All subjects were enrolled at Yuwaprasart Waithayopathum Child Psychiatric Hospital, Samut Prakan, Thailand, and gave written informed consent for CYP2D6 genotype testing. The study was approved by the Ethics Committee of the Faculty of Medicine Ramathibodi Hospital, Bangkok, Thailand (MURA2017/556) and Yuwaprasart Waithayopathum Child Psychiatric Hospital, Samut Prakan, Thailand.