A Gastrointestinal Stromal Tumor, or GIST, is a tumor occurring within the GI tract and is typically classified as a type of soft tissue sarcoma. Familial GIST is a hereditary condition that makes the formation of GISTs far more likely. These tumors cause complications such as abdominal pain, internal bleeding, nausea, and anemia. Approximately 5,000 people in the United States are diagnosed with Familial GIST each year.