ABSTRACT
<p><b>OBJECTIVE</b>To explore the distribution of genetic polymorphisms of methylenetetrahydrofolate reductase (MTHFR) 677C/T, 1298A/C and methionine synthase reductase (MTRR) 66A/G among ethnic Han females from Linyi, and to correlate it with serum level of homocysteine (Hcy).</p><p><b>METHODS</b>A cross-sectional study was carried out. Oral epithelial cell samples were collected from 825 subjects. MTHFR and MTRR gene polymorphisms were determined with a Taqman-Minor Groove Binder (MGB) method. Distribution of gene polymorphisms was analyzed and compared with others regions of China including Weifang, Zhengzhou, Deyang and Hainan. A biochemical assay was also carried out to determine the total Hcy in plasma of 281 subjects. The reductase activity of MTHFR was classified into decreased and stable groups according to genetic polymorphism of MTHFR. Correlation between MTHFR groups and total Hcy level were also explored.</p><p><b>RESULTS</b>(1) The frequencies of MTHFR677CC, CT and TT genotypes of the selected subjects were 16.7%, 48.3% and 35.0%, respectively. The frequencies of MTHFR 1298AA, AC and CC genotypes were 76.0%, 21.6% and 2.4%, respectively. And those of MTRR 66AA, AG and GG genotypes were 54.7%, 39.4% and 5.9%, respectively. For the selected subjects, their frequency of MTHFR 677TT genotype was higher than that of Deyang and Hainan (P< 0.01), whilst the frequency of MTHFR 1298CC genotype was lower than that of Deyang and Hainan (P < 0.01), and the frequency of MTRR 66 GG genotype was lower than that of Hainan (P< 0.01). (2) The Hcy level for those with decreased MTHFR activity was significantly higher than those with stable MTHFR activity (P< 0.05).</p><p><b>CONCLUSION</b>MTHFR gene 677C/T, 1298A/C and MTRR 66A/G polymorphisms in ethnic Han women from Linyi have differed significantly from other regions of China. Decreased MTHFR activity caused by genetic polymorphisms is a risk factor for raised Hcy level.</p>