title: Molecular mechanisms of phenotypic variability in junctional epidermolysis bullosa.
abstract: BACKGROUND
  Junctional epidermolysis bullosa (JEB), a group of hereditary skin fragility disorders, is associated with a wide variety of phenotypes, although all forms are characterised by trauma induced skin blistering and tissue separation at the dermal-epidermal junction zone. A subgroup, coined JEB-other, is associated with mutations in the COL17A1 gene encoding collagen XVII or, more rarely, with mutations in the laminin 332 genes LAMA3, LAMB3, or LAMC2. The objective of this study is comprehensive genotype-phenotype analysis in JEB-other patients with COL17A1 mutations and elucidation of disease mechanisms underlying different skin phenotypes.
  
  
  RESULTS
  COL17A1 mutations and their clinical and cellular consequences were systematically analysed in 43 patients with JEB-other. Cell culture, RT-PCR, and protein biochemistry were applied to assess the effects of splice site mutations-that is, the nature and amounts of transcripts and polypeptides synthesised and their association with the phenotypic outcome. 34 distinct COL17A1 mutations were disclosed, 12 of them novel. mRNA and protein analyses demonstrated that patients with only about 12-14% of the physiological collagen XVII levels had mild cutaneous involvement and a long life span.
  
  
  CONCLUSIONS
  In contrast to complete null phenotypes, presence of minor amounts of collagen XVII protein in JEB skin is associated with mild phenotypic manifestations. The data have significant implications for design of molecular therapies for JEB, since they suggest that already a low extent of collagen XVII restoration will improve skin stability and alleviate symptoms.
authors.affiliation: Department of Dermatology, University Medical Center Freiburg, Hauptstr. 7, 79104 Freiburg, Germany.
authors.forename: Dimitra
authors.initials: D
authors.lastname: Kiritsi
authors.forename: Johannes S
authors.initials: JS
authors.lastname: Kern
authors.forename: Hauke
authors.initials: H
authors.lastname: Schumann
authors.forename: Jürgen
authors.initials: J
authors.lastname: Kohlhase
authors.forename: Cristina
authors.initials: C
authors.lastname: Has
authors.forename: Leena
authors.initials: L
authors.lastname: Bruckner-Tuderman
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001324:Autoantigens / Q000235:genetics*; D001483:Base Sequence; D002648:Child; D016109:Epidermolysis Bullosa, Junctional / Q000235:genetics* / Q000473:pathology*; D005786:Gene Expression Regulation; D023061:Gene Order; D056726:Genetic Association Studies; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation / Q000235:genetics; D024041:Non-Fibrillar Collagens / Q000235:genetics*; D010641:Phenotype; D022821:RNA Splice Sites / Q000235:genetics; D016415:Sequence Alignment; D012867:Skin / Q000473:pathology; D055815:Young Adult; D000097805:Collagen Type XVII
chemical_list: D001324:Autoantigens; D024041:Non-Fibrillar Collagens; D022821:RNA Splice Sites; D000097805:Collagen Type XVII