MEN1 and hyperparathyroidism: A small number of such studies have been performed and show that, in general, the clinical course of these two forms of MEN1 differ with MEN1 patients without MEN1 mutation having a milder disease, later onset, lack of recurrent hyperparathyroidism, lower incidence of entero-pancreatic tumors or skin tumors (angiofibromas, collagenomas) [418,422,450,454,455,456].