CONCORDANCE OF POSITIVE AND NEGATIVE SYMPTOMS IN COAFFECTED SIB-PAIRS WITH SCHIZOPHRENIA.

Positive and negative symptom (NGS) dimensions were examined for their concordance in 46 coaffected schizophrenic sib- pairs. Results showed that the symptom dimensions of negative symptoms (NGS), delusion- hallucination(DHS), and thought disorganization (TDS) could be formulated. Discrete genetic endowment of these three symptom dimensions was not found as shown by the low concordance in sib pair analysis ( kappa = 0.20-0.30). Thirty-seven pairs (80.4%) and 21 pairs (45.7%) had liability, defined by the presence of NGS in any one member of the coaffected sib-pairs, of NGS of "any degree", and of "severe degree" in 46 sib-pairs, respectively. Both groups had high prevalence (59.1-81.0%) of positive symptoms. Another 9 (19.6%) and 25 (54.3%) pairs had no liability of NGS of "any degree" or of "severe degree" out of 46 sib- pairs, respectively. These two groups had high concordance ( kappa = 0.45-1.00) of TDS or DHS between coaffected sib- pairs. Based on the results, it is hypothesized that schizophrenia, as defined by DSM-III-R, may consist of two subtypes: one has liability of NGS and a high prevalence of positive symptoms, while the other has only positive symptoms