Gilbert syndrome (GS) is a syndrome in which the liver of affected individuals processes bilirubin more slowly than the majority. Many people never have symptoms. Occasionally jaundice (a slight yellowish color of the skin or whites of the eyes) may occur.Gilbert syndrome is due to a genetic variant in the UGT1A1 gene which results in decreased activity of the bilirubin uridine diphosphate glucuronosyltransferase enzyme. It is typically inherited in an autosomal recessive pattern and occasionally in an autosomal dominant pattern depending on the type of variant. Episodes of jaundice may be triggered by stress such as exercise, menstruation, or not eating. Diagnosis is based on higher levels of unconjugated bilirubin in the blood without either signs of other liver problems or red blood cell breakdown.Typically no treatment is needed. Gilbert syndrome is associated with decreased cardiovascular health risks. If jaundice is significant phenobarbital may be used, which aids in the conjugation of bilirubin. Gilbert syndrome affects about 5% of people in the United States. Males are more often diagnosed than females. It is often not noticed until late childhood to early adulthood. The condition was first described in 1901 by Augustin Nicolas Gilbert. Signs and symptoms
Jaundice
Gilbert syndrome produces an elevated level of unconjugated bilirubin in the bloodstream, but normally has no consequences. Mild jaundice may appear under conditions of exertion, stress, fasting, and infections, but the condition is otherwise usually asymptomatic.
A meiosis I error can result in isodisomic UPD if the gene loci in question crossed over, for example, a distal isodisomy would be due to duplicated gene loci from the maternal grandmother that crossed over and due to an error during meiosis I, ended up in the same gamete. A meiosis II error can result in heterodisomy UPD if the gene loci crossed over in a similar fashion. Phenotype
Most occurrences of UPD result in no phenotypical anomalies. However, if the UPD-causing event happened during meiosis II, the genotype may include identical copies of the uniparental chromosome (isodisomy), leading to the manifestation of rare recessive disorders. UPD should be suspected in an individual manifesting a recessive disorder where only one parent is a carrier. Uniparental inheritance of imprinted genes can also result in phenotypical anomalies. Although few imprinted genes have been identified, uniparental inheritance of an imprinted gene can result in the loss of gene function, which can lead to delayed development, intellectual disability, or other medical problems. The most well-known conditions include Prader–Willi syndrome and Angelman syndrome. Both of these disorders can be caused by UPD or other errors in imprinting involving genes on the long arm of chromosome 15. Other conditions, such as Beckwith–Wiedemann syndrome, are associated with abnormalities of imprinted genes on the short arm of chromosome 11.