Diagnosis of CML

This section explains how chronic myeloid leukaemia (CML) is diagnosed. CML affects the white blood cells called granulocytes (which are part of the myeloid family).

Many people feel shocked and upset when told they have CML. If you need support, call Cancer Council 13 11 20. 

Learn more about

• Tests to diagnose
• Staging and prognosis
• Your health care team

Philadelphia chromosome

Most cells in the human body have 23 pairs of chromosomes. Chromosomes are threadlike structures that contain sets of instructions known as genes.

In nearly all people with CML, chromosome 22 is abnormal and is known as the Philadelphia chromosome.

The Philadelphia chromosome is not inherited and cannot be passed on to your children – it is a genetic change that happens to some people during their lifetime. This chromosome contains the BCR-ABL gene (see diagram below).

BCR-ABL is considered a cancer gene because it is present only in developing leukaemia cells. It switches on one of the proteins of the leukaemia cells, called tyrosine kinase. This protein tells leukaemia cells to grow and multiply. All people with CML are treated with drugs to block tyrosine kinase (see Targeted therapy).

Gene swap

The Philadelphia chromosome is formed when parts of two chromosomes break off and switch places. A gene from chromosome 22, called BCR, and a gene from chromosome 9, called ABL, create the BCR-ABL gene.

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