In 94% of GS cases, two other glucuronosyltransferase enzymes, UGT1A6 (rendered 50% inactive) and UGT1A7 (rendered 83% ineffective), are also affected.However, Gilbert syndrome can arise without TATA box promoter polymorphic variants; in some populations, particularly healthy Southeast and East Asians, Gilberts syndrome is more often a consequence of heterozygote missense mutations (such as Gly71Arg also known as UGT1A1*6, Tyr486Asp also known as UGT1A1*7, Pro364Leu also known as UGT1A1*73) in the actual gene coding region, which may be associated with significantly higher bilirubin levels.Because of its effects on drug and bilirubin breakdown and because of its genetic inheritance, Gilberts syndrome can be classed as a minor inborn error of metabolism. Diagnosis
People with GS predominantly have elevated unconjugated bilirubin, while conjugated bilirubin is usually within the normal range or is less than 20% of the total. Levels of bilirubin in GS patients are reported to be from 20 μM to 90 μM (1.2 to 5.3 mg/dl) compared to the normal amount of < 20 μM. GS patients have a ratio of unconjugated/conjugated (indirect/direct) bilirubin commensurately higher than those without GS.The level of total bilirubin is often further increased if the blood sample is taken after fasting for two days, and a fast can, therefore, be useful diagnostically. A further conceptual step that is rarely necessary or appropriate is to give a low dose of phenobarbital: the bilirubin will decrease substantially. Tests can also detect DNA variants of UGT1A1 by polymerase chain reaction or DNA fragment sequencing.
In German literature, it is commonly associated with Jens Einar Meulengracht.Alternative, less common names for this disorder include:
Familial benign unconjugated hyperbilirubinaemia
Constitutional liver dysfunction
Familial non-hemolytic non-obstructive jaundice
Icterus intermittens juvenilis
Low-grade chronic hyperbilirubinemia
Unconjugated benign bilirubinemia

Society and culture
Notable cases
Napoleon
Arthur Kornberg, Nobel laureate in Physiology or Medicine, 1959
Nicky Wire, Manic Street Preachers bassist
Alexandr Dolgopolov (tennis player)
Jonas Folger, MotoGP riderHuo Yuanjia (master of Chinese martial art)David Barnea (Mossad Chief)

References
External links
Understanding Gilberts Syndrome and living better with Gilberts Syndrome symptoms
Gilberts syndrome at NIHs Office of Rare Diseases
Gilberts Syndrome BMJ Best Practices monograph