[Heritability of clinical forms of childhood schizophrenia].

Investigated and genetically analyzed were inheritance variants in 225 families of probands with different forms of development of child schizophrenia and 519 blood relatives as well as in 1714 relatives of the 2nd and 3rd grades. Child schizophrenia as seen from the viewpoint of the monogenic model of inheritance with total or partial penetrance of the "major" gene proved inconsistent with the characteristics of family history and population distributions in the disease. The multifactorial model appeared the most adequate to describe the susceptibility system. In the framework of this model the correlation between the susceptibility components specific for a clinical form could be derived from distinguishing between genotypic and environmental components. The data indicate that in malignant and slow progredient schizophrenia the probands were genotypically similar to a greater extent that they were in paroxysmal-progredient form, as revealed by the inheritance coefficient of the former group (28-35%) which was lower than that of the latter group (64%).