ATM and ataxia telangiectasia: ATM mutations cause Ataxia-telangiectasia (AT), an autosomal recessive neurodegenerative disorder characterized by a progressive neuromotor dysfunction resulting from several neuropathological processes dominated by gradual cerebellar cortical atrophy, telangiectasia in the eyes and sometimes on the facial skin, thymic degeneration, immune deficiency, recurrent sinopulmonary infections (at least in some patients), retarded somatic growth, premature aging, gonadal dysgenesis, predisposition to lymphoreticular malignancies, and acute sensitivity to ionizing radiation [3,4,5].