In conclusion, we carried out a GWAS of recurrent early-onset MDD in 1,020 cases and 1,636 controls of European ancestry. No genome-wide significant evidence for association was observed. Of the strongest signals reported in the GenRED sample, the meta-analysis in the companion article17 provides the greatest support for association to SNPs in SP4. Much larger samples may be needed to determine whether there are true associations between MDD and common SNPs.
