GENES AND CHROMOSOMES IN CHRONIC B-CELL LEUKEMIA

Cytogenetic analysis of patients with chronic B-cell leukemia (B-CLL) indicates that 50% have chromosome abnormalities, while fluorescence i n situ hybridization (FISH) and molecular techniques reveal an even hi gher incidence. Trisomy 12 and deletions or translocations of chromoso me 13q14 are the most common abnormalities, but in neither case has th e gene or genes involved in the abnormalities been identified. Combine d FISH and immunophenotyping studies suggest that both abnormalities a re secondary events in B-CLL. Other recurring chromosome abnormalities include 6q-, 11q- and 12p-, but the genes involved in these abnormali ties have not been identified. Involvement of the BCL1, BCLZ, and BCL3 genes has been reported, but the numbers are low and the cases tend t o be atypical. Trisomy 12 in association with complex karyotypic abnor malities is associated with a poor prognosis, and FISH studies show a strong correlation between trisomy 12, atypical morphology, and advanc ed disease. Ten to 15% of patients have mutations of p53 which is asso ciated with advanced disease, resistance to treatment, and poor surviv al. (C) Elsevier Science Inc., 1997.