Parental age and the origin of extra chromosome 21 in Down syndrome

Jyothy, A.; Kumar, K. S. D.; Rao, G. Narsinga; Rao, V. Divakara; Devi, B. Uma; Sujatha, M.; Reddy, P. P.

doi:10.1007/s100380170071

Cited by 36 publications

(24 citation statements)

References 11 publications

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“…1 Free trisomy 21 is found in 95% of DS cases and is due to chromosome 21 nondisjunction, which in most cases occurred during maternal meiosis. 2 The risk factors for meiotic nondisjunction are not very clear, except for advanced maternal age. 3,4 Folic acid has an important role in the process of genetic material distribution during cell division, because of its importance to cellular methylation reactions.…”

Section: Introductionmentioning

confidence: 99%

A80G polymorphism of reduced folate carrier 1 (RFC1) and C776G polymorphism of transcobalamin 2 (TC2) genes in Down's syndrome etiology

et al. 2008

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CONTEXT AND OBJECTIVE:There is evidence that polymorphisms of genes involved in folate metabolism may be associated with higher risk that mothers may bear a Down's syndrome (DS) child. This study therefore had the objective of investigating the A80G polymorphism of the reduced folate carrier 1 (RFC1) gene and the C776G polymorphism of the transcobalamin 2 (TC2) gene as maternal risk factors for DS among Brazilian women. DESIGN AND SETTING:Analytical cross-sectional study with control group, at Faculdade de Medicina de São José do Rio Preto (Famerp). METHODS:Sixty-seven mothers of DS individuals with free trisomy 21, and 113 control mothers, were studied. Molecular analysis of the polymorphisms was performed by means of the polymerase chain reaction with restriction fragment length polymorphism (PCR-RFLP), followed by electrophoresis on 2% agarose gel. RESULTS:The frequencies of the polymorphic alleles were 0.51 and 0.52 for RFC1 80G, and 0.34 and 0.34 for TC2 776G, in the case and control groups, respectively. Thus, there were no differences between the groups in relation to either the allele or the genotype frequency, for both polymorphisms (P = 0.696 for RFC1 A80G; P = 0.166 for TC2 C776G; P = 0.268 for combined genotypes). CONCLUSION:There was no evidence of any association between the RFC1 A80G and TC2 C776G polymorphisms and the maternal risk of DS in the sample evaluated.

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Section: Introductionmentioning

confidence: 99%

A80G polymorphism of reduced folate carrier 1 (RFC1) and C776G polymorphism of transcobalamin 2 (TC2) genes in Down's syndrome etiology

et al. 2008

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“…No se ha podido demostrar que la edad paterna avanzada constituya un factor de riesgo para tener hijos afectados de anomalías cromosó-micas, tanto numéricas como estructurales 10 , excepto para trisomía 21, en que se ha comunicado cierta asociación 11 . Se ha relacionado la edad paterna con la calidad del semen, fertilidad disminuida y abortos espontáneos 12 .…”

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La edad paterna como factor de riesgo para malformaciones congénitas

Z³

et al. 2008

Rev. méd. Chile

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“…Down syndrome (DS), or trisomy 21, results from the gene expression of an extra chromosome 21, which occurs in most cases due to the failure of normal chromosomal segregation during maternal meiosis (1). Individuals with DS present decreased homocysteine (Hcy) concentrations (2).…”

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confidence: 99%

The MTR A2756G polymorphism is associated with an increase of plasma homocysteine concentration in Brazilian individuals with Down syndrome

Biselli

Goloni-Bertollo

Haddad

et al. 2007

Braz J Med Biol Res

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Individuals with Down syndrome (DS) present decreased homocysteine (Hcy) concentration, reflecting a functional folate deficiency secondary to overexpression of the cystathionine ß-synthase gene. Since plasma Hcy may be influenced by genetic polymorphisms, we evaluated the influence of C677T and A1298C polymorphisms in the methylenetetrahydrofolate reductase gene (MTHFR), of A2756G polymorphism in the methionine synthase gene (MTR), and of A80G polymorphism in the reduced folate carrier 1 gene on Hcy concentrations in Brazilian DS patients. Fifty-six individuals with free trisomy 21 were included in the study. Plasma Hcy concentrations were measured by liquid chromatography-tandem mass spectrometry with linear regression coefficient r 2 = 0.9996, average recovery between 92.3 to 108.3% and quantification limits of 1.0 µmol/L. Hcy concentrations >15 µmol/L were considered to characterize hyperhomocystinemia. Genotyping for the polymorphisms was carried out by polymerase chain reaction followed by enzyme digestion and allele-specific polymerase chain reaction. The mean Hcy concentration was 5.2 ± 3.3 µmol/L. There was no correlation between Hcy concentrations and age, gender or MTHFR C677T, A1298C and reduced folate carrier 1 A80G genotype. However, Hcy concentrations were significantly increased in the MTR 2756AG heterozygous genotype compared to the MTR 2756AA wild-type genotype. The present results suggest that the heterozygous genotype MTR 2756AG is associated with the increase in plasma Hcy concentrations in this group of Brazilian patients with DS.

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Parental age and the origin of extra chromosome 21 in Down syndrome

Cited by 36 publications

References 11 publications

A80G polymorphism of reduced folate carrier 1 (RFC1) and C776G polymorphism of transcobalamin 2 (TC2) genes in Down's syndrome etiology

A80G polymorphism of reduced folate carrier 1 (RFC1) and C776G polymorphism of transcobalamin 2 (TC2) genes in Down's syndrome etiology

La edad paterna como factor de riesgo para malformaciones congénitas

The MTR A2756G polymorphism is associated with an increase of plasma homocysteine concentration in Brazilian individuals with Down syndrome

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