Ataxia-telangiectasia

proneness cancer-predisposing genes present in the population at frequencies affect cancer incidence which do not result in cancer with a high enough probability to give rise to "cancer families." gene predisposing to be associated with the gene for debrizoquine metabolism autosomal recessive for A-T2 in the heterozygous (i.e., carrier) state, Homozygotes for A-T show a rare syndrome with a fascinating variety of aspects. Patients are deficient in immune response, show progressive neurological degeneration and defects in organ maturation, and are prone to develop cancer, particularly of the cells of the immune system Ref. Their cells show spontaneous chromosomal instabilities, and there are reports of hypersensitivity to the chromosome-breaking and/or lethal effect of ionizing radiation and certain chemicals such as bleomycin, neocarzinostatin, Adriamycin, and Hoechst 33342. A further addition to this list is phorbol ester (Shiloh, Boston, MA), a tumor that been cause endogenous