Amplification methods in the molecular diagnosis of genetic diseases.

The ability to amplify DNA by the polymerase chain reaction (PCR) technique has revolutionized our ability to test for genetic mutations. Many different assay systems are available for analyzing the amplified DNA and RNA. These techniques can be performed easily on material from adults, children, fetuses, and even single cells from blastomeres and polar bodies. The detection rate of the screening test, as well as the frequency of the mutation in the study population and the technical limitations of the procedure, will determine the usefulness of a positive or negative result. Preimplantation testing provides a paradigm for the ease of use of PCR-based testing, yet also underscores the problems encountered with genetic screening because of the multitude of possible mutations and the possible misinterpretation of results.