Nonparametric linkage analysis between schizophrenia and candidate genes of dopaminergic and serotonergic systems

Background: Alterations in dopaminergic and serotonergic systems have been implicated in the pathophysiology of schizophrenia for many years. This study was performed to assess the possible involvement of the dopamine receptor genes D2 (DR(D2)), D3, D4, serotonin receptor genes (1Dalpha), (1Dbeta), and (2A) in the etiology of schizophrenia. Methods: We examined 33 multiplex schizophrenic families from Portugal . Results: Linkage analysis performed by GENEHUNTER showed nonsignificant linkage for these genes. A maximum nonparametric linkage score of 1.635 (P=.032) at DR(D2) gene was observed, and this finding suggests DR(D2) gene for further studies. Conclusion: the polymorphisms studied at dopamine receptor genes D3, D4, serotonin receptor genes 1Dalpha, 1Dbeta, and 2A do not have a major effect in susceptibility to schizophrenia in a Portuguese population.