del11(p11–13) with overexpression of Wilms' tumor gene during leukemic transformation of myelodysplastic syndrome

Abstract.

We report a case of leukemic transformation from myelodysplastic syndrome (MDS) with a sole chromosome abnormality of del11(p11–13). The patient had been diagnosed as having MDS (refractory anemia with excess of blast cells, RAEB) in May 1998. At that time, cytogenetic analysis of bone marrow cells showed a normal karyotype. The patient received sequential chemotherapy with low-dose cytosine arabinoside (AraC) and macrophage colony-stimulating factor (M-CSF). Complete remission was obtained with this treatment, but the disease gradually progressed after June 1999. Cytogenetical analysis showed del11(p11–13) in 6 of 40 cells analyzed at that time, and the disease had evoluted to overt leukemia in December 1999 with a gradual increase in the abnormal clone. Furthermore, mRNA of the WT1 gene located at chromosome 11p13 was overexpressed during leukemic transformation, whereas it was not detected at the time of the initial diagnosis of MDS (RAEB) in May 1998. It was thought that this chromosome deletion and overexpression of WT1 resulted in the leukemic transformation in this patient. This is the first case report of del11(p11–13) being considered to be the primary cause of leukemic transformation from MDS.