title: Characterization of large genomic deletions in the FBN1 gene using multiplex ligation-dependent probe amplification.
abstract: BACKGROUND
  Connective tissue diseases characterized by aortic aneurysm, such as Marfan syndrome, Loeys-Dietz syndrome and Ehlers Danlos syndrome type IV are heterogeneous and despite overlapping phenotypes, the natural history, clinical manifestations and interventional course for each diagnosis can be quite unique. The majority of mutations involved in the etiology of these disorders are missense and nonsense mutations. However, large deletions and duplications undetected by sequencing may be implicated in their pathogenesis, and may explain the apparent lack of genotype-phenotype correlation in a subset of patients. The objective of this study was to search for large pathogenic deletions and/or duplications in the FBN1, TGFβR1, and TGFβR2 genes using multiplex-ligation dependent probe amplification (MLPA) in patients with aortopathy, in whom no mutations in the FBN1, TGFβR1, and TGFβR2 genes were identified by sequencing.
  
  
  METHODS
  The study included 14 patients from 11 unrelated families with aortic aneurysm. Of those, six patients (including 3 first-degree relatives), fulfilled the revised Ghent criteria for Marfan syndrome, and eight had predominantly aortic aneurysm/dilatation with variable skeletal and craniofacial involvement. MLPA for FBN1, TGFβR1, and TGFβR2 was carried out in all patients. A 385 K chromosome 15 specific array was used in two patients with a deletion of the entire FBN1 in order to define its size and boundaries.
  
  
  RESULTS
  We identified two novel large deletions in the FBN1 gene in four patients of two unrelated families who met clinical diagnostic criteria for Marfan syndrome. One patient was found to have a FBN1 deletion encompassing exons 1-5. The other three patients had a 542 Kb deletion spanning the whole FBN1 gene and five additional genes (SLC24A5, MYEF2, CTXN2, SLC12A1, DUT) in the chromosome 15.
  
  
  CONCLUSIONS
  Our findings expand the number of large FBN1 deletions, and emphasize the importance of screening for large genomic deletions in connective tissue disorders featuring aortopathies, especially for those with classic Marfan phenotype.
authors.affiliation: Department of Pathology, University of Utah Health Science Center, Salt Lake City, UT 84108, USA. larissa.furtado@hsc.utah.edu
authors.forename: Larissa V
authors.initials: LV
authors.lastname: Furtado
authors.forename: Whitney
authors.initials: W
authors.lastname: Wooderchak-Donahue
authors.forename: Alan F
authors.initials: AF
authors.lastname: Rope
authors.forename: Angela T
authors.initials: AT
authors.lastname: Yetman
authors.forename: Tracey
authors.initials: T
authors.lastname: Lewis
authors.forename: Parker
authors.initials: P
authors.lastname: Plant
authors.forename: Pinar
authors.initials: P
authors.lastname: Bayrak-Toydemir
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D002884:Chromosomes, Human, Pair 15; D004252:DNA Mutational Analysis; D005091:Exons; D005260:Female; D000071838:Fibrillin-1; D000071837:Fibrillins; D017353:Gene Deletion; D056726:Genetic Association Studies; D006801:Humans; D008297:Male; D008382:Marfan Syndrome / Q000235:genetics; D008840:Microfilament Proteins / Q000235:genetics*; D020125:Mutation, Missense; D010375:Pedigree; D010641:Phenotype; D017346:Protein Serine-Threonine Kinases / Q000235:genetics; D000077293:Receptor, Transforming Growth Factor-beta Type I; D000077294:Receptor, Transforming Growth Factor-beta Type II; D018125:Receptors, Transforming Growth Factor beta / Q000235:genetics; D055815:Young Adult; D054392:Adipokines
chemical_list: D000071838:Fibrillin-1; D000071837:Fibrillins; D008840:Microfilament Proteins; D017346:Protein Serine-Threonine Kinases; D000077293:Receptor, Transforming Growth Factor-beta Type I; D000077294:Receptor, Transforming Growth Factor-beta Type II; D018125:Receptors, Transforming Growth Factor beta; C000605722:FBN1 protein, human; D054392:Adipokines