Cancer in Homozygotes and Hétérozygotes f Ataxia-Telangiectasia and Xeroderma Pigmentosum in Britain

We have documented mortality and cancer incidence in the families of 67 patients with ataxia-telangiectasia and 48 patients with xeroderma pigmentosum resident in Britain. For both diseases, parents of patients are obligate hétérozygotes and grandparents have a probability of heterozygosity of 0.5. Fourteen ataxia-telangiectasia patients had died by June 30, 1986. This was a significant excess (14 deaths observed, 1.65 expected). Only one death was from a malignancy (non-Hodgkin's lymphoma). Three parents of ataxia-telangiectasia patients had died, all from cancer. The excess from breast cancer (two deaths observed, 0.17 expected) was statistically significant, p < 0.05. However, no excess mortality from malignant neoplasms was found in the grandparents. Five xeroderma pigmentosum patients had died, none from internal malignancies. No excess mortality from malignant neoplasms was re corded in either their parents or grandparents.