Academic Appointments

Professional Education

  • BA, University of California, Berkeley, Molecular Cell Biology (1996)
  • MS, University of California, Irvine, Genetic Counseling (2000)


2016-17 Courses

Stanford Advisees


All Publications

  • Clinical Delineation of the PACS1-Related Syndrome-Report on 19 Patients AMERICAN JOURNAL OF MEDICAL GENETICS PART A Schuurs-Hoeijmakers, J. H., Landsverk, M. L., Foulds, N., Kukolich, M. K., Gavrilova, R. H., Greville-Heygate, S., Hanson-Kahn, A., Bernstein, J. A., Glass, J., Chitayat, D., Burrow, T. A., Husami, A., Collins, K., Wusik, K., Van der Aa, N., Kooy, F., Brown, K. T., Gadzicki, D., Kini, U., Alvarez, S., Fernandez-Jaen, A., McGehee, F., Selby, K., Tarailo-Graovac, M., Van Allen, M., van Karnebeek, C. D., Stavropoulos, D. J., Marshall, C. R., Merico, D., Gregor, A., Zweier, C., Hopkin, R. J., Chu, Y. W., Chung, B. H., de Vries, B. B., Devriendt, K., Hurles, M. E., Brunner, H. G. 2016; 170 (3): 670-675


    We report on 19 individuals with a recurrent de novo c.607C>T mutation in PACS1. This specific mutation gives rise to a recognizable intellectual disability syndrome. There is a distinctive facial appearance (19/19), characterized by full and arched eyebrows, hypertelorism with downslanting palpebral fissures, long eye lashes, ptosis, low set and simple ears, bulbous nasal tip, wide mouth with downturned corners and a thin upper lip with an unusual "wavy" profile, flat philtrum, and diastema of the teeth. Intellectual disability, ranging from mild to moderate, was present in all. Hypotonia is common in infancy (8/19). Seizures are frequent (12/19) and respond well to anticonvulsive medication. Structural malformations are common, including heart (10/19), brain (12/16), eye (10/19), kidney (3/19), and cryptorchidism (6/12 males). Feeding dysfunction is presenting in infancy with failure to thrive (5/19), gastroesophageal reflux (6/19), and gastrostomy tube placement (4/19). There is persistence of oral motor dysfunction. We provide suggestions for clinical work-up and management and hope that the present study will facilitate clinical recognition of further cases. © 2016 Wiley Periodicals, Inc.

    View details for DOI 10.1002/ajmg.a.37476

    View details for Web of Science ID 000373098900018

    View details for PubMedID 26842493

  • Cold-aggravated pain in humans caused by a hyperactive NaV1.9 channel mutant. Nature communications Leipold, E., Hanson-Kahn, A., Frick, M., Gong, P., Bernstein, J. A., Voigt, M., Katona, I., Oliver Goral, R., Altmüller, J., Nürnberg, P., Weis, J., Hübner, C. A., Heinemann, S. H., Kurth, I. 2015; 6: 10049-?


    Gain-of-function mutations in the human SCN11A-encoded voltage-gated Na(+) channel NaV1.9 cause severe pain disorders ranging from neuropathic pain to congenital pain insensitivity. However, the entire spectrum of the NaV1.9 diseases has yet to be defined. Applying whole-exome sequencing we here identify a missense change (p.V1184A) in NaV1.9, which leads to cold-aggravated peripheral pain in humans. Electrophysiological analysis reveals that p.V1184A shifts the voltage dependence of channel opening to hyperpolarized potentials thereby conferring gain-of-function characteristics to NaV1.9. Mutated channels diminish the resting membrane potential of mouse primary sensory neurons and cause cold-resistant hyperexcitability of nociceptors, suggesting a mechanistic basis for the temperature dependence of the pain phenotype. On the basis of direct comparison of the mutations linked to either cold-aggravated pain or pain insensitivity, we propose a model in which the physiological consequence of a mutation, that is, augmented versus absent pain, is critically dependent on the type of NaV1.9 hyperactivity.

