iGen3 16-12

Reciprocal translocation in CML (Chronic Myologenous Leukemia):
the Philadelphia Chromosome

    Standard Chromosomes 9 & 22 are shown at left: they are subject to breakage at the abi and bcr loci, respectively. The so-called Philadelphia Chromosome is detectable cytologically as an extra G-group chromosome due to the apparent shortening of the F-group Chromosome 22 by a reciprocal exchange with Chromosome 9. Juxtaposition of the abl and bcr loci interferes with cancer suppressor genes, and results in a specific form of leukemia. The Philadelphia Chromosome was one of the first genetic conditions shown to be directly associated with cancer.

Figure 2010 PJ Russell, iGenetics 3rd ed.; all text material 2013 by Steven M. Carr