All leukaemia cells have abnormal gene changes. Gene changes happen when something goes wrong when the body is making new blood cells.
The organs and tissues of our body are made up of cells. Every cell contains all the biological information we inherit from our parents. This information is stored in our genes in the centre (nucleus) of every cell. Genes control what the cell does. They are grouped together in chromosomes.
These gene changes happen when something goes wrong when the body is making new blood cells. They are not inherited and they cannot be passed on to any children you have.
The gene changes in different types of leukaemia cells vary from person to person. This is why leukaemia can behave differently in different people.