The percentage of deletion of the B-cell neoplasia-associated gene with multiple splicing: an indicator for the prognosis of CLL

Background: Deletion of the B-cell neoplasia-associated gene with multiple splicing (BCMS) maps to 13q14 is the most common genetic abnormality in B-chronic lymphocytic leukaemia (B-CLL) patients. Previously, CLL patients with del 13q14.1 were known to have a favourable outcome. However, recent research has shown that increased percentage of cells with del 13q may lead to a poor prognosis or may exert an adverse effect on the biological characteristics of this disease.Objectives: To assess the influence of the number of malignant cells carrying del 13q14 (BCMS) on the clinical characteristics and prognosis of CLL patients.Patients and methods: Fluorescence in-situ hybridization technique using a locus-specific identifier 13q14 probe was applied on 76 peripheral blood samples of B-CLL patients, in addition to the routine panel of probes (locus-specific identifier 17p13,11q23 and centromeric 12) together with immunophenotyping using the routine panel for lymphoproliferative disorder.Results: Deletion of 13q14 was detected in 40/76 (52.6%) patients. Those patients with greater than 84% positive cells for the deletion had a statistically significant association with advanced clinical Rai staging, lymphocyte doubling time less than 12 months, lower Hb level, higher total leucocytic count and lower platelet count. Follow-up of all patients showed that 30/76 (39.5%) patients showed a good therapeutic response; 28/30 (93.4%) of the patients were positive for 13q14 (BCMS) deletion, with a percent of cells ranging from 12 to 67%. The remaining 46/76 (60.5%) patients showed a poor therapeutic response; 12/46 (26.1%) of these patients were 13q14 (BCMS) positive, with a percent of positive cells ranging from 84 to 96%. Deletions in 17p13 were detected in 8/76 (10.5%), trisomy 12 was found in 10/76 (13.1%) and 11q23 rearrangements were found in 12/76 (15.7%) patients.Conclusion: The prognostic significance of del 13q14 is dependent on the percentage of positive cells for this deletion. A high number of losses in 13q14 are associated with a poor prognosis.