Chimerism
It is the responsibility of the ordering physician to ensure that informed consent has been obtained from the patient/legal guardian before ordering genetic testing. Please review the following Pre-Test Counselling Information with your patient before requesting any of our genetic tests.
Indications for Testing
Pediatric monitoring post bone marrow transplant; same-sex donor and recipient.
Donor, pre-transplant recipient, and post-transplant recipient samples are required; consult with on-service Molecular Geneticist if these requirements cannot be met.
Contraindications
Pediatric post-BMT monitoring in opposite-sex donor-recipient pairs is performed in the BCCH Cytogenetics laboratory. Generally, monitoring of post-BMT adults is performed in the BCCA molecular genetics laboratory. For contact information for these labs, please see our Can’t Find It? page.
Description of this Assay
Using the AmpFlSTR® Identifiler™ kit, multiplex PCR amplification of 15 genomic short tandem repeat (STR) loci is performed; patterns between donor, pre-transplant recipient, and post-transplant recipient are compared. The sizes of PCR products generated are used to infer their origin as recipient or donor. This allows for the post-transplant assessment of the donor contribution to the bone marrow production of the recipient. Chimerism is confirmed if recipient alleles are identified in the recipient’s post-transplant sample.
Sensitivity and Limitations
This analysis is semiquantitative and is able detect a second cell line when that cell line represents at least 10% of the cell population. The sensitivity of this assay below 10% chimerism has not been accurately determined. Further, for accurate assessment of percent chimerism, informative STR results are required at a minimum of 3 loci; statistically the number of informative loci decreases the biological relationship of related donor-recipient pairs becomes closer.
Turnaround Time
Routine
3 weeks
Specimen Requirements
Blood: 4 mL EDTA is optimal (Minimum: 1 mL EDTA)
DNA: 100 μL at 200 ng/μL is optimal (Minimum: 30 μL at 200 ng/μL)
Bone Marrow: 0.5 mL marrow in EDTA is optimal (Minimum: 0.2 mL)
Label each sample with three patient identifiers; preferably patient name, PHN, and date of birth and ship to the address below. Samples should be shipped at room temperature with a completed MGL Requisition to arrive Monday to Friday (not on Canadian statutory holidays).
Additional Requirements
Donor, pre-transplant recipient, and post-transplant recipient samples are required; consult with on-service Molecular Geneticist if these requirements cannot be met.
Test Price and Billing
Testing is only available to residents of Canada, except in very specific circumstances where testing is urgent or emergent. This test is only available to individuals who are insured by Health Insurance BC (administered through the BC Medical Services Plan (MSP)) and who meet test utilization guidelines or policy. For those without this coverage, contact the laboratory to discuss.
Cautions
Test results should be interpreted in the context of clinical findings and other laboratory data.