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HelpTest Code CHIMU Chimerism Transplant No Cell Sort, Varies
Useful For
Determining the relative amounts of donor and recipient cells in a specimen
An indicator of bone marrow transplant success
Testing Algorithm
Complete chimerism analysis requires 3 specimens, under 3 separate orders, for the 3 separate tests listed below. These specimens should be submitted when collected. An interpretive report will be provided once all specimens are received.
Pre-Transplant:
-CHRGB / Chimerism-Recipient Germline (Pretransplant), Varies
-CHIDB / Chimerism-Donor, Varies
-ADONO / Additional Chimerism Donor (Bill Only), if applicable
Post-Transplant:
-CHIMU / Chimerism Transplant No Cell Sort, Varies or CHIMS / Chimerism Transplant Sorted Cells, Varies
Billing occurs with the following tests:
Pre-transplant:
-CHRGB / Chimerism-Recipient Germline (Pretransplant), Varies
-ADONO / Additional Chimerism Donor (Bill Only), if applicable
Post-Transplant:
-CHIMU / Chimerism Transplant No Cell Sort, Varies
-CHIMS / Chimerism Transplant Sorted Cells, Varies
-SORT1 / Chimerism Cell Sort 1 (Bill Only)
-SORT2 / Chimerism Cell Sort 2 (Bill Only)
For more information see Chimerism-Recipient Germline Testing Algorithm
Special Instructions
Method Name
Polymerase Chain Reaction (PCR) Amplification/Capillary Electrophoresis
Reporting Name
Chimerism Transplant No Cell SortSpecimen Type
VariesOrdering Guidance
This test is for the post-bone marrow transplant evaluation of the presence of donor cells in the post-transplant recipient specimen. For post-bone marrow transplant testing to determine the relative amounts of donor and recipient cells, see CHIMS / Chimerism Transplant Sorted Cells, Varies
Additional Testing Requirements
Shipping Instructions
1. Specimen must arrive within 7 days of collection.
2. Collect and package specimen as close to shipping time as possible.
Necessary Information
Specimen Type is required, either as an answer to the Order Questions or on Chimerism Analysis Information (T594) if not ordering electronically. Testing will be delayed if this information is not provided.
Specimen Required
Submit only 1 of the following specimens:
Specimen Type: Blood
Container/Tube:
Preferred: Lavender top (EDTA)
Acceptable: Yellow top (ACD)
Specimen Volume: 4 mL
Collection Instructions:
1. Only 1 tube is required.
2. Invert several times to mix blood.
3. Label specimen as blood.
4. Send whole blood specimen in original tube. Do not aliquot.
Specimen Type: Bone marrow
Container/Tube:
Preferred: Lavender top (EDTA)
Acceptable: Yellow top (ACD)
Specimen Volume: 2 mL
Collection Instructions:
1. Invert several times to mix bone marrow.
2. Label specimen as bone marrow.
3. Send bone marrow specimen in original tube. Do not aliquot.
Specimen Minimum Volume
Blood: 3 mL
Bone marrow: See Specimen Required
Lesser volumes may be acceptable, depending on white cell count.
Call 800-533-1710 or 507-266-5700 with questions.
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Varies | Ambient (preferred) | 7 days | PURPLE OR PINK TOP/EDTA |
| Refrigerated | 7 days | PURPLE OR PINK TOP/EDTA |
Reject Due To
| Gross hemolysis | Reject |
| Moderately to severely clotted | Reject |
Clinical Information
Patients who have had donor hematopoietic cells infused for the purpose of engraftment (ie, bone marrow transplant recipients) may have their blood or bone marrow monitored for an estimate of the percentage of donor and recipient cells present. This can be done by identifying unique features of the donor's and the recipient's DNA prior to transplantation and then examining the recipient's blood or bone marrow after the transplantation procedure has occurred. The presence of both donor and recipient cells (chimerism) and the percentage of donor cells are indicators of transplant success.
Short tandem repeat (STR) sequences are used as identity markers. STR are di-, tri-, or tetra-nucleotide repeat sequences interspersed throughout the genome at specific sites. There is variability in STR length among people, and the STR lengths remain stable throughout life, making them useful as identity markers. Polymerase chain reaction is used to amplify selected STR regions from germline DNA of both donor and recipient. The lengths of the amplified fragment are evaluated for differences (informative markers). Following allogeneic hematopoietic cell infusion, the recipient blood or bone marrow can be evaluated again for the informative STR regions to identify chimerism and estimate the proportions of donor and recipient cells in the specimen.
Reference Values
An interpretive report will be provided.
Interpretation
An interpretive report will be provided, which defines unique features of the donor's cells.
It is most useful to observe a trend in chimerism levels. Clinically critical results should be confirmed with 1 or more subsequent specimens.
Method Description
Genomic DNA is extracted from blood or bone marrow aspirate samples using an automated extraction machine and used in a commercial kit GlobalFiler PCR Amplification KIT following the manufacturer's instructions. Briefly, 20 different short tandem repeat (STR) marker regions are amplified in single multiplex polymerase chain reaction (PCR) using primers labeled with fluorescent tags. The products are analyzed for size and amount using capillary electrophoresis on a genetic analyzer. For the initial sample on any patient, the test is performed on 3 separate DNA samples: donor germline DNA, recipient germline DNA, and recipient posttransplant sample for chimerism determination. The STR profile of the germline samples is used to identify markers that can distinguish between the donor and recipient. Based on these profiles, the percentage of donor and recipient DNA is then determined in the post-transplant sample using the assumptions and calculations outlined.(Thiede C, Florek M, Bornhauser M, et al: Rapid of mixed chimerism using multiplex amplification of short tandem repeat markers and fluorescence detection. Bone Marrow Transplant. 1999 May;23[10]:1055-1060). Subsequent samples for chimerism evaluation do not need to be accompanied by samples for donor and recipient germline evaluation, as the profiles from the initial testing are kept on file for comparison.(Package insert: GlobalFiler PCR Amplification Kit. User Guide. Applied Biosystems, 2019; Thiede C, Florek M, Bornhauser M, et al: Rapid quantitation of mixed chimerism using multiplex amplification of short tandem repeat markers and fluorescence detection. Bone Marrow Transplant. 1999 May;23[10]:1055-1060)
The sensitivity of this analysis is approximately 5% in a posttransplant specimen (donor and recipient DNA mixed chimerism).
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Test Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
81267-Chimerism (engraftment) analysis, post hematopoietic stem cell transplantation specimen, includes comparison to previously performed baseline analyses, without cell selection
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| CHIMU | Chimerism Transplant No Cell Sort | 34574-4 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| MP026 | Specimen Type | 31208-2 |
| 37313 | Final Diagnosis | 34574-4 |
Forms
1. Chimerism Analysis Information Sheet (T594)
2. If not ordering electronically, complete, print, and send a Hematopathology/Cytogenetics Test Request (T726) with the specimen.
Day(s) Performed
Monday through Friday