Utility of Single-Gene Testing in Cancer Specimens

This was followed by the introduction of the polymerase chain reaction (PCR) in 1983 allowing the analysis of small amounts of DNA and RNA. PCR revolutionized molecular diagnostics and led to an explosion in the number of new single-gene assays, which are tests that identify disease-associated genetic variants in a single target. PCR-based molecular testing frequently used capillary electrophoresis and hybridization with sequence-specific probes, and single-gene testing remained an excellent and dominant option for the next 3 decades. In 2005, next-generation sequencing (NGS) technology was developed and provided the ability to sequence multiple genes simultaneously using one sample. Later, the US Food and Drug Administration (FDA) approved NGS for clinical applications, leading to the introduction of competing platforms and a dramatic drop in the cost of DNA and RNA sequencing. During this genomic era, characterized by a wide variety of molecular technologies and extensive demand for mutation profiling, there remains significant uncertainty about the most practical and cost-effective approaches for a laboratory to adopt. Several considerations may be taken into account when deciding which molecular diagnostic tools to implement. In this review, we evaluate several single-gene testing options with regard to clinical indications, utilities, advantages, and limitations.