SYN2 and major depressive disorder: One example showed hypomethylation of synapsins (SYN2) linked to depression.56 In contrast, a study found that patients with MDD had increased methylation in the TESC gene, negatively correlated with the right parahippocampal cingulum integrity.57 These studies suggest that the association between methylation changes and MDD is diverse, with no common effects throughout the genome or specific genomic locations.