Dubin-Johnson and Rotor Syndromes: A Review and Update of Pathophysiological Mechanisms.

Dubin-Johnson syndrome (DJS) and Rotor syndrome (RS) are rare, autosomal recessive disorders that result in chronic, predominantly conjugated hyperbilirubinemia without cholestasis or hepatocellular injury. Although both conditions are benign and non-progressive, they reflect distinct molecular defects in hepatocellular transport pathways. DJS arises from mutations in the ABCC2 gene encoding the canalicular transporter multidrug resistance-associated protein 2, leading to impaired biliary excretion of conjugated bilirubin and organic anions. In contrast, RS results from combined deficiencies of the sinusoidal transporters OATP1B1 and OATP1B3, encoded by SLCO1B1 and SLCO1B3 genes, respectively, which mediate hepatic reuptake of conjugated bilirubin from the sinusoidal blood. These defects explain the characteristic biochemical and clinical distinctions between the syndromes, including the black hepatic pigmentation and markedly elevated urinary coproporphyrin I fraction in DJS, and the absence of pigmentation with moderate coproporphyrin I predominance in RS. Recent studies have expanded the understanding of how these transporters influence not only bilirubin handling but also the hepatic disposition of various drugs and endogenous metabolites. Recognition of DJS and RS is essential to prevent misdiagnosis of cholestatic or hepatocellular disease, avoid unnecessary investigations, and anticipate altered pharmacokinetics in affected individuals. This review synthesizes current evidence from molecular, biochemical, and clinical studies to highlight how these syndromes illuminate broader principles of hepatic transporter physiology and its relevance to inherited and acquired disorders of bilirubin metabolism.