Zollinger–Ellison syndrome results from hypergastrinaemia and gastric hyperacidity. The disorder is clinically characterised by recurrent peptic ulcer disease, gastroesophageal reflux disease and, often, diarrhoea.^1,2 The syndrome is caused by gastrin-secreting tumours (gastrinomas), which can arise either sporadically (approximately 70–75%) or in association with the autosomal dominant inherited condition, multiple endocrine neoplasia type 1 (MEN1; approximately 25–30%).³ The MEN1 syndrome is also associated with a range of endocrine tumours that predominantly arise in the parathyroid glands, anterior pituitary gland and pancreas.^4,5 Sporadic gastrinomas are usually single and are most commonly located in the pancreas, although some are found in the duodenum. By contrast, gastrinomas found in patients with MEN1 are usually multiple and are most often located in the duodenal wall. Although multiple endocrine macrotumours and microtumours are also commonly found in the pancreas of patients with MEN1, these neoplasms usually secrete a variety of other hormones and are rarely gastrinomas.⁶ These observations on the location and multiplicity of tumours have implications for the surgical resection of gastrinomas, and it is now advised that even when pancreatic tumours are shown by imaging studies, duodenotomy should be performed in all cases that seem to be associated with MEN1.^7,8

MEN1 is caused by germline mutations in the tumour suppressor MEN1 gene located on chromosome 11q13.^9,10 This gene encodes the protein menin, whose functions have not yet been fully defined, …