Research design considerations for linkage studies of affective disorders using recombinant DNA markers.

A genetic linkage study is one approach to resolving the etiology of a major psychiatric disorder either by testing involvement of a specific candidate gene or by demonstrating the existence of some unidentified gene in a specific place on the genome. Because of the complexities of psychiatric disorders, a successful linkage study must be built upon accurate and reliable diagnosis, families with multiple affected members, highly informative genetic markers, and powerful multipoint linkage methods. Over the last decade, great advances have been made in all these areas. Linkage studies are not only appropriate for affective and other major psychiatric disorders but are already beginning to yield promising results.