parents or other care providers to full independence is gradual. The ultimate goal is for the patient to have the essential knowledge and motivation required to cope responsibly with dietary and medical therapeutic regimens by adolescence or early adulthood. Specific illustrative inborn errors of metabolism are discussed (aminoacidemias, urea cycle defects, organic acidemias, fatty acid oxidation defects, disorders of carbohydrate metabolism, lysosomal storage disorders) in light of potential problems encountered in adolescence and adulthood, including issues involving pregnancy and long-term medical, psychosocial, and psychiatric complications.

View details for PubMedID 11986039
Early neonatal diagnosis of long-chain 3-hydroxyacyl coenzyme A dehydrogenase and mitochondrial trifunctional protein deficiencies MOLECULAR GENETICS AND METABOLISM Hintz, S. R., Matern, D., Strauss, A., Bennett, M. J., Hoyme, H. E., Schelley, S., Kobori, J., Colby, C., Lehman, N. L., Enns, G. M. 2002; 75 (2): 120-127
Abstract

Tandem mass spectrometry (MS/MS) has been introduced in several newborn screening programs for the detection of a large number of inborn errors of metabolism, including fatty acid oxidation disorders (FAOD). Early identification and treatment of FAOD have the potential to improve outcome and may be life-saving in some cases; an estimated 5% of sudden infant deaths are attributable to undiagnosed disorders of fatty acid oxidation. We report very early neonatal presentations of long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) and mitochondrial trifunctional protein (TFP) deficiencies confirmed by molecular analysis. Both patients had cardiorespiratory collapse and hypoglycemia, without a history of maternal pregnancy complications. Retrospective MS/MS analysis of the original newborn screening blood spots revealed characteristic acylcarnitine profiles. These cases are among the earliest reported presentations of LCHAD and TFP deficiencies and further illustrate the potential of MS/MS as a valuable tool for newborn screening of FAOD. However, timely analysis and reporting of results to clinicians are essential, because these disorders can manifest in the first few days of life.

View details for DOI 10.1006/mgme.2001.3282

View details for Web of Science ID 000174355300003

View details for PubMedID 11855930
Functional analysis of novel mutations in a congenital disorder of glycosylation Ia patient with mixed Asian ancestry MOLECULAR GENETICS AND METABOLISM Westphal, V., Enns, G. M., McCracken, M. F., Freeze, H. H. 2001; 73 (1): 71-76
Abstract

Congenital disorders of glycosylation (CDG) are caused by autosomal recessive mutations in genes affecting N-glycan biosynthesis. Mutations in the PMM2 gene, which encodes the enzyme phosphomannomutase (mannose 6-phosphate <--> mannose 1-phosphate), give rise to the most common form: CDG-Ia. These patients typically present with dysmorphic features and neurological abnormalities, cerebellar hypoplasia, ataxia, hypotonia, and coagulopathy, in addition to feeding problems. However, the clinical symptoms vary greatly. The great majority of known CDG-Ia patients are of European descent where the most common mutant alleles originated. This ethnic bias can also be explained by lack of global awareness of the disorder. Here we report an Asian patient with prominent systemic features that we diagnosed with CDG-Ia resulting from two new mutations in the PMM2 gene (310C --> G resulting in L104V and an intronic mutation IVS1-1G --> A). The latter mutation seems to result in lower mRNA levels, and the L104V has been functionally analyzed in a yeast expression system together with known mutations. The Filipino and Cambodian origins of the parents show that CDG-Ia mutations occur in these ethnic groups as well as in Caucasians.

View details for Web of Science ID 000168761300009

View details for PubMedID 11350185
Clinical course and biochemistry of sialuria JOURNAL OF INHERITED METABOLIC DISEASE Enns, G. M., Seppala, R., Musci, T. J., Weisiger, K., Ferrell, L. D., Wenger, D. A., Gahl, W. A., Packman, S. 2001; 24 (3): 328-336
Abstract

