Two common non-synonymous coding region polymorphisms (677C>T and 1298A>C) in the MTHFR gene were shown to confer reduced enzyme activity in in vitro assays leading to a decreased pool of methyl-THF and the MTHFR variant 677C>T was associated with an increased risk of hyperhomocysteinemia, particularly in folate-deficient states [1-4]. Here, MTHFR is linked to hyperhomocysteinemia.