XDx Laboratory

 

XDx Reference Laboratory

AlloMap® Molecular Expression Testing assesses gene expression profiles of heart transplant recipients.  Testing is performed only at the CLIA-certified XDx Reference Laboratory in Brisbane, CA.  

 

The AlloMap test is based on standard quantitative real-time polymerase chain reaction methodology (qRT-PCR) (Higuchi et al., 1992) using RNA isolated from peripheral blood mononuclear cells (PBMC).  qRT-PCR is a proven methodology for sensitive, specific and reproducible gene expression measurement. 

 

The XDx Reference Laboratory has optimized and standardized the performance of the AlloMap test processes and implemented extensive quality control procedures that ensure reproducible and reliable testing results. Of the 20 gene assays used in the test, 11 are used in the calculation of the AlloMap Test score and 9 are used for standardization and quality control.

 

Quality Control Testing

The relative expression of the quality control genes used in AlloMap testing provides data that assesses the quality of all aspects of the testing process. These include:

• RNA quantity and quality

There must be a sufficient quantity of purified RNA to perform 60 qRT-PCR reactions (20 genes in triplicate). The RNA must also meet acceptance criteria for purity, which includes testing for the presence of excess genomic DNA, which can interfere with gene expression measurement.

• Gene-specific measurement ranges

The measured quantity of each gene product must fall within an established range.

• Efficiency of  the qRT-PCR

The output of the polymerase chain reaction process, expected to double the target material every cycle, must fall within defined limits.

• Precision

Each of the 20 genes is tested in triplicate. The precision of the 3 replicates must be within an established specification.