Esophageal atresia with tracheoesophageal fistula in both members of monozygotic twins.

A 29-year-old healthy woman bore monozygotic male twins at 37 weeks of gestation by cesarean section. They weighed 2,350 and 2,140 g, respectively. Twin B was found to have a ventricular septal defect. They were diagnosed with esophageal atresia (EA) with tracheoesophageal fistula and underwent primary end-to-end esophageal anastomosis at the age of 1 day. Their postoperative courses were uneventful. Although the incidence of EA is higher in twins than in singletons, usually, EA affects only one of twins. There have been only 20 pairs of twins concordant for the EA anomaly. There is no distinct difference between sporadic EA and EA in both twins (EABT) with regard to sexuality, classification, and incidence of associated anomalies. The zygosity of EABT consisted of 15 monozygosities (83.3%) and 3 dizygosities (16.7%). An overwhelmingly higher incidence of monozygosity than that of dizygosity in EABT suggests that genetic factors must play a considerable role in the embryology in EABT cases.