title: High prevalence of same-sex twins in patients with cloacal exstrophy: Support for embryological association with monozygotic twinning.
abstract: OBJECTIVE
  Previous studies have hypothesized that cloacal exstrophy may be caused by errors early in embryological development related to monozygotic twinning. This study reports the prevalence of twins in a large cohort of patients with cloacal exstrophy.
  
  
  METHODS
  Patients with cloacal exstrophy treated 1974-2015 were reviewed for reports of multiple gestation or conjoined twinning. The genetic sex of the patient and their twin, and any mention of anomaly in the twin were recorded. Neither placental exam nor genetic testing results were available to definitively determine zygosity.
  
  
  RESULTS
  Of 71 patients, 10 had a live born twin (14%), all of whom were of the same genetic sex as the affected patient. One additional patient's twin suffered intrauterine fetal demise, and another patient had a conjoined heteropagus twin. None of the twins were affected by exstrophy-epispadias complex. The rate of twin birth in this cohort was 4.4-7.7 higher than that reported by the Centers for Disease Control in the general population time period (P<0.001), with a striking preponderance of same-sex pairs.
  
  
  CONCLUSIONS
  The highly significant prevalence of same-sex twin pairs within this cohort supports the hypothesis that the embryogenesis of cloacal exstrophy may be related to errors in monozygotic twinning.
  
  
  METHODS
  2b.
authors.affiliation: Department of Surgery, Boston Children's Hospital, 300 Longwood Ave, Boston, MA 02115, USA; Center for Advanced Intestinal Rehabilitation, Boston Children's Hospital, 300 Longwood Ave, Boston, MA 02115, USA. Electronic address: brenna.sullivan@childrens.harvard.edu.
authors.forename: Brenna S
authors.initials: BS
authors.lastname: Fullerton
authors.affiliation: Department of Surgery, Boston Children's Hospital, 300 Longwood Ave, Boston, MA 02115, USA; Center for Advanced Intestinal Rehabilitation, Boston Children's Hospital, 300 Longwood Ave, Boston, MA 02115, USA.
authors.forename: Eric A
authors.initials: EA
authors.lastname: Sparks
authors.affiliation: Department of Surgery, Boston Children's Hospital, 300 Longwood Ave, Boston, MA 02115, USA.
authors.forename: Amber M
authors.initials: AM
authors.lastname: Hall
authors.affiliation: Department of Surgery, Boston Children's Hospital, 300 Longwood Ave, Boston, MA 02115, USA; Center for Advanced Intestinal Rehabilitation, Boston Children's Hospital, 300 Longwood Ave, Boston, MA 02115, USA.
authors.forename: Cristine S
authors.initials: CS
authors.lastname: Velazco
authors.affiliation: Department of Surgery, Boston Children's Hospital, 300 Longwood Ave, Boston, MA 02115, USA; Center for Advanced Intestinal Rehabilitation, Boston Children's Hospital, 300 Longwood Ave, Boston, MA 02115, USA.
authors.forename: Biren P
authors.initials: BP
authors.lastname: Modi
authors.affiliation: Stanford University Department of Surgery and Lucile Packard Children's Hospital, 725 Welch Road, Palo Alto, CA 94304, USA.
authors.forename: Dennis P
authors.initials: DP
authors.lastname: Lund
authors.affiliation: Department of Surgery, Boston Children's Hospital, 300 Longwood Ave, Boston, MA 02115, USA; Center for Advanced Intestinal Rehabilitation, Boston Children's Hospital, 300 Longwood Ave, Boston, MA 02115, USA.
authors.forename: Tom
authors.initials: T
authors.lastname: Jaksic
authors.affiliation: Department of Surgery, Boston Children's Hospital, 300 Longwood Ave, Boston, MA 02115, USA.
authors.forename: W Hardy
authors.initials: WH
authors.lastname: Hendren
mesh_terms: D001006:Anus, Imperforate / Q000196:embryology* / Q000453:epidemiology; D005260:Female; D006554:Hernia, Umbilical / Q000196:embryology* / Q000453:epidemiology; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D008404:Massachusetts / Q000453:epidemiology; D015995:Prevalence; D012189:Retrospective Studies; D012600:Scoliosis / Q000196:embryology* / Q000453:epidemiology; D012737:Sex Factors; D038522:Twinning, Monozygotic; D014430:Twins, Monozygotic / Q000706:statistics & numerical data*; D014564:Urogenital Abnormalities / Q000196:embryology* / Q000453:epidemiology; D000099061:OEIS Complex
keywords: Birth defects; Cloacal exstrophy; Congenital anomalies; Embryogenesis; OEIS; Twins