Adverse effects of atypical
antipsychotics (
AAP) can include obsessive-compulsive (OC) symptoms. Based on
biological evidence of the relationship between the glutamatergic system and both OC disorder and
AAP, this study aimed to determine whether DLGAP3, coding a post-synaptic scaffolding
protein of glutamatergic synapses, is associated with
AAP-induced OC symptoms. Furthermore, we explored the interactions between DLGAP3 and a previously reported susceptibility gene, the
glutamate transporter gene SLC1A1, regarding this phenotype. Subjects were clinically stable
schizophrenia patients receiving
AAP treatment (n = 94), and they comprised an OC group (n = 40) and a non-OC group (n = 54) (patients with and without
AAP-induced OC symptoms, respectively). We performed allelic/genotypic/haplotype association analyses for seven tag single-nucleotide polymorphisms of DLGAP3 and gene-gene interaction analyses with rs2228622 of SLC1A1, observing a nominally significant association between
AAP-induced OC symptoms and rs7525948 in both simple chi-square tests and the regression analyses (nominal P < 0.05). In the logistic regression analysis of gene-gene interaction, we found a significant interaction effect of rs7525948 of DLGAP3 and rs2228622 of SLC1A1 (permutation P = 0.036) on
AAP-induced OC symptoms, with a 30.2 times higher odds for individuals carrying risk genotypes at both loci in comparison with the reference group, which had no risk genotypes. This study provides suggestive evidence that DLGAP3 and its interactive effect with SLC1A1 might be involved in susceptibility to developing OC symptoms in
schizophrenia patients receiving
AAP treatment.