To increase the power of the study to detect significant association, we also included 1 984 unrelated controls (genotyped with Illumina’s HumanOMNI1-QUAD bead chip) from a previously published study on Parkinson’s disease (dbGaP accession number phs000196.v2.p1) 24, 25. Individuals with a self-reported or diagnosed neuropsychiatric disorder at the time of enrollment were excluded from the present study.
