CSF3R and chronic neutrophilic leukemia: With the recent findings of additional genetic lesions in a substantial proportion of CNL patients, and considering the lack of disease-defining CSF3R mutations in others, one of the critical challenges will be molecularly anatomizing this disease: determining additional driver and ancillary mutations, their cooperativity, their interactions with cytogenetic and other extrinsic factors, and their phenotypic, therapeutic, and prognostic implications—and ultimately integrating these variables into an operationally useful schema for prognostication and treatment.