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Objective: This study was performed to assess the possible involvement of the dopamine D(sub 3) receptor gene (DRD3) in the etiology of schizophrenia. The authors' approach included a population study and a family study using both parametric (lod score) and nonparametric (affected pedigree member) methods of linkage analysis. Method: Two different DNA markers were studied at the DRD3 locus. The family study included 35 multiplex families of schizophrenic subjects for the linkage analyses. The population study involved 50 unrelated schizophrenic subjects and 50 normal comparison subjects from the same ethnic and geographic origin. Results: Whichever clinical classification was used to define the pathological phenotype (schizophrenia or schizophrenia spectrum), the results of the lod score and affected pedigree member studies did not provide any evidence of linkage of the DRD3 gene to the illness. The negative results of the association study reinforce these results. Conclusions: The hypothesis that the DRD3 gene has a predisposing role in schizophrenia was not supported by these population and family studies. However, the possibility that this gene has a role in the etiology of the disease cannot be definitely excluded because of the intrinsic limitations of the methods of analysis and the number of subjects studied.

Objective: The possibility that delusions of influence could be related to abnormal recognition of one's own actions was investigated in persons with schizophrenia. Method: Schizophrenic patients with (N=6) and without (N=18) delusions of influence were compared with normal subjects (N=29) on an action recognition task. The image of a virtual right hand holding a joystick was presented to the subjects through a mirror so that the image was superimposed on their real hand holding a real joystick. Subjects executed discrete movements in different directions. Angular biases and temporal delays were randomly introduced in some trials, such that the movement of the virtual hand departed from the movement executed by the subjects. After each trial, subjects were asked whether the movement they saw was their own. Results: Compared with normal subjects, both patient groups made significantly more recognition errors in trials with temporal delays. In trials with angular biases, the error rate of patients with delusions of influence significantly differed from that of comparison subjects and from that of patients without delusions of influence. Conclusions: The findings support the hypothesis that delusions of influence are associated with a quantifiable difficulty in correct self-attribution of actions. This difficulty may be related to a specific impairment of a neural action attribution system. (Am J Psychiatry 2001; 158:454-459)