Recombinant DNA techniques in medicine.

Medical applications of recombinant DNA technology are reviewed. The main impact of these techniques has been in the diagnosis of genetic disease and analysis of the underlying mutations. Two different methods can be used for the diagnosis of genetic disease. When the gene defect is known and DNA probes are available, it may be possible to establish the diagnosis directly. In many cases, however, the gene is unknown or the mutation cannot be detected easily. In these situations, it may still be possible to make a diagnosis. The genotype can be determined indirectly by linkage analysis using sequence variations which alter restriction sites (restriction fragment length polymorphisms) and DNA probes for loci close to the disease locus. Recombinant DNA techniques have also led to a process of 'reverse' genetics for identification and analysis of the causes of genetic disease. Genes can be located, isolated and characterized without any prior knowledge of their function. The nature of the gene product can then be determined and its role in the disease process defined.