The vast expansion in research on tumorigenesis has greatly increased our understanding oftumor development in patients with inherited endocrine tumor syndromes. This book provides an up-to-date summary from clinical basics and latest follow-up guidelines to the most recent molecular findings in multiple endocrine neoplasia Type I syndrome. Articles have been assembled by acknowledged experts in their respective fields to provide current perspectives on the clinical and genetic backgrounds ofthis syndrome and to review carefully the latest discoveries concerning the possible functions and interactions ofmenin, the protein encoded by theMEN1gene, including its possible role in cell cycle regulation, hematopoiesis, and bone development.