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                                          Familial Adenomatous Polyposis

Disease characteristics
Familial adenomatous polyposis (FAP) is caused by mutations in the Adenomatous Polyposis Coli (APC) gene, which controls cell division. Most of the mutations cause the production of an APC protein that is abnormally short and nonfunctional. This short protein cannot suppress the cellular overgrowth that leads to the formation of hundreds to thousands of polyps, which if not treated can become cancerous.

Prevalence

Most individuals with APC mutations will develop colon cancer by age 40, so early diagnosis is imperative. The APC mutations are not common hence there is no concrete carrier rate established the general population. One mutation in APC gene is carried by approximately 6%-8% percent of people of Ashkenazi (eastern and central European) Jewish heritage. This mutation results in the substitution of the amino acid lysine for isoleucine at position 1307 in the APC protein (I1307K). This change was initially thought to be harmless, but has recently been shown to be associated with a 10 to 20 percent increased risk of colon cancer.

Mutation

Familial Adenomatous Polyposis (FAP) have germline mutations, with 95% being nonsense/frameshift mutations leading to premature stop codons. 33% of mutations occur between amino acids 1061-1309. In somatic mutations, over 60% occur within a mutation cluster region (1286-1513). Yet I1307K is the one in Ashkenazi population.

Testing criteria and symptoms
Traces of blood in the stool
History of Colon cancer in young age in family
Being of Ashkenazi Jewish ancestry
 

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