EXTENDED LATENT CLASS APPROACH TO THE STUDY OF FAMILIAL SPORADIC FORMS OF A DISEASE - ITS APPLICATION TO THE STUDY OF THE HETEROGENEITY OF SCHIZOPHRENIA/

When no method exists for detecting genetic forms of a disorder, epide miologists classify probands according to the presence or absence of a n affected relative (familial or sporadic). Not only is this a surroga te measure but if the risk for the disorder is associated with charact eristics such as age and gender, then probands with varied distributio ns of these characteristics among their relatives are subject to miscl assification. A latent class approach is presented which explicitly mo dels the relationship between the affected status of the relatives and the unobservable familial/sporadic status of the proband in order to adjust for these characteristics. Lastly, an approach is introduced to correct for attenuation in measures of association between familial/s poradic status and other variables that could result if probands are m isclassified. This approach incorporates the latent class probabilitie s directly into the regression model without classifying probands. The se methods are applied to a study of the heterogeneity of schizophreni a. (C) 1994 Wiley-Liss, Inc.