Ataxia-telangiectasia (AT) is an autosomal recessive inheritance, characterized by progressive cerebellar ataxia with degeneration of Purkinje cells beginning in early childhood, usually before age 5. Patients with ataxia telangiectasia have increased cancer incidence especially for leukemia and lymphoma. Affective individuals also have hypersensitivity of fibroblasts and lymphocytes to ionizing radiation, non-random chromosomal rearrangements in lymphocytes, thymic hypoplasia with cellular and humoral (IgA and IgG2) immunodeficiencies, elevated serum level of alphafetoprotein AFP, premature aging, and endocrine disorders (e.g. diabetes mellitus DM).