ABCB1 and schizophrenia: However, here further discrepancies are apparent in the literature, where the ABCB1 1236C>T polymorphism showed a significant association with response to risperidone (Xing et al., 2006) and an observed effect of the ABCB1 2677G>T and 3435C>T polymorphisms on risperidone-induced weight gain in patients with schizophrenia (Kuzman et al., 2008).