Definition

A gene formed when pieces of chromosomes 9 and 22 break off and trade places. The ABL gene from chromosome 9 joins to the BCR gene on chromosome 22 to form the BCR::ABL fusion gene. The changed chromosome 22 with the fusion gene on it is called the Philadelphia chromosome. The BCR::ABL fusion gene is found in most people with chronic myelogenous leukemia, and in some people with acute lymphoblastic leukemia or acute myelogenous leukemia. Also called BCR-ABL fusion gene.