Fragile X Testing For Many Ages
December 5, 2008 by Kristina Chew, PhD
Filed under Health
An article in the November Journal of the American Medical Association by researchers at the UC Davis M.I.N.D. Institute calls for Fragile X testing throughout the lifespan. The genetic mutation that is linked to Fragile X, fragile X mental retardation 1 (FMR1), also gives rise to a “family of disorders occurring throughout the entire life span, including the most common heritable form of intellectual disability, fragile X syndrome, and premature menopause (primary ovarian insufficiency).” Further mutations of the gene also are the cause of fragile X–associated tremor/ataxia syndrome (FXTAS), which is “one of the most common single-gene, late-onset neurodegenerative disorders.” Researchers note that, while it might be thought that these disorders are rare, such an assumption is “both false and unwise”; mutations of FMR1 can affect people at different times in their lives. Newborn screening for Fragile X is also being considered.
The research was undertaken by Randi J. Hagerman, MD, director of the Fragile X Research and Treatment Center at the M.I.N.D. Institute, and Paul J. Hagerman, MD, PhD, director of the UC Davis NeuroTherapeutics Research Institute (NTRI). As noted in Science Daily:
Abnormalities in the fragile X gene fall into two categories: those caused by the full mutation and those associated with the premutation.
The full mutation involves greater than 200 copies of a three-nucleotide sequence (CGG) in the FMR1 gene found on the X chromosome.Normal individuals typically have fewer than 40 repeats.
The premutation involves 55-200 CGG repeats in this gene. Individuals with the premutation are known as carriers and the children of female carriers are more likely to be born with the full mutation.
30 percent of boys with the FMR1 are diagnosed with autism and Fragile X syndrome is “the most commonly known single-gene cause of autism,” and is linked to between 2 and 6 percent of autism cases.
On life raising a child with Fragile X, Clare Dunsford’s Spelling Love With an X: A Mother, a Son, and the Gene That Binds Them is a must, and a good, read (and one I must recommend to the library, or if you’re in a book-giving mood for holidays.)
Thanks for bringing attention to this. It’s amazing what research has shown us the last decade about fragile x. It used to be just the child affected. Then it showed that carriers have issues too like POF and anxiety disorders. And more recently the grandparent carrier of the child, more commonly the grandfathers, are showing FXTAS which can be misdiagnosed as Parkinsons. Its scary but exciting that these things are getting found out. The more we know the better we can help
We have had M tested for Fragile X just a few months ago. She does not have Fragile X. However, this post reminds me that when we went to the Cleveland Clinic they highly encouraged M returning for more genetic testing after a few years. That time has come and we need to make an appointment. There are always new things being discovered.
I wonder if it’s possible for someone with a premuation to have autism,but not retardation ?