Spectrum of the KIT Gene Mutations in Gastrointestinal Stromal Tumors in Arab Patients

ABSTRACT

Background: Gastrointestinal stromal tumors are the most common mesenchymal tumors of the gastrointestinal tract, which originate from the interstitial cells of Cajal. These tumors are characterized by expression of CD117 and CD34 antigens and activating mutations in the KIT and PDGFRA genes. While KIT and PDGFRA mutations have been extensively studied in other populations, the spectrum of mutations in Arab patients remains unknown. The study aimed at determining the distribution of KIT and PDGFRA mutations and phenotypic characterization of the gastrointestinal stromal tumors in Arab patients. Methods: Sanger sequencing was used to analyze 52 archived gastrointestinal stromal tumors for mutations in the KIT and the PDGFRA genes. Tumor descriptions were obtained from the clinical reports of patients. Results: In these patients, most tumors occur in the stomach, followed by the rest of the digestive tract. A vast majority of tumors express the CD117 and CD34 antigens. Sequencing of the KIT and PDGFRA genes identified five non-synonymous mutations and 26 deletions (25 novel) in exon 11 of the KIT gene. All non-synonymous mutations and deletions affect the juxta-membrane domain, which is known to inhibit ligand-independent activation of the KIT receptor. No mutations were found in the PDGFRA gene. Conclusions: Molecular profiling of the gastrointestinal stromal tumors in Arab patients identified a unique spectrum of mutations in exon 11 of the KIT gene. These data are important for the diagnosis and management of patients of Arab ethnic origin.