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Genetic testing for familial adenomatous polyposis
1wolfgang.ballhausen@medizin.uni-halle.de
Annals of the New York Academy of Sciences
|July 27, 2000
Summary
Familial adenomatous polyposis (FAP) is a genetic syndrome predisposing to colorectal cancer. A protein truncation test (PTT) identifies mutations in the APC gene in 80% of FAP patients, aiding diagnosis and treatment.
Area of Science:
- Genetics
- Oncology
- Molecular Biology
Background:
- Familial adenomatous polyposis (FAP) is an inherited colorectal cancer predisposition syndrome.
- Phenotypic variants, including Gardner Syndrome, exhibit extracolonic symptoms.
- The adenomatous polyposis coli (APC) gene, identified in 1991, is crucial for Wnt-signaling.
Purpose of the Study:
- To detail a prescreening procedure for identifying germinal mutations in FAP patients.
- To investigate the role of APC gene mutations in colorectal cancer predisposition.
- To explore the molecular basis of FAP and its variants.
Main Methods:
- Utilizing protein truncation test (PTT) for in vitro synthesis of APC gene products.
- Applying cDNA-based coupled in vitro transcription/translation for APC exons 1-14.
- Examining genomic DNA fragments of APC exon 15 for mutations.
Main Results:
- The PTT procedure identifies mutations in approximately 80% of FAP patients.
- Small insertions, deletions, nonsense, and splice-site mutations are predominant.
- Transcriptional silencing or large genomic deletions may explain FAP in remaining cases.
Conclusions:
- The PTT method is effective for germline mutation detection in FAP.
- Understanding APC gene mutations is key to managing colorectal cancer risk.
- Further research into modifier genes could improve FAP patient management.