What is Zollinger-Ellison syndrome is characterized by all of the following except - and explain in detail?
Important points that should raise the possibility of ZES in patients with duodenal ulcer.


ulcers in unusual locations i.e. postbulbar ulcers
recurrent or refractory ulcers
ulcers with diarrhoea
multiple ulcers
ulcers associated with prominent gastric folds
ulcers with findings s/o MEN-1 (endocrinopathy, family history of ulcer or endocrinopathy, nephrolithiasis)
ulcers without H. pylori infection