TATA box polymorphism in the UDP-glucuronosyltransferase-1 gene promoter and neonatal hyperbilirubinemia

This study analyzed the role of the UDP-glucuronosyltransferase (UGT1A1) promoter polymorphism (mutant A[TA]₇TAA versus wild-type A[TA]₆TAA) in the pathophysiology of non-physiological hyperbilirubinemia, in Caucasian Portuguese neonates.

Typing for the TATA box polymorphism was carried out in a study group consisting of 77 jaundiced neonates (19 with physiological and 58 with non-physiological hyperbilirubinemia) and in a background control population consisting of 100 healthy non-jaundiced Caucasian neonates.

In the hyperbilirubinemic group without identified risk factors (n = 54), we found 50% normal homozygotes ([TA]₆/[TA]₆), 33.4% heterozygotes ([TA]₆/[TA]₇), 14.8% mutant homozygotes ([TA]₇/[TA]₇) and a single heterozygote with a TA deletion ([TA]₅/[TA]₆). No statistically significant difference was found between this genotype distribution and that observed in the control group (_² =1.585; p > 0.05). There was also no significant difference in genotype distribution between neonates with physiological and non-physiological hyperbilirubinemia (_² = 3.156; p > 0.05), neither were peak jaundice levels significantly different among the various genotypic groups (_² = 1.469; p > 0.05) except in the jaundiced population with associated risk factors.

Our results indicate that the TATA box polymorphism did not seem to be a major contributing factor to the development of neonatal hyperbilirubinemia in our population but, when associated with other risk factors, seemed to influence the peak jaundice levels.