Based on bone marrow morphology, biopsy (revealing Grade MF-2 fibrosis), and molecular testing (detecting a <i>JAK2</i> <sup>V617F</sup> mutation with a variant allele frequency of 44.67% and an <i>ASXL1</i> mutation), a diagnosis of primary myelofibrosis (PMF) was established. This evidence concerns the gene JAK2 and primary myelofibrosis.