Other well-defined immunodeficiencies

DNA repair mechanisms are critical for immune system maturation. In the absence of genomic stability, not only lymphocyte maturation is imperfect, but other system anomalies and malfunctions would also appear. These include neurodegeneration, growth retardation and cancer predisposition. Di George syndrome is caused by chromosomal deletions on 22q11. The patients do not develop thymus normally and lack parathyroide glands. Cellular immunodeficiency is accompanied by congenital anomalies and hypocalcemia. Wiskott-Aldrich syndrome is an X-linked disorder due to a defective cytoskeleton. The patients are characterized by persistent thrombocytopenia with small platelets, eczema, cellular and humoral immunodeficiency, and autoimmunity. Hyper-IgE syndrome is a human disease of improper cytokine signaling with recurrent skin abscesses, pneumonia and elevated levels of IgE in serum. The syndrome includes other organ defects such as skeletal deformities. Immuno-osseous dysplasias are characterized by association of immunodeficiency and skeletal problems. These patients have variable defects in both humoral and cellular immunity. Chronic mucocutaneous candidiasis is a primary susceptibility to fungal infections and could be inherited in an autosomal dominant or recessive mode. Recurring infections of the skin and mucous membranes with yeasts, mostly Candida albicans, is the common feature. Netherton syndrome is characterized by trichorrhexis invaginata, atopic dermatitis and eczema, high levels of IgE, angioedema, and immunodeficiency. Hoyeraal-Hreidarsson syndrome is characterized by cerebellar hypoplasia, psychomotor retardation, microcephaly, growth failure, and progressive pancytopenia. © 2008 Springer Berlin Heidelberg.