Trisomy of 1q in preleukaemia with progression to acute leukaemia.

Marrow cells from an untreated man with preleukaemia were found to have trisomy for the long arm of chromosome 1 which was translocated to the end of the long arm of number 11, i.e., 46,XY, -11,+t (1:11) (q11 or q12; q25). The same abnormality was found in metaphases from 8 individual granulocytic colonies. With development of acute myelomonocytic leukaemia, in addition to the basic chromosome abnormality, trisomy of chromosome 8 and an extra chromosome number 19 with partial deletion were found. Fibroblasts grown from marrow biopsy material showed a normal diploid complement, 46,XY.