CSF3 and chronic myelogenous leukemia, BCR-ABL1 positive: In patients with CP-CML, a low NAP score is the result of low serum levels of granulocyte colony-stimulating factor (Yuo et al. 1987; Watari et al. 1989; Saitoh and Shibata 1993; Tsushita et al. 1993).