The Danish Hereditary Non-Polyposis Colorectal Cancer Register (HNPCC-R) has formed the basis for many epidemiologic studies supporting risk stratification and both national and international guidelines on surveillance. However, the HNPCC-R is based on voluntary reporting and the completeness of registration is unknown. Hence, we aimed to assess the validity and completeness of the colorectal cancer (CRC) registrations in the...

Juvenile polyposis syndrome (JPS) is a hereditary hamartomatous polyposis syndrome characterized by gastrointestinal juvenile polyps and increased risk of gastrointestinal cancer. Germline pathogenic variants are detected in SMAD4 or BMPR1A , however in a significant number of patients with JPS, the etiology is unknown. From Danish registers, and genetic department and laboratories, we identified all patients in Denmark with a...