Nine new twin pairs with esophageal atresia: A review of the literature and performance of a twin study of the disorder

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. CONCLUSION The observation of higher concordance rates for MZ compared to DZ twin pairs indicates that genetic factors contribute to isolated EA. Birth Defects Research (Part A) 2012. © 2012 Wiley Periodicals, Inc.