SLC6A4 and major depressive disorder: Similarly, Sanabrais-Jiménez et al. [36] investigated SLC6A4 (5HTTLPR/rs25531), DRD2 (rs6275), COMT (rs4680), and MAOA uVNTR polymorphisms’ influences on suicide attempts in Mexican adolescents diagnosed with MDD (DSM-IV major depression).