Gilbert Syndrome
What is Gilbert syndrome?
Gilbert Syndrome is a common, harmless genetic condition in which a liver enzyme essential to the disposal of bilirubin (the chemical that results from the normal breakdown of haemoglobin from red blood cells) is abnormal. The condition has also been referred to as constitutional hepatic dysfunction and familial nonhemolytic jaundice.It is due to a mutation 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 mutation.
Symptoms of Gilbert's syndrome
Most people with Gilbert's syndrome experience short-lived episodes of jaundice (yellowing of the skin and whites of the eyes) due to the build-up of bilirubin in the blood.
As Gilbert's syndrome usually only causes a slight increase in bilirubin levels, the yellowing of jaundice is often mild. The eyes are usually affected most.
Some people also report other problems during episodes of jaundice, including:
- abdominal (tummy) pain
- feeling very tired (fatigue)
- loss of appetite
- feeling sick
- dizziness
Some people with Gilbert syndrome also experience abdominal discomfort or tiredness. However, approximately 30 percent of people with Gilbert syndrome have no signs or symptoms of the condition and are discovered only when routine blood tests reveal elevated unconjugated bilirubin levels.
Genetic stats:
People with Gilbert syndrome have approximately 30 percent of normal bilirubin-UGT enzyme function. As a result, unconjugated bilirubin is not glucuronidated quickly enough. This toxic substance then builds up in the body, causing mild hyperbilirubinemia.
Not everyone with the genetic changes that cause Gilbert syndrome develops hyperbilirubinemia, indicating that additional factors, such as conditions that further hinder the glucuronidation process, may be necessary for the development of the condition.
Diagnosing Gilbert's syndrome:
Gilbert's syndrome can be diagnosed using a blood test to measure the levels of bilirubin in your blood and a liver function test.
When the liver is damaged, it releases enzymes into the blood. At the same time, levels of proteins that the liver produces to keep the body healthy begin to drop. By measuring the levels of these enzymes and proteins, it's possible to build up a reasonably accurate picture of how well the liver is functioning.
If the test results show you have high levels of bilirubin in your blood, but your liver is otherwise working normally, a confident diagnosis of Gilbert's syndrome can usually be made. In certain cases, a genetic test may be necessary to confirm a diagnosis of Gilbert's syndrome.
Differential diagnosis:
While Gilbert's syndrome is considered harmless, it is clinically important because it may give rise to a concern about a blood or liver condition, which could be more dangerous. However, these conditions have additional indicators:
Hemolysis can be excluded by a full blood count, haptoglobin, lactate dehydrogenase levels, and the absence of reticulocytosis (elevated reticulocytes in the blood would usually be observed in haemolytic anaemia).
Viral hepatitis can be excluded by negative blood samples for antigens specific to the different hepatitis viruses.
Cholestasis can be excluded by normal levels of bile acids in plasma, the absence of lactate dehydrogenase, low levels of conjugated bilirubin, and ultrasound scan of the bile ducts.
More severe types of glucuronyl transferase disorders such as Crigler–Najjar syndrome (types I and II) are much more severe, with 0–10% UGT1A1 activity, with sufferers at risk of brain damage in infancy (type I) and teenage years (type II).
Dubin–Johnson syndrome and Rotor syndrome are rarer autosomal recessive disorders characterized by an increase of conjugated bilirubin.
In GS, unless another disease of the liver is also present, the liver enzymes ALT/SGPT and AST/SGOT, as well as albumin, are within normal ranges.
