Influence of polymorphisms in genes SLC1A1, GRIN2B, and GRIK2 on clozapine-induced obsessive-compulsive symptoms.

RATIONALE

Clinical observations indicate that atypical antipsychotics, especially clozapine, induce obsessive-compulsive (OC) symptoms in schizophrenia patients. Recent data from neuroimaging and clinical trials suggest a role for altered glutamate neurotransmission in the etiology of OC disorder (OCD), and SLC1A1, GRIN2B, and GRIK2 have all been reported to regulate glutamate transmission and affect OCD pathophysiology.

OBJECTIVES

This study aimed to determine whether SLC1A1, GRIN2B, and GRIK2 are associated with clozapine-induced OC symptoms.

METHODS

A total of 250 clinically stable schizophrenia patients receiving clozapine treatment were recruited. The Yale-Brown Obsessive Compulsive Scale (Y-BOCS) was used to evaluate the severity of OC symptoms. Based on their Y-BOCS scores, 250 patients were divided into the OC and non-OC groups (patients with or without OC symptoms, respectively). Additionally, three reported OCD susceptibility polymorphisms, SLC1A1 (rs2228622), GRIN2B (rs890), and GRIK2 (rs1556995), were genotyped.

RESULTS

Trends of association with OC symptoms were observed in rs2228622A and rs890T alleles. SLC1A1 and GRIN2B interaction was found in the significant two-locus gene-gene interaction model (p = 0.0021), using the multifactor dimensionality reduction method. Further analysis showed a significant interaction between SLC1A1 and GRIN2B on the Y-BOCS score (F 6, 137 = 7.650, p < 0.001), and individuals with AA/TT genotypes had a significantly higher mean Y-BOCS score than those with other genotypes, except AG/TT.

CONCLUSIONS

These results suggest that SLC1A1, GRIN2B, and interactions between the two may potentially confer a susceptibility to OC symptoms in schizophrenia patients receiving clozapine.