Familial adenomatous polyposis (FAP) is a genetic condition caused by disease-causing genetic variants in the APC gene. FAP increases an individual’s likelihood of developing colorectal/bowel cancer, and in some cases other cancers too. 

People with FAP develop adenomas in their bowels (adenomatous colonic polyps). Adenomas are small benign (non-cancerous/non-spreading) tumours that have the potential to turn into cancers. Many people with FAP also develop tumours and cancers in other parts of the body as well. 

There are two main types of FAP:

• classical FAP (ORPHA:733) – characterised by development of hundreds to thousands of adenomas in the large bowel 
• attenuated FAP (ORPHA:220460) – milder form of FAP, characterised by less than 100 adenomas  

Below on this page is some information about this condition as well as links to useful resources for Australians living with a rare disease.  

Synonyms: Colorectal adenomatous polyposis, familial polyposis coli, intestinal polyposis, polyposis coli and multiple hard and soft tissue tumours, denomatous polyposis, adenomatous polyposis of the colon, classic familial adenomatous polyposis, familial multiple polyposis syndrome, familial polyposis. 

Gardner syndrome was previously classified as a separate condition but is now recognised as a variant of FAP in which individuals have tumours in the colon and soft tissues, head and neck. 

Turcot syndrome with polyposis was also previously classified as a separate condition where individuals have growths in the colon, brain and spinal cord, but is now recognised as a variant of FAP when the APC gene is affected. This differs from non-polyposis Turcot syndrome (now known as part of Lynch syndrome) which affects DNA mismatch repair genes.

Universal rare disease classifications provide a common language for recording, reporting and monitoring diseases. Please visit the Rare Disease Classifications page for more information about these internationally recognised classifications.

ORPHA:733 Familial adenomatous polyposis 

ICD-11: 2B90.Y Other specified malignant neoplasms of colon 

Rare diseases typically display a high level of symptom complexity. There is often a wide range of symptoms and the symptoms may vary between individuals in terms of its presentation, severity, duration and impact. 

Please speak to your medical team to learn more about the symptoms of this condition. 

Rare diseases are often serious and progressive, exhibiting a high degree of symptom complexity, leading to significant disability. Majority of the estimated two million Australians living with a rare disease meet the Australian Government’s definition for disability (in accordance to the Australian Public Service Commission and Australian Bureau of Statistics), and many experience severe and permanent disability impacts. If you or someone you care for is experiencing disability-related impacts from a rare condition, please speak with a health or disability professional for advice. Information about relevant disability support can be found at the RARE Portal’s Disability Support Information page.

FAP is a genetic condition. It is caused by disease-causing genetic changes (variants) in the APC gene on chromosome 5q21-q22. This gene is a type of gene called ‘tumour suppressor’. When this gene does not function correctly, it increases the chance of tumour forming.  

Variants in the APC gene can be inherited or can occur spontaneously (de novo). Genetic variants in APC include single base changes (sequence variants/ a single letter changes in the genetic code), deletions and duplications. Depending upon the type of genetic variation and the part of the APC gene that is affected, the variant may cause either classical or attenuated FAP. For more information on different types of genetic variants, please refer to Centre for Genetics Education: Types of genetic variation.

All individuals have two copies (alleles) of the APC gene – one on each chromosome that is inherited from each parent. FAP is an autosomal dominant condition, which means that having a genetic variant in just one of the APC gene copies can result in FAP.  

The genetic variant can be inherited, which means it can be passed on to the next generation. If a parent has the autosomal dominant gene variant, there is 50% chance that they will pass that genetic variant to each of their children. More information on autosomal dominant inheritance pattern can be found at Centre for Genetics Education: Autosomal dominant inheritance.

If you would like to learn more about the inheritance and impact of this condition, please ask your doctor for a referral to a genetic counsellor. Genetic counsellors are qualified allied health professionals who can provide information and support regarding genetic conditions and testing. More information about genetic counselling can be found at: 

• Information on Genetic Services 
• The National and State Services pages underneath the ‘Genetic Counselling’ sections listed 

A timely diagnosis is critical for better patient outcomes, the provision of the best possible care and treatment options, access to services and support, increased reproductive confidence and the ability to participate in clinical trials. 

Please speak to your medical team to learn more about the available diagnostic pathways for this condition. 

Please speak to your medical team to learn more about the possible treatment or management options for your condition. Treatment will depend on an individual’s specific condition and symptoms. It is also important to stay connected to your medical team so that you can be made aware of any upcoming clinical trial opportunities.

