SMAD4 and hyperinsulinemic hypoglycemia, familial, 4: Specific gene mutations, including MMR deficiency leading to high microsatellite instability (MSI), as well as several other common mutations in CRC, including APC, TP53, KRAS, NRAS, SMAD4, PIK3CA and BRAF, provide valuable insights into tumor biology, therapeutic resistance, and response to targeted therapies.