Symptoms and the genetics of schizophrenia: implications for diagnosis

Abstract

To determine whether genetic influences in schizophrenia are related to the symptoms specified by diagnostic criteria, the case histories of 151 pairs of monozygotic twins from 5 twin studies of schizophrenia were rated for positive and negative symptoms. Concordance rates in monozygotic twins were significantly higher when probands had a greater number of negative symptoms; no evidence of a similar relationship was found for positive symptoms. Negative symptoms may be characteristic of schizophrenia in which there is a greater genetic component. Results have important implications for determining diagnostic criteria and understanding the pathogenesis of schizophrenia.