CNS: Crigler-Najjar syndrome; HRQOL: health-related quality of life; IQ: intelligence quotient; NICU: neonatal intensive care unit; QOL: quality of life; SB5: Stanford-Binet intelligence scale: 5th edition; SF-36: Short Form 36 Health Survey Questionnaire; UDGT: uridine diphosphate glucuronosyl transferase; UGT1A1: uridine 5'-diphosphate glucuronosyltransferase; WHOQOL-BREF: World Health Organization Quality of Life Brief Version.