The most common genetic variant was short heme oxygenase (HO)-1 promoter GT-allele (<24 repeats) (39.4 %), followed by GA at nt388 in hepatic solute carrier organic anion transporter 1B1 (SLCO1B1) (31.1 %), GA at nt211 in UDP-glucuronosyltransferase 1A1 (UGT1A1) (29.3 %), ABO incompatibility (16.2 %), alpha thalassemia (5.0 %), and G6PD deficiency (3.2 %).
The recent identification of a variant promoter in the gene encoding for the bilirubin uridine-diphosphoglucuronosyl-transferase (UGT-1 A) associated with Gilbert's syndrome, allowed us to explore whether the presence of this variant promoter is a risk factor for the development of neonatal hyperbilirubinemia in normal newborns and in association with G6PD deficiency.