Acute lymphoblastic leukemia expressing b3a2 (p210), e1a2 (p190), and variant e1a2 BCR-ABL transcripts: A case report and review of the literature

摘要

The Philadelphia (Ph) chromosome arises from the reciprocal translocation t(9;22)(q34;q11), resulting in the juxtaposition of the ABL gene at 9q34 to the BCR gene at 22qll, which generates the chimeric gene BCR-ABL. The fusion gene is found in more than 95% of patients with chronic myelogenous leukemia (CML), and in 10-20% of, adults and 2-5% of children with acute lymphoblastic leukemia (ALL). It is rarely seen in acute myelogenous leukemia (AML). At the genomic level, three different breakpoint cluster regions in the BCR gene (M-bcr, m-bcr, and mu-bcr) have been reported , which generate commonly different transcripts and somewhat different proteins, b2a2 (p210), b3a2 (p210), ela2 (p190), and c3a2 (p230). The b3a2 or b2a2 fusion transcripts are found in 83-90.4% of patients with CML. In addition, ela2 is present in 60-75% of patients with Ph-positive ALL and only 1% of patients with CML.