title: Nine new twin pairs with esophageal atresia: a review of the literature and performance of a twin study of the disorder.
abstract: BACKGROUND
  Isolated esophageal atresia (EA) is a rare congenital malformation whose etiology remains largely unknown. Nine twin pairs with EA were identified from our clinical service, prompting the performance of a systematic review of the literature and the first reported twin study of isolated EA.
  
  
  METHODS
  A total of 330 twin pairs with EA were identified from the literature. The zygosity, concordance, and malformation (isolated vs. nonisolated) status of all 339 twin pairs were evaluated. A total of 72 twin pairs (4 of 9 / 68 of 330) fulfilled the criteria for inclusion in a classic twin study of isolated EA.
  
  
  RESULTS
  The pairwise concordance rates were 50% (95% confidence interval [CI], 34-66%) for monozygous (MZ) twin pairs and 26% (95% CI, 15-42%) for dizygous (DZ) twin pairs (p = 0.033). The probandwise concordance rates were 67% (95% CI, 53-78%) for MZ twin pairs and 42% (95% CI, 29-56%) for DZ twin pairs (p = 0.011). The MZ/DZ ratios were 1.9 for pairwise analysis and 1.6 for probandwise analysis. The familial risk ratios for MZ and DZ twin pairs were 1700 and 900, respectively.
  
  
  CONCLUSIONS
  The observation of higher concordance rates for MZ compared to DZ twin pairs indicates that genetic factors contribute to isolated EA.
authors.affiliation: Department of Neonatology, Children's Hospital, University of Bonn, Bonn, Germany.
authors.forename: Anna Carina
authors.initials: AC
authors.lastname: Schulz
authors.forename: Enrika
authors.initials: E
authors.lastname: Bartels
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Stressig
authors.forename: Jochen
authors.initials: J
authors.lastname: Ritgen
authors.forename: Eberhard
authors.initials: E
authors.lastname: Schmiedeke
authors.forename: Manuel
authors.initials: M
authors.lastname: Mattheisen
authors.forename: Markus
authors.initials: M
authors.lastname: Draaken
authors.forename: Michael
authors.initials: M
authors.lastname: Ludwig
authors.forename: Soyhan
authors.initials: S
authors.lastname: Bagci
authors.forename: Andreas
authors.initials: A
authors.lastname: Müller
authors.forename: Ulrich
authors.initials: U
authors.lastname: Gembruch
authors.forename: Annegret
authors.initials: A
authors.lastname: Geipel
authors.forename: Christoph
authors.initials: C
authors.lastname: Berg
authors.forename: Andreas
authors.initials: A
authors.lastname: Heydweiller
authors.forename: Haitham
authors.initials: H
authors.lastname: Bachour
authors.forename: Johannes
authors.initials: J
authors.lastname: Schumacher
authors.forename: Peter
authors.initials: P
authors.lastname: Bartmann
authors.forename: Markus M
authors.initials: MM
authors.lastname: Nöthen
authors.forename: Heiko
authors.initials: H
authors.lastname: Reutter
mesh_terms: D004200:Diseases in Twins / Q000453:epidemiology / Q000209:etiology / Q000235:genetics*; D004933:Esophageal Atresia / Q000235:genetics*; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D014429:Twins, Dizygotic / Q000235:genetics*; D014430:Twins, Monozygotic / Q000235:genetics*