MTRR and migraine disorder: In the Phase 2 trial we replicated the treatment options in an independent and larger sample of MA sufferers and examined the genotypic effects of both the MTHFR and MTRR (5-Methyltetrahydrofolate-Homocysteine Methyltransferase Reductase) gene on the reduction of homocysteine and migraine disability in response to vitamin supplementation [14].