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

Abstract 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 ≥ 342µmol/l) in jaundiced term neonates admitted for phototherapy. Methods The inclusion criteria were normal term neonates (gestation ≥ 37 weeks). Parents/care-givers 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)7TAA (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.