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Down Syndrome Research Today is a free monthly online journal that collates and summarizes the latest research about Down Syndrome, including details on education, symptoms, treatment, information.


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Defective thymic progenitor development and mature T-cell responses in a mouse model for Down syndrome.

Lorenzo LP, Shatynski KE, Clark S, Yarowsky PJ, Williams MS

Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.

In addition to archetypal cognitive defects, Down syndrome (DS) is characterized by altered lymphocyte development and function, including premature thymic involution and increased incidence of infections. However, the potential mechanisms for these changes have not been fully elucidated. The current study used the Ts65Dn mouse model of DS to assess deficiencies in T-cell development and possible molecular alterations. Ts65Dn mice exhibited premature thymic involution and a threefold to fourfold decrease in the number and proportion of immature, double-negative thymocyte progenitors. In addition, there were twofold fewer double-positive and CD4 single-positive thymocytes in Ts65Dn thymuses. Reflecting this deficient thymic function, there were fewer naive T cells in the spleen and polyclonal stimulation of peripheral T cells exhibited a marked reduction in proliferation, suggesting a senescent phenotype. In contrast, B-cell progenitors were unchanged in the bone marrow of Ts65Dn mice, but in the spleen, there were decreased transitional and follicular B cells and these cells proliferated less upon antigen receptor stimulus but not in response to lipopolysaccharide. As a potential mechanism for diminished thymic function, immature thymocyte populations expressed diminished levels of the cytokine receptor interleukin-7Rα, which was associated with decreased proliferation and increased apoptosis. Increased oxidative stress and inhibition of the Notch pathway were identified as possible mediators of decreased interleukin-7Rα expression in Ts65Dn mice. The data suggest that immature thymocyte defects underlie immune dysfunction in DS and that increased oxidative stress and reduced cytokine signalling may alter lymphocyte development in Ts65Dn mice.

Published 3 July 2013 in Immunology, 139(4): 447-58.
Full-text of this article is available online (may require subscription).


Articles on Down Syndrome published 1 July 2013:

Screening for down syndrome in the United States: results of surveys in 2011 and 2012.   Arch Pathol Lab Med, 137(7): 921-6.

[Abstract] [Full-text]


Articles on Down Syndrome published 26 June 2013:

Down syndrome is associated with elevated risk of celiac disease: a nationwide case-control study.   J Pediatr, 163(1): 237-42.

[Abstract] [Full-text]


Articles on Down Syndrome published 18 June 2013:

Comparison of combined, biochemical and nuchal translucency screening for Down syndrome in first trimester in Northern Finland.   Acta Obstet Gynecol Scand, 92(7): 769-74.

[Abstract] [Full-text]


Articles on Down Syndrome published 13 June 2013:

Outcomes of treatment for relapsed acute lymphoblastic leukaemia in children with Down syndrome.   Br J Haematol, 162(1): 98-106.

Children with Down syndrome (DS) have a greater risk for developing both acute lymphoblastic leukaemia (ALL) and significant adverse effects of chemotherapy. We investigated their outcome with, and tolerance of, treatment protocols for relapsed ALL optimized in the paediatric population without DS. Probability of survival and causes of treatment failure were determined for 49 children with DS and a matched cohort of 98 children without DS among 2160 children treated for relapsed ALL in clinical ... [Abstract] [Full-text]


Articles on Down Syndrome published 12 June 2013:

Deficits in human trisomy 21 iPSCs and neurons.   Proc Natl Acad Sci U S A, 110(24): 9962-7.

Down syndrome (trisomy 21) is the most common genetic cause of intellectual disability, but the precise molecular mechanisms underlying impaired cognition remain unclear. Elucidation of these mechanisms has been hindered by the lack of a model system that contains full trisomy of chromosome 21 (Ts21) in a human genome that enables normal gene regulation. To overcome this limitation, we created Ts21-induced pluripotent stem cells (iPSCs) from two sets of Ts21 human fibroblasts. One of the ... [Abstract] [Full-text]


Articles on Down Syndrome published 11 June 2013:

Global DNA hypermethylation in down syndrome placenta.   PLoS Genet, 9(6): e1003515.

Down syndrome (DS), commonly caused by an extra copy of chromosome 21 (chr21), occurs in approximately one out of 700 live births. Precisely how an extra chr21 causes over 80 clinically defined phenotypes is not yet clear. Reduced representation bisulfite sequencing (RRBS) analysis at single base resolution revealed DNA hypermethylation in all autosomes in DS samples. We hypothesize that such global hypermethylation may be mediated by down-regulation of TET family genes involved in DNA ... [Abstract] [Full-text]


Articles on Down Syndrome published 10 May 2013:

New insights into the pathobiology of Down syndrome--hyaluronan synthase-2 overexpression is regulated by collagen VI α2 chain.   FEBS J, 280(10): 2418-30.

Down syndrome (DS) is a common birth defect characterized by the trisomy of chromosome 21. DS-affected umbilical cords (UCs) of fetuses show altered architecture of the extracellular matrix. Overexpression of the chromosome 21 genes encoding the collagen type VI (COLVI) chains α1(VI) and α2(VI), COL6A1 and COL6A2, respectively, has also reported to occur in the nuchal skin of DS fetuses. The aim of this study was therefore to evaluate the COLVI content in euploid and DS-affected UCs and ... [Abstract] [Full-text]


Articles on Down Syndrome published 2 May 2013:

Trisomy 21 mosaicism: we may all have a touch of Down syndrome.   Cytogenet Genome Res, 139(3): 189-92.

Ever increasing sophistication in the application of new analytical technology has revealed that our genomes are much more fluid than was contemplated only a few years ago. More specifically, this concerns interindividual variation in copy number (CNV) of structural chromosome aberrations, i.e. microdeletions and microduplications. It is important to recognize that in this context, we still lack basic knowledge on the impact of the CNV in normal cells from individual tissues, including that of ... [Abstract] [Full-text]


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Down Syndrome Books

Schooling Children With Down Syndrome: Toward an Understanding of Possibility (Special Education Series (New York, N.Y.).)

Schooling Children With Down Syndrome: Toward an Understanding of Possibility (Special Education Series (New York, N.Y.).)