Application of traditional clinical pathology quality control techniques to molecular pathology.

Many molecular diagnostic laboratories have evolved from research laboratories, initially performing low numbers of homebrew assays, but many laboratories now perform more kit-based assays, with ever increasing test volumes. One such assay is assessment of bone marrow transplantation engraftment. Allogeneic bone marrow transplantation is performed primarily in the treatment of hematological malignancies. Monitoring of engraftment was traditionally evaluated using minisatellites (variable number tandem repeats) and Southern blotting, but most laboratories now use Food and Drug Administration-cleared microsatellite (short tandem repeats) kits to assess the extent of engraftment. With the increase in equipment reliability, the use of kit-based assays, and the desire to provide the highest quality clinical data, we began applying traditional clinical pathology quality control tools to the molecular diagnostics laboratory. In this study, we demonstrate this approach using a microsatellite-based bone marrow engraftment assay. We analyzed control samples (pure and mixed) for two different microsatellites to establish quality control parameters and constructed Levey-Jennings charts to monitor both the precision and accuracy of this assay. By incorporating these tools into an overall quality assurance program, a laboratory can identify systematic errors and perform corrective actions before actual assay failure, thereby improving the quality of patient care.