This test helps doctors choose treatment more effectively.

Laboratory tests can be done on the blood or bone marrow cells you've given. Your haematologist may order a test to look for abnormalities in the leukaemia cell genes.

This test is called FISH. FISH stands for fluorescent in situ hybridization. The FISH technique makes particular abnormalities in genes glow (fluoresce) and so makes them easier to see.

Using this technique, doctors can now pick up abnormal genes in the cells of 80 out of every 100 people with chronic lymphocytic leukaemia (80%).

FISH helps doctors to divide CLL into different groups. This helps with decisions about treatment so doctors are able to choose treatments more effectively.