Family-Genetic Studies of Psychiatric Disorders

During the past decade new concepts and technologies have improved the conduct of family-genetic studies in psychiatry. We compiled and critically evaluated these advances, including study design, pedigree collection, diagnostic procedures in adults and children, and epidemiologic and genetic approaches to data analysis. These approaches have improved the collection of accurate information on the nature and patterns of psychiatric illness in families. The data generated from well-designed and well-conducted family studies are useful for the identification of homogeneous subgroups of psychiatric disorders, for understanding the spectrum of psychiatric disorders, for examining the associations between psychiatric disorders, and for studying the continuity between adult and childhood manifestations of psychiatric disorders. Findings from these studies also may enhance our capacity to identify the mode of transmission of the psychiatric disorders and to select potentially informative families for future genetic linkage studies using the new recombinant DNA techniques. The adaptation of these methods to routine clinical practice and new directions in the application of family-genetic studies employing more refined assessments and analytic methods are also discussed.