Chimerism Testing and Engraftment Monitoring

Fast Facts

PATHCHAT Edition
Published: 2024
Please contact your local Ampath pathologist for more information.

Purpose of Chimerism Testing

✅ What is Chimerism Testing?

Used to confirm and monitor engraftment in patients who have received an allogeneic haematopoietic stem cell transplant (HSCT).
Detects early relapse and helps guide immunotherapy management decisions.

📌 Chimerism monitoring is essential for evaluating transplant success and early intervention in case of relapse.

✅ 1. Genetic Profiling (STR-Based Chimerism Testing)

Method:
- Semi-quantitative PCR amplification of genomic regions containing short tandem repeats (STRs).
Specimen Requirements:
- Pre-transplant:
  - Patient: Blood sample (EDTA) or buccal swab.
  - Donor: Blood sample (EDTA) or buccal swab.
- Post-transplant:
  - Patient: Blood/bone marrow sample (EDTA).
Limitations:
- Can be performed in both sex-matched and sex-mismatched HSCTs.
Turnaround Time:
- 72 hours from receipt in the laboratory.
Cost (2022 Prices):
- R1534.80 (pre-transplant testing).
- R1534.80 (post-transplant testing).

✅ 2. Fluorescent In Situ Hybridization (FISH) for Chimerism

Method:
- Application of fluorescent DNA probes specific to the X and Y chromosomes.
Specimen Requirements:
- Pre-transplant: None.
- Post-transplant: Blood/bone marrow sample (EDTA or Lithium Heparin tube).
Limitations:
- Only applicable in patients receiving sex-mismatched HSCTs.
Turnaround Time:
- 4 days from receipt in the laboratory.
Cost (2022 Prices):
- R3143.70.

📌 Genetic profiling is widely applicable, while FISH is restricted to sex-mismatched transplants.

✅ How to Request Testing

Genetic profiling can be requested using the mnemonic: DNAPCR.
For FISH requests or additional information, contact the Genetics team at:
- Phone: 012 678 1354.
- Email: chimerism@ampath.co.za.

📌 Ampath offers advanced chimerism testing to support post-transplant monitoring and clinical decision-making.