title: A homozygous nonsense mutation (c.214C->A) in the biliverdin reductase alpha gene (BLVRA) results in accumulation of biliverdin during episodes of cholestasis.
abstract: BACKGROUND
  Green jaundice is a rare finding usually associated with end-stage liver disease. OBJECTIVE The authors investigated two unrelated Inuit women from different geographical areas in Greenland who had episodes of green jaundice associated with biliary obstruction.
  
  
  RESULTS
  The crises were accompanied by increased biochemical markers of cholestasis, together with absent or moderate hyperbilirubinaemia. In contrast, high-performance liquid chromatography tandem mass spectrometry showed hypercholanaemia and high concentrations of biliverdin IXα in serum, urine, bile and milk. Hyperbiliverdinaemia disappeared after surgical correction of the cholestasis. Analysis of the coding sequence of the biliverdin reductase alpha (BVRα) gene (BLVRA) detected three single-nucleotide polymorphisms: c.90G→A, c.214C→A and c.743A→C, which result in p.Ala3Thr, p.Ser44X and p.Gly220Gly, respectively. With the use of TaqMan probes, homozygosity for c.214C→A was found in both patients. Both parents of one of these patients were heterozygous for the inactivating mutation. Her brother was homozygous for normal alleles. Although her sister was also homozygous for the c.214C→A mutation, she had never had hyperbiliverdinaemia or cholestasis. With the use of human liver RNA, the BVRα coding sequence was cloned, and the variant containing c.214C→A was generated by site-directed mutagenesis. Both proteins were expressed in human hepatoma liver cells and Xenopus laevis oocytes. Immunoblotting, immunofluorescence and functional assays of BVRα activity revealed that the mutated sequence generates a truncated protein with no catalytic activity.
  
  
  CONCLUSIONS
  This is the first report of a homozygous BLVRA inactivating mutation indicating that the complete absence of BVRα activity is a non-lethal condition, the most evident phenotypic characteristic of which is the appearance of green jaundice accompanying cholestasis episodes.
authors.affiliation: Queen Ingrid's Hospital, Nuuk, Greenland.
authors.forename: Nikolaj S
authors.initials: NS
authors.lastname: Nytofte
authors.forename: Maria A
authors.initials: MA
authors.lastname: Serrano
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Monte
authors.forename: Ester
authors.initials: E
authors.lastname: Gonzalez-Sanchez
authors.forename: Zeynep
authors.initials: Z
authors.lastname: Tumer
authors.forename: Karin
authors.initials: K
authors.lastname: Ladefoged
authors.forename: Oscar
authors.initials: O
authors.lastname: Briz
authors.forename: Jose J G
authors.initials: JJ
authors.lastname: Marin
mesh_terms: D000328:Adult; D000818:Animals; D001664:Biliverdine / Q000097:blood / Q000378:metabolism* / Q000652:urine; D002779:Cholestasis / Q000235:genetics* / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D003001:Cloning, Molecular; D018389:Codon, Nonsense; D005260:Female; D006801:Humans; D008892:Milk / Q000737:chemistry; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000235:genetics*; D011247:Pregnancy; D011248:Pregnancy Complications / Q000235:genetics*; D014981:Xenopus
chemical_list: D018389:Codon, Nonsense; D044925:Oxidoreductases Acting on CH-CH Group Donors; C019789:biliverdin reductase; D001664:Biliverdine