Abstract: 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). Conclusion 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.