BCR-ABL and JAK2V617F Mutation Co-existence, Rare or Just Unexplored

H. S. Darling, Rajiv Kumar, Rajan Kapoor, Jasjit Singh, Tarun Verma

Current hematology practice distinguishes chronic myeloid leukemia (CML) and other major chronic myeloproliferative neoplasms as different entities classically characterized by positivity of BCR-ABL fusion gene and JAK2V617F mutations. These are different in clinical presentation, molecular genetics, therapy and response to present treatments. Nevertheless, there have been occasional case reports of detection of both mutations in the same patient. Although some of these had been incidentally detected, most have manifested clinically while being treated for one disease. Here, we present two cases of co-existence of BCR-ABL and JAK2V617F positivity. The first one was initially managed as CML. On obtaining adequate molecular and hematological response, thrombocytosis persisted. Hence she was tested for JAK2V617F mutation. In the second case, when we noticed upfront very high platelet counts along with a clinical picture of CML, we tested her for both and was found to be positive for both. Till to date, no such clinical case has been reported from India. The current status and approach to BCR ABL and JAK2 coexistent mutations has been reviewed and discussed.