Dopamine receptor D3 genotype association with greater acute positive symptom remission with olanzapine therapy in predominately caucasian patients with chronic schizophrenia or schizoaffective disorder.

OBJECTIVE

To test association of dopamine receptor D3 (DRD-3) gene polymorphisms with olanzapine response in genetic samples from a registration phase clinical trial.

METHODS

Eighty-eight acutely ill patients with schizophrenia or schizoaffective disorder were genotyped for ser-9-gly (rs6280) and 23 other polymorphisms within the DRD-3 gene. Allelic association of clinical response (mean baseline- to-endpoint reduction in Positive and Negative Syndrome Scale [PANSS] total and subscores) over 6 weeks of olanzapine treatment was assessed using repeated measures analysis of variance.

RESULTS

Ser-9-gly genotypes were associated with differences in PANSS total score improvement from baseline to 6 weeks (p = 0.021). This association was most notable for improvement in positive symptoms (p = 0.0001), with patients with gly/gly genotype significantly more responsive. More patients with the gly/gly genotype had greater positive symptom remission (endpoint rating of minimal or none on all PANSS positive items, 39.1%) compared with patients with gly/ser and ser/ser genotypes (13.8%; p = 0.033). DRD-3 polymorphisms in disequilibrium with ser-9-gly were also significantly associated with greater positive symptom improvement (p = 0.0009-0.021), and one not in complete linkage disequilibrium, with lesser improvement (p = 0.027).

CONCLUSIONS

Gly/gly DRD-3 genotype predicted statistically and clinically significantly better acute positive symptom reduction compared with other ser-9-gly genotypes in patients treated with olanzapine.