Genetic models of schizophrenia.

Multiple threshold models of inheritance are applied to a large sample of Franz Kallmann's (1938) pedigree data on schizophrenia. Paranoid and nonparanoid subtypes are represented in the models at different thresholds on a continuum of genetic-environmental liability. Single major locus and multifactorial-polygenic inheritance are ruled out as modes of transmission. These findings suggest that the paranoid-non-paranoid dichotomy cannot be used as a genetic threshold determinant in the population studied.