Fragile X Testing in Adult Women
INTERPRETING THE TEST RESULTS
If you decide to take the fragile X genetic test, the results typically include the following: Presence or absence of the mutation, the mutation category (premutation, full mutation, both (mosaic), or 'grey zone'), and the size of the gene alteration (“CGG repeat number”).
This is how these results should be interpreted:
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Category
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Repeat Size
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Definition
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No mutation
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Less than 40 repeats
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Person does not have Fragile X Syndrome and is not a carrier of the fragile X premutation. This is the most common result.
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Premutation
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Between 55 – 200 repeats
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Person is a carrier of the fragile X premutation. This is a possible test result for 6 out of 100 women tested through the OB/GYN clinic.
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Full mutation
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More than 200 repeats
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Person has the full Fragile X Syndrome. Few OB/GYN patients will have this result.
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Grey zone
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Between 40 – 55 repeats
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In this case, the grey zone gene is not the cause of the clinical problems of early menopause or reduced fertility. The gene is functional. There is insufficient research to estimate how many OB/GYN patients may have this result.
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Mosaicism
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Full mutation and premutation present in cells tested.
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A rare condition that we do not expect to see. Current research is examining the relationship between mosaicism and the severity of the Fragile X Syndrome.
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Your clinician will discuss your results with you. If you are found to have the premutation level of fragile X, you will be referred to a genetic counselor here at the University of Virginia to help you understand the test results and their potential implications.
If you have any questions, please feel free to call us. Our clinic phone numbers are: Midlife Health Center (434-243-4720) and Reproductive Medicine and Surgery (434-243-4590).
Written by the University of Virginia OB/GYN and Pathology Departments: LM Pastore, CD Williams, JV Pinkerton, L Silverman, LB Karns
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