Functional variant in methionine synthase reductase decreases the risk of Down syndrome in China.

Aim: Down syndrome (DS) is the most common genetic cause of human mental retardation and the genes involved in homocysteine/folate metabolism may play important roles in this condition. Methionine synthase reductase (MTRR) is one of the key regulatory enzymes involved in the metabolic pathway of homocysteine. We investigated whether the polymorphism C524T of the MTRR gene is associated with DS.

Method: A total of 104 mothers of children born with DS and 184 healthy mothers were included. The polymorphisms were detected by polymerase chain reaction and restriction fragment length polymorphism analysis. Plasma folate and total plasma homocysteine (t-Hcy) concentrations were also measured.

Results: Significant differences in the distributions of C524T alleles were observed between case and control mothers; a decreased risk of DS was associated with the 524TT genotype (OR=0.34), CT+TT genotype (OR=0.60). The mean t-Hcy value in the case group was higher than the mean value in the control group. t-Hcy concentrations were lower in TT homozygote than CC homozygote among the cases but not among the controls.

Conclusion: MTRR C524T polymorphism decreases the risk of DS in the Chinese population.