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Familial Adenomatous Polyposis
Also known as : [FAP]


DNA/RNA
Test performed by: LabPLUS - Dept. Diagnostic Genetics - Molecular Genetics


Referral Requirements

Important Note:

Diagnostic: Gastroenterology or Genetic Services only.

Cascade: Genetic Services only.

Contacts:

Gastroenterology can be contacted on (09) 307 4949 ext. 25588.

Genetic Health Service NZ can be contacted on 0800 476 123.


Specimen Collection
EDTA8 mL Adult EDTA Blood
EDTA4 mL Paediatric EDTA Blood

NOTE:

A minimum of 0.5ml can be processed. However, sufficient DNA for downstream testing cannot be guaranteed if less than 4.0ml blood is collected.

Transport all bloods at room temperature within 24-48 hours. If necessary specimens can be refrigerated overnight for transport at room temperature the following day.

For testing of other sample types please contact the laboratory prior to sending.


Turnaround Time: Within 13 weeks
Contact Information

Contact Molecular Genetics via:

Lablink                                                     ext 22000

Mark Greenslade (Technical Head)   ext 22010

Pippa Grainger (Section leader)              ext 22014

Email: DGen@adhb.govt.nz




Background Information

Familial adenomatous polyposis (FAP) is an autosomal dominant condition affecting nearly 1 in 5000 people. It is characterised by the progressive development of hundreds to thousands of adenomatous colon polyps, some of which inevitably progress to carcinoma if the colon is not surgically removed. Age of onset of polyp development can be as early as 11 or 12, and malignant transformation can occur as late as the 7th decade. As classically defined, FAP has no associated extracolonic manifestations. However, there is at least one syndrome complex that is allelic to FAP: Gardner syndrome. Features of Gardner syndrome include colonic polyposis, polyps of the stomach and small intestine, globoid osteoma especially of the mandible and calvarium, congenital hypertrophy of the retinal pigment epithelium, epidermoid cysts and desmoid tumours. Rarely, adrenal carcinoma, thyroid carcinoma, periampullary carcinoma and hepatoblastoma (especially in children under age 4) can be seen in patients with FAP/Gardner. A second condition, Turcot syndrome, may be related to FAP.  It is characterised by colonic polyposis and brain tumours (gliomas).

The disease frequency for this documented condition is 1 in 5000 and an estimated 2 in 5000 individuals are at 50% risk for the disorder. Cancer surveillance for at risk individuals includes annual colonoscopy and upper gastrointestinal endoscopy, annual examination of the skin and annual comprehensive physical including palpation of the thyroid.

APC -associated polyposis conditions are caused by mutations in the APC gene. Molecular genetic testing of APC detects disease-causing mutations in up to 95% of probands with typical FAP. Molecular genetic testing is most often used in the early diagnosis of at-risk family members and in the confirmation of the diagnosis of FAP or attenuated FAP in individuals with equivocal findings (e.g., fewer than 100 adenomatous polyps).

Molecular genetic testing for APC is available.

For more information about the Molecular Genetics service:

Molecular Genetics information page


Last updated at 15:49:04 22/03/2021