Polymorphisms of 5,10-methylenetetrahydrofolate reductase and cystathionine beta-synthase genes as a risk factor for neural tube defects in Sétif, Algeria

Abstract

Background: Neural tube defects (NTD) are severe congenital malformations due to a failure in neural tube formation at the beginning of pregnancy. The etiology of NTD is multifactorial, with environmental and genetic determinants. We suggest a study of gene-gene interactions regarding the possible association of NTD with specific mutations of 5,10-methylenetetrahydrofolate reductase (MTHFR) and cystathionine beta-synthase (CBS) genes.

Patients and methods: The genetic analysis of the MTHFR C677T polymorphism was performed by real-time polymerase chain reaction (PCR) on a Light Cycler, the CBS genotype was analyzed by PCR in a thermal cycler. Ninety-two mothers who had conceived NTD children and 48 fathers were investigated. A group of 147 adults, including 82 apparently healthy women, was used as control.

Results: Among control mothers, 35 (43%) were heterozygous for the C677T variant and 14 (17%) were TT homozygous. Among the cases, 25 (52%) out of 48 mothers and 22 (46%) out of 48 fathers carried the T allele; 9 mothers (19%) and 5 fathers (10%) had the TT genotype. A homozygous C677T mutation was not an NTD risk factor in this preliminary study in an Algerian population; a possible gene-gene interaction between the MTHFR C677T polymorphism and the CBS 844ins68 has also been examined in relation to NTD, but no such association has been shown. There was a statistically significant difference between the heterozygosity genotype frequency of CBS polymorphisms in mothers with a previous child with NTD compared with the mother controls (odds ratio: 3.72; 95% CI: 1.59-8.73).

Conclusion: Our results with Algerian NTD mothers did not show a significant association for any group, suggesting that the thermolabile variant C677T in the MTHFR gene is not a risk factor for a mother to have NTD offspring; rather, folic acid supplementation or fortification should become mandatory for all women of reproductive age in Algeria.