Meta-analyses of MTHFR studies show a statistically significantly higher risk of ischaemic heart disease in TT homozygotes (the variant with higher homocysteine)[2]–[4] than in CC homozygotes (the variant with lower homocysteine), but meta-analyses of randomised trials of homocysteine lowering have indicated that folic acid, which lowers homocysteine does not reduce the risk of ischaemic heart disease.[3], [5]. The gene discussed is MTHFR; the disease is heart disorder.