Genetic Testing for FAP

Last Modified: June 10, 2009

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Question

Dear OncoLink "Ask The Experts,"

FAP is very prevalent in our family. My son has had 3 genetic tests done in an effort to locate his mutation so that other family members could get blood tests to see if they have it, but they have not been able to locate the mutation in any of the affected family members. I have heard that it matters where the test is done- that different labs are better at detecting the gene abnormalities. Is this true?

Answer

Jill Stopfer, MS, CGC, Certified Genetic Counselor, responds:

It is not the hospital or lab that matters in the detection rate of genetic mutations in the APC gene, it is the technique used by that lab.  So the question to ask is: was the person affected with FAP tested by sequencing, including testing for large genomic deletions and rearrangements?  The genetic counselor  / genetics professional who arranged the testing should be able to answer this question.  It is absolutely true that depending on which lab was used, different techniques may have been used, which can affect the accuracy or “completeness” of the testing.