Collaborative Stage

Note 1: This is a special molecular diagnostic test performed on tumor tissue to identify mutations in specific parts (called exons) of the KIT gene. Certain patterns of mutations correlate with the anatomic site and morphology of GIST tumors and can predict response to treatment with agents such as imatinib (Gleevec). Some mutations are associated with acquired resistence to imatinib treatment.
Note 2: Another name for KIT is CD117.
Note 3: See Site-Specific Factor 12 for coding information about KIT expression detected with immunohistochemistry. See Site-Specific Factor 14 for coding information about mutations of the PDGFRA gene.

Code	Description
000	KIT gene test performed, negative for mutations
010	KIT gene test performed, positive for mutation of exon 9
020	KIT gene test performed, positive for mutation of exon 11
030	KIT gene test performed, positive for mutation of exon 13
040	KIT gene test performed, positive for mutation of exon 17
800	KIT gene test performed, positive for other specified mutation
810	KIT gene test performed, positive for more than one mutation
850	KIT gene test performed, positive NOS; specific mutation(s) not stated
988	Not applicable: Information not collected for this case
997	KIT gene test ordered, results not in chart
998	KIT gene not done (test was not ordered and was not performed)
999	Unknown Not documented in patient record

CS Site-Specific Factor 13
KIT Gene Mutations