Extra chromosome 12 and prognosis in chronic lymphocytic leukaemia.

Peripheral blood lymphocytes from 22 consecutive patients with chronic lymphocytic leukaemia were stimulated with the polyclonal B-cell mitogens lipopolysaccharide from E. coli (LPS) and Epstein-Barr virus (EBV). Stimulation was successful for chromosome analysis in 14 patients. Eleven patients had chromosomal aberrations and 7 of these had an extra chromosome 12. In 2 patients an extra chromosome 12 was the only abnormality, while additional aberrations were found in 5 patients. 3 patients had complex aberrations involving deletion of chromosome 6. 1 of these patients also had a translocation between chromosomes 12 and 14. 1 patient had a translocation between chromosomes 11 and 14. In 3 patients no aberrations were detected. The time elapsing between diagnosis and appearance of clinical symptoms which were indications for treatment was significantly shorter in patients with an extra chromosome 12 than in these without this abnormality. Thus, it appears that an extra chromosome 12 is associated with a more rapid course of the disease, and may therefore be of importance for the predition of prognosis.