Contributions of SOX2 to esophageal specification of AFG epithelia have been demonstrated using combinations of hypomorphic Sox2 alleles, leading to degrees of tracheoesophageal fistula (Que et al., 2007), similar to various aspects of human congenital tracheoesophageal fistula cases (Wong et al., 2016; Zhang et al., 2017). This evidence concerns the gene SOX2 and Tracheoesophageal fistula.