Adult-onset variant ataxia-telangiectasia diagnosed by exome and cDNA sequencing

Ataxia-telangiectasia (A-T) is an autosomal recessive disorder caused by mutations in ATM, encoding a serine-threonine protein kinase that is crucially involved in DNA repair mechanisms. Clinical features include cerebellar degeneration, telangiectasia, immunodeficiency, and an increased risk of malignancies.¹ The classic form of A-T is characterized by infantile, rapidly progressing neurodegeneration and can be differentiated from variant A-T with a comparably milder disease course.^2,3 However, only a tiny fraction of patients first present with symptoms in adulthood.⁴ The broad phenotypic spectrum of A-T now becomes gradually disentangled owing to the increased availability of comprehensive genetic testing.⁵