With this background, in the present study, we investigated 53 polymorphisms from five genes (RGS4, SLC6A3, PIP4K2A, BDNF and PI4KA) in 423 south Indian schizophrenia cases segregated into low and high severity of illness to assess their influence on antipsychotic response. The gene discussed is RGS4; the disease is schizophrenia.