CYTOGENETIC AND MOLECULAR STUDY OF CHRONI C MYELOGENOUS LEUKEMIA - ITS RELATION TO DISEASE EVOLUTION

The aim of this study was to perform a cytogenetic and molecular study in patients with chronic myelogenous leukemia and to seek a possible relation beetween bcr gene break points and the clinical evolution of the disease. The cytogenetic study allowed to establish the presence o f Ph chromosome and the molecular study localized the break point in b cr region of chromosome 22 using the Southern tecnique, hybridizing wi th bcr fragment derived probes bcr1 and bcr2. Forty eight patients wer e studied, 27 male (aged 46.5 years) and 21 female (aged 56). Forty se ven patients were Ph +. A rearrangement in 3' bcr region was found in 25 patients and in 5' region in 23. During the follow up period 20 pat ients developed a blast crisis or accelerated phase. In 11 of these th e rearrangement was in region'3 and their chronic phase lasted a mean of 33.1 months; in 9 the rearrangement was in region 5' and their chro nic phase lasted 44.1 months. There were no differences in event - fre e survival between those with rearrangement in region 3' or 5', howeve r these was a tendency towards a longer chronic phase duration in thos e with 5' breaks. The lack of correlation between the location of brea k points and the evolution of the disease may be due to a selection of patients with a better evolution and the exclusion of those with a ra pid progession to blast crisis or accelerated phase.