title: Mechanisms of natural gene therapy in dystrophic epidermolysis bullosa.
abstract: Revertant mosaicism has been reported in several inherited diseases, including the genetic skin fragility disorder epidermolysis bullosa (EB). Here, we describe the largest cohort of seven patients with revertant mosaicism and dystrophic EB (DEB), associated with mutations in the COL7A1 gene, and determine the underlying molecular mechanisms. We show that revertant mosaicism occurs both in autosomal dominantly and recessively inherited DEB. We found that null mutations resulting in complete loss of collagen VII and severe disease, as well as missense or splice-site mutations associated with some preserved collagen VII function and a milder phenotype, were corrected by revertant mosaicism. The mutation, subtype, and severity of the disease are thus not decisive for the presence of revertant mosaicism. Although collagen VII is synthesized and secreted by both keratinocytes and fibroblasts, evidence for reversion was only found in keratinocytes. The reversion mechanisms included back mutations/mitotic recombinations in 70% of the cases and second-site mutations affecting splicing in 30%. We conclude that revertant mosaicism is more common than previously assumed in patients with DEB, and our findings will have implications for future therapeutic strategies using the patient's naturally corrected cells as a source for cell-based therapies.
authors.affiliation: Department of Dermatology and Venereology, University Medical Center, Freiburg, Germany.
authors.forename: Dimitra
authors.initials: D
authors.lastname: Kiritsi
authors.affiliation: Department of Bioengineering, Universidad Carlos III de Madrid, Regenerative Medicine Unit, CIEMAT and CIBER de Enfermedades Raras (U714), Madrid, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Garcia
authors.affiliation: Department of Dermatology and Venereology, University Medical Center, Freiburg, Germany; Department of Dermatology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Renske
authors.initials: R
authors.lastname: Brander
authors.affiliation: Department of Dermatology and Venereology, University Medical Center, Freiburg, Germany.
authors.forename: Cristina
authors.initials: C
authors.lastname: Has
authors.affiliation: Department of Human Genetics, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
authors.forename: Rowdy
authors.initials: R
authors.lastname: Meijer
authors.affiliation: Department of Bioengineering, Universidad Carlos III de Madrid, Regenerative Medicine Unit, CIEMAT and CIBER de Enfermedades Raras (U714), Madrid, Spain.
authors.forename: Maria
authors.initials: M
authors.lastname: Jose Escámez
authors.affiliation: Center for Human Genetics, Freiburg, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Kohlhase
authors.affiliation: Department of Dermatology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands; Department of Genetics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Peter C
authors.initials: PC
authors.lastname: van den Akker
authors.affiliation: Department of Human Genetics, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
authors.forename: Hans
authors.initials: H
authors.lastname: Scheffer
authors.affiliation: Department of Dermatology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Marcel F
authors.initials: MF
authors.lastname: Jonkman
authors.affiliation: Department of Bioengineering, Universidad Carlos III de Madrid, Regenerative Medicine Unit, CIEMAT and CIBER de Enfermedades Raras (U714), Madrid, Spain.
authors.forename: Marcela
authors.initials: M
authors.lastname: Del Rio
authors.affiliation: Department of Dermatology and Venereology, University Medical Center, Freiburg, Germany; Freiburg Institute for Advanced Studies, University of Freiburg, Freiburg, Germany.
authors.forename: Leena
authors.initials: L
authors.lastname: Bruckner-Tuderman
authors.affiliation: Department of Dermatology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands. Electronic address: a.m.g.pasmooij@umcg.nl.
authors.forename: Anna M G
authors.initials: AMG
authors.lastname: Pasmooij
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D024143:Collagen Type VII / Q000235:genetics; D016108:Epidermolysis Bullosa Dystrophica / Q000235:genetics* / Q000628:therapy; D005455:Fluorescent Antibody Technique; D015316:Genetic Therapy; D006801:Humans; D008875:Middle Aged; D009030:Mosaicism; D009154:Mutation
chemical_list: C569053:COL7A1 protein, human; D024143:Collagen Type VII