Genetically confirmed Dubin-Johnson syndrome presenting as long-standing isolated conjugated hyperbilirubinaemia

Isolated hyperbilirubinaemia with normal liver enzymes is frequently attributed to Gilbert syndrome, but predominance of conjugated bilirubin warrants evaluation for inherited disorders of bilirubin transport. We report a genetically confirmed case of Dubin-Johnson syndrome in a young adult with a 10-year history of intermittent jaundice and persistently conjugated hyperbilirubinaemia, despite normal liver biochemistry and imaging. Extensive evaluation excluded haemolysis, viral hepatitis, autoimmune liver disease and structural biliary pathology. Targeted genetic testing identified a homozygous loss-of-function variant in the ABCC2 gene, establishing the diagnosis. The patient required no specific treatment and remained clinically stable on follow-up. This case emphasises the importance of recognising Dubin-Johnson syndrome in long-standing conjugated hyperbilirubinaemia and the role of genetic testing in avoiding unnecessary invasive investigations in this benign, non-progressive condition.