Association of C677T gene polymorphisms of methylenetetrahydrofolate reductase and plasma homocysteine level with hyperlipidemia

Objective: To study the association of methylenetetrahydrofolate reductase (MTHFR) gene C677T mutation and plasma homocysteine (Hcy) levels with hyperlipidemia.

Methods: Blood samples were collected from 1591 adults for detecting MTHFR gene C677T polymorphism with polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), plasma Hcy levels with enzymatic cycling method, and blood lipid levels as well. The patients were divided according to the lipid levels into hyperlipidemia group (n=694) and healthy control group (n=897) and the differences in MTHFR gene C677T polymorphisms and plasma Hcy levels were compared.

Results: The hyperlipidemia group and healthy control group showed no significant differences in CC, CT, or TT genotype frequencies or C and T allele frequencies of MTHFR C677T gene, and had comparable plasma Hcy levels (P>0.05). Patients with 3 different MTHFR C677T genotypes had significant differences in plasma Hcy levels (P<0.01) but not in blood lipid levels (P>0.05). Pairwise comparison indicated a significantly higher plasma Hcy level in TT genotype than in CC and CT genotypes (P<0.01), and the latter two genotypes showed no significant difference (P>0.05).

Conclusions: MTHFR C677T polymorphisms and plasma Hcy levels are closely related but neither of them is associated with hyperlipidemia. The TT genotype is associated with a significantly higher plasma Hcy level than CC and CT genotypes.