Abstract: Objective To investigate the relationship between methylene tetrahydrofolate reductase (MTHFR)gene polymorphism and systemic lupus erythematosus.Methods Forty patients with SLE and 20 normal human controls were enrolled into this study.Plasma levels of homocysteine(Hcy)were mea-sured by fluorescence polarization immunization assay,and MTHFR 677 polymorphism was analyzed by polymerase chain reaction-restriction fragment length polymorphism(PCR-RFLP).Results The plasma Hcy level was significantly higher in SLE patients than in the controls,but was of no difference between the patients with active SLE and those with inactive SLE.The frequency of MTHFR 677 TT genotype was 62.5% in SLE groups,significantly higher than the frequencies of other two genotypes,CC and CT in SLE patients,and than that in the normal controls(62.5% vs 15%,P<0.001).The MTHFR 677 C→T mutation was associated with a significant increase of Hcy plasma evels in SLE patients,and the increase of Hcy was more significant in patients with TT genotype than those with CT genotype.Conclusions The polymor-phism of MTHFR gene is an important factor that influences the Hcy levels in SLE patients.The MTHFR 677 TT genotype may be a susceptibility factor of SLE,or be closely linked to the susceptibiliy genes of SLE.

Key words: Lupus erythematosus, MTHFR, Homocysteins, Polymorphism