Summary statistics from the combined discovery and replication phases of a GWAS meta-analysis of PD were used,2 including 8 055 803 genotyped and imputed variants in up to 26 035 patients with PD and 403 190 controls of European ancestry. For the purposes of this study, all alleles were aligned on the forward strand, and all effect sizes and allele frequencies were converted with respect to the nonreference allele in build GRCh37. All genes overlapping the region 1 Mb upstream or downstream of a single-nucleotide variation (SNV) with an association with PD of P ≤ 5 × 10−8 were selected for the initial analysis. The analysis was then extended to include all genes in the genome, to identify candidate genes in loci that have not reached genome-wide significance in the PD GWAS but where the collective evidence with expression data suggests a colocalized signal.
