Two genes were significantly associated with MDD at the genome-wide significance level: the PALMD gene on chromosome 1 (Z-score = 4.725, P = 1.15 × 10−6) and the PIACIN1 gene on chromosome 16 (Z-score = 4.627, P = 1.85 × 10−6)(Figure 5). Here, PALMD is linked to major depressive disorder.