Ataxia telangiectasia (AT) is a rare autosomal recessive neurodegenerative disease with a prevalence between 1 in 40,000 and 1 in 100,000 live births worldwide, caused by biallelic mutations in the Ataxia Telangiectasia Mutated (ATM) gene (Chr 11q22.3–23.1). Here, ATM is linked to ataxia telangiectasia.