Approximately half of surveyed physicians perform cytogenetic analyses and test for detrimental non-driver myeloid mutations in MF patients; however, even though the majority of physicians consider testing for non-driver myeloid mutations in MF and the JAK2 allele burden in PV patients to be therapeutically and prognostically relevant, less than half of them actually order them in everyday practice. The gene discussed is JAK2; the disease is acquired polycythemia vera.