X-RAY-SENSITIVITY OF LYMPHOCYTES OF APLASTIC-ANEMIA AND DIAMOND-BLACKFAN-ANEMIA PATIENTS AS DETECTED BY CONVENTIONAL CYTOGENETIC AND CHROMOSOME PAINTING TECHNIQUES

Frequencies of spontaneously occurring and X-ray induced, stable and u nstable types of chromosome aberrations in peripheral blood lymphocyte s from two groups of radiosensitive patients, i.e., aplastic anemia (A A) and Diamond-Blackfan anemia (DBA), were determined. Two types of st aining methods, i.e., chromosome painting with two cocktails of chromo some-specific DNA libraries (Nos. 1, 3, X and Nos. 2, 4 and 8), as wel l as conventional Giemsa staining, were employed. Chromosome painting was done with single and multicolor fluorescence in situ hybridization (FISH). The frequencies of spontaneously occurring chromosome aberrat ions in AA and DBA patients were not significantly different from heal thy individuals. Hypersensitivity to X-rays was seen both in G(0) as w ell as in G(2) phase of the cell cycle in lymphocytes from AA and DBA patients, confirming our earlier findings using micronucleus (DBA) and G(2) radiosensitivity (AA) assays.