TRISOMY-12 AND STRUCTURAL ABNORMALITIES OF 13Q14 OCCURRING IN THE SAME CLONE IN CHRONIC LYMPHOCYTIC-LEUKEMIA

Trisomy 12 and deletions or translocations of 13q14 are the commonest cytogenetic abnormalities in chronic lymphocytic leukaemia but rarely co-exist in the same patient. We describe eight patients from a series of > 400 patients with CLL in whom trisomy 12 and t or del 13 occur i n the same clone. Using FISH we have identified clones with trisomy 12 alone, t or del 13q14 alone and both abnormalities, in each of the pa tients studied. This implies that neither trisomy 12 nor t or del 13q1 4 is the initiating event in leukaemogenesis, but does not exclude the possibility of a submicroscopic abnormality of 13q14 occurring as an early event.