We did not detect any mutations in genes encoding classical splicing factors (SF3B1, SRSF2, ZRSR2, U2AF1; CP-CML PBC, n = 10) and in the non-coding U1-snRNA 12 (CP-CML PBC, n = 17), unlike in other blood malignancies such as MDS where splicing gene mutations are common [4]. The gene discussed is U2AF1; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.