These criteria [203] were divided into those strongly supportive of ZES diagnosis (clinical; PUD with positive SRS; positive histology; positive secretin test; PUD with MEN1; gastrinomas by histology); moderately supportive of ZES diagnosis (positive SRS with positive histology with absence of atrophic gastritis [291,292,293,294]); weakly supportive of ZES diagnosis (MEN1 present with positive SRS) [291,292,295,296,297]. This evidence concerns the gene MEN1 and Zollinger-Ellison syndrome.