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 Chimerism analysis (XX/XY) Post-BMT

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 patients who have received sex-mismatched bone marrow transplants, X/Y FISH is a useful means of rapidly screening large numbers of bone marrow cells for the presence of host cells that may be a sign of engraftment failure or early relapse.
Please note that this technique is different from, but complementary to, molecular chimerism analysis based on PCR of STR markers.
Where possible, post-BMT follow-up samples are monitored by XY FISH only, unless frank relapse is detected, in which case conventional karyotyping will also be performed, specimen type permitting.

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 Post BMT samples are treated as routine; 95% should be reported within 21 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.