Two independent studies report that common variants at five genes are risk factors for sporadic Parkinson's disease. These studies, published online this week in Nature Genetics, are the largest genome-wide association studies to date for Parkinson's disease and add to our understanding of the common genetic variants that increase risk of Parkinson's in the general population.
Parkinson's disease (PD) is a neurodegenerative disease that affects 1-2% of people above the age of 65 and is characterized by tremors, sluggish movement, muscle stiffness, and difficulty with balance. Although there are medical treatments available that may improve symptoms, there are no treatments that can slow down or halt the progression of PD.
Tatsushi Toda and colleagues analyzed 2000 Japanese patients and found strong associations with risk of PD to the genes PARK16, BST1, SNCA and LRRK2. In the second study, Andrew Singleton and colleagues analyzed the genomes of about 5000 patients of European ancestry and detected strong associations of PD risk to variants within the genes SNCA and MAPT. Both teams compared their data with each other and suggested that variants at PARK16, SNCA and LRRK2 confer a risk of PD in both the Japanese and European populations, while risk variants at BST1 and MAPT are population-specific.
Mutations in SNCA, LRRK2 and MAPT have previously been linked to rare, dominant forms of parkinsonism or dementia with parkinsonian features, indicating that the same genes involved in rare forms of parkinsonism also contribute to the complex genetic basis of typical PD.