Dubin-Johnson syndrome (DJS) is a benign disorder of the liver which is inherited in an autosomal recessive manner and causes mild hyperbilirubinemia (Haimi-Cohen, Merlob, Marcus-Eidlits and Amir 511). It is seen most frequently among Iraqi and Iranian Jews, and is not usually diagnosed until adolescence. It is rarely seen in the neonatal period, and only occasionally presents as severe cholestasis at this age. Haimi-Cohen, Merlob, Marcus-Eidlits and Amir report on a pair of fraternal twins, one of whom displayed hyperbilirubinemia at birth. After extensive blood work and a laparotomy, the only finding was an intrahepatic paucity of bile ducts. The patient was treated with phenobarbital, and the bilirubin concentrations gradually returned to normal. Both twins presented with a history of jaundice at age 16 and were diagnosed with DJS.
DJS is classified as a metabolic disorder typically causing mild hyperbilirubinemia, a typical bromosulfophthalein curve, and black cytoplasmic pigment in the hepatocytes (512). However, this black pigment was not seen in the twin who exhibited hyperbilirubinemia neonatally (513). The authors explain that children with DJS often do not exhibit this pigment until age four. Coproporphyrin excretion in DJS patients is abnormal: in normal patients, coproporphyrin III represents more than 75 percent of the total urinary coproporphyrins, and a finding of more than 80 percent of coproporphyrin I when congenital erythropoietic porphyria has been excluded, is diagnostic of DJS. Another diagnostic feature of DJS is that bilirubin diester conjugates are more numerous than monoester conjugates, differentiating DJS from other hepatobiliary disorders.
The molecular basis for Dubin-Johnson syndrome has been identified, and has been found to be an absence of a functional multidrug resistance protein called, MRP2, with the symbol ABCC2, from the canalicular membrane of the he
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