Personalized Chimerism Test that Uses Selection of Short Tandem Repeat or Quantitative PCR Depending on Patient's Chimerism Status

Short Tandem Repeats (STRs) as Biomarkers for the Quantitative Follow-Up of Chimerism after Stem Cell Transplantation: Methodological Considerations and Clinical Application

“…There were more informative (able to discriminate between donor and recipient) alleles for STR-PCR than for qPCR, when normalized to the number of alleles screened (12 and 33, respectively). Therefore, the mean percentage of informative loci was 31% for STR-PCR and 20% for qPCR ( Figure 3), which is concordant with previous publications [26].…”

“…Another practical issue of concern is chimerism follow-up, both to monitor engraftment early after transplant and to anticipate relapse, in patients that receive HSCT from different donors (two transplants from different donors, cord blood transplant with third-party Human Leukocyte Antigen (HLA)-mismatched donor, or double cord transplant). Because a biallelic marker is not able to differentiate between more than two individuals, it is very difficult to find enough markers when DNA from three different origins is present in a post-transplant sample [26]. As STR are highly polymorphic, in our experience, STR-PCR shows a good performance for the detection of DNA from three different individuals [27].…”

“…In our experience, the average total DNA in a pretransplant sample yields around 15 µg, which would be exhausted after 20 follow-up tests. Tyler et al [26] showed that although this issue is unlikely, the calculated reference (∆Cq) can be reused from the previous experiment with no significant differences if pretransplant DNA is exhausted.…”

“…Analysis by qPCR targeting insertion deletion polymorphisms (indel) is an easy and well-known technique, which achieves better sensitivity (0.01-0.1%) in PB and BM in comparison with STR-PCR [18,[20][21][22][23][24]. Nevertheless, the clinically significant threshold of recipient cell percentage is not yet well established, as well as the quantification capacity in comparison with STR-PCR, especially when high recipient cell percentages are present [21,25,26].…”

Monitoring of Chimerism in Rare Haematological Malignant Diseases after Allogeneic Haematopoietic Stem Cell Transplantation

“…A number of studies have shown that chimerism evaluation based on PCR amplification of polymorphic microsatellite STR markers is a readily applicable technique, informative almost for all patients, but less sensitive then real-time PCR of SNP and NPs DNA method. It is important to notice that complete, mixed chimerism, decreasing chimerism, and increasing chimerism are only the relative terms, because different laboratories have their own criteria to differentiate between complete donor chimerism and mixed decreasing chimerism, based on the method that is used, its sensitivity and local policies [43][44][45]. However, both provide a powerful tool in post-transplant decision making.…”