Haplotype-based association of HTR2A rs6311-rs6313 with early risperidone-clozapine response in Batak patients with schizophrenia.

Background

Risperidone-clozapine response varies substantially in schizophrenia. HTR2A polymorphisms may influence antipsychotic response, but rs6311-rs6313 haplotypes remain unexplored in the Indonesian Batak population. This study evaluated associations of HTR2A rs6311-rs6313 with early risperidone-clozapine response.

Methods

This prospective observational case-control study included 160 Batak inpatients with schizophrenia, comprising 80 responders and 80 nonresponders to risperidone-clozapine therapy. Genetic analyses included Hardy-Weinberg equilibrium (HWE), minor allele frequency (MAF), linkage disequilibrium, genotype and allele association, haplotype, permutation testing, genetic models, and multivariable logistic regression.

Results

Genotype distributions conformed to HWE (P > 0.05), with both variants showing a MAF of 0.28 and strong linkage disequilibrium (r2 = 0.969, D' = 0.98). The rs6311 GG/rs6313 CC genotype was significantly associated with nonresponse to risperidone-clozapine therapy [odds ratio (OR) = 3.69, 95% confidence interval (CI): 1.10-12.36; P = 0.034], while the rs6311 G/rs6313 C allele was also associated with nonresponse (OR = 1.71, 95% CI: 1.04-2.80; P = 0.034). The recessive model remained significant after multivariable adjustment (adjusted OR = 3.36, 95% CI: 1.02-11.07; P = 0.046). TA and CG haplotypes remained significant after 10 000 permutations (P = 0.0415 and P = 0.0416), whereas single-marker associations lost significance (P = 0.0607).

Conclusion

HTR2A variation was associated with early risperidone-clozapine response, with consistent signals under the recessive model and at the haplotype level. Haplotype associations remained significant after permutation correction, suggesting that haplotype analysis may provide a more robust approach for detecting pharmacogenetic contributions to treatment response.