Dubin-Johnson and rotor syndromes: A review and update of pathophysiological mechanisms
image: RS and DJS are benign genetic causes of conjugated hyperbilirubinemia due to defects in hepatocellular transport of conjugated bilirubin and organic anions. DJS arises from MRP2 mutations that impair canalicular efflux of bilirubin glucuronides, producing conjugated hyperbilirubinemia. RS results from reduction or loss of function of the sinusoidal uptake transporters OATP1B1 and OATP1B3, leading to impaired hepatic clearance of conjugated bilirubin and increased urinary coproporphyrin excretion. In adults, both disorders follow a benign course, with fluctuating jaundice, preserved hepatic function, and no risk of progression to chronic liver disease. In DJS, some newborns have been reported to develop cholestasis, which was self-limited and resolved spontaneously with hepatic maturity. Importantly, impaired transporter activity may influence drug disposition, underscoring the need for clinical awareness to prevent misdiagnosis and to anticipate drug–disease interactions. Extensive liver testing, biopsy, and genetic analysis are typically unnecessary and should be reserved for atypical cases or diagnostic uncertainty. Management requires no specific therapy. Reassurance of benign outcomes is important, and genetic counseling may be appropriate for families with confirmed mutations or when there is concern for inheritance.
Credit: Bianca Thakkar
Dubin‑Johnson syndrome (DJS) and Rotor syndrome (RS) are rare autosomal recessive disorders causing chronic conjugated hyperbilirubinemia without cholestasis or liver injury. DJS results from ABCC2 mutations impairing canalicular excretion of conjugated bilirubin via MRP2. RS results from combined OATP1B1 and OATP1B3 deficiencies impairing hepatic reuptake of conjugated bilirubin from sinusoidal blood. Key distinctions include black hepatic pigmentation and markedly elevated urinary coproporphyrin I in DJS, versus normal liver appearance and moderate coproporphyrin I predominance in RS. Both conditions affect drug disposition. Recognition is essential to prevent misdiagnosis and anticipate drug interactions. This review synthesises current evidence on these syndromes and their relevance to hepatic transporter physiology.
Introduction
DJS and RS are benign genetic causes of chronic conjugated hyperbilirubinemia. DJS is due to ABCC2 mutations encoding the canalicular transporter MRP2. RS is due to simultaneous mutations in SLCO1B1 and SLCO1B3 encoding sinusoidal OATP1B1 and OATP1B3. Both are rare, often underdiagnosed, and have implications for drug metabolism.
Physiology of Bilirubin Excretion
Conjugated bilirubin is excreted into bile via canalicular MRP2. When saturated, MRP3 on the sinusoidal membrane exports it back into blood, where OATP1B1/1B3 mediate re‑uptake into downstream hepatocytes, preventing saturation of proximal detoxification. Bile salt secretion involves NTCP/OATP1B1/1B3 for uptake, and BSEP (primary) and MRP2 (secondary) for canalicular excretion; MRP3 provides a basolateral escape route.
Dubin‑Johnson Syndrome
Epidemiology: Rare; highest in Iranian and Moroccan Jewish populations (~1 in 1,300). Onset typically in adolescence; males earlier. Both genders affected equally.
Pathophysiology: Autosomal recessive ABCC2 mutations cause MRP2 loss. Conjugated bilirubin accumulates and is redirected via MRP3 into blood. Compensatory MRP3 upregulation prevents significant cholestasis. Stress, infection, pregnancy, and oral contraceptives can precipitate jaundice. Neonatal cholestasis occurs rarely due to immature MRP3, resolving with maturation.
Clinical Presentation: Intermittent jaundice and dark urine in adolescence; episodes last days to weeks and resolve spontaneously. Pruritus is absent. Black hepatic pigmentation (incidental) results from defective epinephrine metabolite excretion forming melanin‑like pigments.
Laboratory Findings: Total bilirubin 2–5 mg/dL, >50% conjugated. Normal transaminases, ALP, GGT, albumin, PT. Classic: normal total urinary coproporphyrin but >80% coproporphyrin I. Impaired excretion of MRP2 substrates (e.g., certain antibiotics, chemotherapeutics) can alter drug pharmacokinetics.
Imaging & Histopathology: Hepatobiliary scintigraphy shows delayed uptake and persistent liver enhancement. Liver biopsy reveals black pigment granules in centrilobular hepatocytes (PAS‑positive, not bile pigment).
Clinical Course: Benign, non‑progressive. No treatment required. Genetic counselling available.
Rotor Syndrome
Pathophysiology: Autosomal recessive; requires biallelic pathogenic variants in both SLCO1B1 and SLCO1B3. OATP1B1/1B3 loss impairs hepatic reuptake of conjugated bilirubin, which accumulates in blood and is renally excreted. Canalicular MRP2 remains intact, so bile flow is normal and cholestasis does not occur. Glucuronidated bile acids accumulate, but total bile acids are not elevated.
Clinical Presentation: Mild, non‑episodic conjugated hyperbilirubinemia with intermittent jaundice and dark urine. Not triggered by stress, pregnancy, or estrogens. No pruritus. Liver appears normal (no pigmentation).
Laboratory Findings: Total bilirubin 2–5 mg/dL, >50% conjugated. Normal transaminases, ALP, GGT. Hallmark: total urinary coproporphyrin increased 2.5–5× normal, with coproporphyrin I comprising ~65% of total. OATP1B1/1B3 deficiency substantially increases plasma levels of many drugs (statins, ezetimibe, ARBs, methotrexate, cyclosporine, rifampicin, antiretrovirals, anticancer agents).
Imaging & Histopathology: Scintigraphy shows minimal or absent hepatic uptake with prominent renal excretion. Liver biopsy is normal without pigment deposition.
Clinical Course: Benign, non‑progressive; no liver dysfunction. No treatment required. Avoid drugs that are OATP1B1/1B3 substrates.
Distinguishing Features
DJS and RS share conjugated hyperbilirubinemia but differ in pathophysiology, liver appearance, and urinary coproporphyrin patterns. DJS involves MRP2 (canalicular) dysfunction with black liver and >80% coproporphyrin I; RS involves OATP1B1/1B3 (sinusoidal) dysfunction with normal liver and ~65% coproporphyrin I. Neonatal cholestasis and pregnancy exacerbation occur only in DJS. Drug interactions differ: MRP2 substrates in DJS versus OATP1B1/1B3 substrates (broader and higher risk) in RS.
Conclusions
DJS and RS are benign genetic causes of conjugated hyperbilirubinemia with distinct molecular defects. Recognition prevents misdiagnosis and unnecessary invasive testing. Both have benign courses without progression to chronic liver disease. However, transporter defects significantly affect drug disposition, requiring clinical awareness of potential drug‑disease interactions. Genetic counselling may be appropriate for affected families.
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The study was recently published in the Journal of Clinical and Translational Hepatology.
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