APC (adenomatous polyposis coli) (eg, familial adenomatosis polyposis [FAP], attenuated FAP) gene analysis; full gene sequence
CPT4 code
Name of the Procedure:
APC Gene Analysis; Full Gene Sequence
Common Name(s): Familial Adenomatous Polyposis (FAP) Gene Testing
Summary
APC gene analysis involves sequencing the entire APC gene to identify mutations that cause familial adenomatous polyposis (FAP) or attenuated FAP. This genetic test helps in diagnosing and managing families predisposed to this hereditary form of colorectal cancer.
Purpose
The APC gene analysis aims to detect mutations in the APC gene that lead to FAP, a condition characterized by the development of numerous polyps in the colon and rectum, which may progress to colorectal cancer. Identifying these mutations allows for early intervention and preventive measures to reduce cancer risk.
Indications
- Family history of FAP or multiple cases of colorectal cancer.
- Presence of numerous colorectal polyps.
- Early-onset colorectal cancer.
- Patients with attenuated FAP presenting fewer polyps and later onset.
Preparation
- No special dietary restrictions or fasting required.
- A comprehensive family medical history may be reviewed.
- Counseling about the implications of genetic testing may be provided.
Procedure Description
- Sample Collection: A blood sample or sometimes a saliva sample is collected from the patient.
- DNA Extraction: DNA is extracted from the collected sample in a laboratory.
- Gene Sequencing: The entire APC gene is sequenced using advanced technologies to detect any mutations.
- Data Analysis: Bioinformatics tools analyze the genetic sequence to identify mutations linked to FAP.
Duration
The procedure itself (sample collection) takes a few minutes. The overall process, including sequencing and analysis, typically takes several weeks.
Setting
- Outpatient clinic or hospital laboratory for sample collection.
- Specialized genetic testing laboratories for sequencing and analysis.
Personnel
- Phlebotomist or nurse for sample collection.
- Geneticist and laboratory technicians for DNA sequencing and analysis.
- Genetic counselor for result interpretation and patient counseling.
Risks and Complications
- Minimal risk associated with blood sample collection, such as slight bruising or infection.
- Psychological impact of test results, particularly if a mutation is found.
Benefits
- Precise identification of genetic mutations allows for targeted surveillance and preventive measures.
- Early detection and management significantly reduce the risk of colorectal cancer.
- Families can make informed decisions about screening and preventive surgery.
Recovery
- No physical recovery needed as the procedure is non-invasive.
- Patients may need emotional support or counseling to cope with results.
Alternatives
- Regular colonoscopy screenings without genetic testing.
- Other genetic tests focusing on different genes (e.g., MUTYH-associated polyposis).
- Pros: Non-invasive, direct diagnostic information.
- Cons: Lack of genetic insight might delay preventive measures.
Patient Experience
- The sample collection is relatively quick and painless.
- Patients may feel anxious while waiting for results.
- Genetic counselors are available to provide emotional support and guidance.