Acute lymphoblastic leukaemia with an e1a3 BCR-ABL1 fusion.

摘要

Approximately 25-30% of adult patients with acute lymphoblastic leukaemia have evidence of the Philadelphia chromosome (Ph+ ALL). Identification of BCR-ABL1 transcripts is vital as these patients have a relatively adverse prognosis necessitating intensive therapies including allogeneic transplantation in eligible patients. More recently, it has been demonstrated that incorporation of a tyrosine kinase inhibitor into treatment regimens significantly improves prognosis [1]. Approximately 70% of Ph+ ALL patients express ela2 BCR-ABL1 transcripts and 25% express either el3a2 or el4a2 BCR-ABL1 transcripts, with a number of other less common, variant transcripts reported that usually involve fusion of alternate exons [2]. The ela3 BCR-ABL1 variant fusion transcript, lacking ABL1 exon a2 that partially encodes the src homology 3 (SH3) domain, has been described in three cases of chronic myeloid leukaemia (CML), all with a relatively indolent clinical course [3, 4]. In Ph+ ALL, this BCR-ABL1 genotype has only been reported previously in 8 adult patients [2, 5-7] and 1 paediatric case [8], making any relationships between phenotype and outcome difficult to ascertain. We describe the clinical course of a further case of Ph+ ALL with an ela3 BCR-ABL1 fusion.