In particular, a myeloid neoplasm-relevant 27-gene panel was used for next-generation sequencing (NGS) in 133 Mayo Clinic PV patients, revealing that 53% of them harbored one or more sequence variants/mutations other than JAK2/CALR/MPL; the most frequent were TET2 and ASXL1. Adverse variants/mutations, in terms of overall (OS), leukemia-free (LFS), or myelofibrosis-free survival, included ASXL1, SRSF2, and IDH2, with a combined prevalence of 15%. This evidence concerns the gene ASXL1 and leukemia.