Gene probe analysis demonstrates independent clonal evolution of co-existent chronic myeloid and chronic lymphocytic leukaemia.

We describe a case of Philadelphia-positive chronic myeloid leukaemia occurring simultaneously with B-cell chronic lymphocytic leukaemia in a 69-yr-old male. Gene probe analysis of DNA from both peripheral blood and bone marrow provided evidence for the independent evolution of 2 clones in this case, with a predominant population showing immunoglobulin heavy chain gene rearrangement and a smaller population showing a rearrangement within the breakpoint cluster region of chromosome 22.