APC (adenomatous polyposis coli) (eg, familial adenomatosis polyposis [FAP], attenuated FAP) gene analysis; duplication/deletion variants
CPT4 code
Name of the Procedure:
APC Gene Analysis for Duplication/Deletion Variants (Also known as Adenomatous Polyposis Coli Gene Analysis; used for conditions like Familial Adenomatosis Polyposis [FAP] and Attenuated FAP)
Summary
This gene analysis is a laboratory test that examines the APC gene for any large duplications or deletions. It helps in identifying genetic variations that could lead to conditions such as Familial Adenomatosis Polyposis (FAP) or its attenuated form.
Purpose
The primary goal is to identify genetic mutations in the APC gene that can cause FAP or attenuated FAP. This helps in early detection, management, and treatment planning for patients at risk of developing numerous polyps in the colon, which may lead to colorectal cancer.
Indications
- Family history of FAP or polyposis syndromes
- Multiple colorectal polyps detected via colonoscopy
- Early onset colorectal cancer
- Genetic counseling for family members of affected individuals
Preparation
- No specific preparation like fasting is required.
- A blood sample or a buccal swab might be needed.
- Patients usually undergo genetic counseling before and after the test to understand the implications of the results.
Procedure Description
- Sample Collection: A blood sample or a buccal swab is collected.
- DNA Extraction: DNA is extracted from the collected sample.
- Gene Analysis: Advanced techniques such as Multiplex Ligation-dependent Probe Amplification (MLPA) are used to identify duplications or deletions in the APC gene.
- Interpretation: A geneticist analyzes the results to identify any significant variants.
Duration
The entire process from sample collection to result interpretation typically takes a few weeks.
Setting
The sample can be collected in a hospital, outpatient clinic, or during a routine doctor's visit and then sent to a specialized laboratory for analysis.
Personnel
- A phlebotomist or nurse collects the sample.
- Medical laboratory scientists and geneticists perform the gene analysis.
- Genetic counselors provide pre- and post-test counseling.
Risks and Complications
- Risks are minimal and primarily involve the sample collection, such as slight pain or bruising at the blood draw site.
- Rarely, there may be emotional distress from learning about a genetic predisposition to cancer.
Benefits
- Early detection of FAP allows for regular monitoring and intervention, significantly reducing the risk of colorectal cancer.
- Family members can be tested to understand their risk and take preventive measures if necessary.
Recovery
- There are no physical recovery requirements as the procedure is non-invasive.
- Psychological support might be necessary depending on the test results.
Alternatives
- Other genetic tests might include sequencing of the APC gene, which looks for other types of mutations rather than just large duplications or deletions.
- Regular colonoscopies are an alternative, although not a substitute, as they help in monitoring for polyps without identifying genetic risk.
Patient Experience
- The sample collection is quick and involves minimal discomfort.
- There is a waiting period for results which can cause anxiety; genetic counseling can help manage this.
- Upon receiving results, patients often require support and detailed explanations to understand the implications for themselves and their families.