Philadelphia chromosome - image description

This diagram shows how the Philadelphia chromosome is made when a section of chromosome 9 joins on to a section of chromosome 22. Chromosome 9 is a large, long chromosome. It has two parts. The top part is short, the bottom part is long. The bottom of the longer part of the chromosome has an area labelled the ABL gene.

Chromosome 22 is a smaller chromosome. It also has two parts. The top part is small, the bottom part is long. The small top part and the top of the longer part have an area labelled the BCR gene.

On the right side of the diagram, the ABL gene from Chromosome 9 and the BCR gene from Chromosome 22 are combined together. This makes the Philadelphia chromosome. This chromosome has a small part at the top and a longer part of the bottom. The bottom part is labelled as a fusion gene, which is BCR and ABL combined.