Current and emerging techniques for diagnostic mutation detection: an overview of methods for mutation detection.

1. Mutation Detection: An Introduction This chapter provides a broad overview of the range of mutation detection techniques that are now available. For the purposes of this chapter, a mutation can be defined as a sequence change in a test sample compared with the sequence of a reference standard. This definition implies nothing about the phenotypic consequences (e.g., pathogenicity) of a mutation. A polymorphism may be defined as a mutation that occurs in a substantial proportion (>1%) of a population and is tacitly assumed to be non-pathogenic, although the true pathogenicity may be unknown. A polymorphism has also been defined as a Mendelian trait that exists in the population, with the frequency of the more rare of the two alleles greater than 1–2% (1). If we accept that DNA sequence is a Mendelian trait, then the two definitions of polymorphism are the same. The detection of a single base change in the human genome requires a signal background ratio of 1 6 × 109—a formidable task. To achieve such selectivity in the field of electronics would require amplification and noise reduction, and it is no surprise that analogous processes are found in molecular genetics—for example, amplification by the polymerase chain reaction (PCR) and noise reduction by the stringent annealing of probes and primers. Mutation detection techniques can be divided into techniques that test for known mutations (genotyping) and those that scan for any mutation in a par-