The latter point likely contributes to the finding in one large comparative study of esophageal disease in the two groups of ZES patients [236], that the MEN1/ZES patients had a 3-fold higher incidence of esophageal stricture, a 5-fold higher BE occurrence, 8-fold higher development of dysplasia, and one MEN1/ZES patient developed an esophageal adenocarcinoma, whereas none were seen in 315 sporadic ZES patients who had been followed for a mean of 14 years. This evidence concerns the gene MEN1 and dysplasia.