Peroxisome proliferator-activated receptor gamma PPARG) Pro12Ala: Lack of association with weight gain in psychiatric inpatients treated with olanzapine or clozapine

Background and Objective: Weight gain is a common problem of treatment with atypical antipsychotics. However, the dimension of body weight change differs interindividually, and various genetic factors are considered to be associated with this effect. Peroxisome proliferator-activated receptor gamma (PPARG) Pro12Ala polymorphism and its reported relationship to type 2 diabetes susceptibility and body mass accumulation prompted us to investigate the impact of this single nucleotide polymorphism (SNP) on antipsychotic-induced changes of body weight and body mass index (BMI) in a naturalistic study design. Methods: Included were 138 olanzapine- and 32 clozapine-treated psychiatric inpatients whose demographic data, medical anamnesis, and drug treatment were assessed at admission to hospital and 4 weeks thereafter. The PPARG Pro12Ala SNP was determined with a validated real-time PCR assay. Results: In contrast to previous investigations, we did not detect significant variations of weight gain among the different PPARG Pro12Ala genotypes. Conclusion: Our results suggest that the examined polymorphism appears to play a minor or no role in clinical practice concerning antipsychotic drug-induced weight gain.