A critical look at the association of human genetic syndromes with sensitivity to ionizing radiation.

Individuals with inherited heterozygosity for mutations involving tumor suppressor genes may be at greater risk for ionizing radiation-induced cancer even though their cells may not show increased cytotoxicity or chromosome damage. In addition, many human genetic syndromes have been reported to show increased sensitivity to ionizing radiation. In most instances the effects are small and/or not reproducible. Only in the genetic disease ataxia-telangiectasia (AT) is radiosensitivity consistently outside the normal range. Even AT heterozygotes (0.68 to 7.7% of the population) appear to be slightly radiosensitive, and their elevated cancer risk may result from exposure to ionizing radiation. Current research has concentrated on the isolation of the gene or genes responsible for this disease.