Molecular Test Listing

Molecular Requisition

FAMILIAL ADENOMATOUS POLYPOSIS: (FAP)

Familial adenomatous polyposis (FAP) or Gardner syndrome is a condition which leads to one of two principal forms of hereditary colon cancer. The one in 7,000 individuals who have FAP begin to develop polyps following puberty.  However, they may have a 10-year progression before the onset of early symptoms such as diarrhea, abdominal discomfort and rectal bleeding.  If a patient does not undergo a resection of the colon or endoscopic removal of polyps, their risk of cancer approaches 100% by age 50.  Endoscopic inspection and polyp removal is often recommended every six months in at-risk individuals. 

FAP is the result of a mutation in the APC gene (5q21). FAP is inherited in an autosomal dominant manner, and is considered fully penetrant.   Most of the mutations lead to premature truncation of the APC protein. The most effective method of identifying patients who have inherited FAP is by tracking the condition through the family using an approach called linkage analysis.

To perform linkage testing DNA samples must be obtained on multiple family members. An accurate family history and clinical assessment is essential for correct interpretation of results.

 

REASONS FOR REFERRAL:
  • To identify individuals at risk for colon cancer.
  • Individuals with a family history of FAP who want to assess the need for regular colonoscopy.
  • Individuals with a family history of FAP who wish to undergo prenatal or preconception testing.

TESTING METHODOLOGY:
  • Linkage: Testing involves tracking the gene through the family using highly polymorphic microsatellite markers surrounding, or within the APC gene, by PCR technology.
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    • The choice of testing strategy involves many factors. A discussion with the laboratory is recommended before sending a specimen.

    •  This approach can be the most informative stratagem for eliminating risk; however, it requires samples from multiple critical family members, including at least two affected individuals. An accurate family history is essential for correct interpretation of results.

    SPECIMEN REQUIREMENTS:
    • Basic pedigree detailing clinical history.
    • Blood EDTA (purple top) tubes:  

                Newborn: minimum 1-2 mL          

                Child/Adult: prefer 2 tubes of 3-5 mL

    • Alternate sample: Paraffin block, or 5 unstained sections on slides from the block.

  • A Molecular Genetics Laboratory Test Requisition must accompany the specimen. Contact the Molecular Laboratory at 918-502-1721 to obtain further information.

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    TURNAROUND TIME:     15 working days

    CPT CODES: