P026 Variant Philadelphia translocation in chronic myeloid leukemia

Abstract

Objective. The Philadelphia chromosome (Ph), due to t(9 ; 22)(q34 ; q 11.2), is the cytogenetic hallmark of chronic myeloid leukemia (CML) and is observed in more than 90% of the cases. Five to ten percent of patients with Ph positive CML have variant translocations involving chromosomes other than 9 and 22. Methods. We analysed 12 cases with variant Ph positive CML between 1994. and 2006. by conventional and molecular cytogenetic analysis. Conventional cytogenetic analysis was perfonned on bone marrow specimens after 24-48 h of culturing. Fluorescent in situ hibridization (FISH) was perfonned on slides of culture or freshly prepared slides. Results. Among the 164 patients with Ph 12 (7.2%) had variant translocations, involving one (n=11) or two (n=1) additional translocation partner chromosome. The median age was 46 years (range 18-69 years). Eight patients (66.6%) were in chronic phase, and four (33.3%) in accelerated phase, three with clonal evolution. The distribution of the breakpoints on sites other than 9q34 and 22q 11 has shown involvement of the following chromosomes: 6p23q23, 11q15 two patients, 12q24, 14p12, 15p13, 16p13, 17pl1, 18p12, 19p13, 21q22 and 22q13 two patients. Cytogenetic features of clonal evolution disease were combinations of double Ph. The BCR-ABL rearrangement were con finned by FISH. Conclusion. The clinical course and impact of these variants on long-tenn outcome is not well known, and conclusions are conflicting. Some studies have suggested that patients with variant Ph trans locations may have an adverse prognosis, while others have suggested that these translocationes have no impact on prognosis.