Chapter 21 - Sources of Errors in Molecular Testing

Abstract

Molecular diagnostics is a rapidly growing discipline in laboratory medicine, with new methods and new applications continually becoming available and improvements being made. Molecular techniques are now routinely used in the diagnosis and management of many infectious diseases and are increasingly being applied to other areas such as cancer detection. A wide variety of nucleic acid detection methods are available, including amplified and nonamplified techniques. Many assays are commercially available and approved by the U.S. Food and Drug Administration, allowing laboratories to implement them relatively easily. Improvements to molecular assays include simplified formats (extraction, amplification, and detection in a single device) and automated extraction platforms that allow large numbers of samples to be processed at one time. Qualitative as well as quantitative molecular techniques are commercially available, and some laboratories develop their own home-brew assays. Despite the enormous improvements made during the past few years, occasional problems occur in molecular diagnostic laboratories. Several fundamental features of molecular testing require laboratories to be alert for problems with testing that may give rise to erroneous results. Some of the more frequently seen interferences that can occur with molecular testing are discussed in this chapter. As with other sections of the laboratory, a strong program of quality control and quality assurance is necessary for detection of problems, monitoring of errors, and implementing methods to improve quality if systematic errors are occurring in the molecular laboratory. Although analytical errors can occur with molecular testing, good-quality control programs mean that errors are kept to a minimum. This chapter outlines the most common interferences in molecular diagnostics testing and describes methods to prevent and deal with these problems.