1 Division of Pediatric Gastroenterology, Department of Pediatrics, Chang Gung Children's Medical Center, Chang Gung Memorial Hospital, 5 Fu-Hsing Street, Guishan District, Taoyuan City, 33305, Taiwan; Chang Gung University College of Medicine, 259, Wenhua 1st Rd., Taoyuan City, 33302, Taiwan. Electronic address: hcchao1021@gmail.com.