Finite mixture regression model analysis on antipsychotics induced weight gain: investigation of the role of the serotonergic genes.

Antipsychotics-induced weight gain is a complex phenomenon with a relevant underlying genetic basis. Polymorphisms of serotonin receptors and related proteins were genotyped in 139 schizophrenia patients and incorporated as covariates in a mixture regression model of weight gain in combination with clinical covariates. The HTR1D rs6300 polymorphism was showing a slight significance conferring risk for obesity (heavy weight gain group) under additive model. After correcting for multiple testing all the genetic predictors were non-significant, however the clinical predictors were associated with the risk of heavy weight gain. These findings suggest a role of ethnicity and olanzapine in increasing the risk for obesity in the heavy weight gain group and haloperidol protecting against heavy weight gain. The mixture regression model appears to be a useful strategy to highlight different weight gain subgroups that are affected differently by clinical and genetic predictors.