Sister chromatid exchanges induced by nitrogen mustard in Fanconi's anemia. Application to the detection of heterozygotes and interpretation of the results

Nitrogen mustard-induced SCE were studied on Fanconi's anemia (FA) patients, FA parents, and control lymphocyte cultures. When low doses of nitrogen mustard were added at the time cultures were initiated, a distinction could be made between FA heterozygotes and controls. In FA heterozygotes increase of SCE levels higher than that observed in controls was found, thus allowing the recognition of heterozygotes. FA cells appeared to be more sensitive to nitrogen mustard than FA heterozygous and control cells. The data argues in favor of an excision-repair defect, and is discussed in the light of possible repair and SCE production mechanisms.