Breakpoint cluster region‐Abelson (BCR‐ABL) negative myeloproliferative neoplasms (MPNs) are chronic myeloid neoplasms initiated by the acquisition of gene mutation(s) in a haematopoietic stem cell, leading to clonal expansion and over‐production of blood cells and their progenitors. The gene discussed is ABL1; the disease is myeloproliferative disorder.