Q57 – 74: Chimerism Studies (Cord Blood Units, Beta Thalassemia, and Sickle Cell Disease Only)

*Chimerism Studies
This section relates to chimerism studies from allogeneic HCTs using cord blood units, or for allogeneic HCT recipients whose primary disease is beta thalassemia or sickle cell disease only. If this was an autologous HCT, an allogeneic HCT using a bone marrow or PBSC product, and / or allogeneic HCT recipient whose primary disease for transplant was not beta thalassemia or sickle cell disease, continue to the disease assessment section.

!Chimerism Studies
Chimerism study questions can only be completed on the 100-day, 6-month, 1 year, and 2 year follow-up forms. These questions will be skipped for all subsequent reporting periods.

Chimerism studies are performed to determine the percent of blood or marrow cells post-transplant that are produced from donor hematopoietic stem cells and the percent that are produced from host (recipient) hematopoietic stem cells. Different types of blood cells and a variety of laboratory tests can be used to determine if a chimera (presence of both donor- and host-derived cells) exists. If cytogenetic testing was performed to look for disease markers, and the donor and recipient are different sexes, the test may also be used to determine if a chimera exists. If the donor and recipient are of the same sex, cytogenetic testing using the common staining technique, known as giemsa banding (G-banding), cannot be used to determine if there is a chimera. However, quinicrine banding (Q-banding) can be used to identify if the cells are of donor origin or not in a same-sex transplant, as this staining technique highlights inherited chromosome polymorphisms on certain human chromosomes including 3, 4, 13, 15, 21, 22, and Y. This is not a commonly used staining technique and is only helpful when the polymorphism is documented pre-HCT.

*Failed Chimerism Studies
If chimerism studies were attempted, but no evaluable results were obtained, do not report the test.
When a multi-donor chimerism exists and includes a donor (or donors) from a previous HCT, report as a multi-donor chimerism though there may only be one donor for the current transplant.

Question 57 – 58: Were chimerism studies performed since the date of last report?

Indicate whether chimerism studies were performed within the reporting period. If Yes, indicate whether documentation was submitted to CIBMTR (e.g., chimerism laboratory reports).

If chimerism studies were not performed within the reporting period, select No.

Question 59: Were chimerism studies assessed for more than one donor / multiple donors?

Indicate whether this HCT included product(s) from multiple donors. When a multi-donor chimerism exists and includes a donor or donors from a previous HCT, report as a multi-donor chimerism even though there may only be one donor for the current transplant.

*Reporting Multiple Chimerism Studies:
FormsNet3^SM application: Complete the chimerism-specific questions for each chimerism study by adding an additional instance in the FormsNet3^SM application.
Paper form submission: Copy the chimerism-specific questions for each chimerism study since the date of last report.

!Question 61 has been “hidden” in FormsNet3 for the current revision of this form. If an NMDP donor ID had been previously entered, this field will not be hidden and can be edited as needed. However, if an NMDP donor ID has not been entered yet, this field will be hidden and skipped until the form is revised and the question is removed from the form.

Question 60 – 74: Provide date(s), method(s) and other information for all chimerism studies performed since the date of last report

When reporting chimerism studies for multiple donors, there should be one instance for each donor for each chimerism test results. For haplo cords, (i.e., haplo donor PBSC and CBU), there should be an instance for both the CBU and the PBSC.

Transplant centers may perform frequent chimerism studies. If there is a need to reduce the number of chimerism study results reported due to volume, ensure that the following are reported at a minimum:

• Studies performed on or at approximately Day+28
• Most recent studies performed prior to the date of contact, particularly for Day+100
• Most recent studies performed prior to and after an intervention (such as a donor cellular infusion)
• The first result to show complete / 100% donor chimerism
  

Chimerism – Single Donor

Data Field	Description
60. Global Registration Identifiers for Donors (GRID)	The GRID standard (ICCBBA ST-015) is a 19-character donor identifier used to ensure that each donor ID is globally unique. For more information about the GRID, see the Pre-TED (2400) Forms Instruction Manual
61. NMDP cord blood unit ID	If the donor or one of the donors was an NMDP cord blood unit, enter the 9 digit NMDP cord blood unit ID.
62. Registry donor ID	If the donor or one of the donors was a non-NMDP unrelated PBSC or marrow donor, enter the registry donor ID.
63. Non-NMDP cord blood unit ID	If the donor or one of the donors was a non-NMDP cord blood unit, enter the non-NMDP registry donor ID.
64. Donor date of birth or age	If the donor was related or the cord blood unit was related or supplied by a non-NMDP registry, provide the date of birth, if known; if date of birth is not known, provide the donor’s age at donation.
65. Sex	If the donor was related or the cord blood unit was related or supplied by a non-NMDP registry, provide the biological sex.
66. Date sample collected	Enter the date the sample was collected for the chimerism test.
67 – 68. Method	Report the test method used for the reported chimerism study. Cytogenetic testing methods include karyotyping and fluorescent in situ hybridization (FISH). Cytogenetic methods are only valid for sex mismatched transplants with the exception of quinicrine banding. VNTR / STR is one of the most common molecular methods for assessing chimerism. See the Chimerism Methods table below for additional details on chimerism testing methods.
69. Cell source	Report whether the specimen taken for chimerism testing was from a Bone marrow or Peripheral blood source.
70 – 71. Cell type	Indicate the cell type tested. If the specimen was not sorted for a specific cell line, indicate Unsorted / whole. See the Chimerism Cell Types table below for additional details on cell markers unique to certain cell lines.
72. Total cells examined	Cytogenetic testing methods include karyotyping and fluorescent in situ hybridization (FISH), each of which examines a specific and relatively low number of cells – generally 15 to 200, depending on specimen and test method. If a cytogenetic method was used, enter the total number of cells that were examined. If a non-cytogenetic test was used, leave these boxes blank.
73. Number of donor cells	Cytogenetic methods, karyotyping and FISH, examine a specific and relatively low number of cells – generally 15 to 200, depending on specimen and test method. If a cytogenetic method was used, enter the total number of cells that were examined and found to be of donor origin. If a non-cytogenetic test was used, leave these boxes blank.
74. Percent donor cells	Molecular testing methods include VNTR / STR, RFLP, and AFLP. Report the percentage of donor cells identified by molecular testing. If the test result did not detect any recipient cell population within the sensitivity of the assay, report 100% donor cells. If the test detected recipient cells, but indicated donor cells “> n%,” report “n + 1” percent donor cells. If the test detected donor cells but indicated donor cells “< n%,” report “n – 1” percent donor cells.

