MATERNAL RISK FOR DOWN SYNDROME AND ASSOCIATION BETWEEN MTHFR C677T AND A1298CGENE POLYMORPHISMS: A SYSTEMATIC REVIEW AND META-ANALYSIS OF CASE-CONTROL STUDIES.
Case-control studies, down syndrome, gene polymorphisms, maternal risk.
Down Syndrome or Trisomy 21 is the result of the presence of an extra copy of genetic material and is the most common chromosomal alteration in humans. It was clinically described for the first time in England and is one of the most common causes of intellectual disability in the population. Several studies around the world support the hypothesis that genetic polymorphisms involved in folate metabolism may be related to maternal risk for DS. Many studies were performed to assess the role of MTHFR C677T and/or A1298C polymorphisms as a maternal risk factor for DS, however, the results of these studies produced conflicting and/or inconclusive data. We performed a systematic review and meta-analysis to clarify the associations between the frequency of C677T and/or A1298C polymorphisms of the MTHFR gene with maternal risk for DS. The search strategy selected 41 eligible case-control studies containing 3918 cases and 5232 controls. The association between MTHFR C677T and maternal risk for DS showed statistically significant differences according to genotype models when all studies were included. Subgroup analysis by region revealed a significant association in the Asian population for all genetic models investigated. Significant associations were also found in the dominant model (TT+CT) vs CC from the North American and South American regions. No statistically significant difference was found for the investigated genetic models regarding A1298C polymorphism and maternal risk for DS. The results of this meta-analysis support that the MTHFR C677T polymorphism is associated with maternal risk for SD, but there was no significant association with the MTHFR A1298C polymorphism. Regarding the combined genotypes, our results showed no significant association between the 677CT/1298AC genotype and the maternal risk of having a child with DS.