The production of species containing the C‐terminus of glucagon rather than oxyntomodulin is consistent with the tumour being derived from pancreatic alpha cells rather than the gut, as prohormone convertase 2 is responsible for proglucagon cleavage at the C‐terminus of the glucagon sequence,30 and is expressed in normal alpha‐cells but not intestinal L‐cells. The gene discussed is GCG; the disease is neoplasm.