Dopamine receptor DRD4 gene polymorphism and its association with schizophrenia spectrum disorders and personality traits of patients

A vast body of associative studies reported a role of highly polymorphic dopamine receptor DRD4 gene in regulation of emotional processes and development of mental disorders. The present study addresses allele, genotype and haplotype distribution of 3 polymorphic DRD4 markers (-809G/A, -616G/C n -521C/T) in Russian patients with schizophrenia spectrum disorders and their relation to the disease and personality traits. A sample included 151 patients with ICD-10 diagnosis of schizophrenia, schizoaffective psychosis and schizotypal personality disorders, 89 their first-degree non-psychotic relatives and 131 mentally healthy individuals. No differences in allele and genotype frequency was found between the patients and the controls. Transmission disiquilibrium test (TDT) did not reveal a preferential transmission of either allele from parents to proband. The 521C/T n -616G/C markers were linked to the disease when the Ell program has been used in the analysis. Patients with the GG (-809G/A) and GG (-616G/C) genotypes had higher scores on the Hypomania scale (MMPI) comparing to the GA(-809G/A)+AA(-809G/A) and GC(616G/C)+CC(-616G/C) genotypes but the association did not reach a level of significance (p=0,06). The results confirmed the literature reports on the relation of the DRD4 gene to schizophrenia and personality traits related to social activity.