Frequent allelic loss of the RB, D13S319 and D13S25 locus in myeloid malignancies with deletion/translocation at 13q14 of chromosome 13, but not in lymphoid malignancies

Abstract

In order to identify a commonly deleted region of 13q14 on chromosome 13, we performed fluorescence in situ hybridization (FISH) on 17 patients with myeloid malignancies and 12 patients with lymphoid leukemia/lymphoma who exhibited either deletion or translocation at 13q14. Three cosmid probes (RB, D13S319 and D13S25) hybridizing to sequences on 13q14 were used. Fourteen of the 17 patients with myeloid malignancies (82.4%) exhibited allelic loss at the RB, D13S319 and D13S25 locus, whereas only three of the 12 patients with lymphoid malignancies (25.0%) exhibited loss within these loci. These three patients had chronic lymphocytic leukemia (CLL). Six, two and one of the remaining nine lymphoid leukemia/lymphoma patients had breakpoints centromeric to the RB gene, telomeric to D13S25 and within the D13S319 locus, respectively. A high frequency of allelic loss was found using these probes in patients with myeloid malignancies, compared to in patients with leukemia in the lymphoid origin, except CLL patients. These results indicate that loss of the RB gene itself or a region between RB and D13S319, which includes commonly deleted loci, may play an important role in myeloid leukemogenesis.