The classical triad of MEN1-related tumors (PHPT, GEP, and pituitary) was present in 49 (28%), PHPT and GEP tumors in 67 (38%), and PHPT and pituitary tumors in 35 (20%), whereas PHPT alone or associated with minor tumors (adrenal lesions, lung and thymic carcinoids, gastrointestinal stromal tumors, and pheochromocytomas) was observed in 24 (14%) affected patients of the whole series. This evidence concerns the gene MEN1 and gastrointestinal stromal tumor.