Inherited sensitivity to X-rays in man.

Ataxia-telangiectasia (A-T), an inherited disorder giving radiation sensitivity and cancer-proneness, is discussed in terms of a defect in ability to repair DNA damage. A new assay using damaged recombinant DNA molecules suggests that the fidelity of repair of DNA double-strand breaks is reduced in an A-T cell line. Specific chromosomal changes in some A-T patients appear to be associated with cancer induction, and it is suggested that these could be linked to a DNA repair-fidelity defect. However, a general correlation between radiosensitivity and cancer-proneness is difficult to establish at present, partly because of diversity in radiosensitivity in the normal population.