Patients with AT carrying typical ATM variants have a severe clinical picture characterized by early onset ataxia before 8 years, loss of the ability to walk, oculomotor apraxia and ocular telangiectasia before the age of 15, and clinical immunodeficiency with IgA deficiency in 60% of cases (Fievet et al., 2019). This evidence concerns the gene ATM and ataxia telangiectasia.