Gastrointestinal stromal tumor (GIST) Genetics - Kit, pdgfra and wild type GIST - Basics - Part 1
Gastrointestinal stromal tumors (GISTs) are a type of rare cancer that can develop in the gastrointestinal (GI) tract, most commonly in the stomach or small intestine. The genetics of GISTs have been the subject of extensive research, and most cases of GISTs are associated with specific genetic mutations.
The majority of GISTs are driven by mutations in two key genes: KIT and PDGFRA (Platelet-Derived Growth Factor Receptor Alpha). These mutations lead to the uncontrolled growth and division of cells in the GI tract, resulting in the formation of tumors. Here is some important information about the genetics of GISTs:
KIT Mutations: The KIT gene encodes a protein known as KIT receptor tyrosine kinase, which plays a crucial role in cell signaling and regulation of cell growth. Mutations in the KIT gene are the most common genetic abnormalities in GISTs, occurring in approximately 80-85% of cases. These mutations activate the KIT protein, leading to the continuous stimulation of cell growth.
PDGFRA Mutations: Mutations in the PDGFRA gene are less common than KIT mutations but are still significant, occurring in about 5-10% of GIST cases. Similar to KIT mutations, PDGFRA mutations activate the PDGFRA receptor tyrosine kinase, promoting cell proliferation and tumor development.
Wild-Type GISTs: In a subset of GISTs, neither KIT nor PDGFRA mutations are present, and these are referred to as wild-type GISTs. These tumors may have mutations in other genes or signaling pathways that drive their growth. Research is ongoing to understand the underlying genetics of wild-type GISTs.
Secondary Mutations: In some cases, GISTs may develop secondary mutations in KIT or PDGFRA over time, leading to resistance to targeted therapies like imatinib (Gleevec), which is commonly used to treat GISTs. These secondary mutations can make the tumors more difficult to manage.
Understanding the specific genetic mutations in a GIST is essential for personalized treatment decisions. Targeted therapies, such as imatinib, sunitinib, and regorafenib, have been developed to inhibit the activity of the mutated KIT or PDGFRA proteins, leading to better outcomes for many GIST patients. Genetic testing and molecular profiling of GISTs are crucial for identifying the most appropriate treatment strategy.