Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8849979 | Saudi Journal of Biological Sciences | 2018 | 4 Pages |
Abstract
Down syndrome (DS) is the most common form of human genetic mental retardation. Several polymorphisms in genes coding folic acid cycle enzymes have been associated to the risk of bearing a DS child; however, the results are controversial. S-adenosyl-l-methionine (SAM) is an important intermediate of folic acid pathway and acts as methyl donor and substrate for DNA (cytosine-5)-methyltransferase 3B (DNMT3B - EC 2.1.1.37) de novo methylation processes during embryogenesis. Recent studies suggest that a functional polymorphism of DNMT 3B in maternal genotype may be associated with a decreased risk of having a DS child. We herein investigate the association of this polymorphism with the occurrence of DS in a Brazilian population. We have genotyped 111 mothers of DS infants (MDS) and 212 control mothers (CM) through PCR-RFLP. The observed genotypic frequencies were CCÂ =Â 0.22; CTÂ =Â 0.49 and TTÂ =Â 0.29 in CM, and CCÂ =Â 0.30; CTÂ =Â 0.52 and TTÂ =Â 0.18 in MDS. Allelic frequencies were CÂ =Â 0.47 and TÂ =Â 0.53 in CM and CÂ =Â 0.56 and TÂ =Â 0.44 in MDS. No deviation of HWE was observed, and both DNMT 3B rs2424913 genotype (Ï2Â =Â 4.53; DFÂ =Â 1; PÂ =Â 0.03) and allelic (Ï2Â =Â 4.90; DFÂ =Â 1; PÂ =Â 0.03) frequencies show significant differences between MDS and CM. The presence of the mutant DNMT 3B T allele decreases 30% the risk of bearing a DS child (ORÂ =Â 0.69; 95% CI: 0.50-0.96; PÂ =Â 0.03), and the risk is diminished up to 45% in association with the homozygous genotype (ORÂ =Â 0.54; 95% CI: 0.31-0.96; PÂ =Â 0.04). Our results suggest that women harboring the single nucleotide polymorphism DNMT 3B rs2424913 have a decreased risk of a DS pregnancy, and further studies are necessary to confirm this protective effect.
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Authors
Cláudia Melo de Moura, Pedro Ribeiro Bastos, Julyana S.V. Ribeiro, Márcia Gonçalves Ribeiro, Márcia Rodrigues Amorim, Marcelo Aguiar Costa-Lima,