Hyperplastic polyposis syndrome: phenotypic presentations and the role of MBD4 and MYH.

Background & Aims: Hyperplastic polyposis syndrome (HPS) is defined phenotypically with multiple, large and/or proximal hyperplastic polyps. There is no known germ-line predisposition. We aimed to characterize the clinicopathologic features of 38 patients with HPS and explore the role of germ-line mutations in the base excision repair genes MBD4 and MYH.