Abstract:

Ataxia telangiectasia is an autosomal recessive disorder characterized by progressive cerebellar ataxia, immunodeficiency, telangiectasia, chromosomal instability, cancer susceptibility and radiation sensitivity. The ataxia telangiectasia gene is located on chromosome 11q22-23. Various degrees of abnormalities in T and B cell immunity have been described. We report a 9-year-old boy diagnosed as ataxia telangiectasia including clinical features of progressive ataxia, telangiectasia, immunodeficiency and elevated serum levels of alpha fetoprotein. Immunologic evaluation revealed high levels of serum IgM and very low IgG and IgA levels. Immune fixation electrophoresis showed monoclonal IgM and kappa increase. His lymphocyte phenotyping studies and CD40 ligand on T lymphocytes were normal. His monoclonal gammapathy of the IgM type was attributed to failure of the switch process from IgM production to IgA and IgG, due to a recombination defect.

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