Chimerism Testing

Clinical Significance of Marrow Transplant Engraftment Monitoring (Chimerism Testing)

Marrow Transplant Engraftment (Chimerism) Monitoring assesses the relative ratio of donor and recipient cell populations in the post-transplant peripheral blood and/or bone marrow of the patient.

The early and reliable determination of donor engraftment, graft rejection, or disease relapse after transplantation is often difficult on clinical and/or morphologic grounds alone. Polymorphic DNA loci are segments of DNA that vary among individuals and provide clinically useful information.

The chimerism test is based on the detection of differences in allele types between the donor and recipient cells at several short tandem repeat (STR) loci. The length of the repeats (alleles) at each locus, as measured after DNA amplification, determines the allele types of the blood or marrow sample. The differences in the allele pattern of the two cell sources (graft donor and recipient) enables the lab to objectively distinguish donor and patient DNA and to determine the ratio of these two cell populations.

Experience

BRT has been testing for chimerism using STR technology since 1998 and has worked extensively with STR technology since 1997. The STR laboratory processes thousands of samples each year with protocols in place to ensure quality processing and testing of samples from the time of receipt until a report is transmitted. BRT participates in the CAP Chimerism Testing proficiency test and meets the quality requirements of a broad range of oversight agencies. Multiple accreditation reflects the commitment of BRT to its Quality Management System and dedication to providing its customers with timely and accurate services.

Test Sensitivity

Chimerism Testing using STRs has sufficient sensitivity to allow most phenotypes to be detected at levels of 2.5% of the total DNA, at a given locus. The information content of the test, which determines the specificity that enables related donors to be distinguished separately within the sample, is over 99.999%