For depressive symptoms, the most interesting genes—MGAT5 (mannosyl (alpha-1,6-)-glycoprotein beta-1,6-N-acetyl-glucosaminyltransferase) and NCKAP5/NAP5 (Nck-associated protein 5)—were located 300–400kb 5’ to a SNP replicated in the German and NTR cohorts. Mgat5 mouse knockouts exhibit lower depression-like behaviours especially under stress-induced conditions (Soleimani et al. 2008); and a GWAS of bipolar disorder reported NAP5 as a gene/region worthy of further study (Smith et al. 2009). Our associated SNP is some distance from these genes and, and in the CEU population, is located in a recombination hotspot, making it less likely that this variant relates to these genes. Additionally, gene-based testing did not show significant associations of these two genes with depression symptoms.
