Two myelodysplastic syndrome cases with the inv(11)(p15q23) as a sole chromosomal abnormality.

Two myelodysplastic syndrome cases (one with acute nonlymphocytic leukaemia (M2) transformed from myelodysplastic syndrome (MDS), and the other with chronic myelomonocytic leukaemia following refractory anaemia with excess of blasts in transformation) showed the inv(11)(p15q23) as a sole chromosomal abnormality. Gene probes for c-Ha-ras-1 and c-ets-1 were hybridized to metaphase cells from bone marrow of these patients. c-ets-1 gene, which is mapped to 11q23, was demonstrated to have translocated to the short arm in the rearranged chromosome 11 in both cases. On the other hand, c-Ha-ras-1 gene, which is located at 11p15, was translocated to the long arm in the rearranged chromosome 11 in patient 1, and deleted in patient 2. Our findings suggest that there may be heterogeneity in molecular events involved in the chromosomal rearrangement among the inv(11)-carrying MDS.