Not all MTHFR gene variations have a notable association with the MTHFR enzyme activity. There are two important MTHFR SNPs, rs1801133 and rs1801131, which have earned the spotlight. These variations are known to affect approximately 1 in 4 people significantly and about 1 in 2 people mildly. There are multiple studies on these MTHFR gene variations and MTHFR enzyme activity
