Stage 1 analysis included 290 patients with epilepsy and revealed a higher load of adverse psychotropic side effects of LEV in patients carrying genetic variants associated with decreased dopaminergic activity: rs1611115 (dopamine-β-hydroxylase, DBH), rs4680 (catechol-O-methyltransferase, COMT), and rs1800497 (dopamine receptor D2-associated ANKK1 TAQ-1A).