NNMT and folate deficiency: It is noteworthy, however, that in a Japanese study, there was no difference in plasma Hcy concentrations between the AA, AG, and GG genotypes of NNMT; however, the GG genotype of NNMT was associated with elevated plasma Hcy only when it coexisted with other confounding factors, such as age, folate deficiency, and/or polymorphisms of the C677T gene in MTHFR (Zhang et al. 2007).