Recent genetic and biochemical research studies have focused on the biological effects of SNP variation in enzymes that require a vitamin as a cofactor for function. An interesting example is the A222V variant in methylene-tetrahydrofolate reductase (MTHFR)1. MTHFR is an enzyme of enormous clinical interest, as it is a member of the folate / homocysteine pathway, which has been implicated in neural tube defects as well as a potential risk factor for stroke and coronary heart disease. The biological effects in people with either one or two copies of mutant form of MTHFR can be reversed by elevated folate in their diets; the folate-remedial variant of MTHFR occurs in 3 out of 10 people of all ethnicities.
This well studied example with MTHFR highlights two interesting characteristics of vitamin-responsive genes: (1) Genetic variation effecting biological function occur commonly in the general population, and (2) Enzyme systems with vitamin cofactors are involved in pathways associated with medical conditions involving serious disease.
1. Yamada K, et al., (2001) Proc Natl Acad Sci USA 98:14853-14858
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