Identification of candidate genes for familial early-onset essential tremor

Xinmin Liu, Nora Hernandez, Sergey Kisselev, Aris Floratos, Ashley Sawle, Iuliana Ionita-Laza, Ruth Ottman, Elan D. Louis, Lorraine N. Clark

Research output: Contribution to journalArticle

19 Scopus citations

Abstract

Essential tremor (ET) is one of the most common causes of tremor in humans. Despite its high heritability and prevalence, few susceptibility genes for ET have been identified. To identify ET genes, whole-exome sequencing was performed in 37 early-onset ET families with an autosomal-dominant inheritance pattern. We identified candidate genes for follow-up functional studies in five ET families. In two independent families, we identified variants predicted to affect function in the nitric oxide (NO) synthase 3 gene (NOS3) that cosegregated with disease. NOS3 is highly expressed in the central nervous system (including cerebellum), neurons and endothelial cells, and is one of three enzymes that converts L-arginine to the neurotransmitter NO. In one family, a heterozygous variant, c.46G4A (p.(Gly16Ser)), in NOS3, was identified in three affected ET cases and was absent in an unaffected family member; and in a second family, a heterozygous variant, c.164C4T (p.(Pro55Leu)), was identified in three affected ET cases (dizygotic twins and their mother). Both variants result in amino-acid substitutions of highly conserved aminoacid residues that are predicted to be deleterious and damaging by in silico analysis. In three independent families, variants predicted to affect function were also identified in other genes, including KCNS2 (KV9.2), HAPLN4 (BRAL2) and USP46. These genes are highly expressed in the cerebellum and Purkinje cells, and influence function of the gamma-amino butyric acid (GABA)-ergic system. This is in concordance with recent evidence that the pathophysiological process in ET involves cerebellar dysfunction and possibly cerebellar degeneration with a reduction in Purkinje cells, and a decrease in GABA-ergic tone.

Original languageEnglish (US)
Pages (from-to)1009-1015
Number of pages7
JournalEuropean Journal of Human Genetics
Volume24
Issue number7
DOIs
StatePublished - Jul 1 2016
Externally publishedYes

ASJC Scopus subject areas

  • Genetics
  • Genetics(clinical)

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    Liu, X., Hernandez, N., Kisselev, S., Floratos, A., Sawle, A., Ionita-Laza, I., Ottman, R., Louis, E. D., & Clark, L. N. (2016). Identification of candidate genes for familial early-onset essential tremor. European Journal of Human Genetics, 24(7), 1009-1015. https://doi.org/10.1038/ejhg.2015.228