ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive: Four main findings were obtained as follows: (1) 12% of imatinib-resistant CML patients showed >10-fold increases in BCR-ABL levels; (2) 6% showed the genomic amplification of BCR-ABL by fluorescence in situ hybridization; (3) additional chromosomal aberrations were observed in 53% of patients; (4) point mutations in the ABL tyrosine kinase domain were detected in 35% of imatinib-resistant CML patients.