Background: Methylenetetrahydrofolate reductase (MTHFR) is involved in the formation of methyl donors, which contribute to DNA methylation. DNA methylation is an essential epigenetic feature playing a critical role in gene regulation and cellular differentiation. In addition, MTHFR activity affects plasma homocysteine levels. A functional polymorphism in the MTHFR gene (677C>T, rs1801133) leading to reduced enzyme activity has been associated with chronic plaque psoriasis in a Chinese population. This finding, however, has not yet been either confirmed or refuted in other populations. The purpose of the present study was to investigate a hypothesized association between the MTHFR 677C>T polymorphism and the presence of chronic plaque psoriasis in a Caucasian population.
Methods: Genotypes for the MTHFR 677C>T polymorphism were determined in 310 patients and 247 control subjects. In a subgroup of 33 patients and 33 sex- and age-matched control subjects, fasting plasma homocysteine concentrations were determined by high-performance liquid chromatography and immunological assays were used for the measurement of folate and vitamin B(12).
Results: Prevalence of the homozygous MTHFR 677TT genotype did not significantly differ between patients and controls (15.2% vs 11.7%, P = 0.24). Mean plasma homocysteine concentrations were significantly higher in psoriasis patients than among control subjects (13.5 +/- 5.3 micromol/l vs 11.0 +/- 2.2 micromol/l, P = 0.026). No significant differences between either mean plasma folate or vitamin B(12) concentrations were observed between both groups.
Conclusion: Our data suggest that the MTHFR 677C>T gene polymorphism is not associated with chronic plaque psoriasis among Caucasians.