5-HT2C, a serotonin (5-hydroxytryptamine, 5-HT) receptor, has been the subject of considerable research because of its high affinity for risperidone, an effective first-line atypical neurolepic drug.Recent studies have shown that upstream of the 5-HT2C gene including rs6318 (cys23ser) and rs3813929 (-759C/T), play a crutical role in psychiatric drug efficacy, as well as in side effects such as weight gain and eating disorder.However there have been inconsistencies in the research findings.We therefore postulated that the polymorphisms upstream of the gene might influence risperidone efficacy.