Skip to main content

Login to North West London Pathology – consumables service

If you need a new account or you have a query about your order, please telephone the pathology call centre on 0203 313 5353.

If you have forgotten your password you can reset this yourself. Please click here if you have forgotten your password.

Results Line and Enquiries

0203 313 5353

FISH analysis for Chronic Myeloid Leukaemia

Category Specialist Integrated Haematological Malignancy Diagnostic Service (SIHMDS) >> Cytogenetics
Test background

FISH involves the application of fluorescent DNA probes specific to genes or genetic regions of interest that highlight abnormalities involving these regions.

Clinical Indications

In CML the pathogenic chromosome rearrangement is the t(9;22) or its variants, which gives rise to the BCR::ABL1 gene fusion. Conventional cytogenetic analysis is carried out routinely on diagnostic CML samples, in addition to a FISH using BCR::ABL1 probes for the rapid identification of the BCR::ABL1 gene fusion. Further FISH may also be used at the discretion of the laboratory.

In cases of CML, FISH is useful in the following scenarios:

• Rapid identification of BCR::ABL1 at diagnosis or sudden relapse

• Identifying and monitoring BCR::ABL1 aberrations that are cryptic at the level of conventional cytogenetics

• In cases where a sample has failed to produce metaphases, or in which the disease cells are suspected of having failed to divide

• Cases in which only a BM/PB smear is available.

• CML patients in advanced phase often acquire additional chromosomal abnormalities in their BCR::ABL1-positive clone. FISH can be useful in clarifying these aberrations, and monitoring their presence following further treatment.

FISH probes commonly applied to CML samples include, but are not limited to, the following:

BCR::ABL1 t(9;22)

MECOM (EVI1) 3q26

TP53 17p13

Chromosome 8 centromere

Reference range


Sample & container required A minimum of 2-3mls Bone marrow in lithium heparin.
3-5mls peripheral blood in lithium heparin (if disease cells are present in sufficient numbers to allow cell culture and/or FISH studies, as appropriate)

EDTA PB and BM samples (>1ml) are acceptable for FISH only studies as appropriate. Please note the laboratory does not provide transport medium. Samples sent in transport media from an external laboratory containing Lithium heparin will be accepted if no other media available
Sample volume Samples would not be rejected on the basis of small volume, however, 5 mL is ideal.
Turnaround time Diagnosis: Rapid FISH tests (identification of BCR::ABL1 at diagnosis): 95% should be reported within 3 calendar

Diagnostic karyotype: 14 calendar days

Follow-up: Post treatment follow-up samples are treated as routine; 95% should be reported within 21 calendar days

Relapse/Transformation CML karyotypes: 14 calendar days

If the blood counts are abnormal (high or low white cell count) the volumes of BM/PB requested can be adjusted accordingly. For culture (karyotyping) a WCC of 5×10^6 cells per ml is optimal.

Delayed samples:
Samples should arrive in the laboratory as soon as possible after sampling. Samples delayed in transit may yield poor quality or failed results.