MTRR and Dravet syndrome: Methylenetetrahydrofolate reductase (MTHFR), Methionine Synthase Reductase (MTRR), Methionine Synthase (MTR) genes are key regulators of folate metabolism pathways and polymorphic variants of these genes have been reported as maternal risk factors for DS birth in many ethnic populations, though results are contradictory21–23.