[Chronic myeloid leukemia: cytogenetic and molecular study and its relationship with the disease course]

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 between bcr gene break points and the clinical evolution of the disease. The cytogenetic study allowed to establish the presence of Ph chromosome and the molecular study localized the break point in bcr region of chromosome 22 using the Southern technique, hybridizing with bcr fragment derived probes bcr1 and bcr2. Forty eight patients were studied, 27 male (aged 46.5 years) and 21 female (aged 56). Forty seven 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 patients developed a blast crisis or accelerated phase. In 11 of these the 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 chronic phase lasted 44.1 months. There were no differences in event-free survival between those with rearrangement in region 3' or 5', however these was a tendency towards a longer chronic phase duration in those with 5' breaks. The lack of correlation between the location of break 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 rapid progression to blast crisis or accelerated phase.