The four genetic missense variations 677C>T in MTHFR (rs1801133), 66A>G in MTRR (rs1801394), 776C>G in TCN2 (rs1801198), and 716 G>A in BHMT (rs3733890) have influence on protein function (Table 1), and have been reported to be associated with cleft lip. The gene discussed is MTHFR; the disease is cleft lip.