Chimerism Methods

Method	Description
Karyotyping for XX / XY	Cells are grown in culture, stained, and examined under a microscope to identify the number of cells matching the sex of the donor. This method is only valid when donor and recipient are sex mismatched.
Fluorescent in situ hybridization (FISH) for XX / XY	Cells are exposed to fluorescent DNA probes which attach to X and Y chromosomes. A microscope is used to identify the *number *of cells matching the sex of the donor. This method is only valid when donor and recipient are sex mismatched. Do not report FISH testing for disease-specific abnormalities in the chimerism section of the Post-TED.
Restricted fragment length polymorphisms (RFLP)	A restriction fragment is a portion of DNA which has been cut out by an enzyme. RFLP testing begins by isolating DNA from the sample. Enzymes are used to cut the DNA at specific loci resulting in many unique restriction fragments. The fragments are separated according to size by electrophoresis. The unique pattern of separation is used to identify the percent donor DNA present in the sample.
Variable number tandem repeat (VNTR), micro- or minisatellite	VNTR refers to a portion of DNA containing a repeating sequence of base pairs (micro- or minisatellite). The number of times a micro- or minisatellite repeats within specific loci can differ between individuals. These differences are used to distinguish donor DNA from recipient DNA. VNTR testing involves obtaining samples from the recipient and donor prior to transplant. Specific loci are compared to determine which loci contain VNTRs unique to the donor. After transplant, DNA is isolated from recipient samples. Donor-specific VNTRs are amplified by PCR techniques. The sample is then analyzed to determine the percent donor DNA present.
Small tandem repeat (STR), micro- or minisatellite	STR also refers to a portion of DNA containing a repeating sequence of base pairs (micro- or minisatellite). The number of times a micro- or minisatellite repeats within specific loci can differ between individuals. These differences are used to distinguish donor DNA from recipient DNA. STR testing involves obtaining samples from the recipient and donor prior to transplant. Specific loci are compared to determine which loci contain STRs unique to the donor. After transplant, DNA is isolated from recipient samples. Donor-specific STRs are amplified by PCR techniques. The sample is then analyzed to determine the percent donor DNA present.
Amplified fragment length polymorphisms (AFLP)	A restriction fragment is a portion of DNA which has been cut out by an enzyme. AFLP testing begins by isolating DNA from the sample. Enzymes are used to cut the DNA at specific loci resulting in many unique restriction fragments. Many restrictions fragments are amplified using PCR techniques. The fragments are separated according to size by electrophoresis. The unique pattern of separation is used to identify the percent donor DNA present in the sample. Report AFLP testing using the VNTR/STR method option on the 2450 form.

Chimerism Cell Types

Cell Type	Description
Unsorted / whole	The peripheral blood or bone marrow sample has not been sorted or selected for a certain cell line.
Red blood cells	Also known as RBCs or erythrocytes; carry the CD235a cell marker
Hematopoietic progenitor cells	Includes CD34+ cells
Total mononuclear cells	Total mononuclear cells would be a specimen containing only and both lymphocytes and monocytes
T cells	Includes CD3+, CD4+, and / or CD8+ cells
B cells	Includes CD19+ or CD20+ cells
Granulocytes	Also known as polymorphonuclear leukocytes (PMNs, PMLs) and includes neutrophils, eosinophils, and basophils. Includes CD33+ cells
NK cells	Includes CD56+ cells
Other, specify	Use this option to report cell types that do not fit in a category above.

Section Updates:

Question Number	Date of Change	Add/Remove/Modify	Description	Reasoning (If applicable)
Q60- 74	7/20/2023	Add	Clarification added on how to report haplo cords: When reporting chimerism studies for multiple donors, there should be one instance for each donor for each chimerism test results. For haplo cords, (i.e., haplo donor PBSC and CBU), there should be an instance for both the CBU and the PBSC.	Added for clarification

Copyright © 2004-2024 The Medical College of Wisconsin, Inc. and NMDP. All Rights Reserved.
CIBMTR® (Center for International Blood and Marrow Transplant Research) is a research collaboration between the Medical College of Wisconsin and NMDP.