U2AF1 and chronic neutrophilic leukemia: Further, Dao et al. evaluated 10 cases of CSF3RT618I-positive myeloid neoplasms including aCML, CNL, or MPN not otherwise specified and unexpectedly found frequent mutations in U2AF1 (four of 10 cases of chronic myeloid neoplasms, not defined further in this study)148, which had previously been observed in primary myelofibrosis, MDS, and CMML130.