Dubin–Johnson syndrome

Dubin–Johnson syndrome is an inherited disorder of bilirubin transport that causes chronic conjugated hyperbilirubinemia and dark pigmentation of liver cells, usually without liver damage.

ABCC2: ABCC2 is a gene encoding the canalicular transporter MRP2, which exports organic anions from liver cells into bile. Variants in this gene impair the transporter responsible for the syndrome’s bilirubin-excretion defect.
Conjugated hyperbilirubinemia: Conjugated hyperbilirubinemia is an elevated blood concentration of bilirubin that has been conjugated in the liver. It is the defining biochemical abnormality in this syndrome.
Rotor syndrome: Rotor syndrome is a rare inherited disorder causing chronic, usually harmless conjugated hyperbilirubinemia without dark liver pigmentation. It resembles this syndrome in blood tests but lacks its characteristic hepatic pigment.
Liver function tests: Liver function tests are blood measurements used to assess liver injury, bile-flow abnormalities, and synthetic function. They typically show isolated conjugated hyperbilirubinemia with otherwise largely normal results.
Prognosis: Prognosis is the expected course and outcome of a medical condition. The syndrome generally persists lifelong but does not shorten life or cause progressive liver damage.
MRP2: MRP2 is a transporter protein on the canalicular membrane of hepatocytes that moves conjugated organic compounds into bile. Its impaired activity traps conjugated bilirubin and other compounds within liver cells.
Bilirubin: Bilirubin is a yellow pigment formed mainly during the breakdown of heme in aging red blood cells. Its conjugated form accumulates in blood when hepatic export is impaired.
Gilbert syndrome: Gilbert syndrome is a common inherited condition causing mild, intermittent unconjugated hyperbilirubinemia. It elevates unconjugated rather than conjugated bilirubin and does not pigment the liver.
Urinary coproporphyrin: Urinary coproporphyrin is a measurement of porphyrin compounds excreted in urine, used in evaluating heme metabolism and liver transport. A characteristic shift in urinary coproporphyrin isomer proportions can support diagnosis.
Inheritance pattern: An inheritance pattern describes how a genetic trait or disorder is transmitted through families. Dubin–Johnson syndrome is usually inherited in an autosomal recessive pattern.

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