BCR and chronic myelogenous leukemia, BCR-ABL1 positive: Chronic myeloid leukemia (CML) is a clonal myeloproliferative neoplasm derived from a fusion of the Abelson murine leukemia (ABL1) gene on chromosome 9 with the breakpoint cluster region (BCR) gene on chromosome 22 in primitive hematopoietic cells resulting in the expression of an oncoprotein called BCR-ABL1 leading to uncontrolled cell proliferation and suppression of apoptosis [88].