DOG1, "discovered on GIST 1" encodes for a protein of unknown function that is highly sensitive and specific for gastrointestinal stromal tumors (GIST). GISTs occur in bowel walls and are proposed to originate from the interstitial cells of Cajal. The majority of GISTs harbor activating mutations in KIT but approximately 5-15% of GIST are negative for c-Kit by immunohistochemistry, mainly associated with mutations in the PDGFRA gene.

 

Antibodies against DOG1 have been shown to be highly sensitive and specific, demonstrating 98-100% reactivity to GIST. DOG1 staining pattern is cytoplasmic and membranous, staining tumor cells and interstitial cells of Cajal. Its sensitivity was deemed superior to c-Kit in that many cases with PDGFRA mutations that failed to show c-kit reactivity were DOG-1 positive.