Conditions · Metabolism: heme, bilirubin and iron
Dubin-Johnson syndrome !
A benign inherited condition in which the liver poorly excretes conjugated bilirubin into bile; the liver looks black.
Updated 2026-11-01
Structures involved
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In biochemistry
In physiology
Why it happens
What it is
Chronic conjugated hyperbilirubinemia from failure of the canalicular transporter MRP2 (ABCC2 gene), with dark pigment in hepatocytes.
Who gets it
Rare; its highest frequency (about 1 in 1300) has been described among Jews of Iranian and Moroccan origin; isolated cases worldwide.
Causes
- Autosomal recessive inheritance: ABCC2 variants
Risk factors
- Pregnancy and oral contraceptives (increase jaundice)
Pathophysiology
Bilirubin is conjugated normally, but without MRP2 it cannot leave into the canaliculus and refluxes into the blood. A melanin-like pigment (adrenaline derivatives) collects in lysosomes and darkens the liver. Coproporphyrin excretion also changes: total urinary coproporphyrin is normal but over 80 % is isomer I.
Symptoms and signs
- Mild, intermittent jaundice
- Sometimes dark urine or right upper quadrant discomfort
- Many have no symptoms
Diagnosis
- Clinical
- Mild conjugated jaundice in a young adult with otherwise normal liver tests.
- Tests
- High direct bilirubin with normal alkaline phosphatase and transaminases; urinary coproporphyrins over 80 % isomer I; ABCC2 gene testing.
- Imaging
- Hepatobiliary scintigraphy shows prolonged liver visualisation with delayed gallbladder filling; ultrasound rules out obstruction.
Treatment
- Conservative
- No treatment is needed; its benign nature is explained
- Follow-up
- Watching jaundice during pregnancy or with hormonal contraceptives
Complications
- None serious; possible interactions with drugs excreted by MRP2
Prognosis
Excellent.
Test yourself
Think of the answer, then tap the question to see it.
Which transporter fails in Dubin-Johnson syndrome?
MRP2 (ABCC2), which pumps conjugated bilirubin into bile.
Which gross finding is typical of the liver in Dubin-Johnson?
A black liver from melanin-like pigment in lysosomes.
How do urinary coproporphyrins distinguish Dubin-Johnson from Rotor?
In Dubin-Johnson the total is normal with over 80 % isomer I; in Rotor the total is high.
Related conditions
Educational information, not medical advice. For any symptom, see a health professional.
Sources: Dubin-Johnson syndrome: MedlinePlus Genetics (MedlinePlus, US National Library of Medicine, 2026); ABCC2 gene: MedlinePlus Genetics (MedlinePlus, US National Library of Medicine, 2026); Bilirubin blood test: MedlinePlus Medical Encyclopedia (MedlinePlus, US National Library of Medicine, 2026).
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