Genetic Factors and Delayed TSB Monitoring and Treatment as Risk Factors Associated with Severe Hyperbilirubinemia in Term Neonates Admitted for Phototherapy

Objectives: This study aimed to determine whether maternal-fetal blood group isoimmunization, breastfeeding, birth trauma, age when first total serum bilirubin (TSB) was measured, age of admission, and genetic predispositions to hemolysis [due to genetic variants of glucose-6-phosphate dehydrogenase (G6PD) enzyme], and reduced hepatic uptake and/or conjugation of serum bilirubin [due to genetic variants of solute carrier organic anion transporter protein family member 1B1 (SLCO1B1) and uridine diphosphate glucuronosyltransferase family 1 member A1 (UGT1A1)] were significant risk factors associated with severe neonatal hyperbilirubinemia (SNH, TSB >= 342 mu mol/l) in jaundiced term neonates admitted for phototherapy. Methods: The inclusion criteria were normal term neonates (gestation >= 37 weeks). Parents/caregivers were interviewed to obtain data on demography, clinical problems, feeding practice and age when first TSB was measured. Polymerase chain reaction-restriction fragment length polymorphism method was used to detect common G6PD, UGT1A1 and SLCO1B1 variants on each neonate's dry blood specimens. Results: Of 1121 jaundiced neonates recruited, 232 had SNH. Logistic regression analysis showed that age (in days) when first TSB was measured [adjusted odds ratio (aOR) = 1.395; 95% confidence interval (CI) 1.094-1.779], age (in days) of admission (aOR = 1.127; 95% CI 1.007-1.260) and genetic mutant UGT1A1 promoter A(TA)(7)ATAA (aOR = 4.900; 95% CI 3.103-7.739), UGT1A1 c.686C>A (aOR = 6.095; 95% CI 1.549-23.985), SLCO1B1 c.388G>A (aOR = 1.807; 95% CI 1.242-2.629) and G6PD variants and/or abnormal G6PD screening test (aOR = 2.077; 95% CI 1.025-4.209) were significantly associated with SNH. Conclusion: Genetic predisposition, and delayed measuring first TSB and commencing phototherapy increased risk of SNH.