Correlation and familial aggregation of dimensions of psychosis in affected sibling pairs from China.

BACKGROUND A number of studies with conflicting results have examined the familiality of schizophrenia syndromes in Western populations. AIMS The objective of this study was to determine, using clinical data from concordant sibling pairs, whether symptom dimensions and other clinical characteristics of schizophrenia show familial aggregation and are therefore potentially useful traits in genetic studies. METHOD We measured clinical and demographic features, and symptom dimensions of schizophrenia in 137 families from China who had two or more affected members with schizophrenia. Within-sibling pair correlation was assessed with intraclass correlation coefficient and kappa statistics. RESULTS Global functioning, positive, disorganisation and dysphoric symptoms, premorbid schizotypal and schizoid traits, premorbid social adjustment, type and age at illness onset all showed significant evidence of familial aggregation. DSM-IV schizophrenia subtypes were also found to be familial. CONCLUSIONS This is the first study in a large non-European population to confirm that schizophrenia dimensions and clinical characteristics show significant familiality, implying possible heritability. This supports their use in the delineation of homogeneous subsets for future genetic studies.