Sialuria is a rare inborn error of metabolism in which excessive free sialic acid (N-acetylneuraminic acid, NeuAc) is synthesized. A defect in the feedback inhibition of UDP-N-acetylglucosamine (UDP-GlcNAc) 2-epimerase by the end-product of the sialic acid synthetic pathway, CMP-NeuAc, is the mechanism underlying this overproduction. Recent evidence suggests that sialuria is an autosomal dominant disorder. Only five patients have been documented to have such an enzymatic defect. We report a longitudinal study of one of the original sialuria patients, to age 11 years. Although he has coarse features and massive hepatomegaly, he has shown normal growth and relatively normal development. Pulmonary function testing showed minimal small airway obstruction. At 11 years, he developed intermittent abdominal pain and transient transaminase elevation above his baseline. Sialuria should be considered in the differential diagnosis of a patient with a phenotype suggestive of a mucopolysaccharidosis or oligosaccharidosis in the absence of developmental regression or prominent dysostosis multiplex. We recommend close monitoring of liver and pulmonary function in sialuria patients.

View details for Web of Science ID 000169331400002

View details for PubMedID 11486897
Molecular correlations in phenylketonuria: Mutation patterns and corresponding biochemical and clinical phenotypes in a heterogeneous California population PEDIATRIC RESEARCH Enns, G. M., Martinez, D. R., Kuzmin, A. I., Koch, R., Wakeem, C. K., Woo, S. L., Eisensmith, R. C., Packman, S. 1999; 46 (5): 594-602
Abstract

We studied 133 California phenylketonuria (PKU) patients and one obligate heterozygote to delineate the molecular basis of PKU in a population with greater ethnic diversity than in previous studies, and to determine whether a correlation exists between genotype and clinical phenotype, with the latter defined by both the diagnostic pretreatment blood phenylalanine (PHE) level and cognitive (IQ) test scores. To determine PAH genotypes, we used PCR-mediated amplification, denaturing gradient gel electrophoresis, and direct sequencing on dried whole blood samples. Where possible, mutation severity was defined according to predicted in vitro PAH enzyme activity estimated by using Cos cell expression analysis for a given mutation. We then asked whether mutation severity, as defined by such expression analysis, correlated with pretreatment PHE levels or with IQ test results. A mutation was identified in 236 (88%) of 267 mutant alleles. Seventeen new mutant alleles were found; A47E, T81P, I102T, E182G, T328D, Y343P, K371R, Y387H, A389E, E422K, IVS9nt5, IVS11nt20, delS70, del364-368/del198-220, delF299, delT323, and -1C/T. In striking contrast to a number of studies in other populations, in this study, based on predicted PAH activity, we observed no correlation between mutation severity and pretreatment PHE levels. There was also no correlation between genotype and IQ. We conclude that in samples collected from an ethnically heterogeneous population, there is no correlation of mutation severity with either pretreatment PHE levels or IQ measurement in treated patients. We caution that genetic counseling in PKU should incorporate the notion that prognosis may not be predicted with precision based on mutation analysis in a given patient.

View details for Web of Science ID 000083247000017

View details for PubMedID 10541324
Apparent cyclophosphamide (cytoxan) embryopathy: A distinct phenotype? AMERICAN JOURNAL OF MEDICAL GENETICS Enns, G. M., Roeder, E., Chan, R. T., Catts, Z. A., Cox, V. A., Golabi, M. 1999; 86 (3): 237-241
Abstract

Cyclophosphamide (CP) is an alkylating agent widely used in treating cancer and autoimmune disease. CP is classified as a pregnancy risk factor D drug and is teratogenic in animals, but population studies have not conclusively demonstrated teratogenicity in humans. Six isolated reports of prenatally exposed infants with various congenital anomalies exist, but to date no specific phenotype has been delineated. The purpose of this report is to document a new case of in utero CP exposure with multiple congenital anomalies and to establish an apparent CP embryopathy phenotype. The mother had systemic lupus erythematosus and cyclophosphamide exposure in the first trimester. She also took nifedipine, atenolol, clonidine, prednisone, aspirin, and potassium chloride throughout pregnancy. The infant had growth retardation and multiple anomalies including microbrachycephaly, coronal craniosynostosis, hypotelorism, shallow orbits, proptosis, blepharophimosis, small, abnormal ears, unilateral preauricular pit, broad, flat nasal bridge, microstomia, high-arched palate, micrognathia, preaxial upper limb and postaxial lower limb defects consisting of hypoplastic thumbs, and bilateral absence of the 4th and 5th toes. Chromosomes were apparently normal. The reported cases of in utero exposure to cyclosposphamide shared the following manifestations with our patient: growth deficiency, developmental delay, craniosynostosis, blepharophimosis, flat nasal bridge, abnormal ears, and distal limb defects including hypoplastic thumbs and oligodactyly. We conclude that (a) cyclophosphamide is a human teratogen, (b) a distinct phenotype exists, and (c) the safety of CP in pregnancy is in serious question.

