Genomic instability in a chronic lymphocytic leukemia patient with mono-allelic deletion of the DLEU and RB1 genes

Abstract

The most frequent cytogenetic abnormality detected in chronic lymphocytic leukemia (CLL) patients is the presence of a deletion within the chromosome band 13q14. Deletions can be heterogeneous in size, generally encompassing the DLEU1 and DLEU2 genes (minimal deleted region), but at times also including the RB1 gene. The latter, larger type of deletions are associated with worse prognosis. Genomic instability is a characteristic of most cancers and it has been observed in CLL patients mainly associated with telomere shortening. Cytogenetic and fluorescence in situ hybridization studies of a CLL patient showed a chromosomal translocation t(12;13)(q15;q14), a mono-allelic 13q14 deletion encompassing both the DLEU and RB1 genes, and genomic instability manifested as chromosomal breaks, telomeric associations, binucleated cells, nucleoplasmic bridges, and micronucleated cells. In conclusion, our CLL patient showed genomic instability in conjunction with a 13q14 deletion of approximately 2.6 megabase pair involving the DLEU and RB1 genes, as well as other genes with potential for producing genomic instability due to haploinsufficiency.