Limiting clinical heterogeneity in schizophrenia : can affected Xhosa sib pairs provide valid subtypes?
BACKGROUND Schizophrenia is a heterogeneous disorder, which has been shown to have both environmental and genetic risk factors. Since family history (genetic loading) of psychosis appears to be one of the strongest risk factors for the development of schizophrenia, the investigation of affected sib pairs can be used to explore shared familial factors. The Xhosa-speaking inhabitants in the Western, Eastern and Southern Cape provinces, an African population of relatively homogeneous ethnicity, provided a sample of the first large clinical phenotype of schizophrenia. AIM The main aim of this study was to identify shared symptoms or symptom clusters in a sample of Xhosa-speaking sib pairs, with the aid of structured assessment tools.