View details for Web of Science ID 000082714300008

View details for PubMedID 10482872
Progressive neurological deterioration and MRI changes in cblC methylmalonic acidaemia treated with hydroxocobalamin JOURNAL OF INHERITED METABOLIC DISEASE Enns, G. M., Barkovich, A. J., Rosenblatt, D. S., Fredrick, D. R., Weisiger, K., Ohnstad, C., Packman, S. 1999; 22 (5): 599-607
Abstract

Cobalamin C (cblC) defects result in decreased activity of both methylmalonyl-CoA mutase and N5-methyltetrahydrofolate:homocysteine methyltransferase (methionine synthase), with subsequent methylmalonic acid-uria and homocystinuria. Patients typically show failure to thrive, developmental delay and megaloblastic anaemia. Vitamin B12 therapy has been beneficial in some cases. We report a now 4-year-old Hispanic girl with cblC disease documented by complementation analysis, with progressive neurological deterioration and worsening head MRI changes while on intramuscular hydroxocobalamin begun at age 3 weeks. Oral carnitine and folic acid were added at age 1 year. Blood levels of methylmalonic acid were reduced to treatment ranges. In the absence of acute metabolic crises, she developed microcephaly, progressive hypotonia and decreased interactiveness. Funduscopic examination was normal at age 13 months. At age 19 months, she developed nystagmus, and darkly pigmented fundi and sclerotic retinal vessels were observed on examination. Her neonatal head MRI was normal. By age 1 year, the MRI showed diffuse white-matter loss with secondary third and lateral ventricle enlargement, a thin corpus callosum, and normal basal ganglia. At age 15 months, progression of the white-matter loss, as well as hyperintense globi pallidi, were present. Interval progression of both grey- and white-matter loss was seen at age 27 months. We therefore caution that progressive neurological deterioration and head MRI abnormalities may still occur in cblC disease, despite early initiation of hydroxocobalamin therapy and improvement in toxic metabolite concentrations in physiological fluids.

View details for Web of Science ID 000080750600004

View details for PubMedID 10399092
Severe congenital anomalies requiring transplantation in children with Kabuki syndrome AMERICAN JOURNAL OF MEDICAL GENETICS Ewart-Toland, A., Enns, G. M., Cox, V. A., Mohan, G. C., Rosenthal, P., Golabi, M. 1998; 80 (4): 362-367
Abstract

Kabuki syndrome (KS) is a rare multiple malformation disorder characterized by developmental delay, distinct facial anomalies, congenital heart defects, limb and skeletal anomalies, and short stature. Renal anomalies have been reported in a few cases of KS, but to our knowledge, hepatic anomalies have not. Here, we document two cases of KS requiring liver or kidney transplantation: one with severe hepatic and renal anomalies and one with severe renal anomalies. Both cases had the characteristic facial appearance of children with KS, postnatal growth deficiency, and developmental delay. At birth, case 1 presented with hypoglycemia, ileal perforation, right hydroureter, and hydronephrosis. The patient subsequently developed hyperbilirubinemia, hepatic abscess, and cholangitis. At age 8 months, he underwent a liver transplant. Hepatic pathology diagnosed neonatal sclerosing cholangitis. Case 2 presented with renal failure at age 6 years. Renal ultrasound study showed markedly dysplastic kidneys requiring transplantation. In addition to characteristic findings of KS, she had coronal synostosis and was shown to have immune deficiency and an autoimmune disorder manifesting as Hashimoto thyroiditis and vitiligo. We conclude: 1) severe hepatic and renal anomalies leading to organ failure can occur in KS; 2) patients with neonatal sclerosing cholangitis should be examined closely for features of KS; 3) coronal synostosis may occur in KS; and 4) immune deficiency and autoimmune disorder can be associated with KS.

