10 Basic Science 1 Department of Gastroenterology, University Clinical Center, Internal Medicine Hospital, Tuzla, Bosnia and Herzegovina 2 Institute for Pathology, University Clinical Center, Tuzla, Bosnia and Herzegovina 3 Institute for Biochemistry, University School of Medicine, Ljubljana, Slovenia 4 Institute of Biochemistry, University of Oxford, Great Britain Corresponding author: Nada Pavlović-Čalić University Clinical Center Tuzla Trnovac bb 75 000 Tuzla, Bosnia and Herzegovina e-mail: nada.pavlovic-calic@ukctuzla.ba Received: 29. 10. 2006. Accepted: 30. 01. 2007. Hereditary non polyposis colorectal cancer in a random sample of colorectal cancer patients Nada Pavlović-Čalić 1 , Izet Eminović 2 , Vesna Hadžiabdić 3 , Kasim Muminhodžić 1 , Radovan Komel 3 , Davor Pavlović 4 Introduction Colorectal cancer is one of the most fre- quent: it is the second most frequent in men and �omen, just afer lung cancer and breast cancer, respectively. A signifcant number of people are at high risk of developing colorec- tal cancer if they carry germ line mutations. Molecular genetics promises to be the key for identifcation of the population at high risk of developing colorectal cancer. Ge- netic testing could be clinically used in the future to diagnose sporadic and hereditary colorectal cancer. Mutations cause uncontrolled multi- plication and the uncontrolled gro�th of mutated cells �ithin the body. Mutations of control genes (control the cell cycle) cause genome instability. Te most frequent muta- tion is of the p53 gene – a guardian of the Objective Te goal of this prospective research �as to deter- mine genetic and endoscopic changes in patients �ith spo- radic colorectal cancer and to diagnose HNPCC. Patients and Methods Te group consisted of 40 patients, having colorectal cancer. Colonoscopy �as performed, genetic test- ing for the loss of heterozygousity and microsatellite instabil- ity (MSI). Results HNPCC �as diagnosed using the Amster- dam and Bethesda criteria in the group of sporadic colorectal cancer in 15% of the cases, and exhibited an MSI-H for the chromosome 2p �here the hMSH2 mismatch repair gene is localized. Te greatest number of patients �ith sporadic co- lon cancer and HNPCC displayed Astler-Coller B2 and C1 spread levels. Conclusion Te research results indicate that the colonoscopy should be used as a screening method for colorectal cancer. It is necessary to design a colorectal cancer screening program for the general population and high risk individuals. Tere is a need to form National colorectal can- cer, HNPCC and FAP registries. Key Words: Colorectal cancer, Genetics, Endoscopy, HNPCC.