CPT® Code 81267

Chimerism (engraftment) analysis, post transplantation specimen (eg, hematopoietic stem cell), includes comparison to previously performed baseline analyses; without cell selection

Molecular genetic testing, specifically chimerism analysis, is a critical procedure performed to assess the extent of chimerism following hematopoietic stem cell transplantation. This analysis involves the identification of genetic profiles from both the donor and the recipient, allowing for a comprehensive evaluation of the proliferation of donor cells within the recipient's blood, bone marrow, or other tissues. The term "chimerism" refers to the presence of two genetically distinct cell lines within an individual, which can occur post-transplantation. It is important to note that while complete conversion to donor cells is a possible outcome, the presence of both donor and recipient cells does not necessarily indicate graft failure. The testing process utilizes genomic polymorphisms known as short tandem repeat (STR) loci, which consist of repeated core DNA sequences located at specific gene loci. These sequences contain information within their flanking regions, which are essential for creating oligonucleotide primer pairs used in the testing process. The polymerase chain reaction (PCR) amplification technique is employed to amplify the DNA samples, followed by separation of the strands through methods such as electrophoresis gel or capillary electrophoresis (CE). This PCR-based STR/CE method is particularly advantageous as it allows for the simultaneous testing of multiple DNA strands using minimal sample sizes. Additionally, this technique has demonstrated effectiveness in various applications, including the analysis of graft failure, severe leukopenia, hematopoietic cell subset fractions, double cord blood donor units, and cases involving a second transplant from a different donor.