ASK DR. H: Understanding Fragile X syndrome

Q: What can you tell me about “Fragile X syndrome”? — Anonymous, Dublin

A: Fragile X syndrome may be the most common cause of genetically inherited mental retardation you’ve never heard of. One in every 2,000 males and 1 in every 4,000 females are born with it. Surprisingly, 1 in 259 women in the general population carry the Fragile X gene.

fragile x

Elly and Mike Scott's son, Morgan, has Fragile X syndrome. Photo by Bob Andres,

It’s a bit tricky, because there are some who have the genetic defect and are normal by all appearances and IQ tests — and then there are those at the other end of the spectrum with severe mental retardation; specific physical appearances (long face and large ears and mitral valve prolapse and double-jointed fingers); and behavioral problems like autism or attention-deficit (hyperactivity) disorder. Those with Fragile X syndrome may have symptoms that fall anywhere in this spectrum.

This is a genetically inherited disorder, and not everyone with large ears or hyperactivity has it.

What goes wrong in Fragile X syndrome? Every gene is made up of many units of DNA sequences. In Fragile X, there seems to be a stuttering-like repeat of the same DNA sequence. Normally, there’s supposed to be some repeating of this DNA sequence — about six to 45 copies. But in Fragile X, there are 200 or more copies of this DNA sequence. This stuttering gene defect results in the shutting off a certain protein called “FMR-1”, and the signs and symptoms of Fragile X syndrome.

Unfortunately, there’s no cure for Fragile X syndrome.

Treatment includes special educational instruction; speech therapy; physical and occupational therapy; and medication to deal with attention-deficit disorder, hyperactivity, aggression and depression. Future treatments may involve gene therapy where the sequential repetition of DNA that seems to shut down FMR-1 production and bring about Fragile X syndrome is repaired.

For more information, check out the National Fragile X Foundation at

Dr. Mitchell Hecht is a physician specializing in internal medicine. Send questions to him at: “Ask Dr. H,” P.O. Box 767787, Roswell, GA 30076. Because of the large volume of mail received, personal replies are not possible.

Become a fan of AJC Health Care on Facebook and follow ajchealthcare on Twitter for more health care news and health advice.

One comment Add your comment


January 1st, 2010
2:15 pm

Here is some additional information about the “genetics” of this condition that was written by our Genetic Counselor and other genetic professionals: I hope it helps. Thanks, AccessDNA