UGT1A1 and neonatal jaundice: Neonatal jaundice occurs in more than 60% of normal newborns during their first week of life (Bhutani and Johnson, 2009a; Bhutani and Johnson, 2009b; Karen et al., 2009) as a result of excessive unconjugated bilirubin (UCB) formation and transient inability of the neonatal liver to clear bilirubin rapidly enough from the blood owing to delayed expression of UGT1A1, encoding UDP-glucuronosyltransferase 1a1 (UGT1A1).