This product is for the individual who is heterozygous or homozygous for the C677T or A1298C and is under methylating (has little or no COMT and MAO) and needs more methyl groups. As you can see by the ingredient list, this product contains methylcobalamin to support MTR and MTRR and TMG (Trimethylglycine) to support BHMT. This product contains both folinic acid and (6S)-5Methylfolate (Quatrefolic). It supports both the A1298C (which may need folinic acid) and the C677T (which needs methyl folate). Even if the indvividual doesn’t have the A1298C, other variants may impede the folinic acid being used in the BH4 (neurotransmitter) cycle, so folinic may also be needed in this situation as well.