Genetic epidemiologic studies of affective disorders in childhood and adolescence.

The application of the methods of genetic epidemiology appears to be one of the most promising avenues to unravel the complex mechanisms through which genes may exert their influence. The approaches of genetic epidemiology are particularly important for those diseases which are characterized by moderate degrees of heritability and lack of direct correspondence between the underlying vulnerability factors and the ultimate expression of the disease, as is the case for affective disorders. The application of the methods of genetic epidemiology to children of affected parents may also elucidate environmental risk factors and early signs of the disorder. Perhaps the most important implication of the identification of genetic markers for affective disorders is the opportunity for prevention of the disorders. Early identification of youngsters who do manifest early signs of the disorders would facilitate secondary and tertiary prevention of the consequences of those conditions.