title: Identification of COL4A5 defects in Alport's syndrome by immunohistochemistry of skin.
abstract: BACKGROUND
  The COL4A3-COL4A4-COL4A5 network in the glomerular basement membrane is affected in the inherited renal disorder Alport's syndrome (AS). Approximately 85% of the AS patients are expected to carry a mutation in the X-chromosomal COL4A5 gene and 15% in the autosomal COL4A3 and COL4A4 genes. The COL4A5 chain is also present in the epidermal basement membrane (EBM). It is predicted that approximately 70% of the COL4A5 mutations prevent incorporation of this chain in basement membranes.
  
  
  METHODS
  We investigated whether or not COL4A5 defects could be detected by immunohistochemical analysis of the EBM. Punch skin biopsies were obtained from 22 patients out of 17 families and two biopsy specimens from healthy males were used as controls.
  
  
  RESULTS
  In four cases with the COL4A5 frameshift or missense mutations, the COL4A5 chain was either lacking from the EBM (male) or showed a focally negative pattern (female). In three other patients with a COL4A5 missense mutation, a COL4A3 and a COL4A4 mutation, respectively, the COL4A5 staining was normal. A (focally) negative EBM-COL4A5 staining was found in three patients of six families with a diagnosis of AS and in one family of a group of four families with possible AS.
  
  
  CONCLUSIONS
  The (focal) absence of COL4A5 in the EBM of skin biopsy specimens can be used for fast identification of COL4A5 defects. Combined with polymorphic COL4A5 markers, both postnatal and prenatal DNA diagnosis are possible in the family of the patient.
authors: Department of Molecular Cell Biology and Genetics, University of Maastricht, The Netherlands.
authors: F T
authors: FT
authors: van der Loop
authors: L A
authors: LA
authors: Monnens
authors: C H
authors: CH
authors: Schröder
authors: H H
authors: HH
authors: Lemmink
authors: M H
authors: MH
authors: Breuning
authors: E D
authors: ED
authors: Timmer
authors: H J
authors: HJ
authors: Smeets
mesh_terms: D000911:Antibodies, Monoclonal; D001485:Basement Membrane / Q000378:metabolism*; D003094:Collagen / Q000235:genetics* / Q000378:metabolism*; D004252:DNA Mutational Analysis; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D009394:Nephritis, Hereditary / Q000175:diagnosis* / Q000235:genetics; D010375:Pedigree; D012867:Skin / Q000378:metabolism*
chemical_list: D000911:Antibodies, Monoclonal; D003094:Collagen