A case of <i>CALR</i> mutation in <i>JAK2</i>-negative patient with polycythemia

Abstract

JAK2 mutations can be associated with any phenotypic form of chronic myeloproliferative neoplasia, while MPL and CALR mutations occur, as a rule, in cases of essential thrombocythemia and primary myelofibrosis and they are not observed in polycythemia vera. In this article we describe a clinical case of CALR mutation (c.1154_1155insGTGTC; p.E386fs*46) presence in a JAK2 -negative polycythemia vera patient at age 36. In January 2018 changes in his hemogramm were recorded for the first time. In June 2018, based on a diagnostic study of bone marrow trepanobiopsy, a diagnosis of polycythemia vera was made. Molecular genetic study of the patient’s DNA didn’t reveal mutations in the JAK2 (12 and 14 exons) and the MPL genes. CALR mutation was revealed during the screening by heteroduplex analysis with the electrophoresis in polyacrylamide gel. Then the mutation was identified by Sanger’s DNA sequencing as с.1154_1155insGTGTC; p.E386fs*46. The allelic burden level as determined by pyrosequencing was 20 % (June 2018). In conclusion we can suppose that the revealed CALR mutation с.1154_1155insGTGTC; p.E386fs*46 plays its role in our patient’s polycythemia phenotype.