SCIENTIFIC BACKGROUND
Meulengracht (Gilbert) syndrome (Meulengracht's disease) leads to mild, chronically stable or intermittent, non-conjugated hyperbilirubinemia in the absence of structural liver disease or hemolysis. It is the most common disorder of the hepatic bilirubin metabolism and one of the most common causes of icterus neonatorum. Serum bilirubin concentration is about 1-6 mg/dl.
Meulengracht (Gilbert) syndrome is caused by a congenital, autosomal recessive restriction of the synthesis of bilirubin-UDP-glucuronyltransferase to about 30% residual activity. In most cases, the synthesis disorder is caused by a dinucleotide expansion in the TATA box region of the UGT1A1 gene (UGT1A1*28 allele, rs3064744), which reduces the transcription rate of the gene. The frequency of homozygous carriers of this promoter expansion is about 10-19% in the general population, with clinically manifested cases estimated at 2-12%. The phenotype is modulated by environmental factors and diet (fat, alcohol, and nicotine intake). In addition, carriers of UGT1A1 promoter expansion should expect intolerance symptoms during chemotherapy with irinotecan.
References
Memon et al. 2016, Pediatr Res. 79:378 / Strassburg 2010, Best Pract Res Clin Gastroenterol 24:555 / Perera et al. 2008, Pharmacotherapy 28: 755 / Teng et al. 2007, Clin Genet 72:321 / Servedio et al. 2005, Hum Mutat 25:325