We retrospectively reviewed the databases of seven studies on acute lymphoblastic leukemia (ALL) by the Associazione Italiana Ematologia Oncologia Pediatrica (AIEOP) to identify patients with associated genetic disease, other than Down's syndrome. Forty-two patients were reported to have associated genetic conditions that included beta-thalassemia (n=10), ataxia-telangiectasia (n=5), neurofibromatosis (n=3), Sotos syndrome (n=2) and other individual conditions. Patients with ataxia-telangiectasia, all with T-cell ALL, had a higher frequency of adverse events.