Publications by authors named "Henri Blehaut"

Article Synopsis
  • Down syndrome (DS) is linked to trisomy of human chromosome 21 and features intellectual disability, studied through two mouse models with extra gene copies.
  • RNA analysis showed different gene expression patterns tied to chromatin and synaptic functions in each model, while a large-scale protein interaction study found numerous connections to intellectual disability-related genes.
  • Key proteins from chromosome 21 were found at crucial synaptic sites, revealing potential links between Down syndrome, autism risk genes, and other brain disorders like Alzheimer's disease.
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Background: Early cognitive intervention is the only routine therapeutic approach used for amelioration of intellectual deficits in individuals with Down's syndrome, but its effects are limited. We hypothesised that administration of a green tea extract containing epigallocatechin-3-gallate (EGCG) would improve the effects of non-pharmacological cognitive rehabilitation in young adults with Down's syndrome.

Methods: We enrolled adults (aged 16-34 years) with Down's syndrome from outpatient settings in Catalonia, Spain, with any of the Down's syndrome genetic variations (trisomy 21, partial trisomy, mosaic, or translocation) in a double-blind, placebo-controlled, phase 2, single centre trial (TESDAD).

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Scope: Trisomy for human chromosome 21 results in Down syndrome (DS), which is among the most complex genetic perturbations leading to intellectual disability. Accumulating data suggest that overexpression of the dual-specificity tyrosine-(Y)-phosphorylation regulated kinase 1A (DYRK1A), is a critical pathogenic mechanisms in the intellectual deficit.

Methods And Results: Here we show that the green tea flavonol epigallocatechin-gallate (EGCG), a DYRK1A inhibitor, rescues the cognitive deficits of both segmental trisomy 16 (Ts65Dn) and transgenic mice overexpressing Dyrk1A in a trisomic or disomic genetic background, respectively.

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Forty percent of people with Down syndrome exhibit heart defects, most often an atrioventricular septal defect (AVSD) and less frequently a ventricular septal defect (VSD) or atrial septal defect (ASD). Lymphoblastoid cell lines (LCLs) were established from lymphocytes of individuals with trisomy 21, the chromosomal abnormality causing Down syndrome. Gene expression profiles generated from DNA microarrays of LCLs from individuals without heart defects (CHD(-); n = 22) were compared with those of LCLs from patients with cardiac malformations (CHD(+); n = 21).

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Down syndrome or trisomy 21 is the most common genetic disorder leading to mental retardation. One feature is impaired short- and long-term spatial memory, which has been linked to altered brain-derived neurotrophic factor (BDNF) levels. Mouse models of Down syndrome have been used to assess neurotrophin levels, and reduced BDNF has been demonstrated in brains of adult transgenic mice overexpressing Dyrk1a, a candidate gene for Down syndrome phenotypes.

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Article Synopsis
  • Seven genes linked to folate metabolism on chromosome 21 may influence cognitive functions in children with Down's syndrome (DS) due to folate deficiency.
  • A study was conducted with DS children aged 3 to 30 months using leucovorin or placebo for 12 months to assess developmental age improvements.
  • Results indicated that while the overall intent-to-treat analysis did not show a benefit, a closer look revealed that leucovorin significantly enhanced developmental age in certain groups, especially those receiving thyroid treatment, with no adverse effects reported.
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Background: Hyperhomocysteinemia, characterized by increased plasma homocysteine level, is associated with an increased risk of atherosclerosis. On the contrary, patients with Down syndrome appear to be protected from the development of atherosclerosis. We previously found a deleterious effect of hyperhomocysteinemia on expression of DYRK1A, a Down-syndrome-associated kinase.

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The cause of the non-disjunction leading to trisomy 21 remains unclear. Recent evidence has suggested that 5,10-methylenetetrahydrofolate reductase (MTHFR) and/or methionine synthase reductase (MTRR) might contribute to the maternal risk of trisomy 21. The purpose of the present study was to analyse these findings among the French population and to investigate whether common polymorphisms in genes of the folate and homocysteine pathway, including the MTHFR 677C > T, MTHFR 1298A > C, the methionine synthase (MTR) 2756A > G, the cystathionine beta-synthase (CBS) 844Ins68 and the reduced folate carrier (RFC-1) 80G > A polymorphisms, contribute to the risk of trisomy 21.

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Background: The effects of supplementation with B vitamins and of common polymorphisms in genes involved in homocysteine metabolism on plasma total homocysteine (tHcy) concentrations in trisomy 21 are unknown.

Objectives: We aimed to determine the effects of orally administered folic acid and of folic acid combined with vitamin B-12, vitamin B-6, or both on tHcy in adults with trisomy 21. The study was also intended to analyze the possible influence of gene polymorphisms.

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