Use of polymerase chain reaction for diagnosis of inherited disorders

The polymerase chain reaction (PCR) is a rapid method for generating a 10(6)- to 10(7)-fold increase in the number of copies of a discrete DNA or RNA sequence. The technique is being used for rapid prenatal diagnosis and carrier testing of several inherited disorders. After PCR, mutations producing single-gene disorders can be detected by several different methods, including endonuclease digestion and gel electrophoresis (applicable when a mutation affects an endonuclease recognition site), gel electrophoresis (used for detection of deletions), and hybridization to an oligonucleotide probe specific for a mutation. Less often, gene sequencing of a PCR product is used to rapidly identify a mutation. In addition, the PCR technique can be applied to polymorphism analysis to provide diagnosis by linkage analysis. In other areas, PCR is being used to detect and characterize microbial pathogens and to characterize mutations associated with carcinogenesis. The PCR method is useful in situations in which the amount of DNA sample is limited, such as in forensics and prenatal testing, or in which the quality of the DNA sample is poor.