Juvenile Polyposis Syndrome (JPS)
JPS is a hereditary condition that causes gastrointestinal polyps of juvenile histology, typically in the first two decades of life. There is an increased risk for gastrointestinal cancer in individuals with JPS which begins in the 20's and increases in the 30's. The majority of this carcinoma risk is attributed to the colorectum; however cancers are also known to occur in the stomach, duodenum, small bowel, pancreas and biliary tree. The largest study to date of JPS suggests the incidence of colorectal cancer is 17-22% by 35 years of age and approaches 68% by 60 years of age.
Approximately 20-50% of all individuals with JPS have a family history of the disease. JPS is an autosomal dominant condition, meaning that each child of an individual confirmed to have JPS is at 50% risk for the condition. Genetic mutations in two genes, SMAD4 and BMPR1A, have been found in approximately 50% of patients. Those with a family history of JPS are more likely to have an identifiable mutation. Carcinoma outside of the colorectum is more likely to occur in individuals with SMAD4 mutations, while individuals with BMPR1A mutations appear to primarily be at increased risk for colorectal cancer.
American Society of Clinical Oncology: http://www.cancer.net/cancer-types/juvenile-polyposis-syndrome
Genetics Home Reference: http://ghr.nlm.nih.gov/condition/juvenile-polyposis-syndrome