CausesBy Mayo Clinic staff
Gilbert's syndrome is caused by an abnormal gene that you inherit from your parents. The gene controls an enzyme that helps break down bilirubin in your liver. With an ineffective gene, excess amounts of bilirubin build up in your blood.
How the body normally processes bilirubin
Bilirubin is a yellowish pigment that's made when your body breaks down old red blood cells. Bilirubin travels through your bloodstream to the liver. Normally an enzyme in liver cells breaks down the bilirubin and removes it from the bloodstream. The bilirubin passes from the liver into the intestines with bile. It's then excreted in stool. A small amount of bilirubin remains in the blood.
How the abnormal gene is passed through families
The abnormal gene that causes Gilbert's syndrome is common. Many people carry one copy of this abnormal gene. Two abnormal copies are usually needed to cause Gilbert's syndrome.
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