[Therapy-related MDS/leukemia carrying dup(11) (q21q23) with MLL gene tandem duplication].

A 42-year-old woman had been given a diagnosis of malignant lymphoma, follicular, small cleaved cell. She had undergone chemotherapy including etoposide (1,500 mg/total) and was in her second complete remission. Four years and 4 months later, refractory anemia with excess of blasts (RAEB) with dup(11) (q21q23) x 2 developed in the patient and progressed to acute myeloid leukemia (AML-M5b). Despite regression of the AML to RAEB, a clone with the additional abnormality of del(20) (q11q13.1) appeared and transformed the RAEB into AML-M6. Rearrangement of the MLL gene was observed, and FISH analysis demonstrated that the signal sequences from the gene's 5' and 3'-terminal regions had detached. RT-PCR techniques detected a tandem duplication of MLL gene exons 2 through 8. This was considered to be one of the mechanisms behind the formation of the 11q23 abnormality observed in this patient.