Bio

Clinical Focus


  • Movement Disorders
  • Ataxia
  • Dystonia
  • Parkinsonian Disorders
  • Huntington Disease
  • Neurology

Academic Appointments


Professional Education


  • Medical Education:University of Washington School of Medicine (2003) WA
  • Board Certification: Neurology, American Board of Psychiatry and Neurology (2009)
  • Fellowship:University of Toronto (2010) ONCanada
  • Fellowship, Toronto Western Hospital, Movement Disorders (2009)
  • Residency:University of Washington (2007) WA
  • Internship:University of Washington School of Medicine (2004) WA

Research & Scholarship

Current Research and Scholarly Interests


Genetics of movement disorders such as dystonia, parkinsonian disorders, and ataxia.
• Identifying multiplex families to find novel genes
• Characterizing clinical phenotypes of genetic diseases

Publications

Journal Articles


  • Parallel PARKing: Parkinson's Genes Function in Common Pathway NEURON Chuang, R. S., Gitler, A. D. 2013; 77 (3): 377-379

    Abstract

    Parkinson's disease (PD) is associated with diverse genetic and environmental susceptibilities. Functional connections between PD genes have remained elusive. In this issue of Neuron, MacLeod et al. (2013) link three PD susceptibility genes, LRRK2, PARK16, and VSP35, to a common cellular pathway and show how these deficits contribute to dysfunction.

    View details for DOI 10.1016/j.neuron.2013.01.014

    View details for Web of Science ID 000317030800001

    View details for PubMedID 23395366

  • Phenotype in parkinsonian and nonparkinsonian LRRK2 G2019S mutation carriers NEUROLOGY Marras, C., Schuele, B., Munhoz, R. P., Rogaeva, E., Langston, J. W., Kasten, M., Meaney, C., Klein, C., Wadia, P. M., Lim, S., Chuang, R. I., Zadikof, C., Steeves, T., Prakash, K. M., de Bie, R. M., Adeli, G., Thomsen, T., Johansen, K. K., Teive, H. A., Asante, A., Reginold, W., Lang, A. E. 2011; 77 (4): 325-333

    Abstract

    Using a family study design, we describe the motor and nonmotor phenotype in probands with LRRK2 G2019S mutations and family members and compare these individuals to patients with idiopathic Parkinson disease (iPD) and unrelated controls.Probands with G2019S mutations and their first-degree relatives, subjects with iPD, and unrelated control subjects were identified from 4 movement disorders centers. All underwent neurologic examinations and tests of olfaction, color vision, anxiety, and depression inventories.Tremor was more often a presenting feature among 25 individuals with LRRK2-associated PD than among 84 individuals with iPD. Subjects with LRRK2-PD had better olfactory identification compared with subjects with iPD, higher Beck Depression Inventory scores, and higher error scores on Farnsworth-Munsell 100-Hue test of color discrimination. Postural or action tremor was more common among 29 nonmanifesting mutation carriers compared with 53 noncarriers within the families. Nonparkinsonian family members had higher Unified Parkinson's Disease Rating Scale motor scores, more constipation, and worse color discrimination than controls, regardless of mutation status.Although tremor is a more common presenting feature of LRRK2-PD than iPD and some nonmotor features differed in degree, the phenotype is largely overlapping. Postural or action tremor may represent an early sign. Longitudinal evaluation of a large sample of nonmanifesting carriers will be required to describe any premotor phenotype that may allow early diagnosis.

    View details for Web of Science ID 000293123300010

    View details for PubMedID 21753163

  • Rasagiline-Induced Spontaneous Ejaculation MOVEMENT DISORDERS Chuang, R. S., Lang, A. E. 2009; 24 (14): 2160-2161

    View details for DOI 10.1002/mds.22746

    View details for Web of Science ID 000271696400020

    View details for PubMedID 19735087

  • Serotonin and Parkinson's disease: On movement, mood, and madness. Movement Disorders Fox S, Chuang R, Brotchie J 2009; 24 (9): 1255-1266
  • Myoclonus-dystonia: Significance of large SGCE deletions HUMAN MUTATION Grunewald, A., Djarmati, A., Lohmann-Hedrich, K., Farrell, K., Zeller, J. A., Allert, N., Papengut, F., Petersen, B., Fung, V., Sue, C. M., O'Sullivan, D., Mahant, N., Kupsch, A., Chuang, R. S., Wiegers, K., Pawlack, H., Hagenah, J., Ozelius, L. J., Stephani, U., Schuit, R., Lang, A. E., Volkmann, J., Munchau, A., Klein, C. 2008; 29 (2): 331-332

    Abstract

    Myoclonus-dystonia (M-D) is an autosomal-dominant movement disorder caused by mutations in SGCE. We investigated the frequency and type of SGCE mutations with emphasis on gene dosage alterations and explored the associated phenotypes. We tested 35 M-D index patients by multiplex ligation-dependent probe amplification (MLPA) and genomic sequencing. Mutations were found in 26% (9/35) of the cases, all but three with definite M-D. Two heterozygous deletions of the entire SGCE gene and flanking DNA and a heterozygous deletion of exon 2 only were detected, accounting for 33% (3/9) of the mutations found. Both large deletions contained COL1A2 and were additionally associated with joint problems. Further, we discovered one novel small deletion (c.771_772delAT, p.C258X) and four recurrent point mutations (c.289C>T, p.R97X; c.304C>T, p.R102X; c.709C>T, p.R237X; c.1114C>T, p.R372X). A Medline search identified 22 articles on SGCE mutational screening. Sixty-four unrelated M-D patients were described with 41 different mutations. No genotype-phenotype association was found, except in patients with deletions encompassing additional genes. In conclusion, a rigorous clinical preselection of patients and careful accounting for non-motor signs should precede mutational tests. Gene dosage studies should be included in routine SGCE genetic testing.

    View details for DOI 10.1002/humu.9521

    View details for Web of Science ID 000253033000020

    View details for PubMedID 18205193

  • Parkinson's disease--opportunities for novel therapeutics to reduce the problems of levodopa therapy Prog Brain Res Fox S, Chuang R, Brotchie J 2008; 172: 479-494
  • Inhibition of T-type voltage-gated calcium channels by a new scorpion toxin NATURE NEUROSCIENCE Chuang, R. S., Jaffe, H., Cribbs, L., Perez-Reyes, E., Swartz, K. J. 1998; 1 (8): 668-674

    Abstract

    The biophysical properties of T-type voltage-gated calcium channels are well suited to pacemaking and to supporting calcium flux near the resting membrane potential in both excitable and non-excitable cells. We have identified a new scorpion toxin (kurtoxin) that binds to the alpha 1G T-type calcium channel with high affinity and inhibits the channel by modifying voltage-dependent gating. This toxin distinguishes between alpha 1G T-type calcium channels and other types of voltage-gated calcium channels, including alpha 1A, alpha 1B, alpha 1C and alpha 1E. Like the other alpha-scorpion toxins to which it is related, kurtoxin also interacts with voltage-gated sodium channels and slows their inactivation. Kurtoxin will facilitate characterization of the subunit composition of T-type calcium channels and help determine their involvement in electrical and biochemical signaling.

    View details for Web of Science ID 000077323400010

    View details for PubMedID 10196582

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