About attenuated familial adenomatous polyposis

Attenuated Familial Adenomatous Polyposis (or AFAP for short) is an inherited genetic condition caused by a defect in the adenomatous polyposis coli (APC) gene. There are two known forms of FAP – classical or attenuated – both of which if left untreated can inevitably lead to the individual developing colon and/or rectal cancer.

Affecting only 1 in every 10,000 people this is an extremely rare disease and there is still so much to be discovered surrounding the mutation.

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Classic FAP is characterised by hundreds to thousands of precancerous colorectal polyps (adenomatous polyps) which tend to appear on average at around 16 years of age and if left untreated (without colectomy) usually develop colon/rectal cancer in their third or fourth decade.
The attenuated version of FAP, which is what Jinny was diagnosed with in 2020, appears to be less aggressive with a fewer amount of polyps, and these being more present later in life. Never the less, this does not take away the risk of developing colon/rectal cancer.

Along with polyps developing in the bowel, both forms of FAP also cause polyps to form in the stomach and duodenum, thus increasing the risk of stomach cancer.
The mutation can also cause osteomas (bony growths), dental abnormalities, soft tissue tumours which are benign (desmoid tumours) and harmless black dots at the back of the eyes called CHRPE (congenital hypertrophy of the retinal pigment epithelium).

Either FAP or AFAP is diagnosed by a simple blood test. You would usually have this test if a parent or sibling carried the mutation, or if you have screening that shows a high amount of polyps. If your parent has the genetic mutation then there is a 50/50 chance it will be passed to you.

The current treatment is regular screening which in the UK is based on the Spiegelman scale. This is used to ‘grade’ the bowel polyps and takes into account the amount, size and visual appearance of the polyps.
Screening includes both colonoscopies to check the large bowel and gastroscopies to check the stomach and duodenum. Your referring consultant or surgeon will be able to discuss your screening with you and any outcomes.
It is likely that during a screening, that biopsies will be taken for testing – you will be advised of these results as soon as they are available.

There will come a point in a patients life with AFAP/FAP that surgery will be recommended to prevent bowel cancer. This could be a partially colectomy (removal of some of the large bowel where polyps cannot be removed) or full removal of the large bowel – resulting in either a permanent ileostomy or ileoanal pouch (J-pouch). This is dependent on each patient and would be something to be discussed with your surgeon.