WAS and chronic myelogenous leukemia, BCR-ABL1 positive: This includes no relevant increase in blast numbers, making it difficult to recognize the molecular evolution of CML patients.16, 39, 40 The observed inhibition of WASP expression coincided exactly with this transition, as patients in CP still express WASP at levels similar to healthy individuals, whereas patients in AP and BC has significantly less WASP (Figure 1b).