CSF3R and chronic neutrophilic leukemia: CNL is strongly associated with a somatic CSF3R mutation and in recognition of this strong genotype-phenotype association, the ICC allows a diagnosis of CNL in the presence of CSF3R mutation with a WBC ≥13 × 109/L provided other criteria are met, while the WHO-HAEM5 continues to require a WBC ≥25 × 109/L for all cases, as in WHO-HAEM4R.