Association between MTHFR C677T and A1298C gene polymorphisms and maternal risk for Down syndrome: A protocol for systematic review and/or meta-analysis

Influence of different forms of folic acid supplementation on pregnancy outcomes under various exposure factors

BACKGROUND

Folic acid supplementation has been shown to provide benefits in preventing neural tube defects and other birth defects, as well as reducing adverse pregnancy outcomes.

OBJECTIVE

This study aimed to examine the impact of various folic acid supplementation methods on pregnancy.

METHODS

TaqMan-MGB technology was used to detect polymorphisms in the folate metabolism-related genes, MTHFR C677T and A1298C. Blood-related biochemical indicators, including HCY levels and history of adverse pregnancy, were examined in relation to different exposure factors (MTHFR gene polymorphism, HCY levels, and adverse pregnancy history) and their impact on pregnancy outcomes. Various forms of folic acid intervention were implemented in a population with an adverse pregnancy history and high HCY levels to analyze the effects of reducing HCY levels and improving pregnancy outcomes.

RESULTS

Exposure factors, such as adverse pregnancy history, HCY, and medium-to-high risk of gene metabolism, were closely associated with pregnancy outcomes. Interestingly, methylfolate efficiently reduced the serum HCY levels. More importantly, the methylfolate group exhibited a significantly lower incidence of adverse pregnancies than the synthetic folic acid group.

CONCLUSION

In this study, the risk factors, including adverse pregnancy history, HCY, and medium-to-high risk of gene metabolism, were confirmed to lead to the poorer pregnancy outcomes in our cohort. 5-methyltetrahydrofolate may be an effective approach for decreasing the incidence of adverse pregnancy outcomes.

Genetic aetiology of Down syndrome birth: novel variants of maternal DNMT3B and RFC1 genes increase risk of meiosis II nondisjunction in the oocyte

The aim of the present work was to explore the intriguing association of maternal folate regulator gene polymorphisms and mutations with the incidence of chromosome 21 nondisjunction and Down syndrome birth. We tested polymorphisms/mutations of DNMT3B and RFC1 genes for their association with meiotic errors in oocyte among the 1215 Down syndrome child-bearing women and 900 controls. We observed that 23 out of 31 variants of DNMT3B and RFC1 exhibited an association with meiosis II nondisjunction in maternal age-independent manner. Additionally, we have reported 17 novel mutations and 1 novel polymorphic variant that are unique to the Indian Bengali speaking cohort and increased odds in favour of meiosis II nondisjunction. We hypothesize that the risk variants and mutations of DNMT3B and RFC1 genes may cause reduction in two or more recombination events and also cause peri-centromeric single exchange that increases the risk of nondisjunction at any age of women. In silico analyses predicted the probable damages of the transcripts or proteins from the respective genes owing to the said polymorphisms. These findings from the largest population sample tested ever revealed that mutations/polymorphisms of the genes DNMT3B and RFC1 impair recombination that leads to chromosome 21 nondisjunction in the oocyte at meiosis II stage and bring us a significant step closer towards understanding the aetiology of chromosome 21 nondisjunction and birth of a child with Down syndrome to women at any age.