The ABL1/BCR DNA-FISH Probe is designed to detect the translocation between the ABL1 gene on chromosome 9q34 and the BCR gene on chromosome 22q11 by fluorescence in situ hybridization (FISH). This reciprocal translocation results in the Philadelphia chromosome (Ph), the der(22), and is the hallmark of chronic myeloid leukemia (CML). Approximately 90-95% of CML and up to 5% of pediatric and 20% of adult acute lymphocytic leukemia (ALL) are Ph positive.[ ABL1/BCR FISH is used in diagnosis, prognosis, and monitoring of t(9;22) in CML and ALL patients. A subset of CML (~10%) and ALL (~5%) cases exhibit large deletions adjacent to the breakpoints on chromosomes der(9) and der(22). Such submicroscopic losses carry a poor prognosisand can be detected by the Cancer Genetics Italia DNA-FISH Probe.