Whole-exome sequencing identified heterozygous variants c.1564-165del, p.(Glu5221lefsTer43), and c.7630-2A>C in the serine/threonine-protein kinase ATM (ataxia-telangiectasia mutated) gene, confirming the diagnosis of ataxia-telangiectasia. The gene discussed is ATM; the disease is Ataxia-telangiectasia.