Indian Journal of Medical and Paediatric Oncology | 2019
A novel in-frame 231bp deletion mutation in ABL1 kinase activation loop
Abstract
Tyrosine kinase domain (TKD) mutation is one of the most common causes for tyrosine kinase inhibitors resistance in patients with chronic myeloid leukemia (CML). Mutations in the exon 7 of ABL1 gene are one of the most common TKD mutations, especially in the Indian population, but they are frequently underreported, and their clinical significance is not clear. We are reporting a novel ABL1 exon 7 mutation in a previously diagnosed and treated patient CML who presented at the blast crisis stage. Cytogenetic studies showed multiple copies of Philadelphia (Ph) chromosome along with isochromosome 17. Kinase domain mutation studies showed a novel 231bp in-frame deletion mutation (p. 372_448del) in the activation loop of BCR-ABL1 chimeric protein. The given mutation would result in a complete loss of activation loop, including DFG domain-regulating activation status of the catalytic domain. This mutation, along with cytogenetic abnormalities, could have contributed to progression to blast crisis.