However, our study does have some limitations: i) difficulty in assessing the true incidence of de novo mutations in the sporadic MEN1 cohort, due to unavailability of genetic data of proband’s parents; ii) possible referral bias for the unusually high frequency of non-functioning pituitary tumors in our series due to our Endocrine Unit also being a referral center for pituitary disease; iii) lack of GCM2 gene mutational analysis in FIHP kindreds. This evidence concerns the gene GCM2 and pituitary tumor.