Three Genetic Variants That Modify Huntington’s Disease Age of Onset Are Located; Two on Chromosome 15 and One on Chromosome 8; GWAS of Over 4,000 HD Patients Provides New Clues to Possible Disease Intervention

A study that took a novel approach to investigating factors affecting the emergence of symptoms of Huntington’s disease (HD) has identified at least two genome sites that house variants that can hasten or delay symptom onset. In its report in the July 30, 2015 issue of Cell, the multi-institutional research team describes how genome-wide association analysis of samples from more than 4,000 HD patients found that particular variants on two chromosomes were more common in individuals who first exhibited HD-associated movement disorders either earlier or later than would otherwise have been expected. The article is titled “Identification of Genetic Factors that Modify Clinical Onset of Huntington’s Disease.” “Most previous research into ways of delaying the onset of HD symptoms have focused on studying the mutant protein in cells or in animal models, but the relevance of abnormalities in those systems to what actually happens in patients remains a huge assumption,” says James Gusella, Ph.D., Director of the Center for Human Genetic Research (CHGR) at Massachusetts General Hospital (MGH), and corresponding author of the Cell paper. “Our approach does not rely on model systems, but on DNA samples and clinical data from human patients. In essence, we are analyzing the results of a ‘clinical trial’ conducted by nature, a trial in which naturally occurring variations in genes other than the HD gene intervened to influence the course of the disease. Now it is up to scientists to figure out how those genetic interventions work and to build on them to develop effective therapies based on understanding how these processes operate in humans.” Dr.
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