Abstract
The causes of neonatal hyperbilirubinemia in Asian and Caucasian population differ. There is a higher incidence of Asian forms of Gilbert's syndrome (GS), Southeast Asian Ovalocytosis, 6-glucose phosphatedehydrogenase deficiency, thalassemia and sickle cell anemia in the Asian population.
We describe a case of a eutrophic Vietnamese boy from the second pregnancy, who was admitted to the hospital for marked icterus and fatigue with unconjugated hyperbilirubinemia of 455 µmol/l. Laboratory examinations did not support suspicion of alloimmunization (blood type of the child 0+, mother B+, direct Coombs test negative), or increased haemolysis (reticulocytes 5.8 %o), liver function tests were normal.
Levels of bilirubin dropped rapidly after phototherapy, the boy was discharged and followed-up by general practitioner. At three weeks of age, the boy returns with total bilirubin level of 389 µmol/l.
The directly indicated molecular genetic examination documented the mutation c.211G>A (p.Gly71Arg) in the first exon of the UGT1A1 gene in a homozygous form. The gene encodes the enzyme bilirubin UDP-glucuronyltransferase, which is essential for the conjugation of bilirubin in hepatocytes.
It is important to emphasize that the prevalent mutation in GS in the Caucasian population is located in the promoter of the gene and that genetic testing for these mutation in the Caucasian population would miss this form of GS.