Additional trisomies amongst patients with chronic lymphocytic leukemia carrying trisomy 12: the accompanying chromosome makes a difference

Recurrent cytogenetic abnormalities in chronic lym- phocytic leukemia (CLL), namely deletions of chromo- somes 11q, 13q, 17p and trisomy 12 (+12), define sub- groups of patients with different clinical behavior and response to treatment. 1 We and others previously report- ed a minor proportion of CLL cases with co-existing tri- somies of chromosomes 12 and 19 who share specific clinico-biological characteristics. 2-4 However, since the cohort was small, no definitive conclusions could be drawn. Here, we analyzed a large, multi-institutional series. We confirm and significantly extend previous observations through the identification of subgroups of +12 CLL cases harboring particular concurrent trisomies demonstrating distinctive clinico-biological profiles. We analyzed an unselected cohort of 4486 CLL patients with available classic cytogenetic (n=4285) or high-density 250K single nucleotide polymorphism (SNP)-array (n=201) data. We identified 712 cases (16% of the cohort) carrying +12. 5 Median time from diagnosis to cytogenet- ic/SNP analysis was 1.5 months (range 0-194); the major- ity of cases included in survival analysis were untreated prior to testing (94%). The study was approved by the local Ethics Review Committees. Details of the study cohort and the methodologies used are provided in the Online Supplementary Appendix.