Genetics, behaviour and psychiatry: historical burdens and perspective

Familiar, twin, adoption and linkage studies represent the usual tools for assessing the possible role of genetics in mental disease. These genetic approaches have been refined in the last years and a number of methodological problems are absent in recent approaches. While there is no doubt that schizophrenia, mood disorders and autism are characterized by a genetic component no linkage study has been successful up to date, apart, probably, the case of autism. The existence of a genetic component does not minimize the role of the environment and of critical life events. It is also evident that no major genes are responsible for these psychiatric diseases: thus, quantitative trait loci analyses might prove fruitful in future research to track the role of different genes contributing to the outcome of different psychopathologies. The main problem, however, is the difficulty of carrying out quantitative analyses since the today's diagnostic tools do not allow a quantitative approach to these phenotypes.