MAD1L1 and major depressive disorder: Additionally, a study comparing monozygotic twins discordant for MDD reported affected twins to have greater variance in methylation in MAD1L1 than their unaffected co-twins108, supporting our observation of association between depression phenotype and DNA methylation levels of MAD1L1. Genetic polymorphism in SLC29A2 showed suggestive association in candidate-gene studies (p-value < 0.05) with depression and depression with fatigue phenotypes in men109, as well with childhood trauma score within MDD cases110.