An autosomal recessive inherited disorder characterized by choreoathetosis beginning in childhood, progressive cerebellar ataxia; telangiectasis of conjunctiva and skin; dysarthria; B- and T-cell immunodeficiency, and RADIOSENSITIVITY to IONIZING radiation. Affected individuals are prone to recurrent sinobronchopulmonary infections, lymphoreticular neoplasms, and other malignancies. serum alpha-fetoproteins are usually elevated. (Menkes, Textbook of child neurology, 5th ed, p688) The gene for this disorder (ATM) encodes a cell cycle checkpoint protein kinase and has been mapped to chromosome 11 (11q22-q23).