    View details for DOI 10.1038/ncomms10049

    View details for PubMedID 26645915

  • Underutilization of Genetics Services for Autism: The Importance of Parental Awareness and Provider Recommendation JOURNAL OF GENETIC COUNSELING Vande Wydeven, K., Kwan, A., Hardan, A. Y., Bernstein, J. A. 2012; 21 (6): 803-813


    Reasons for the underutilization of genetics services by families of children with autism spectrum disorders (ASD) are not well understood. We report the identification of factors associated with this underuse. Survey-based study of parents and/or guardians of children with ASD. One hundred fifty-five families completed the questionnaire. Thirty-one of 155 (20%) children had seen a genetics professional. Forty-nine of 154 (32%) children had undergone genetic testing. Parents whose child saw a genetics professional were more likely to 1) Have a primary provider refer for or suggest a genetics evaluation 2) Have asked for a referral, and/or 3) Know another person with a genetic cause of ASD. amilies of children with ASD who have not received genetics services are less aware of their availability and utility. They are also less likely to have their provider recommend a clinical genetics evaluation. Efforts should be taken to increase awareness of both health providers and parents regarding the usefulness of genetics services for ASD.

    View details for DOI 10.1007/s10897-012-9494-x

    View details for Web of Science ID 000311509200011

    View details for PubMedID 22415587

  • Marked variability in the radiographic features of cartilage-hair hypoplasia: Case report and review of the literature AMERICAN JOURNAL OF MEDICAL GENETICS PART A Kwan, A., Manning, M. A., Zollars, L. K., Hoyme, H. E. 2012; 158A (11): 2911-2916


    Cartilage-hair hypoplasia (CHH) is a rare recessive metaphyseal chondrodysplasia characterized by severe short stature, ectodermal dysplasia, anemia in childhood, immune deficiency, susceptibility to malignancy, and normal intelligence. Short, thick long bones, metaphyseal flaring and irregularities, and globular epiphyses at the knees and ankles are the typical radiographic findings. The diagnosis is primarily made on the basis of clinical features, although mutations in the RMRP gene have recently been described in affected individuals, facilitating confirmation of the clinical diagnosis in atypical patients. We present a patient with two RMRP mutations whose stature and ectodermal features supported the diagnosis of CHH, but whose radiographic findings and other extraskeletal findings did not. We propose that the most consistent and reliable features of CHH are short stature of prenatal onset and ectodermal dysplasia, and suggest that the diagnosis of CHH be considered and mutation analysis pursued even when typical radiographic findings are absent.

    View details for DOI 10.1002/ajmg.a.35604

    View details for Web of Science ID 000310071700041

    View details for PubMedID 22987807

  • Report of Two Patients and Further Characterization of Interstitial 9p13 Deletion-A Rare But Recurrent Microdeletion Syndrome? AMERICAN JOURNAL OF MEDICAL GENETICS PART A Niemi, A., Kwan, A., Hudgins, L., Cherry, A. M., Manning, M. A. 2012; 158A (9): 2328-2335


    To date, an interstitial deletion of 9p13 has been described only two times in the medical literature. These reports were based on routine chromosomal analysis. We report on two additional patients with an interstitial deletion of 9p13 further defined on array CGH who share clinical features with the other two patients previously described. Our first patient is a 16-year-old girl with a 5.9?Mb deletion at 9p13.3-9p13.1, initially detected on routine karyotype analysis and further characterized on array CGH. Our second patient is a 7½-year-old boy with a 4.8?Mb deletion also at 9p13.3-9p13.1. Patients with 9p13 deletion appear to have mild to moderate developmental delay, social and interactive personality, behavior issues such as attention deficit-hyperactivity disorder, short stature, prominent antihelices, hypoplastic nails, and precocious/early puberty. Our 16-year-old patient is the oldest patient described thus far. This report further characterizes this condition and helps to delineate the long-term prognosis in these patients.

    View details for DOI 10.1002/ajmg.a.35536

    View details for Web of Science ID 000310068700037

    View details for PubMedID 22887577

  • What Is Your Diagnosis? The Diagnosis: Trichorhinophalangeal Syndrome Type I CUTIS Snyder, J. R., Berk, D. R., Kwan, A., Hudgins, L., Bruckner, A. L. 2012; 89 (2): 56-?

