Dubin–Johnson syndrome

Genetic liver disease

Dubin–Johnson syndrome is a rare, autosomal recessive, benign disorder that causes an isolated increase of conjugated bilirubin in the serum. Classically, the condition causes a black liver due to the deposition of a pigment similar to melanin. This condition is associated with a defect in the ability of hepatocytes to secrete conjugated bilirubin into the bile, and is similar to Rotor syndrome. It is usually asymptomatic, but may be diagnosed in early infancy based on laboratory tests. No treatment is usually needed. abnormal urinary color, biliary tract abnormality, and conjugated bilirubinemia. Impaired biliary excretion of bilirubin glucuronides is due to a mutation in the canalicular multiple drug resistance protein 2 (MRP2). A darkly pigmented liver is due to polymerized epinephrine metabolites, not bilirubin. Dubin–Johnson syndrome is due to a defect in the multiple drug resistance protein 2 gene (ABCC2), located on chromosome 10. In post mortem autopsy, the liver will have a dark pink or black appearance due to pigment accumulation. Plentiful canalicular multiple drug resistant protein causes bilirubin transfer to bile canaliculi. An isoform of this protein is localized to the apical hepatocyte membrane, allowing transport of glucuronide and glutathione conjugates back into the blood. High levels of gamma glutamyl transferase (GGT) help in diagnosing pathologies involving biliary obstruction.

Dubin–Johnson syndrome is a benign condition and no treatment is required. However, it is important to recognize the condition so as not to confuse it with other hepatobiliary disorders associated with conjugated hyperbilirubinemia that require treatment or have a different prognosis.

Prognosis is good, and treatment of this syndrome is usually unnecessary. Most patients are asymptomatic and have normal lifespans.