Combined immunodeficiency in a patient with mosaic monosomy 21.

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Combined immunodeficiency in a patient with mosaic monosomy 21.

Immunol Res. 2016 Aug;64(4):841-7

Authors: Rechavi E, Levy-Mendelovich S, Stauber T, Shamash J, Reinstein S, Vernitsky H, Adam D, Simon AJ, Lev A, Raas-Rothschild A, Somech R

Abstract
Monosomy 21 is an extremely rare genetic disorder presenting with a wide array of symptoms. Recurrent infections, some life threatening, have been reported in several monosomy 21 patients and attributed to an, as of yet, undefined immunodeficiency. Here we report on a 3-year-old boy with mosaic monosomy 21 who presented with clinical and laboratory evidence of immunodeficiency. Despite suffering from infections highly suggestive of a cell-mediated immune defect, the patient's T cells displayed normal counts, subsets and proliferation capability. T cell receptor repertoire was diverse, and de novo T cell production was intact. Consistent with earlier case reports, our patient displayed mildly low B cell counts with hypogammaglobulinemia. B cell subsets demonstrated mainly naïve and marginal zone B cells that have not undergone class switch. Subsequently, IgG, IgA and IgE levels were near absent, whereas IgM level was normal. De novo B cell production and B cell receptor diversity were normal. Together, these results are indicative of a defect in immunoglobulin class switching as the principal cause of immunodeficiency in monosomy 21. A better understanding of the immunodeficiency in this syndrome will enable targeted treatment and prevention of infections in order to prevent morbidity and mortality in these patients.

PMID: 27216863 [PubMed - indexed for MEDLINE]

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