MTR and Dravet syndrome: The present meta-analysis consists of an evaluation of MTR c.2756A>G (rs1805087), MTRR c.66A>G (rs1801394), TC2 c.776C>G (rs1801198), CβS c.844ins68, and MTHFD1 c.1958G>A (rs2236225) polymorphisms and maternal risk for DS.