Categories: Homeostasis / metabolism phene

Links to possible relevant human trait(s) and/or gene(s) in OMIM: 237500 (trait)

Mendelian trait/disorder: yes

Mode of inheritance: Autosomal recessive

Disease-related: yes

Key variant known: no

Cross-species summary: Bilirubin is an orange bile pigment produced by the breakdown of haem and reduction of biliverdinin. Bilirubin often occurs conjugated with glucuronic acid. An excess of conjugated bilirubin in the blood is called hyperbilirubnaemia II or Dubin-Johnson syndrome. As with hyperbilirubinaemia I, there is also an excess of phylloerythrin in the blood. [Researched by Philippa Beard]

Species-specific description: The first report of this disorder in sheep was by Arias et al. (1964), who presented evidence of autosomal recessive inheritance in Corriedales, which appears to be a good model for the human disorder (Cornelius et al., 1965). The biochemical/molecular cause of this disorder has not yet been determined. [Researched by Philippa Beard]

Clinical features: Clinical signs include photodynamic dermatitis predominantly around the eyes, and on the ears, due to the increased blood and liver phyllorethrin concentration. Progressive anorexia and amaciation eventually leads to death within six months (Cornelius et al., 1965). On post mortem, the livers are dark brown to black, and there is some discolouration of the kidneys. No jaundice is observed. [Researched by Philippa Beard]

Pathology: Histopathology shows brown-black granules in hepatocytes and Kupffer's cells. Hepatic architecture is nowmal. [Researched by Philippa Beard]