All the cells in our body carry genetic material which determines how each cell will function. This genetic material is made up of genes which are stored on 23 pairs of chromosomes. Each pair of chromosomes is numbered, 1 to 22, with the last two chromosomes being the sex chromosomes X and Y.

In about 6 out of 10 cases of acute myeloid leukaemia [AML] doctors can recognise abnormal changes in the chromosomes of the leukaemic white blood cells.

One such change is the inversion 16, also called inv(16). Here a piece of one of the pair of chromosome 16 has been picked out and turned upside down before being slotted back into the same place. Because of this, a very important gene that is involved in the development of white cells, CBF*, is disrupted and can't work properly any more. This leads to the uncontrolled growth of the leukaemia and also prevents the cells growing into normal healthy white cells.

About 1 in 10 people with AML have inv(16).

People with an inv(16) AML tend to respond better to chemotherapy. Their chances of a remission are higher and their survival rates are also higher. Because of this people with inv(16) are called a 'good risk' group in the treatment of AML. So if you have AML then having inv(16) indicates that your disease is one of the subgroups that will respond well to treatment.