Objective: Genetic mapping, the method of comparing an inheritance pattern of a disease to that of a chromosomal region, has brought about a revolution in the field of human inherited diseases. Diseases which exhibit a more complex pattern of inheritance now afford the next challange in the application of genetic mapping to the field of human disease. This article aims to review the application of genetic mapping to affective disorders.

Method: Review of literature concerning the molecular genetics of affective disorders.

Findings: This article describes the evidence for a genetic role in affective disorders, reviews the research to date and describes the difficulties arising out of the complex nature of these disorders.

Conclusions: Although progress to date in psychiatric genetics has been somewhat disappointing, the combined approach of using all the genetic tools currently available on large collections of affected individuals and families should enable the genetic basis of affective disorders to be identified.

The two major psychiatric disorders, schizophrenia and the major affective disorders are among the most common genetic conditions in man. The precise biochemical defects which cause these disorders are unknown. This article reviews the new recombinant DNA techniques and their application to date in attempting to locate the genes responsible for these disorders. As has been demonstrated for other genetic conditions, these techniques may help to elucidate the biochemical defects which lead to the development of the more genetic forms of these psychiatric illnesses.