A MLL-KIAA0284 fusion gene in a patient with secondary acute myeloid leukemia and t(11;14)(q23;q32)

MLL aberrations are found in approximately 10% of acute leukemias. More than 80 different MLL fusion genes have been cytogenetically described but a significant number of MLL fusion partners remain unidentified on the molecular level. We describe here the case of a patient who developed secondary acute myeloid leukemia five years after the patient had received adjuvant radiochemotherapy because of breast cancer. This therapy comprised 4 cycles epirubicin/cyclophosphamide, a mitoxantrone-based high-dose chemotherapy with autologous stem cell transplantation and a subsequent radiation. Cytogenetic bone marrow analysis revealed a translocation t(11;14)(q23;q32), with a MLL split signal in FISH analysis. By applying a long-distance inverse PCR method the KIAA0284 gene was identified as translocation partner. Both breakpoints, on chromosomes 11 and 14, were characterized. The breakpoint in the KIAA0284 gene was located 5′ of the putative start codon and an in-frame MLL-KIAA0284 transcript was detectable by RT-PCR. The KIAA0284 gene has hitherto not been implicated in hematologic diseases and has never been reported as a translocation partner. Its physiological function is unknown. The expression of KIAA0284 in various tissues and hematologic diseases was investigated by real time quantitative PCR and turned out to be very low in all lymphatic and myeloid diseases investigated