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HelpTest Code CHRGB Chimerism-Recipient Germline (Pretransplant), Varies
Reporting Name
Chimerism-Recipient GermlineUseful For
Evaluating the recipient cells prior to bone marrow transplant
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.
Pretransplant:
-CHRGB / Chimerism-Recipient Germline (Pretransplant), Varies
-CHIDB / Chimerism-Donor, Varies
-ADONO / Additional Chimerism Donor (Bill Only), if applicable
Posttransplant:
-CHIMU / Chimerism Transplant No Cell Sort, Varies or CHIMS / Chimerism Transplant Sorted Cells, Varies
Billing occurs with the following tests:
Pretransplant:
-CHRGB / Chimerism-Recipient Germline (Pretransplant), Varies
-ADONO / Additional Chimerism Donor (Bill Only), if applicable
Posttransplant:
-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
Method Name
Polymerase Chain Reaction (PCR) Amplification/Capillary Electrophoresis
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
VariesOrdering Guidance
This test is for the pre-bone marrow transplant evaluation of the recipient specimen.
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
The following information is required. Provide either as answers to the Order Questions or on Chimerism Analysis Information (T594) if not ordering electronically. Testing will be delayed if this information is not provided:
Donor:
-Full name and date of birth (DOB)
-If unrelated donor, provide full identification number and date of birth (DOB). If DOB is not provided, an arbitrary date such as 01/01/2020 can be used.
Specimen type
Specimen Required
Submit only 1 of the following specimens:
Specimen Type: Whole blood
Container/Tube:
Preferred: Lavender top (EDTA)
Acceptable: Yellow top (ACD)
Specimen Volume: 4 mL
Collection Instructions:
1. Invert several times to mix blood.
2. Label specimen as blood.
3. 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 Type: Extracted DNA from blood or bone marrow
Container/Tube: 1.5- to 2-mL tube
Specimen Volume: Entire specimen
Collection Instructions:
1. Label specimen as extracted DNA from blood or bone marrow
2. Indicate volume and concentration of the DNA
Specimen Type: Buccal swab
Supplies: Buccal Swab Kit (T543)
Container/Tube: Buccal smear collection kit
Specimen Volume: 2 Cyto-Pak brushes-1 per cheek
Collection Instructions:
1. Patient should rinse out mouth vigorously with mouthwash for approximately 15 seconds.
2. Remove Cyto-Pak brush from container only touching "stick" end. Save container.
3. Using medium pressure, rotate brush several times on inside of cheek.
4. Return brush to container and cap.
5. Repeat steps 2 through 4 on other cheek using second brush.
6. It is important that patient's buccal cells are not contaminated with cells from any other source. Do not touch bristles. Do not brush too vigorously. If blood appears, discard brush and restart collection process.
7. Label each container with patient's name and order number or hospital/clinic number.
Additional Information: It is important that the cells do not dry out during shipping. Ensure that container is tightly sealed.
Specimen Minimum Volume
Whole blood: 3 mL
Bone marrow/buccal swab: See Specimen Required
Extracted DNA from blood or bone marrow: 50 microliters at 20 ng/microliter
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 | |
| Refrigerated | 7 days |
Reject Due To
| Gross hemolysis | Reject |
Special Instructions
Reference Values
An interpretive report will be provided.
Day(s) Performed
Monday through Friday
CPT Code Information
81265-Comparative analysis using Short Tandem Repeat (STR) markers; patient and comparative specimen (eg, pre-transplant recipient and donor germline testing, post-transplant non-hematopoietic recipient germline [eg, buccal swab or other germline tissue sample] and donor testing, twin zygosity testing or maternal cell contamination of fetal cells)
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| CHRGB | Chimerism-Recipient Germline | 31208-2 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| MP007 | Donor | 44780-5 |
| MP014 | Specimen Type | 31208-2 |
| 83186 | Chimerism-Recipient Germline | No LOINC Needed |
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.
This test evaluates the recipient specimen prior to bone marrow transplant.
Interpretation
An interpretive report will be provided under CHIMU / Chimerism Transplant No Cell Sort, Varies or CHIMS / Chimerism Transplant Sorted Cells, Varies. This includes whether chimerism is detected and, if detected, the approximate percentage of donor and recipient cells. Sorted cell analysis permits more detailed evaluation of chimeric status in T-cell and myeloid cell fractions, which can be helpful in clinical management.
It is most useful to observe a trend in chimerism levels. Clinically critical results should be confirmed with 1 or more subsequent specimens.
Cautions
Sensitivity varies with the proportions of donor and recipient cells in the specimen. For this reason, results are reported as approximate and rounded to the nearest 5% or 10%, depending on the calculated percentage of donor cells. For example, if the percent donor is 10% or less, it is reported as 5% donor cells. If the percent of donor cells is 90% or higher, it is reported as 95% donor cells. In rare cases (eg, matched related stem cell transplants), short tandem repeat patterns may be identical (ie, noninformative) and chimeric status cannot be determined with this test. Use of alternative approaches (eg, XY fluorescence in situ hybridization in patients with opposite sex transplants) may be required.
Method Description
Genomic DNA is extracted using an automated extraction platform and is then used in a commercial GlobalFiler polymerase chain reaction (PCR) Amplification Kit, following the manufacturer's instructions. Briefly, 20 different short tandem repeat (STR) marker regions are amplified in single multiplex PCR using primers labeled with fluorescent tags. The products are analyzed for size and amount using capillary electrophoresis. For the initial sample on any patient, the test is performed on 3 separate DNA samples: donor germline DNA, recipient germline DNA, and recipient post-transplant 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 in Thiede et al 1999. 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.
The sensitivity of this analysis is approximately 5% in a post-transplant specimen (donor and recipient DNA mixed chimerism).(Thiede C, Florek M, Bornhauser M, et al: Rapid quantification of mixed chimerism using multiplex amplification of short tandem repeat markers and fluorescence detection. Bone Marrow Transplant. 1999 May;23[10]:1055-1060; Ludeman MJ, Zhong C, Mulero JJ, et al: Developmental validation of GlobalFiler PCR amplification kit: a 6-dye multiplex assay designed for amplification of casework samples. Int J Legal Med. 2018 Nov;132[6]:1555-1573. doi: 10.1007/s00414-018-1817-5)