    View details for Web of Science ID 000300545400002

    View details for PubMedID 22474724

  • Ectopia Lentis as the Presenting and Primary Feature in Marfan Syndrome AMERICAN JOURNAL OF MEDICAL GENETICS PART A Zadeh, N., Bernstein, J. A., Niemi, A. K., Dugan, S., Kwan, A., Liang, D., Hyland, J. C., Hoyme, H. E., Hudgins, L., Manning, M. A. 2011; 155A (11): 2661-2668


    Marfan syndrome (MFS) is a multisystem connective tissue disorder with primary involvement of the ocular, cardiovascular, and skeletal systems. We report on eight patients, all presenting initially with bilateral ectopia lentis (EL) during early childhood. These individuals did not have systemic manifestations of MFS, and did not fulfill the revised Ghent diagnostic criteria. However, all patients had demonstratable, disease-causing missense mutations in the FBN1 gene. Based on molecular results, cardiovascular imaging was recommended and led to the identification of mild aortic root changes in seven of the eight patients. The remaining patient had mitral valve prolapse with a normal appearing thoracic aorta. The findings presented in this paper validate the necessity of FBN1 gene testing in all individuals presenting with isolated EL. As we observed, these individuals are at increased risk of cardiovascular complications. Furthermore, we also noted that the majority of our patient cohort's mutations occurred in the 5' portion of the FBN1 gene, and were found to affect highly conserved cysteine residues, which may indicate a possible genotype-phenotype correlation. We conclude that in patients with isolated features of EL, FBN1 mutation analysis is necessary to aid in providing prompt diagnosis, and to identify patients at risk for potentially life-threatening complications. Additionally, knowledge of the type and location of an FBN1 mutation may be useful in providing further clinical correlation regarding phenotypic progression and appropriate medical management.

    View details for DOI 10.1002/ajmg.a.34245

    View details for Web of Science ID 000297199700009

    View details for PubMedID 21932315

  • Clues to an Early Diagnosis of Kallmann Syndrome AMERICAN JOURNAL OF MEDICAL GENETICS PART A Kaplan, J. D., Bernstein, J. A., Kwan, A., Hudgins, L. 2010; 152A (11): 2796-2801


    Kallmann syndrome (KS) is defined by the association of idiopathic hypogonadotropic hypogonadism and anosmia/hyposmia. Diagnosis is frequently delayed, however, because hypogonadotropic hypogonadism is usually not apparent until puberty and individuals with anosmia/hyposmia are often unaware of this sensory deficit. Mutations in at least six genes have been associated with KS; however, the sensitivity of molecular testing is only about 30% and, therefore, the diagnosis is largely based on clinical findings. We describe the findings in six individuals with KS, which demonstrate the utility of associated anomalies in making this diagnosis. Analysis of our case series and literature review suggests the consideration of KS for males with microphallus and/or cryptorchidism and for any patient with hearing loss, renal agenesis, and/or synkinesis. Conversely, patients with features of KS should have an audiology evaluation and a renal ultrasound.

    View details for DOI 10.1002/ajmg.a.33442

    View details for Web of Science ID 000284005700019

    View details for PubMedID 20949504

  • Brachydactyly A-1 mutations restricted to the central region of the N-terminal active fragment of Indian Hedgehog EUROPEAN JOURNAL OF HUMAN GENETICS Byrnes, A. M., Racacho, L., Grimsey, A., Hudgins, L., Kwan, A. C., Sangalli, M., Kidd, A., Yaron, Y., Lau, Y., Nikkel, S. M., Bulman, D. E. 2009; 17 (9): 1112-1120


    Mutations in the gene Indian Hedgehog (IHH) that cause Brachydactyly A-1 (BDA1) have been restricted to a specific region of the N-terminal active fragment of Indian Hedgehog involving codons 95, 100, 131, and 154. We describe two novel mutations in codons 128 and 130, not previously implicated in BDA1. Furthermore, we identified an independent mutation at codon 131 and we also describe a New Zealand family, which carries the 'Farabee' founder mutation and haplotype. All of the BDA1 mutations occur in a restricted area of the N-terminal active fragment of the IHH and are in contrast to those mutations causing an autosomal recessive acrocapitofemoral dysplasia, whose mutations are located at the distal N- and C-terminal regions of IHH-N and are physically separated from the BDA1-causing mutations. The identification of multiple independent mutations in codons 95, 100, and now in 131, implicate a discrete function for this region of the protein. Finally, we present a clinical review of all reported and confirmed cases of BDA1, highlighting features of the disorder, which add to the spectrum of the IHH mutations.