Healthcare professionals involved in the care of individuals with FAP may include general practitioners (GP), oncologists and surgeons. The need for different healthcare professionals may change over a person’s lifetime and extend beyond those listed here. 

Clinical care for rare diseases often involves a multidisciplinary team of medical, care and support professionals. Please note that the information provided here is as a guide and that RVA does not necessarily monitor or endorse specific clinics or health experts.

For many rare diseases, palliative care services may be relevant and useful. Palliative care services are available for people (adults, children and their families) living with a life-limiting illness. Palliative care services provide assistance, support, resources and tools to help people manage their illness and the symptoms, ease pain, and improve comfort and quality of life. Palliative care is not only for end-of-life care. It can also help at any stage of illness from diagnosis onwards, and will look different for different people. For more information about palliative care and how it can help you, please visit:

• Australian Institute of Health and Welfare: Palliative care Overview
• Australian Government Department of Health, Disability and Ageing: Palliative care
• Palliative Care Australia

If you know of any relevant care guidelines, please let us know via the Contribute page. 

Individuals living with rare diseases may have complex medical issues and disabilities, which are not always visible. It is often useful to refer to their medical history as well as personal information such as a medical card, doctor’s letter, or if available, a rare disease passport, for relevant information.

If you know of any relevant emergency management guidelines or information relevant to emergency care, please let us know via the Contribute page. 

There are specific considerations around participating in rare disease research, including clinical trials. It is important to be mindful of issues such as data privacy, research ethics, consent and differences in research regulations between Australia and other countries.

If you are interested in finding clinical trials for your condition, please visit the following websites; however, there may not be any clinical trials available:

• Australian Clinical Trials
• ClinicalTrials.gov

It is best to discuss your interest in any clinical trials with your medical team to determine suitability and eligibility.

We are not aware of any rare disease organisations specifically for FAP in Australia or internationally. If you know of any rare disease organisation, please let us know via the Contribute page.

Australian Organisations:
Rare Cancers Australia 
Website: https://www.rarecancers.org.au/knowledgebase/cancer-types/familial-adenomatous-polyposis-fap/ 

Bowel Cancer Australia 
Website: https://www.bowelcanceraustralia.org/  

Please note that RVA does not monitor or endorse each group/organisation’s operational governance and activities. When engaging with a group, please consider the information on the RARE Portal’s Finding Helpful Peer and Community Supports page.

FAP varies between individuals, and each person’s experience is unique.  

If you would like to share your personal story with RVA, please visit the Rare Voices Australia: Share Your Story page. RVA will consider your story for publishing on our website and inclusion on the RARE Portal.

For information on available government and social services that provide support for individuals with a rare disease, please visit the National and State Services pages.

People living with a rare disease, including families and carers, often face unique challenges such as diagnostic delays, misdiagnoses, limited treatment options, and limited access to rare disease specialists and support. These challenges may impact people’s emotional wellbeing and quality of life. Many people find it helpful to seek mental health and wellbeing support to cope with ongoing stress and uncertainty. Connecting with people who have shared experiences through a support group may also be helpful. Information about relevant mental health and wellbeing support can be found at:

• Mental Health and Wellbeing Support for Australians Living with a Rare Disease
• The National and State Services pages underneath the ‘Mental Health’ sections listed

Further information on FAP can be found at: 

• Cancer Institute NSW: Familial adenomatous polyposis; a guide for people with FAP, and their family and friends 
• eviQ: Facts for people and families with Familial Adenomatous Polyposis 
• Rare Cancers Australia: Familial Adenomatous Polyposis (FAP) 
• Rare Cancers Australia: Gardner Syndrome 
• Rare Cancers Australia: Turcot Syndrome 
• Cancer Institute NSW: Familial Adenomatous Polyposis 
• Centre for Genetics Education: Bowel cancer and inherited susceptibility

Royal Australian College of General Practitioners (RACGP): Familial colorectal cancer 

eviQ: General practitioner referral guidelines for cancer genetics assessment 

GeneReviews®: APC-Associated Polyposis Conditions 

Online Mendelian Inheritance in Man, OMIM®: # 75100; Familial adenomatous polyposis 1; fap1 

Orphanet: Familial adenomatous polyposis 

Human Phenotype Ontology (HPO): Familial adenomatous polyposis 

This page has been developed by Rare Voices Australia (RVA)’s RARE Portal team. If you would like to see more information added to this page, please reach out via the Contact form. If you would like to share relevant resources for this condition, please visit the Contribute page. 

If you are aware of any additional information that may benefit stakeholders with an interest in this page, or if you notice any broken links or inaccurate information, please let us know via the Contribute page.