MTHFR and erectile dysfunction: Various genes, including MTHFR [20], NOS1 [21], CYP17A1 [19], APOC3, APOB, LDLR, and LPL [22], as well as CLDN5, COL7A1, LDHA, MAP2K2, RETSAT, SEMA3A, TAGLN, and TBC1D1 [23], have been linked to erectile dysfunction.