    View details for DOI 10.1038/ejhg.2009.18

    View details for Web of Science ID 000269449900004

    View details for PubMedID 19277064

  • 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


    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

  • Clinical Utility of Array Comparative Genomic Hybridization: Uncovering Tumor Susceptibility in Individuals with Developmental Delay JOURNAL OF PEDIATRICS Adam, M. P., Justice, A. N., Schelley, S., Kwan, A., Hudgins, L., Martin, C. L. 2009; 154 (1): 143-146


    Microarray-based comparative genomic hybridization can determine genome-wide copy number alterations at the kilobase level. We highlight the clinical utility of microarray-based comparative genomic hybridization in determining tumor susceptibility in 3 patients with dysmorphic features and developmental delay, likely decreasing both morbidity and mortality in these patients.

    View details for DOI 10.1016/j.jpeds.2008.07.045

    View details for Web of Science ID 000262272500031

    View details for PubMedID 19187739

  • Unilateral aquagenic wrinkling of the palms associated with aspirin intake ARCHIVES OF DERMATOLOGY Khuu, P. T., Duncan, K. O., Kwan, A., Hoyme, H. E., Bruckner, A. L. 2006; 142 (12): 1661-1662

    View details for Web of Science ID 000242803400033

    View details for PubMedID 17179009

  • 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; 140 (14): 1567-1572


    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 PubMedID 16761293

  • 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


    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

  • Sequence and analysis of chromosome 1 of the plant Arabidopsis thaliana NATURE Theologis, A., Ecker, J. R., Palm, C. J., Federspiel, N. A., Kaul, S., White, O., Alonso, J., Altafi, H., Araujo, R., Bowman, C. L., Brooks, S. Y., Buehler, E., Chan, A., Chao, Q. M., Chen, H. M., Cheuk, R. F., Chin, C. W., Chung, M. K., Conn, L., Conway, A. B., Conway, A. R., Creasy, T. H., Dewar, K., Dunn, P., Etgu, P., Feldblyum, T. V., Feng, J. D., Fong, B., Fujii, C. Y., Gill, J. E., Goldsmith, A. D., Haas, B., Hansen, N. F., Hughes, B., Huizar, L., Hunter, J. L., Jenkins, J., Johnson-Hopson, C., Khan, S., Khaykin, E., Kim, C. J., Koo, H. L., Kremenetskaia, I., Kurtz, D. B., Kwan, A., Lam, B., Langin-Hooper, S., Lee, A., Lee, J. M., Lenz, C. A., Li, J. H., Li, Y. P., Lin, X. Y., Liu, S. X., Liu, Z. A., Luros, J. S., Maiti, R., Marziali, A., Militscher, J., MIRANDA, M., Nguyen, M., Nierman, W. C., Osborne, B. I., Pai, G., Peterson, J., Pham, P. K., Rizzo, M., Rooney, T., Rowley, D., Sakano, H., Salzberg, S. L., Schwartz, J. R., Shinn, P., Southwick, A. M., Sun, H., Tallon, L. J., Tambunga, G., Toriumi, M. J., Town, C. D., Utterback, T., Van Aken, S., Vaysberg, M., Vysotskaia, V. S., Walker, M., Wu, D. Y., Yu, G. X., Fraser, C. M., Venter, J. C., Davis, R. W. 2000; 408 (6814): 816-820


    The genome of the flowering plant Arabidopsis thaliana has five chromosomes. Here we report the sequence of the largest, chromosome 1, in two contigs of around 14.2 and 14.6 megabases. The contigs extend from the telomeres to the centromeric borders, regions rich in transposons, retrotransposons and repetitive elements such as the 180-base-pair repeat. The chromosome represents 25% of the genome and contains about 6,850 open reading frames, 236 transfer RNAs (tRNAs) and 12 small nuclear RNAs. There are two clusters of tRNA genes at different places on the chromosome. One consists of 27 tRNA(Pro) genes and the other contains 27 tandem repeats of tRNA(Tyr)-tRNA(Tyr)-tRNA(Ser) genes. Chromosome 1 contains about 300 gene families with clustered duplications. There are also many repeat elements, representing 8% of the sequence.

    View details for Web of Science ID 000165831300038

    View details for PubMedID 11130712