Fragile X Syndrome

Thanks so much for this new forum!

My neice was diagnosed with Fragile X Syndrome.  Does this mean that I could have children with Fragile X Syndrome?  If so, is there some test that I can have to find out whether I carry this gene?

[Lisa Kessler, MS, CGC]

Fragile X syndrome is one of the most common forms of inherited mental retardation. It is caused by a gene that is carried on the X chromosome. You didn’t say if your niece is related through a brother or a sister. This will impact the chance that you could be a carrier of fragile X syndrome, and if you could have children with this disorder.

Testing is available for fragile X syndrome. It is recommended that you visit a genetic counselor. A genetic counselor will take your family history, get medical records on your relevant family (with their permission), determine the chance that you are a fragile X carrier, and review the pros and cons of testing. If you are a carrier, a counselor will discuss with you what that means for you and your children.

A genetic counselor can be found through the National Society of Genetic Counselors.

[SallyN]

There is a very reliable and accurate test to diagnose Fragile X.  Any physician can order a Fragile X Southern Blot DNA test and PCR analysis.  Both should be ordered, the Southern Blot is better to diagnose full-mutations and the PCR is better to diagnose pre-mutations.

If they offer a chromosome analysis, decline that test, it has proven unreliable to diagnose FX and is costly.

Do they know if the mother or the father is the carrier? Is the carrier one of your siblings?  If so, you should be tested, if not, there would be no need to test.

Accurate and detailed information onFragile X is available from the National Fragile X Foundation - 925-938-9300 or through The Fragile X Research Foundation - 978-462-1866.