Accordingly, in this study, we investigated the association between ABCB1 genetic polymorphisms and ANS dysfunction in patients with schizophrenia treated with four atypical antipsychotic drugs—risperidone, olanzapine, quetiapine, and aripiprazole—to clarify whether ABCB1 genetic polymorphisms alter their adverse effects. The gene discussed is ABCB1; the disease is schizophrenia.