CASE HISTORY – January 2015

Familial adenomatous polyposis: an overview and a family case report

Authors: Piret Laidre, Jaan Soplepmann, Oivi Uibo, Kairi Raime, Maria Yakoreva, Gerli Mirka, Hanno Roomere, Katrin Õunap

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Familial adenomatous polyposis (FAP) is an autosomal dominant colon cancer predisposition syndrome. The FAP is characterised by development of hundreds to thousands of adenomas in the colorectum. Almost all affected patients will develop colorectal cancer (CRC) if left untested and untreated in the early stage. The syndrome is caused by mutations in the tumour suppressor gene APC. The FAP a rare condition and accounts for approximately 1% of all CRC cases.

We identified a large Estonian family (altogether 27 relatives in three generations) with the classical FAP syndrome.

The index patient was a 36-year-old female with severe colorectal polyposis and CRC. We surveyed the pedigree and performed genetic analysis to 17 family members in 2 generations (age 5 – 42 years).

In this family 4 persons have been diagnosed with CRC and three of them have died. In addition, there are 7 persons with colorectal polyposis: they were selected for colonoscopy after genetic investigation, which identified the pathogenic mutation c.3184_3187delCAAA; p.Gln1062Valfs*63 in their APC gene. Two patients have passed prophylactic colon resection.

The early clinical manifestations of FAP are nonspecifi c. Thorough the pedigree investigation together with appropriate genetic counselling, molecular screening and colonoscopy for high risk individuals, it is important to find asymptomatic FAP patients. Regular screening of at risk FAP patients expectedly improves their survival.