title: Glomerular involvement in the arthrogryposis, renal dysfunction and cholestasis syndrome.
abstract: BACKGROUND
  Arthrogryposis, renal dysfunction and cholestasis (ARC) syndrome is a multisystem autosomal-recessive disorder caused by defects in the VPS33B and VIPAR genes, involved in localization of apical membrane proteins. Affected children usually die by 1 year of age, often secondary to infective complications. The classic renal manifestation previously described in ARC syndrome is proximal-tubular dysfunction. The aim of this study is to gain further insight into the renal manifestations of this syndrome.
  
  
  METHODS
  Clinical review of three cases of ARC syndrome presenting to a tertiary centre. Together with measurement of VPS33B and VIPAR protein expression in the human glomerulus.
  
  
  RESULTS
  The cases demonstrated severe failure to thrive and in addition to commonly described features profound proteinuria and albuminuria, together with hypoalbuminaemia, suggesting glomerular involvement of this syndrome. Western blotting of conditionally immortalized human glomerular cells and ex vivo immunofluorescent analysis of the human glomerulus revealed that VPS33B and VIPAR were highly expressed in glomerular endothelium, and podocytes, but not in the mesangium.
  
  
  CONCLUSIONS
  ARC syndrome affects the glomerulus as well as the proximal tubule in the kidney. Our molecular studies suggest that both cell types that constitute the glomerular filtration barrier are affected in this condition, providing an explanation for the albuminuria that we have observed in our cases.
authors.affiliation: Department of Child and Adolescent Health , University of Bristol , Bristol , UK ; Department of Paediatric Nephrology , Bristol Royal Hospital for Children , Bristol , UK.
authors.forename: Amelia
authors.initials: A
authors.lastname: Holme
authors.affiliation: Academic Renal Unit , University of Bristol , Bristol , UK.
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Hurcombe
authors.affiliation: MRC Laboratory for Molecular Cell Biology , University College London , London , UK.
authors.forename: Anna
authors.initials: A
authors.lastname: Straatman-Iwanowska
authors.affiliation: Department of Paediatric Nephrology , Bristol Royal Hospital for Children , Bristol , UK.
authors.forename: Carol I
authors.initials: CI
authors.lastname: Inward
authors.affiliation: MRC Laboratory for Molecular Cell Biology , University College London , London , UK ; Department of Paediatric Metabolic Medicine , Great Ormond Street Hospital , London , UK.
authors.forename: Paul
authors.initials: P
authors.lastname: Gissen
authors.affiliation: Department of Paediatric Nephrology , Bristol Royal Hospital for Children , Bristol , UK ; Academic Renal Unit , University of Bristol , Bristol , UK.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Coward
keywords: ARC syndrome; VIPAR; VPS33B; albuminuria; glomerulus