Sequential fluorescence in situ hybridization analyses for trisomy 12 in chronic leukemic B-cell disorders

Background and Objectives. Trisomy 12 is one of the most common chromosomal abnormalities in B-cell chronic lymptrocytic leukemia (CLL). The aberratio n is readily detected by fluorescence in situ hybridization (FISH). There a re only a few reports in which FISH analyses have been used to study the ex pansion of the trisomy 12 clone over time. Design and Methods. Repeat FISH analyses were performed in 77 patients with a chronic leukemic B-cell disorder. The aim was to study the development o f the trisomy 12 clone throughout the course of the-disease, to measure the effect of therapy on the proportion of trisomic cells, and to relate the f indings to the response to therapy. Results. Fifty-eight of the 60 patients with no trisomy 12 at the initial t est were consistently disomic for chromosome 12, while 2 patients seemingly acquired trisomy 12 during folIow-up. Seventeen patients showed trisomy 12 at the first test. Expansion of the trisomy 12 clone was seen in all patie nts with a progressive lymphocytosis. In contrast to poor responders, patie nts responding well to chemotherapy showed a significant decrease in the pr oportion of CD19(+) cells with trisomy 12. The effect of purine analogs in patients with trisomy 12 seemed inferior, both clinically and when studying the effect on the trisomic clone. Interpretations and Conclusions. There is a strong association between expa nsion of the trisomy 12 clone and progressive disease, both in treated and untreated patients. Conversely, reduction of the trisomic B-cell clone was linked to clinical response to chemotherapy. Acquisition of trisomy 12 rema ins a rare event. (C) 2001, Ferrata Storti Foundation.