Chimerism Analysis

QTRACE^® Chimerism Analysis

The QTRACE^® Genotyping Plates, Monitoring Assays and Software meet the needs of any research application that requires highly sensitive detection and quantification of the genome of one individual in the background of another individual or individuals. A genetic chimera is an organism with two or more genetically distinct cell populations, i.e. cell populations with different genomes.

The presence of two different human genomes can also arise simply by mixing cells from two individuals, e.g. by cross-contamination of two cell lines or in forensic tissue samples.

In the monitoring (quantification) test, one or more of the informative assays identified in the genotyping test is used to quantify the DNA of interest in an unknown sample relative to a reference sample (calibrator). Any of the informative assays identified in the genotyping test can be used to perform a quantification test. The amount of the sample is determined relative to the amount of the same genome in the reference sample, and the result is expressed as a percentage (ratio). For example, a result of 5% indicates that there is 5% of genome A in the unknown sample relative to the reference sample. The simplest case assumes that the reference sample has 100% of genome A.

The informativeness of a multi-locus genotyping panel is a measure of the probability of finding at least one informative assay between two individual genomes (or DNA samples). Informativeness is calculated from the population frequency estimates of the alleles used to make up a multi-locus genotyping panel, and thus differs between ethnic populations. In addition, the informativeness of any panel of polymorphic loci is higher in unrelated individuals than in related individuals.

Once recipient specific markers have been found, quantification is performed to monitor engraftment. The fraction of DNA positive for the informative marker in the unknown composition is determined relative to the pure reference sample DNA and the result is expressed as a percentage (ratio).
The QTRACE^® Assays represent a rapid (results are obtained within 2.5 hours) and sensitive (the validated detection limit is 0.1% minor component of a genomic DNA mixture using 150 ng DNA input) solution for chimerism testing.

The QTRACE^® software was designed specifically for the QTRACE^® INDEL Assay Set. The software provides a streamlined workflow for both the genotyping and quantification tests. The sofware guides the user through assay setup, performs data analysis, generates results reports and stores the data collected for samples over time.