Fanconi's anemia--chromosome breakage studies in homozygotes and heterozygotes.

The in vitro enhancement of chromosome breakage by diepoxybutane (DEB) and mitomycin C (MMC) was studied in 24 Fanconi's anemia (FA) homozygotes and 28 heterozygotes. Both drugs were shown to enhance chromosome breakage significantly in the homozygotes. In the great majority of cases, DEB and MMC stressing are reliable techniques for the definitive cytogenetic diagnosis of FA homozygosity. However, the present study provides no evidence that individual FA heterozygotes can be differentiated from normal individuals on the basis of spontaneous, DEB- or MMC-induced chromosome breakage.