Ans. b (Epinephrine metabolite) (Ref. Robbins Pathologic basis of disease 7th/ 887-888; Table 18-4)Dubin-Johnson syndrome# Hereditary defect in hepatocellular excretion of bilirubin glucuronides across the canalicular membrane due to absence of the canalicular protein, the multidrug resistance protein 2 (MRP2; located on chromosome 10q24), that isresponsible for transport of bilirubin glucuronides and related organic anions into bile.# The liver is darkly pigmented owing to coarse pigmented granules within the cytoplasm of hepatocytes.# Electron microscopy reveals that the pigment is located in lysosomes, and it appears to be composed of polymers of epinephrine metabolites., not bilirubin pigment.# The liver is otherwise normal.# Apart from chronic /recurrent jaundice (fluctuating intensity), patients are asymptomatic and have normal life span.OTHER HEREDITARY HYPERBILIRUBINEMIASCrigler-Najjar syndrome type I# The enzyme UGT1A1 is completely absent.6# The liver is incapable of synthesizing a functional enzyme, and the colorless bile contains only trace amounts of unconjugated bilirubin.# The liver is morphologically normal by light and electron microscopy.# However, serum unconjugated bilirubin reaches very high levels, producing severe jaundice and icterus.# Without liver transplantation, this condition is invariably fatal.Crigler-Najjar syndrome type II# It is a less severe, nonfatal disorder in which UGT1A1 enzyme activity is greatly reduced, and the enzyme is capable of forming only monoglucuronidated bilirubin.# Almost all patients develop normally and the only major consequence is extraordinarily yellow skin from high levels of circulating unconjugated bilirubin; but there is a risk of neurologic damage from kemicterus.# Phenobarbital improves bilirubin glucuronidation by inducing hypertrophy of hepatic endoplasmic reticulum.Gilbert syndrome# It is a relatively common, benign, somewhat heterogeneous inherited condition presenting with mild, fluctuating hyperbilirubinemia.# Main cause is reduction in hepatic bilirubin glucuronidating activity (UGT1A1) to about 30% of normal.# Gilbert syndrome has no clinical consequence except for the anxiety.Rotor syndrome# It is a rare form of asymptomatic conjugated hyperbilirubinemia with multiple defects in hepatocellular uptake and excretion of bilirubin pigments.# The liver is not pigmented.# As with Dubin-Johnson syndrome, patients with Rotor syndrome exhibit jaundice but otherwise live normal lives.