Definition:

Ataxia-telangiectasia (AT) is an autosomal recessive disorder with a birth frequency of about 1 in 300 000. It is a progressive neurodegenerative disease associated with abnormal eye movements and cutaneous telangiectasia, immunodeficiency, and premature aging. The product of the causative gene ATM is a 350 kDa protein of the phosphatidylinositol 3-kinase family that is involved in mitogenic signal transduction, intracellular protein transport, and cell cycle control.