Seven case-control cohorts were combined to identify 44 loci associated with major depression. The first cohort included 29 case-control samples of European descent where lifetime diagnosis of major depressive disorder was ascertained using structured clinical interviews (DSM-V, ICD-9, ICD-10), clinician-administered checklists, or review of medical records. Six additional cohorts of European ancestry, including the Hyde et al study (23andMe, Inc), determined case status using other methods including national or hospital treatment registers, self-reported symptoms or treatment by a medical professional, or direct interviews. Analyses comparing the original cohort with the additional ones indicated strong correlation of common genetic variants and little evidence of heterogeneity. 130,664 cases and 330,470 controls from these cohorts were included in the current analyses.
