Background: Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors and exhibit a high frequency of oncogenic KIT  or PDGFRA  mutations. Tyrosine kinase inhibitors (TKIs) have been mainly used in the treatment of GISTs bearing KIT/PDGFRA  mutations. However, other mutation profiles have been found to affect the sensitivity to and effectiveness of TKIs in the treatment of GISTs. 
Purpose: The aim of the present study was to describe the mutational status of multiple genes in GIST samples and to provide information for finding potential predictive markers of therapeutic targets in Chinese GIST patients. 
Patients and methods: MassARRAY spectrometry was used to test 40 Chinese GIST patients for 238 mutations affecting 19 oncogenes. 
Results: A total of 14 oncogenes with 43 mutations were detected in 38 samples, with a mutation frequency of 95%. Among these mutation samples, 26 GISTs were found for KIT  or PDGFRA  mutations, while 12 were KIT/PDGFRA  wild-type. Approximately half of the GIST samples harbored multiple mutations. The most frequent mutations were found in KIT  (62.5%), CDK4  (17.5%), NRAS  (15%) and EGFR  (12.5%). Other mutations included PIK3CA  and AKT1  (10%), BRAF  and ABL1  (7.5%), PDGFRA , ERBB2  and HRAS  (5%), and AKT2 , FLT3  and KRAS  (2.5%). New mutated genes (CDK4 , AKT2 , FLT3 , ERBB2 , ABL1  and AKT1 ), a higher BRAF  mutation frequency (7.5%) and new BRAF mutation sites (G464E) were found in Chinese GIST patients.
Conclusion: This study demonstrated useful mutations in a small fraction of Chinese GIST, but targeted therapeutics on these potential predictive markers need to be investigated in depth especially in Oriental populations.
Keywords: gastrointestinal stromal tumor (GIST), mutation, tyrosine kinase receptor, oncogene