Electrophoretic methods for mutation detection and DNA sequencing

Since its development in 1985, polymerase chain reaction (PCR) has revolutionized basic and applied research (1,2). In 1993, Mullis was awarded the Nobel Prize in Chemistry for the development of PCR. With DNA or cDNA as a template, millions of copies of a target sequence are generated during the reaction. Introduction of the thermophilic Thermus aquaticus polymerase increased the specificity of the reaction and made automation and routine use possible (3-5). The ability of PCR to produce multiple copies of a discrete portion of the genome has resulted in its incorporation into techniques used in a wide variety of research and clinical applications. An extraordinary range of clinical applications of PCR have emerged, including diagnosis of inherited disease, human leukocyte antigen (HLA) typing, identity testing, infectious disease diagnosis and management, hematologic disease diagnosis and staging, and susceptibility testing for cancer. The development of technically simple and reliable methods to detect sequence variations in specific genes is becoming more important as the number of genes associated with specific diseases grows. DNA sequencing is considered the gold standard for characterization of specific nucleotide alteration(s) that result in genetic disease. Although sequencing was long considered too cumbersome, expensive, and operator dependent for use in the clinical laboratory, a combination of clinical need and improved technology has brought automated DNA sequencing into routine clinical use. However, even though sequencing technology is now firmly entrenched in the clinical molecular diagnostics laboratory, it is still too expensive and time-consuming for all the laboratory's mutation-detection needs. There are a number of PCR-based mutation-detection strategies that can be used to identify both characterized and uncharacterized mutations and sequence variations.