One allele deletion of the RB1 gene in a case of refractory anemia with del(13)(q12q14): a fluorescence in situ hybridization study of the RB1 gene

The tumor suppressor gene RB1 is known to be located on chromosome band 13q14. We investigated the involvement of the RB1 gene in a case of refractory anemia with del(13)(q12q14) by florescence in situ hybridization (FISH) analysis using the RB1 locus (13q14) DNA probe. Bone marrow cells derived from this patient exhibited a single signal of the RB1 gene in 58 of 100 bone marrow cells, as determined by interphase FISH analysis. Hematopoietic colony-forming assays showed that the absolute number of erythroid, myeloid, and mixed colonies was comparable to that of normal subjects. FISH analysis of selected colonies revealed that only a single signal for the RB1 gene was detected in five of five granulocyte macrophage–colony-forming units (CFUs), four of five erythroid burst-forming units, and two of four mixed CFUs (total 11/14: 78.6%). Thus, the majority of hematopoietic progenitor cells lacked one allele of the RB1 gene, suggesting that in this particular case the RB1 gene played an important role in abnormal hematopoiesis.