ATM and ataxia telangiectasia: However, the carriers of biallelic ATM GPVs are affected by ataxia–telangiectasia (AT, OMIM #208900), which is a rare autosomal recessive syndrome characterized by progressive cerebellar ataxia, cutaneous telangiectasias, increased risk of developing hematologic and solid tumors, and immunodeficiency [66,68,69].