Attempts to detect ataxia telangiectasia (AT) heterozygotes by cytogenetical techniques

AT cells are known to be more sensitive than normal human cells to ionizing radiation as well as other agents, as judged by cell survival, induced chromosomal aberrations, and micronuclei. The inhibition of DNA replication following X-irradiation is less in AT cells than in normal cells. Four different cell lines heterozygous for AT were investigated for their response to various treatments in order to see whether they behaved in an intermediate way. In most of the tests, the heterozygous AT cells behaved like normal cells. In the frequencies of induced chromosomal aberrations following X-rays, there was heterogeneity in response, with one cell line showing a definite intermediate response.