rs274622

This pharmacogenetic study in 61 first-episode schizophrenia patients found that GRM3 rs1468412 TT genotype was associated with worsening spatial working memory performance after antipsychotic treatment (p=0.001, Cohen's d=0.75), while GRM3 rs6465084 AA genotype was associated with improved negative symptoms after treatment (p=0.046). No significant associations were found between COMT Val158Met or DRD2/ANKK1 variants and cognitive or symptom changes.

This genetic association and functional analysis study identified a rare Kozak sequence variant (rs148754219) in the GRM3 (metabotropic glutamate receptor 3) gene significantly associated with bipolar disorder in 1099 cases and 1152 controls (P=0.005, odds ratio 4.20). The variant was found in 1.7% of bipolar cases versus 0.3% of controls. Functional experiments demonstrated that the variant creates a novel transcription factor binding site and strongly suppresses translation of one GRM3 isoform, suggesting a mechanism for increased bipolar disorder risk.

This candidate gene association study examined 95 treatment-refractory schizophrenia patients genotyped for seven GRM3 markers. Two SNPs (rs1989796 and rs1476455) at the 3' end of the gene were significantly associated with global psychosis symptoms measured by BPRS total scores (rs1476455: CC genotype 55.1±10.4 vs A-carriers 48.3±9.2, F=7.6, p=0.0071; rs1989796: CC genotype 50.1±5.7 vs T-carriers 55.8±10.5, F=7.1, p=0.0091), but not with negative symptoms.

This comprehensive review examines the genomics of schizophrenia and pharmacogenomics of antipsychotic drugs, synthesizing evidence on over 200 genes associated with psychotic disorders. The authors discuss five categories of genes relevant to antipsychotic response: disease-associated genes, mechanism-of-action genes, drug metabolism genes (particularly CYP2D6, CYP2C19, CYP2C9, CYP3A4), drug transporter genes, and pleiotropic genes. The review details pharmacogenomic profiles of 20+ antipsychotic drugs and demonstrates significant ethnic and interindividual variation in drug metabolism phenotypes, with examples including CYP2D6 extensive metabolizers (55.71% of population), intermediate metabolizers (34.7%), poor metabolizers (2.28%), and ultra-rapid metabolizers (7.31%).

This systematic review of 98 studies examined biological predictors of clozapine response in treatment-resistant schizophrenia patients. Of 379 different gene variants investigated across 70 genetic studies, only three variants (DRD3 Ser9Gly rs6280, HTR2A His452Tyr, and GNB3 C825T) achieved independent replication. Non-genetic predictors included higher prefrontal cortical volumes and lower HVA:5-HIAA ratio in cerebrospinal fluid.

A systematic review of 98 studies investigating biological predictors of clozapine response in treatment-resistant schizophrenia. Of 70 genetic studies examining 379 variants, only three genetic variants have independently replicated findings: DRD3 Ser9Gly (rs6280), HTR2A His452Tyr, and GNB3 C825T (rs5442/rs5443). Non-genetic predictors include higher prefrontal cortical structural integrity and activity, and lower HVA:5-HIAA ratio in cerebrospinal fluid.

Replication study and meta-analysis of GRM3 gene polymorphisms (rs274622, rs1468412, rs2299225) in 1,916 Japanese schizophrenia patients and 1,915 controls found no associations with schizophrenia (allelic P=0.68-0.74). Meta-analysis of five case-control studies including >3,000 patients each also failed to support associations previously reported in Japanese and Chinese populations, with pooled odds ratios of 0.99 (rs1468412, P=0.87) and 1.01 (rs2299225, P=0.67).