MNX1–ETV6 fusion gene in an acute megakaryoblastic leukemia and expression of the MNX1 gene in leukemia and normal B cell lines

Patients with infant acute myeloid leukemia (AML) who carry a t(7;12)(q36;p13) translocation have been reported to have a poor clinical outcome. MNX1–ETV6 fusion transcripts (previously HLXB9–ETV6) were rarely detected in AML patients having t(7;12)(q36;p13). A 23-month-old girl with acute megakaryoblastic leukemia (AMKL) exhibited chromosome abnormalities, including add(7)(q22), and del(12)(p12p13). Southern blot analysis of bone marrow cells showed an ETV6 gene rearrangement. Reverse transcriptase-polymerase chain reaction (RT-PCR) followed by sequence analysis revealed the presence of an MNX1–ETV6 fusion gene. The patient responded well to chemotherapy, achieved complete remission, and at writing had been in complete remission for 60 months. The MNX1 expression by RT-PCR was significantly more frequent in Epstein–Barr virus–transformed B-cell lines derived from normal adult lymphocytes than in leukemic cell lines. This represents a novel case of an AMKL patient with MNX1–ETV6 fusion transcripts who had a good prognosis.