In line with this hypothesis in the sporadic cases of parathyroid adenomas [33, 34], pancreatic [35, 36] and anterior pituitary tumours [37, 38], as well as in carcinoids of lung, thymus and stomach [39, 40], lipomas [38], and skin tumours [41] loss of heterozygosity at the menin locus has been described. This evidence concerns the gene MEN1 and parathyroid gland adenoma.