Familial adenomatous polyposis (FAP) is an inherited condition characterized by the development of numerous polyps in the colon and rectum.
More specifically, FAP is a genetic disorder that primarily affects the gastrointestinal tract. Individuals with FAP typically develop hundreds to thousands of precancerous polyps in their colon and rectum. If left untreated, these polyps almost invariably progress to colorectal cancer. FAP is also known as hereditary polyposis of the colorectum, familial polyposis, or Gardner's syndrome (though Gardner's syndrome has additional manifestations outside of the colon).
Key aspects of FAP include:
- Inherited Condition: FAP is caused by mutations in the APC gene, which is involved in regulating cell growth. These mutations are usually inherited from a parent, but can also occur spontaneously.
- Polyp Formation: The defining feature of FAP is the development of numerous adenomatous polyps in the colon and rectum. These polyps are benign initially but have a high risk of becoming cancerous.
- Cancer Risk: Individuals with untreated FAP have a near 100% lifetime risk of developing colorectal cancer, typically starting in their 30s or 40s.
- Extracolonic Manifestations: While primarily affecting the colon, FAP can also lead to other health problems, including:
- Desmoid Tumors: Noncancerous tumors that can grow in the abdomen.
- Osteomas: Benign bone tumors, especially in the skull and jaw.
- Epidermoid cysts: Benign skin cysts.
- Congenital Hypertrophy of the Retinal Pigment Epithelium (CHRPE): Pigmented lesions in the retina.
- Other Cancers: Increased risk of cancers of the stomach, small intestine, thyroid, brain (medulloblastoma), and pancreas.
Diagnosis and Management:
- Genetic Testing: Individuals with a family history of FAP can undergo genetic testing to determine if they have the APC gene mutation.
- Screening: Regular colonoscopies are crucial for individuals at risk of or diagnosed with FAP, typically starting in adolescence.
- Treatment: The primary treatment for FAP is surgery to remove the colon (colectomy) to prevent colorectal cancer. This can be done preventatively or after polyps have developed. Further surveillance is necessary to monitor for other possible complications.
In summary, Familial Adenomatous Polyposis is a serious genetic condition requiring proactive screening and treatment to mitigate the high risk of colorectal cancer and manage potential extra-colonic manifestations.
