The aim: Familial adenomatous polyposis (FAP) is an autosomal dominant hereditary disease characterised by development of hundreds and thousands adenomatous polyps of colorectal region. In almost 100% cases a carcinomatous restructuring has developed. This transformation is caused by germinative mutation of APC gene. Our project is concerned to optimalisation of conditions for the estimation of mutations which cause premature termination of translation and development of truncated non-functioning protein. Methods: The estimation was carried out by Protein Truncation Test (PTT) which detects a defected protein on basis in vitro transcription/translation of initial DNA sequence of the followed gene which was amplified by polymerase chain reaction (PCR). Proteins were separated by polyacrylamide gel electrophoresis then overblotted and visualised by chemoluminiscence. Result: The optimalisation of conditions for amplification of target area of APC gene and in vitro transcription/ translation with subsequent detection of truncated protein was carried out. Further, the method for patients selection who were tested for the presence of mutation in the target area was evaluated. The functionality of our system by testing of clinically diagnosed FAP was verified. Conclusion: Protein Truncation Test is a powerful method for presymptomatic diagnosis of familial adenomatous polyposis. In the present time we can use that for confirmation or exclusion of the presence more than 70% of all mutation in APC gene which cause the synthesis of truncated protein.

        Key words: adenomatous polyposis coli gene (APC gene) – familial adenomatous polyposis (FAP) – protein truncation test (PTT)