Homozygosity of the interleukin-10 receptor 1 G330R allele is associated with schizophrenia

Infections of unknown origin and an altered immune response have been hypothesized to play a role in the pathogenesis of schizophrenia. We have previously identified two single nucleotide polymorphisms (SNPs) of the IL‐10 receptor 1 (IL‐10R1) causing a substitution of glycine 330 to arginine (G330R) and of serine 138 to glycine (S138G). A possible association between these IL‐10R1 variants and schizophrenia has been investigated in the present study. DNA of 101 unrelated Austrian patients with a DSM‐III‐R (Diagnostic and Statistical Manual of Mental Disorders) consensus diagnosis of schizophrenia (n = 70) or schizoaffective disorder (n = 31) and DNA of 121 German schizophrenic patients (DSM‐III‐R) was analyzed for the presence of S138G and G330R by allele‐specific multiplex PCRs. Data from patients were compared with 250 unrelated, psychiatric healthy controls. No difference in allele frequency was detected between patients and controls (G330R: 34.0% vs. 30.0%, P = 0.208; S138G: 19.7% vs. 16.6%, P = 0.235; by Fisher's exact test). However, there was a significant difference in genotype distribution (wt/wt, wt/mut, mut/mut) for G330R between patients (46.8%, 38.3%, 14.9%) and controls (47.6%, 44.8%, 7.6%; Fisher's test P = 0.032). No such difference was seen for S138G. Our results suggest that homozygosity of the IL‐10R1 G330R allele is associated with schizophrenia and may contribute to the expression of disease phenotype in susceptible individuals. © 2006 Wiley‐Liss, Inc.