View details for Web of Science ID 000077302900011

View details for PubMedID 9856564
Congenital diaphragmatic defects and associated syndromes, malformations, and chromosome anomalies: A retrospective study of 60 patients and literature review AMERICAN JOURNAL OF MEDICAL GENETICS Enns, G. M., Cox, V. A., Goldstein, R. B., Gibbs, D. L., Harrison, M. R., Golabi, M. 1998; 79 (3): 215-225
Abstract

Congenital diaphragmatic defects (CDDs) may occur in malformation syndromes of varied causes. Syndromic cases of CDDs due to chromosomal defects, autosomal recessive, autosomal dominant, or X-linked inheritance have been described. In order to determine the frequency and nature of syndromes, malformations, and chromosome abnormalities associated with CDDs, we reviewed the records of all patients with CDDs evaluated over a 4-year period. During the 4-year interval, a total of 60 patients was evaluated. Of these, 29 had a therapeutic or spontaneous abortion, and 31 received postnatal care. On prenatal ultrasonography, 20 of 60 (33%) of patients with CDDs had additional anomalies. Additional anomalies, besides CDDs, were present in 15 of 31 (48%) of liveborn patients on newborn evaluation. In total, 16 patients with multiple anomalies were evaluated. Of these, 12 of 16 (75%) had additional abnormalities detected by prenatal ultrasonography. The 4 of 16 (25%) without additional anomalies on prenatal sonography had multiple anomalies found neonatally, lethal multiple pterygium syndrome being diagnosed in one case. Prenatal chromosome analysis was performed in 7 of 16 patients, and all had postnatal karyotypes. All initial karyotypes were normal. Tetrasomy 12p was documented on postnatal fibroblast analysis in one case who had percutaneous umbilical blood sampling (PUBS). Syndromes diagnosed postnatally in 7 of 16 patients (44%) include: Fryns syndrome (2), Simpson-Golabi-Behmel syndrome (2), tetrasomy 12p (1), Brachmann-de Lange syndrome (1), and lethal multiple pterygium syndrome (1). We were unable to make a specific diagnosis in 9 of 16 patients (56%) with multiple malformations. In patients with CDDs, a normal prenatal karyotype, especially if obtained by PUBS, and absence of other detected abnormalities by fetal ultrasonography, do not exclude the presence of other major anomalies, including chromosome abnormalities and severe multiple malformation syndromes.

View details for Web of Science ID 000076065100013

View details for PubMedID 9788565

Conference Proceedings

Long-term follow-up of a patient with early onset CBLG disease Niemi, A. K., Cusmano-Ozog, K., Rosenblatt, D. S., Enns, G. M. ACADEMIC PRESS INC ELSEVIER SCIENCE. 2011: 306-307
View details for Web of Science ID 000287773800117
Nitrogen sparing therapy revisited 2009 Enns, G. M. ACADEMIC PRESS INC ELSEVIER SCIENCE. 2010: S65-S71
Abstract

Although the protocol that most experienced metabolic centers in the United States follow for treating acute hyperammonemia in urea cycle disorders (UCDs) is similar to that proposed by Brusilow and Batshaw in the early 1980s, over the years a steady evolution has taken place. Continued developments in intensive care, surgical and hemodialysis techniques, fluid and electrolyte management, cardiovascular support, and emergency transport have contributed to improved management of acute hyperammonemia. Compared to historical data, survival of urea cycle patients has also improved following treatment with alternative pathway therapy, in addition to appropriate supportive care, including the provision of adequate calories to prevent catabolism and promote anabolism and hemodialysis if needed. However, overall neurological outcomes have been suboptimal. There are currently a number of exciting prospective new therapies on the horizon, including novel medications or cell-based treatments. Nevertheless, the therapeutic expertise that is currently in place at centers specializing in management of metabolic emergencies already has the potential to improve survival and outcome in these children significantly. The early identification of UCD patients so that transport to a metabolic treatment center may be carried out without delay continues to be a major area of focus and challenge.

View details for DOI 10.1016/j.ymgme.2010.02.007

View details for Web of Science ID 000276985100011

View details for PubMedID 20202877

Gregory Enns

Associate Professor of Pediatrics (Genetics) at the Lucile Packard Children's Hospital

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