Puneet Garg

Identification of genetic correlates of response to Risperidone: Findings of a multicentric schizophrenia study from India

Risperidone is most commonly used as an antipsychotic in India for treatment of schizophrenia. However, the response to treatment with risperidone is affected by many factors, genetic factors being one of them. So, we attempted to evaluate the association between dopamine D2 (DRD2) receptor, serotonergic (5HT2A) receptor and CYP2D6 gene polymorphisms and response to treatment with risperidone in persons with schizophrenia from North India. It was a multicentric 12-weeks prospective study, undertaken in patients diagnosed with schizophrenia according to International Classification of Diseases 10th revision, Diagnostic Criteria for Research module (ICD-10 DCR). Patients were treated with incremental dosages of risperidone. Nine gene polymorphisms from three genes viz. DRD2, 5-HT2A and CYP2D6 along with socio-demographical and clinical variables were analyzed to ascertain the association in response to risperidone treatment. The change in the Positive and Negative Syndrome Scale (PANSS) was used to measure the outcome. Significant differences in the frequencies of single nucleotide proteins (SNPs) rs180498 (Taq1D) and rs 6305 (C516T) polymorphisms were found amongst the groups defined according to percent decline in PANSS. The CYP2D6*4 polymorphism differed significantly when drop outs were excluded from analysis. Presence of DRD2 Taq 1 D2D2 and 5-HT2A C516T CT genotypes in patients were more likely to be associated with non-response to risperidone. Ser311Cys (rs1801028) mutation was absent in the North Indian patients suffering from schizophrenia.

An association study of dopaminergic (DRD2) and serotoninergic (5-HT2) gene polymorphism and schizophrenia in a North Indian population

The aim of this study was to investigate whether single nucleotide polymorphisms (SNPs) in DRD2 and 5-HT2 receptor genes are associated with schizophrenia in North Indian population. Four hundred forty-three patients who met ICD10-DCR criteria for schizophrenia were enrolled from six participating centers along with 443 genetically related healthy subjects and 150 genetically unrelated healthy participants. A total of 7 gene polymorphisms from DRD2 (rs1800497, rs1079597, rs1800498, rs1801028) and 5-HT2 A (rs6313, rs6311, rs6305) were genotyped for their association with schizophrenia. No significant difference was found in frequency of various genotypes and alleles of the studied markers for DRD2 and 5-HT2 A genes between the cases and their genetic controls. However, significant differences were noted for rs1079597 genotype (Taq1B; p = 0.039) and its allele frequencies (p = 0.029) in persons with schizophrenia and the unrelated healthy controls. The DRD2 (Taq1 A-B-D) and 5-HT2 A (rs6311-rs6313-rs6305) haplotype frequencies differed significantly for A2B1D2 [p = 0.038; OR = 0.685 (95%CI = 0.479-0.981)] and ACC [p = 0.001; OR = 0.621 (95%CI = 0.461-0.838)] for the cases vs genetically related healthy controls. Similarly, significant difference was observed for the frequencies of GCC [p = 0.006; OR = 0.692 (95%CI = 0.532-0.900)] and ACC [p < 0.001; OR = 3.622 (95%CI = 1.73-7.585)] in the cases and unrelated healthy controls. Unlike previous research from India as well as abroad, the predominance of B1 allele of rs1079597 in patients with schizophrenia and absence of Cys311 in all study participants is a salient difference. Concluding, the B2 allele of rs1079597 may increase the risk of schizophrenia while the A2B1D2 haplotype may be protective in North Indian population.