My diagnosis

The diagnosis I have at the time of writing (this may change) is that I have Attenuated Familial Adenomatous Polyposis (AFAP).

Reliable Source of Information

I want to be very careful that the information I share about this condition is precise and accurate.  Until I had a diagnosis, I had never heard of FAP or AFAPbut I have found that there is a good source of information on the website of St Mark’s Hospital, London and I have used them as my source of reference to give a very general overview of the condition.

Attenuated Familial Adenomatous Polyposis (AFAP)

There is not much information available on the internet to explain the difference between the diagnosis of FAP and AFAP. My understanding at the time of writing is  the difference between the two is that Attenuated means that the onset happens later in life than FAP and it tends to be less virulent. It appears that AFAP is less common than FAP and there is less information on the condition.

Familial Adenomatous Polyposis (FAP)

FAP is a rare condition (6,000 people in the UK)  that causes people to develop polyps inside the large bowel (colon and rectum). These polyps are the type that slowly develop into bowel cancer. With early detection the condition can be managed by removing them as they occur but for some people who have hundreds or sometimes thousands of them, the only option is to have the bowel removed as without this procedure bowel cancer is inevitable.

What Causes FAP/AFAP?

FAP is caused by an alteration in the APC gene on chromosome 5.

How is the Condition Inherited?

As FAP is a dominantly inherited it means that a person with the condition has a 50% chance of passing it on to their children. This is because we each have two copies of our genes and it depends if someone with FAP passes on the normal copy of the APC gene or the one with the fault that causes FAP. This is why each child will have 50% chance of inheriting FAP or not.

Testing for the Gene

About 10% of people with FAP have a new genetic alteration that has not been passed from a parent. When it is known that FAP is in the family, genetic testing is offered to the children of FAP patients and this is usually done by blood analysis.

Treatment for FAP

A colonoscopy is also used for clinical diagnosis and regular check ups.  Some polyps can be removed but if polyps exceeds 100 he large bowel and/or polyps are found to be above 1 cm in size then prophylactic (preventative surgery) is offered.


Different types of surgery are explained on the surgery page of St Mark’s website

Other Associations

People with FAP also get polyps in the upper gastrointestinal (GI) tract, stomach and duodenum and along with colonoscopy patients will also have an examination of these areas with gastroscopy.

Other conditions associated with FAP are –

Desmoids, Osteomas, Sebaceous cysts, and eye condition called CHRPE and there may be an increased risk of thyroid, childhood hepatoblastoma, adrenal adenoma cancer and CNS tumours but these are still rare conditions and as such I have not included them. Details can be found on St Mark’s website.