title: Clinical and molecular characterization of 40 patients with classic Ehlers-Danlos syndrome: identification of 18 COL5A1 and 2 COL5A2 novel mutations.
abstract: BACKGROUND
  Classic Ehlers-Danlos syndrome (cEDS) is a rare autosomal dominant connective tissue disorder that is primarily characterized by skin hyperextensibility, abnormal wound healing/atrophic scars, and joint hypermobility. A recent study demonstrated that more than 90% of patients who satisfy all of these major criteria harbor a type V collagen (COLLV) defect.
  
  
  METHODS
  This cohort included 40 patients with cEDS who were clinically diagnosed according to the Villefranche nosology. The flowchart that was adopted for mutation detection consisted of sequencing the COL5A1 gene and, if no mutation was detected, COL5A2 analysis. In the negative patients the presence of large genomic rearrangements in COL5A1 was investigated using MLPA, and positive results were confirmed via SNP-array analysis.
  
  
  RESULTS
  We report the clinical and molecular characterization of 40 patients from 28 families, consisting of 14 pediatric patients and 26 adults. A family history of cEDS was present in 9 patients. The majority of the patients fulfilled all the major diagnostic criteria for cEDS; atrophic scars were absent in 2 females, skin hyperextensibility was not detected in a male and joint hypermobility was negative in 8 patients (20% of the entire cohort). Wide inter- and intra-familial phenotypic heterogeneity was observed. We identified causal mutations with a detection rate of approximately 93%. In 25/28 probands, COL5A1 or COL5A2 mutations were detected. Twenty-one mutations were in the COL5A1 gene, 18 of which were novel (2 recurrent). Of these, 16 mutations led to nonsense-mediated mRNA decay (NMD) and to COLLV haploinsufficiency and 5 mutations were structural. Two novel COL5A2 splice mutations were detected in patients with the most severe phenotypes. The known p. (Arg312Cys) mutation in the COL1A1 gene was identified in one patient with vascular-like cEDS.
  
  
  CONCLUSIONS
  Our findings highlight that the three major criteria for cEDS are useful and sufficient for cEDS clinical diagnosis in the large majority of the patients. The borderline patients for whom these criteria fail can be diagnosed when minor signs of connective tissue diseases and family history are present and when genetic testing reveals a defect in COLLV. Our data also confirm that COL5A1 and COL5A2 are the major, if not the only, genes involved in cEDS.
authors.affiliation: Division of Biology and Genetics, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Ritelli
authors.forename: Chiara
authors.initials: C
authors.lastname: Dordoni
authors.forename: Marina
authors.initials: M
authors.lastname: Venturini
authors.forename: Nicola
authors.initials: N
authors.lastname: Chiarelli
authors.forename: Stefano
authors.initials: S
authors.lastname: Quinzani
authors.forename: Michele
authors.initials: M
authors.lastname: Traversa
authors.forename: Nicoletta
authors.initials: N
authors.lastname: Zoppi
authors.forename: Annalisa
authors.initials: A
authors.lastname: Vascellaro
authors.forename: Anita
authors.initials: A
authors.lastname: Wischmeijer
authors.forename: Emanuela
authors.initials: E
authors.lastname: Manfredini
authors.forename: Livia
authors.initials: L
authors.lastname: Garavelli
authors.forename: Piergiacomo
authors.initials: P
authors.lastname: Calzavara-Pinton
authors.forename: Marina
authors.initials: M
authors.lastname: Colombi
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D003094:Collagen / Q000235:genetics; D024062:Collagen Type V / Q000145:classification / Q000235:genetics*; D004535:Ehlers-Danlos Syndrome / Q000175:diagnosis / Q000235:genetics / Q000473:pathology*; D005190:Family; D005260:Female; D057895:Haploinsufficiency; D006801:Humans; D008297:Male; D009154:Mutation; D059365:Nonsense Mediated mRNA Decay
chemical_list: C530725:COL5A1 protein, human; D024062:Collagen Type V; D003094:Collagen