Juvenile polyposis syndrome is an autosomal dominant genetic condition characterized by the appearance of multiple juvenile polyps in the gastrointestinal tract. Polyps are abnormal growths arising from a mucous membrane. These usually begin appearing before age 20, but the term juvenile refers to the type of polyp (i.e benign hamartoma, as opposed to adenoma for example), not to the age of the affected person. While the majority of the polyps found in juvenile polyposis syndrome are non-neoplastic, hamartomatous, self-limiting and benign, there is an increased risk of adenocarcinoma. Solitary juvenile polyps most commonly occur in the rectum and present with rectal bleeding. The World Health Organization criteria for diagnosis of juvenile polyposis syndrome are one of either:

More than five juvenile polyps in the colon or rectum; or
Juvenile polyps throughout the gastrointestinal tract; or
Any number of juvenile polyps in a person with a family history of juvenile polyposis. Signs and symptoms
Age of onset is variable. The term juvenile in the title of juvenile polyposis syndrome refers to the histological type of the polyps rather than the age of onset. Affected individuals may present with rectal bleeding, abdominal pain, diarrhea or anemia. On colonoscopy or sigmoidoscopy polyps that vary in shape or size are present. The polyps can be sessile or pedunculated hamartomatous polyps. Genetics
Juvenile polyposis syndrome can occur sporadically in families or be inherited in an autosomal dominant manner.Two genes associated with juvenile polyposis syndrome are BMPR1A and SMAD4.
Diagnosis
Diagnosis is made based on features as well as by the very early onset of serious eye and ear disease. Because Marshall syndrome is an autosomal dominant hereditary disease, physicians can also note the characteristic appearance of the biological parent of the child. A genetic test can be performed in  Stickler syndrome diagnosis is made by doing a genetic test for the several collagen genes as well as other genes that are associated with Stickler as well as considering the presence and severity of Spondyloepiphyseal Dysplasia with association of reduced height and growth rate as well as other connective tissue features like skin hyperextensibility and poor wound healing. It is an area of active research, also the genetic testing being expensive supports that the diagnosis is made depending on the features. Treatment
There is no medical treatment for either syndrome but there are some recommendations that can help with prevention or early identification of some of the problems. Children with either syndrome should have their hearing tested, and adults should be aware that the hearing loss may not develop until the adult years. Yearly visits to an ophthalmologist or other eye care professional who has been informed of the diagnosis of Stickler or Marshall syndrome is important for all affected individuals. Children should have the opportunity to have myopia corrected as early as possible, and treatment for cataracts or detached retinas may be more effective with early identification.