MTHFR and cardiovascular disorder: In a meta-analysis, Ioannidis et al. [2] assessed 43 validated gene-disease associations across 697 study populations of various ethnicities and found that frequencies of polymorphisms in seven cardiovascular disease genes – APOE, ACE, ITGB3, MTHFR, F2, PON1, and PON2 – varied significantly between ethnicities (I2 ≥ 75%; I2 being a measure of the extent to which the heterogeneity is not due to chance) [2].