The key difference between FAP and Gardner syndrome is that FAP is a genetic condition where an affected person develops more than 100 adenomatous colon polyps, while Gardner syndrome is a variant of FAP where an affected person develops other tumors including epidermoid cysts, fibromas desmoid tumors, and osteomas in addition to multiple adenomatous colon polyps, outside the gastrointestinal organs.
Familial adenomatous polyposis (FAP) is an inherited genetic condition caused by mutations in the APC gene. On the other hand, Gardner syndrome is a phenotypic variant of familial adenomatous polyposis characterized by numerous adenomatous polyps and other tumors outside the gastrointestinal tract. Gardner was the first person to describe this syndrome in 1951. Gardner syndrome is also due to mutations in the APC gene.
CONTENTS
1. Overview and Key Difference
2. What is FAP
3. What is Gardner Syndrome
4. Similarities – FAP and Gardner Syndrome
5. FAP vs. Gardner Syndrome in Tabular Form
6. Summary – FAP vs. Gardner Syndrome
What is FAP?
Familial adenomatous polyposis (FAP) is an inherited genetic disorder characterized by tumors of the large intestine and rectum. This condition can lead to hundreds or thousands of polyps inside the colon or rectum. The typical symptoms of symptoms FAP may include bloody stool, unexplained diarrhea, constipation for a long period, abdominal cramps, decrease in size of stool, pain due to gas, bloating, fullness, unexplained weight loss, lethargy, and vomiting. Classical FAP, AFAP (attenuated FAP), Gardner syndrome, and Turcot syndrome are all subtypes of FAP, which are due to genetic alterations in the APC gene. The risk of FAP is higher if people have a parent, child, brother, or sister with this condition.
Figure 01: FAP
FAP can be diagnosed through digital rectal exams, fecal occult blood tests, flexible sigmoidoscopy, colonoscopy, barium enema, and genetic testing. Furthermore, FAP is treated through colorectal surgery by completely removing the cancer from the colon and medications such as sulindac (Clinoril®) and celecoxib (Celebrex®).
What is Gardner Syndrome?
Gardner syndrome is a rare inherited genetic disorder and a variant of FAP. APC gene mutations also cause it and follow an autosomal dominant inheritance pattern. People with this condition develop multiple adenomatous colon polyps. In addition, these people also develop other tumors outside the gastrointestinal organs, such as epidermoid cysts (lumps in or under the skin), fibromas (fibrous tumors), desmoid tumors (non-cancerous fibrous tumors that can develop anywhere in the body), and osteomas (lumps in or on the bone). Moreover, the symptoms of this condition may include growths in the colon, dental abnormalities like the development of extra teeth, bony tumors on the skull, and other bones and cysts under the skin. The risk factors for Gardner syndrome are having at least one parent with this condition and a spontaneous mutation in the APC gene.
Figure 02: Gardner Syndrome
Garner syndrome can be diagnosed through GI tract endoscopy, blood tests, and genetic tests for APC gene mutation. Furthermore, treatment options for Garner syndrome may include medications such as an NSAID (sulindac) or a COX2 inhibitor (celecoxib), surgeries such as removal of the colon, managing dental abnormalities, a healthy lifestyle with proper nutrition, exercise, and stress reduction activities.
What are the Similarities Between FAP and Gardner Syndrome?
- FAP and Gardner’s syndrome are two associated genetic disorders.
- Gardner syndrome is a variant of FAP.
- Both affect the colon and lead to the development of adenomatous colon polyps.
- Both genetic conditions are due to APC gene mutations and follow autosomal dominant inheritance patterns.
- Young people are affected by both genetic conditions.
- Both genetic conditions can be diagnosed through endoscopy, blood tests, and genetic tests.
- They can be treated through specific medications and surgeries.
What is the Difference Between FAP and Gardner Syndrome?
FAP is a genetic condition where an affected person develops more than 100 adenomatous colon polyps, while Gardner syndrome is a variant of FAP where an affected person develops other tumors outside the gastrointestinal organs in addition to multiple adenomatous colon polyps. Thus, this is the key difference between FAP and Gardner syndrome. Furthermore, in FAP, polyps usually develop at the age of 20 and convert to colon cancer by the age of 39 and 40. On the other hand, in Gardner syndrome, polyps usually develop at the age of 16 and convert to colon cancer by the age of 34 and 43.
The infographic below presents the differences between FAP and Gardner syndrome in tabular form for side-by-side comparison.
Summary – FAP vs. Gardner Syndrome
Familial adenomatous polyposis (FAP) is the most common adenomatous polyposis syndrome, which is an autosomal dominant inherited genetic disorder. There are four subtypes of FAP such as classical FAP, AFAP (attenuated FAP), Gardner syndrome, and Turcot syndrome. All these subtypes are due to genetic alterations in the APC gene. FAP is characterized by tumors (adenomatous polyps) of the large intestine and rectum, while Gardner syndrome is a variant of FAP where it develops other tumors outside the gastrointestinal organs, including epidermoid cysts, fibromas, desmoid tumors, osteomas other than multiple adenomatous colon polyps. So, this summarizes the difference between FAP and Gardner syndrome.
Reference:
1. “Familial Adenomatous Polyposis.” Cancer.Net.
2. “Gardner Syndrome.” Cleveland Clinic.
Image Courtesy:
1. “Familial Adenomatous Polyposes colon -2” By Department of Pathology, Calicut Medical College – Calicut Medical College (CC BY-SA 4.0) via Commons Wikimedia
2. “Gardner1” By Bhama PK, Chugh R, Baker LH, Doherty GM. Gardner’s syndrome in a 40-year-old woman: successful treatment of locally aggressive desmoid tumors with cytotoxic chemotherapy. World Journal of Surgical Oncology. 4, 96. 2006. PMID 17173703. DOI:10.1186/1477-7819-4-96 (CC BY 2.0) via Commons Wikimedia