ABSTRACT
Background: Down syndrome, the most common trisomy 21 arises from abnormal chromosomal segregation. The etiology includes genetic and acquired factors. The main genetic factor that is well appreciated for onset of Down syndrome pregnancy is MTHFR gene polymorphism. But till date, no final conclusion has arrived despite multiple studies on this gene polymorphism
Aim: To investigate the risk of MTHFR gene polymorphisms, C677T and A1298C, with Down syndrome pregnancies and a meta-analysis of published literature
Subjects and methodology: PCR-RFLP method was used to genotype C677T and A1298C polymorphism. For meta-analysis the literature was retrieved from PubMed database with the key words, MTHFR polymorphism; C677T; A1298C and Down syndrome
Results: Mothers carrying C677T polymorphism had a risk of 2.48 times compared with control subjects while A1298C polymorphism carriers had 1.60 times and 2.12 times increased risk under assumption of dominant and recessive model. However, meta-analysis of published studies resulted in 1.26 times and 1.32 times increased risk of Down syndrome pregnancies among the C677T carries under the assumption of recessive and dominant models of inheritance. Considering A1298C polymorphism, dominant model predicated no risk; recessive model resulted in 1.34 times increased risk in CC genotype individuals. In subgroup analysis, Indian studies had a risk of 1.61 times and 1.44 times under recessive and dominant model of C677T polymorphism inheritance while A1298C polymorphism carriers had a risk of 1.75 and 1.46 under the assumption of recessive and dominant inheritance
Conclusion: Our study suggests that both C677T and A1298C polymorphisms are significantly associated with the risk of DS pregnancy
Abbreviations: DS, Down syndrome; MTHFR, methylenetetrahydrofolate reductase; MTR, methionine synthase remethylation of homocysteine to methionine; MTRR, methionine synthase reductase; CBS, cystathionine beta-synthase; QF-PCR, Quantitative fluorescent PCR; OR, odds ratio; HWE, Hardy Weinberg equilibrium