Written by Siri Dasai
Edited by Anirudh Koneru
Published on 10/12/2020
Gastrointestinal stromal tumor (GIST) is a type of tumor found in the gastrointestinal (GI) tract. It most commonly occurs in the stomach or small intestine, and the tumors are thought to grow from specialized cells in the GI tract called interstitial cells (NIH, 2020).
The majority of GISTS are caused by a mutation in either the KIT or PDGFRA genes; however, about 10 to 15% of cases in adults and 85% of cases in children are not caused by these mutations. They were originally grouped under the umbrella terms “wild-type” and “pediatric-like”, and these forms of GIST are rare, which is why we are highlighting them today (NORD, 2020).
Essentially, pediatric and wild-type GISTS are rare forms of GIST tumors that are “not [often] associated with mutations in either the KIT or PDGFRA genes,” the most common locations for gist mutations (rarediseases.org, 2020).
Signs and Symptoms
GISTs usually present with subjective symptoms, including feeling full earlier, bloating, weight loss, and nausea. Observable signs of GIST include anemia (a low red blood cell count) or lumps and masses in the abdomen that may be seen or felt. GI bleeding may also occur, though signs and symptoms differ depending on the factors such as tumor location and size.
One of the most common symptoms of GIST in general, including pediatric and wild-type, is abdominal pain. About 30-79% of patients exhibit this symptom. Generally, signals of imminent pediatric or wild-type gist are present in the abdominal region due to the gastrointestinal aspect of the disease.
Etiology
GISTs are a form of sarcoma cancer, most commonly caused by mutations in the KIT or PDGFRA genes. As mentioned before, the majority of GIST cancers arise from mutations in these two genes.
However, pediatric and wild-type GIST arise from genes excluding the KIT or PDGRA genes, and research has shown that there are at least twenty other genes that cause these tumors. About 10 to 15% of cases in adults and 85% of cases in children are categorized as pediatric and wild-type, and these are rare forms of GIST.
The tumors arise from specialized cells in the GI tract known as interstitial cells of Cajal (ICC), which are cells that regulate peristalsis (contractions that move food through the digestive tract). Once a mutation occurs in a gene, it may cause a tumor to be formed if uncontrolled cell division occurs, rapidly forming mutated cells.
Diagnosis
GIST is usually diagnosed through a biopsy (sample of removed tissue) taken through an endoscopy (inserting a long, thin tube into the esophagus) or through the skin. Computer tomography (CT) or magnetic resonance (MR) scans are also often used to diagnose and locate the tumor. Once the tumor is found, doctors characterize the tumor and diagnose the patient accordingly. Since a rare disease tends to be more difficult to diagnose, doctors often consult “a person’s medical history, symptoms, physical exam, and laboratory test results in order to make a diagnosis” (rarediseases.info.nih.gov, 2017).
Rarity
While GISTs itself are fairly common, pediatric and wild-type gists are quite rare. As a result, scientists have found it relatively difficult to conduct studies and gather information on these GISTs. The exact prevalence is unknown, though estimates range from 3.2–19 people per million in the general population (NORD, 2020).
Resources
Facebook Groups
Clinical trials for pediatric and wild-type GIST and other rare diseases around the world can be found on clinicaltrials.gov .
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Citations
Gastrointestinal Stromal Tumors. (2020, June 15). NORD (National Organization for Rare Disorders). https://rarediseases.org/rare-diseases/gastrointestinal-stromal-tumors/
Gastrointestinal Stromal Tumors | Genetic and Rare Diseases Information Center (GARD) – an NCATS Program. (2017). National Center for Advancing Translational Sciences. https://rarediseases.info.nih.gov/diseases/8598/gastrointestinal-stromal-tumors
NIH. (2020, August 17). Gastrointestinal stromal tumor - Genetics Home Reference - NIH. Retrieved September 01, 2020, from https://ghr.nlm.nih.gov/condition/gastrointestinal-stromal-tumor
Pediatric and wildtype gastrointestinal stromal tumour (GIST): new therapeutic approaches. (2010, July 1). PubMed Central (PMC). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2949288/#:%7E:text=Pediatric%20gastrointestinal%20stromal%20tumor%20(GIST,different%20in%20children%20and%20adults.
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