[The relationship between polymorphism of gene involved in folate metabolism, homocysteine level and risk of Down syndrome].
OBJECTIVE
To investigate whether the polymorphism in methylenetetrahydrofolate reductase (MTHFR) gene involved in folate metabolism is associated with Down syndrome (DS).


METHODS
One hundred Chinese mothers who gave birth to babies with DS and 100 control mothers were chosen. Genotype of MTHFR 677 was determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and concentration of plasma homocysteine (HCY) was measured by chemiluminescence.


RESULTS
The MTHFR 677T allele frequency was significantly different among case mothers, compared with control mothers (P=0.002); the odds ratio for the heterozygous CT genotype was 2.12 (95%CI: 1.14-3.94), whereas for the homozygous TT genotype, the odds ratio was 3.43 (95%CI:1.41-8.36). The mean plasma HCY concentration [(9.04 +/- 3.85) mu mol/L] of cases was significantly different from that of controls [(6.53 +/- 2.06) mu mol/L](P <0.01). The presence of the 677C>T substitution in one or both alleles was associated with increased plasma HCY both in case mothers and control mothers (P < 0.01). Interestingly, although both being MTHFR 677CC, the plasma HCY concentrations were higher in case mothers than in control mothers, the increase was not dependent on MTHFR genotype (P < 0.01).


CONCLUSIONS
Our results provide evidences that plasma HCY and genetic polymorphism in gene of folate pathway are risk factors for mothers to have a DS child in China.
Wang
Wen
W
Department of Genetics and Developmental Biology, Southeast University Medical School, Nanjing, Jiangsu, 210009 PR China.
Xie
Wei
W
Wang
Xiu ying
Xy
D000328:Adult; D000483:Alleles; D001483:Base Sequence; D016022:Case-Control Studies; D004314:Down Syndrome / Q000097:blood / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D005260:Female; D005492:Folic Acid / Q000378:metabolism*; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D042965:Methylenetetrahydrofolate Reductase (NADPH2) / Q000235:genetics*; D009154:Mutation; D011110:Polymorphism, Genetic; D011247:Pregnancy
D006710:Homocysteine; D005492:Folic Acid; D042965:Methylenetetrahydrofolate Reductase (NADPH2)