Bilirubin Genetics for the Nongeneticist: Hereditary Defects of Neonatal Bilirubin Conjugation

Abstract
The UGT 1A1 gene controls bilirubin conjugation by determining the structure of the enzyme glucuronosyltransferase, which is synthesized in the hepatocyte. Like any gene, UGT 1A1 consists of coding and noncoding areas (Fig 1). Of primary importance to the subsequent discussion is the exon, that portion of the DNA molecule which carries the genetic code. Separating the exons from each other are the introns, which are noncoding sequences of base pairs, and thus are not expressed in protein synthesis. An additional noncoding area of the gene is the promoter (bottom left of Fig 1, top of Fig 2), which is an upstream regulatory region controlling gene expression. The UGT promoter contains a TATAA box, which is a DNA sequence of …