Approximately 1 in 10,000 babies born in the US will have familial adenomatous polyposis (FAP) resulting from a germline adenomatous polyposis coli (APC) mutation. As the disorder is inherited in an autosomal-dominant pattern, males and females are equally affected; however, onset of symptoms and colorectal cancer may manifest earlier in females than males.[6]Bjork J, Akerbrant H, Iselius L, et al. Epidemiology of familial adenomatous polyposis in Sweden: changes over time and differences in phenotype between males and females. Scand J Gastroenterol. 1999;34:1230-1235.
http://www.ncbi.nlm.nih.gov/pubmed/10636071?tool=bestpractice.com
There do not appear to be significant racial, ethnic, or geographical differences in the incidence of FAP, nor do environmental factors appear to affect the disease incidence.[6]Bjork J, Akerbrant H, Iselius L, et al. Epidemiology of familial adenomatous polyposis in Sweden: changes over time and differences in phenotype between males and females. Scand J Gastroenterol. 1999;34:1230-1235.
http://www.ncbi.nlm.nih.gov/pubmed/10636071?tool=bestpractice.com
[12]Yang J, Gurudu SR, Koptiuch C, et al. American Society for Gastrointestinal Endoscopy guideline on the role of endoscopy in familial adenomatous polyposis syndromes. Gastrointest Endosc. 2020 May;91(5):963-82.e2.
https://linkinghub.elsevier.com/retrieve/pii/S0016-5107(20)30054-7
http://www.ncbi.nlm.nih.gov/pubmed/32169282?tool=bestpractice.com
Only 1% to 2% of all colorectal cancer is secondary to FAP.[12]Yang J, Gurudu SR, Koptiuch C, et al. American Society for Gastrointestinal Endoscopy guideline on the role of endoscopy in familial adenomatous polyposis syndromes. Gastrointest Endosc. 2020 May;91(5):963-82.e2.
https://linkinghub.elsevier.com/retrieve/pii/S0016-5107(20)30054-7
http://www.ncbi.nlm.nih.gov/pubmed/32169282?tool=bestpractice.com
[13]Burt RW, Bishop DT, Lynch HT, et al. Risk and surveillance of individuals with heritable factors for colorectal cancer. WHO Collaborating Centre for the Prevention of Colorectal Cancer. Bull World Health Organ. 1990;68:655-665.
http://www.ncbi.nlm.nih.gov/pubmed/2289301?tool=bestpractice.com
Incidence rates specifically for attenuated FAP have not been reported. Given that this condition also arises from germline mutations in APC, but that these mutations result in an attenuated phenotype of fewer than 100 adenomas and later onset of colorectal cancer, attenuated FAP probably has a similar profile to FAP with no difference by race, ethnicity, or geographical origins. The spontaneous mutation rate for attenuated FAP is unknown, as occurrence of the disease is probably underestimated because of the more subtle polyp phenotype and later age of onset of colorectal cancer that may mimic sporadic colorectal cancer, rather than attenuated FAP.