The etiology of depression – a worldwide leading cause of disability (1) – is not well understood. As indicated by family, twin and adoption studies, genetic factors mediate part of vulnerability to major depressive disorder (MDD) with a modest heritability of around 40% (2). However, we understand little of the specific genetic architecture of MDD. Multiple genome-wide association studies (GWAS) for MDD have been published (3–10). The largest MDD GWAS was the mega-analysis by the MDD Working Group of the Psychiatric Genomics Consortium (PGC). In that study, over 9,000 MDD cases and 9,500 controls were analyzed but no association with MDD reached genome wide significance (7). Recently, CONVERGE (China, Oxford and VCU Experimental Research on Genetic Epidemiology) consortium identified two genome-wide significant associations in 5,303 Chinese women with severe and recurrent MDD (near the SIRT1 gene, P=2.53×10−10 and in an intron of the LHPP gene, P=6.45×10−12) (11). A GWAS of depressive symptoms (heritability 23%–29%) (12, 13) in the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) consortium in approximately 50,000 people from the general population found no genome-wide
