heterozygous mthfr mutation c677tmthfr mutations c677t and a1298chomozygous mthfr mutation c677tmthfr gene mutation c677tmthfr c677t treatmentheterozygous mthfr c677tmthfr c677t homozygousmthfr c677t polymorphismmthfr c677t and a1298cgene mthfr c677tc677t mutation heterozygousc677t mutation homozygous
