II. Genotype-environment interaction in the schizophrenia spectrum: qualitative observations.

Previous reports from the Finnish Adoptive Family Study of Schizophrenia have documented significant interplay between genetics (G) and family rearing (E), leading to adoptee outcomes of schizophrenia spectrum disorders. Quantitative evidence for this interplay is significantly enhanced when both high genetic liability and severe environmental dysfunction are present. However, when either genetic liability is low or the rearing environment is healthy, the adoptees appear to be resiliently protected against a pathologic outcome.

I. Genotype-environment interaction in the schizophrenia spectrum: genetic liability and global family ratings in the Finnish Adoption Study.

In the Finnish Adoption Study, a national sample of adoptees with high versus low genetic liability for schizophrenia spectrum disorders was indexed by DSM-III-R diagnoses of their biological, adopting-away mothers. The rearing-family environments of the adoptees were independently evaluated from global ratings of directly observed adoptive family relationships. The interaction of high genetic liability and dysfunction of the rearing families predicted highly significantly to schizophrenia spectrum disorder of the adoptees at 21-year follow-up.

Observing relationships in Finnish adoptive families: Oulu Family Rating Scale.

Adoption studies were intended to separate genetic from environmental "causal" factors. In earlier adoption studies, psychiatric diagnostic labels for the adoptive parents were used as a proxy for the multiple dimensions of the family rearing environment. In the Finnish Adoption Study, research design provided the opportunity to study directly the adoptive family rearing environment.

Genotype-environment interaction in schizophrenia-spectrum disorder. Long-term follow-up study of Finnish adoptees.

Background: Earlier adoption studies have convincingly confirmed the importance of a genetic contribution to schizophrenia. The designs, however, did not incorporate observations of the rearing-family environment.

Aims: To test the hypothesis that genetic factors moderate susceptibility to environmentally mediated risks associated with rearing-family functioning.

Genetic boundaries of the schizophrenia spectrum: evidence from the Finnish Adoptive Family Study of Schizophrenia.

Objective: Identification of the genetically related disorders in the putative schizophrenia spectrum is an unresolved problem. Data from the Finnish Adoptive Family Study of Schizophrenia, which was designed to disentangle genetic and environmental factors influencing risk for schizophrenia, were used to examine clinical phenotypes of schizophrenia spectrum disorders in adopted-away offspring of mothers with schizophrenia spectrum disorders.

Method: Subjects were 190 adoptees at broadly defined genetic high risk who had biological mothers with schizophrenia spectrum disorders, including a subgroup of 137 adoptees at narrowly defined high risk whose mothers had DSM-III-R schizophrenia.