CENTURY OF SCHIZOPHRENIA GENETICS - A REVIEW

Family risks in older studies of schizophrenia are briefly reviewed, pointing out difficulties that were responsible for considerable variability in the results as well as consequent problems with a genetic interpretation. The cumulative world data on twins and on foster-reared close relatives are also presented. Greatly improved precision in data on different relatives is seen in more recent investigations, due to application of more uniform methods of diagnosis and inclusion of the general population as one basic group. While the older data were difficult to explain, the newer results show a satisfactory fit to modified dominant inheritance when it is taken into account that penetrance must be expected to be elevated in certain classes of relatives burdened with extra risk factors.