Abstract
Polymorphisms in key genes involving the folate pathway have been reported to be associated with the risk of orofacial cleft (OFC) and several studies were published with conflicting results. A meta-analysis of the previous studies of allelic association between OFC with A1298C polymorphisms of the methylenetetrahydrofolate reductase (MTHFR) gene was carried out. Odds ratios (ORs) with 95% confidence intervals (CIs) were estimated to assess the association between MTHFR A1298C polymorphism and OFC risk. A total of 11 studies including 1628 cases and 2676 controls were involved in this meta-analysis. No statistical relationship was found with any genetic model (C vs. A (Additive): OR = 1.14, 95%CI = 0.76-1.65, P = 0.47; CC vs. AA (homozygote): OR = 0.90, 95%CI = 0.72-1.15, P = 0.0.41; AC vs. AA (co-dominant): OR = 0.97, 95%CI = 0.85-1.11, P = 0.0.63; CC+AC vs. AA (Dominant): OR = 0.96, 95%CI = 0.84-1.1 , P = 0.51; CC vs. AC+AA (Recessive): OR = 0.93, 95%CI = 0.74-1.16, P = 0.52). The present meta-analysis supports that the common A1298C polymorphism of MTHFR gene is not risk factor for OFC. Key words: Orofacial cleft, cleft lip, cleft palate, methylenetetrahydrofolate reductase (MTHFR), A1298C, folic acid.
Highlights
Of craniofacial congenital abnormalities comprised orofacial cleft (OFC) or cleft lip and/or palate (CL/P)
Among several genes that take part in folate metabolism, the methylenetetrahydrofolate reductase gene (MTHFR) has been the most frequently reported to be associated with OFC
The following inclusion criteria were used: (i) studies must have a case–control study, (ii) study must be published as full papers, (iii) authors must investigate patients with cleft lip and palate cases and healthy control subjects, (iv) authors must provide information on genotype frequencies of the MTHFR A1298C polymorphism or sufficient data for the calculation, (iv) studies with overlapping cases and/or controls, the largest study with extractable data was included
Summary
Of craniofacial congenital abnormalities comprised orofacial cleft (OFC) or cleft lip and/or palate (CL/P). Prenatal folic acid supplementation to pregnant women has been shown to reduce the incidence of CL in many (van Rooij et al., 2004; Badovinac et al, 2007; Rouget et al, 2005; Yazdy et al, 2007; Wilcox et al, 2007), but not all (Ray et al., 2003) populations studied (Sozen et al, 2009). Several studies established that polymorphisms in genes implicated. Genomics in folate metabolism may play a significant role in the OFC etiology. Among several genes that take part in folate metabolism, the methylenetetrahydrofolate reductase gene (MTHFR) has been the most frequently reported to be associated with OFC
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