TAA repeat variation in the GRIK2 gene does not influence age at onset in Huntington's disease
Ji-Hyun Lee ; Jong-Min Leea ; Madaline B. Harrison ; Diane Lucente ; Samuel Frank ; Tetsuo Ashizawa ; Randi Jones ; Marina Frontali ; Andrea Novelletto ; Elizabeth McCusker ; Herminia D. Rosas ; Steven M. Hersch ; Marie-Helene Saint-Hilaire ; Ronald J. Trent ; Oksana Suchowersky ; Carmen Ayuson ; Estrella Gomez-Tortosa ; Cinzia Gellera ; Ferdinando Squitieri ; Russell L. Margolis ; Christopher A. Ross ; Martha Nance ; Patrick J. Morrison ; Michael R. Hayden ; Audrey E. Hendricks ; Tiffany Hadzi ; Shotaro Kishikawa ; Jayalakshmi S. Mysore ; Tammy Gillis ; Eliana Marisa Ramos
Biochemical and Biophysical Research Communications, Vol.424(3) : 404~408, 2012
Biochemical and Biophysical Research Communications
Huntington's disease is a neurodegenerative disorder caused by an expanded CAG trinucleotide repeat whose length is the major determinant of age at onset but remaining variation appears to be due in part to the effect of genetic modifiers. GRIK2, which encodes GluR6, a mediator of excitatory neurotransmission in the brain, has been suggested in several studies to be a modifier gene based upon a 3' untranslated region TAA trinucleotide repeat polymorphism. Prior to investing in detailed studies of the functional impact of this polymorphism, we sought to confirm its effect on age at onset in a much larger dataset than in previous investigations. We genotyped the HD CAG repeat and the GRIK2 TAA repeat in DNA samples from 2,911 Huntington's disease subjects with known age at onset, and tested for a potential modifier effect of GRIK2 using a variety of statistical approaches. Unlike previous reports, we detected no evidence of an influence of the GRIK2 TAA repeat polymorphism on age at motor onset. Similarly, the GRIK2 polymorphism did not show significant modifier effect on psychiatric and cognitive age at onset in HD. Comprehensive analytical methods applied to a much larger sample than in previous studies do not support a role for GRIK2 as a genetic modifier of age at onset of clinical symptoms in Huntington's disease.