LAUSR

Background Categorical syndrome such as schizophrenia could be the complex of many continuous mental structure phenotypes including several personality development/degeneration dimensions. Previous many models suggest that personality dimensions are heritable and influence the genetic loading of schizophrenia. The psychobiological model of personality suggests an individual's temperament is heritable and regulated by neurotransmission linked to the pathophysiology of schizophrenia. Recently, evidence has appeared that dimensions of character are also heritable and may influence the risk for schizotypy. This is the study to search heritability and familiality of personality dimensions in the Korean schizophrenic LD (Linkage Disequilibrium) families. Methods We have recruited 179 probands (with schizophrenia) with their parents and siblings whenever possible. We have used NEO questionnaires for measuring personality and symptomatic dimensions. Heritabilities of personality dimensions in total 472 family members were estimated using Sequential Oligogenic Linkage Analysis Routines(SOLAR). Personality dimensions in total family members were compared with those in 336 healthy unrelated controls for measuring the familialities using ANOVA analysis. Genetic/environmental correlations with symptomatic dimensions for significant personality dimensions aggregated in families were also investigated using SOLAR. Results Heritability: Four of the 5 NEO variables were significantly heritable and were included in the subsequent analyses. Familial aggregation: The three groups (control, unaffected 1st degree relative, case) were found to be significantly different and with the expected order of average group scores for all heritable dimensions. Low Extroversion and low Conscientiousness could differentiate the cases from the 1st degree relatives and controls qualitatively. Genetic/environmental correlation: genetic/environmental correlations with schizophrenic phenotype was suggested. Discussion Our results show that the aberrations in several personality dimensions could form the complexity of schizophrenic syndrome as a result of genetic-environment coactions or interactions in spite of some limitations (recruited family, phenotyping). Four of the five NEO variables (Extroversion, Conscientiousness, Neuroticism, Openness) were significantly heritable and were included in the subsequent analyses. Two endophenotypes (low Extroversion and low Conscientiousness) could differentiate the cases from the 1st degree relatives and controls qualitatively. The control, unaffected 1st degree relative, and case groups were significantly different and with the expected order of average group scores for two endophenotypes. (Neuroticism and Openness) Based on these results genetic and environmental correlations with schizophrenic phenotype was suggested. Finally, future genome-wide linkage and association studies with much more complete pedigrees are expected.