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1.
J Mol Neurosci ; 2020 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-32445071

RESUMO

Down syndrome (DS) is the most common form of mental disability of genetic etiology. Nondisjunction of chromosome 21 is the leading cause of the syndrome. In general, free trisomy 21 cases originate from missegregation in maternal meiosis. Several reports have suggested an association between genetic variants in genes encoding folate metabolizing enzymes and the predisposition to chromosome missegregation. We have conducted a case-control study of 109 DS case mothers (MDS) and 248 control mothers (CM) to assess the association between DHFR del19bp polymorphism and an increased risk of bearing a DS child. Genomic DNA was extracted from buccal cells, and molecular analysis of DHFR del19pb polymorphism was performed by polymerase chain reaction (PCR). Both MDS and CM allelic and genotypic distributions were in Hardy-Weinberg equilibrium. The frequency of DHFR del19pb-mutated allele was 0.54 in MDS and 0.46 in CM. Overall analysis showed that the mutant allele was borderline associated with DS risk (OR 1.38; 95% CI 1.00-1.89; P = 0.05) and a weak positive association for del/del and/or wt/del genotypes of DHFR del19pb polymorphism compared to homozygous wt/wt genotype was identified (OR = 1.75; 95% CI 1.01-3.03; P = 0.05). When we have analyzed data stratified by age, there is an increased risk of bearing a DS child associated with the polymorphic allele (OR = 1.49; 95% CI 1.03-2.16; P = 0.03), suggesting that DHFR del 19-bp polymorphism could be an independent risk factor for DS in women aged < 40 years old.

2.
Saudi J Biol Sci ; 25(1): 101-104, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29379364

RESUMO

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 CC = 0.22; CT = 0.49 and TT = 0.29 in CM, and CC = 0.30; CT = 0.52 and TT = 0.18 in MDS. Allelic frequencies were C = 0.47 and T = 0.53 in CM and C = 0.56 and T = 0.44 in MDS. No deviation of HWE was observed, and both DNMT 3B rs2424913 genotype (χ2 = 4.53; DF = 1; P = 0.03) and allelic (χ2 = 4.90; DF = 1; P = 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 (OR = 0.69; 95% CI: 0.50-0.96; P = 0.03), and the risk is diminished up to 45% in association with the homozygous genotype (OR = 0.54; 95% CI: 0.31-0.96; P = 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.

3.
Mol Biol Rep ; 40(3): 2115-25, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23184006

RESUMO

The association between Down syndrome (DS) and maternal polymorphisms in genes encoding folic acid metabolizing enzymes remains a controversial issue. A meta-analysis was performed to evaluate the association of maternal MTHFR 677C > T polymorphism and the risk of having a child with DS. Case-control studies were screened from major literature databases. Twenty articles from 13 countries worldwide, with a total of 2,101 DS and 2,702 control mothers, attended the inclusion criteria. We found a 50 % increase for the association of maternal homozygous TT genotype and DS in both fixed (OR = 1.51; 95 % CI 1.22-1.87) and random effects models (OR 1.54; 95 % 1.15-2.05). Similarly, a significant pooled OR was found for the heterozygote CT, with an OR 1.26; 95 % CI 1.10-1.43 (fixed effects model) and OR 1.28; 95 % 1.08-1.51 (random effects model). As ultra-violet B solar radiation highly depends on latitude, and can promote, in less pigmented skin, intravascular folate photolysis, we stratified the analysis by latitude region, defining as Tropical (between 23.5(°) S and 23.5(°) N), Sub-Tropical (between 23.5(°) and 40(°) N and S), and Northern (≥ 40(o) N). Significant association was only found for Sub-Tropical area, both using fixed and random effect models. In conclusion, MTHFR 677C > T polymorphism is a moderate risk factor for DS for some populations, and populations located in Sub-Tropical region seem to be at greater risk. Latitude, ethnicity, skin pigmentation, and red blood cell folate are important variables to be considered in future studies.


Assuntos
Síndrome de Down/genética , Predisposição Genética para Doença , Metilenotetra-Hidrofolato Redutase (NADPH2)/genética , Polimorfismo Genético , Alelos , Criança , Feminino , Genótipo , Humanos , Masculino , Mães , Razão de Chances
4.
JBP, j. bras. odontopediatr. odontol. bebê ; 2(5): 32-36, jan.-fev. 1999. tab
Artigo em Português | LILACS, BBO - Odontologia | ID: lil-405774

RESUMO

Dentro da prática de Odontologia para Bebês, a verificação da saúde oral da futura mamãe tem sido sugerida como uma das formas de predizer o risco de cárie do futuro bebê. Uma vez assistindo às gestantes, o profissional deverá ser capaz, não só de restabelecer, da melhor maneira possível, a sua saúde oral, como também esclarecer todas as suas dúvidas em relação ao seu estado oral e aos procedimentos propostos. O objetivo deste trabalho foi verificar, na casuística do Serviço de Informação Teratogênica do Rio de Janeiro, quais são as principais dúvidas das gestantes em relação à Odontologia e qual seria a sua natureza. Das 2.016 consultas recebidas entre 1992 e 1998, 1.077 foram consideradas pertinentes ao serviço, ou seja, se referiam a riscos ambientais para uma gestação em curso ou que estava sendo planejada. Das consultas pertinentes ao serviço, 53 (4,9 por cento) foram dúvidas relacionadas à Odontologia. As dúvidas principais se relacionaram aos riscos para o bebê em formação caso a gestante se submetesse ao tratamento dentário (29 casos) e ao exame radiográfico (10 casos). Os outros casos se relacionaram com a manifestação do herpes labial ou ao uso de medicação antiviral tópica, ao uso de complementos vitamínicos com flúor e aos riscos relacionados à vacina contra a hepatite B. O número importante de consultas relacionadas a Odontologia demonstra a necessidade do dentista, que se propõe a assistir a gestante, oferecer todas as informações relativas ao risco para o bebê em formação, diminuindo assim, a ansiedade envolvida em uma consulta odontológica


Assuntos
Humanos , Feminino , Gravidez , Assistência Odontológica , Serviços de Informação , Brasil , Educação em Saúde Bucal , Saúde Bucal , Cuidado Pré-Natal
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