Hamid Galehdari - Dept. of Genetics, Faculty of Sciences, Shahid Chamran University of Ahvaz, Ahvaz, Iran
Azam Ahmadi Shadmehr - Dept. of Genetics, Faculty of Sciences, Shahid Chamran University of Ahvaz, Ahvaz, Iran
Mahmoud Kalantar - Dept. of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.
Alimohammad Foroughmand - Dept. of Genetics, Faculty of Sciences, Shahid Chamran University of Ahvaz, Ahvaz, Iran

Background and Objectives: Hereditary nonpolyposis colorectal cancer (HNPCC) is an autosomal dominant cancer predisposition syndrome caused by germ-line mutations in DNA mismatch repairgenes. Tumors arising as a result of these mutations display instability in a sequence area knownas microsatellites. Studies have shown that some Bethesda markers (BAT25, BAT26) are more efficient than others in identifying Microsatellite Instability (MSI) in tumors of HNPCC patients.The aim of this study was to evaluate the possible benefits of two MSI markers BAT25 and BAT26 to identifying microsatellite instability in tumor tissues from HNPCC patients. Material & Methods: We used 49 cases gathered from north-east Iran. Microsatellite Instabilityanalysis was performed using fluorescent-labeled primers. Statistical analysis was achieved using SPSS software. Results: 24/5% (12/49) and 34.7% (17/49) of the cases showed MSI in BAT25 and BAT26, respectively. None of tumor sample was MSI positive for both markers. Conclusion: MSI frequency is considerably lower, compared to other findings. This might be due to the fact that environment and Race has great influence on MSI frequency

Hereditary nonpolyposis colorectal cancer, Mismatch repair, Microsatellite instability,Mononucleotide markers, Iran