Folate

Folate (Vitamin B9) is involved in the metabolism of nucleic acids (the building blocks of RNA and DNA and is important for the synthesis of red blood cells. It is also critical in methylation.

Its active form, tetrahydrofolate (THF) is involved in pyrimidine nucleotide synthesis and is important in pregnancy and infancy.

Deficiency
Deficiency of either folate or Vitamin B12 can lead to megaloblastic anema

MTHFR mutation
The 5,10-methylenetetrahydrofolate reductase (MTHFR) gene influences the metabolism of folic acid, the synthetic form found in many supplements and fortified foods.