A novel BCR-ABL fusion gene (e2/1a) in a patient with Philadelphia-positive chronic myelogenous leukaemia and an aggressive clinical course

A novel variant BCR-ABL mRNA transcript was detected by reverse transcripti on polymerase chain reaction (RT-PCR) in a patient with Philadelphia positi ve (Ph+ve) chronic myelogenous leukaemia (CML) who had an aggressive clinic al course. Sequence analysis of the amplified cDNA fragment revealed an in- frame fusion with part of BCR exon e2 joined to part of ABL exon 1a, PCR of genomic DNA from this patient demonstrated that this unusual chimaeric mRN A resulted from breakpoints that fell within each of these exons. This is t he first report of breakpoints occurring within both ABL and BCR exons and the first fusion to involve ABL exon 1a.