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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 See notes section
Sample volume Samples would not be rejected on the basis of small volume, however, 5 mL is ideal.
Turnaround time Post treatment FISH analysis is treated as routine; 95% should be reported within 21 calendar days according to national guidelines. Please note however that the average turn around for X/Y FISH in our laboratory is approximately 4 days.

Sample required:
Bone marrow in cytogenetic transport medium (preferred) or lithium heparin is usually the sample of choice. EDTA samples are only suitable in cases requiring X/Y FISH only. If in doubt please use lithium heparin. Samples which are non-sterile, clotted or collected in sodium citrate, fixative or saline are not suitable.
To ensure appropriate analysis and interpretation it is important to provide clear and concise clinical information