Karyotypic evolution in CLL: identification of a new sub-group of patients with deletions of 11q and advanced or progressive disease.

Chronic lymphatic leukaemia (CLL) is the most common leukaemia and is characterized by long-term survival. Previous studies have shown that karyotypic abnormalities are relatively stable and that certain abnormalities may be associated with a poor prognosis. In a prospective 5-year study of 45 patients with typical CLL, sequential karyotypic studies were undertaken every 6-12 months. Clonal karyotypic abnormalities were identified in 62% of patients, either at diagnosis or during the study period with 38% (17/45) exhibiting clonal evolution. In patients with no clinical disease progression, 13q abnormalities were most commonly detected compared with 11q deletions in patients with progressive disease. Karyotypic evolution was significantly associated with progressive disease (12/16, 75% vs 5/29, 17%; P < 0.001, chi2). Thus, karyotypic evolution is not uncommon in CLL, is usually associated with disease progression and deletions of 11q are the commonest detected abnormalities.