Fragile X

Older news items (pre-2010) brought over from the old website

New method of scoring IQ tests for fragile X children

IQ tests can tell us little about the learning abilities of children with intellectual disabilities, as parents of such children know only too well. So it’s exciting to learn that a new system of scoring IQ tests has been devised for children with fragile X syndrome. This new test reflects the variability evident among learning disabled children, and tells parents, teachers and doctors how a child with fragile x syndrome deviates from the normal population in every sub-test area. The researchers also found a significant correlation between the scores and the level of FMR1 protein in the blood (the protein expressed by the normal variant of the so-called fragile X gene), and between the IQ test scores and scores on the Vineland Adaptive Behavior Composite, which measures personal and social skills used in everyday living.

[886] Reiss, A. L., Hall S., Hessl D., Nguyen D. V., Green C., Chavez A., et al.
(2009).  A solution to limitations of cognitive testing in children with intellectual disabilities: the case of fragile X syndrome.
Journal of Neurodevelopmental Disorders. 1(1), 33 - 45.

Acne drug may help those with Fragile X syndrome

A new mouse study has found that a readily available drug called minocycline, used widely to treat acne and skin infections, helps Fragile X syndrome. Human trials have already been approved. The study has revealed that dendritic spine development is impaired in mice with Fragile X, and that this drug reduces levels of the enzymes interfering with their healthy development. The mice showed healthier dendritic spines, reduced anxiety, and improved cognition.

[863] Bilousova, T. V., Dansie L., Ngo M., Aye J., Charles J. R., Ethell D. W., et al.
(2009).  Minocycline promotes dendritic spine maturation and improves behavioural performance in the fragile X mouse model.
Journal of Medical Genetics. 46(2), 94 - 102.

Fragile X retardation syndrome corrected in mice

In another study targeting the glutamate receptor mGluR5, researchers have fixed multiple defects in fragile X mice by reducing these receptors by 50%. They achieved this through genetic engineering, but drugs blocking mGluR5 receptors are now entering human clinical trials. Fragile X is the most common form of inherited mental retardation and a leading identified genetic cause of autism.

[1306] Dölen, Gül, Osterweil E., Rao S. B. S., Smith G. B., Auerbach B. D., Chattarji S., et al.
(2007).  Correction of Fragile X Syndrome in Mice.
Neuron. 56(6), 955 - 962.

Mouse study points to new therapy for Fragile X sufferers

A mouse study has found evidence that fragile X mutation produces a highly selective impairment to long-term potentiation in hippocampal cells, and that adding brain-derived neurotrophic factor (BNDF) proteins to the hippocampus restored it.

[1064] Lauterborn, J. C., Rex C. S., Kramar E., Chen L. Y., Pandyarajan V., Lynch G., et al.
(2007).  Brain-Derived Neurotrophic Factor Rescues Synaptic Plasticity in a Mouse Model of Fragile X Syndrome.
J. Neurosci.. 27(40), 10685 - 10694.

Fundamental defect in fragile X syndrome identified and corrected

In an exciting new cell study, scientists have not only discovered the fundamental defect that causes fragile X syndrome (the most common inherited form of mental retardation), but also how to correct the problem. It is hoped that this will eventually lead to the development of human therapies for this previously untreatable condition.

[647] Nakamoto, M., Nalavadi V., Epstein M. P., Narayanan U., Bassell G. J., & Warren S. T.
(2007).  Fragile X mental retardation protein deficiency leads to excessive mGluR5-dependent internalization of AMPA receptors.
Proceedings of the National Academy of Sciences. 104(39), 15537 - 15542.

Fragile X syndrome -- A stimulating environment restores neuronal function in mice

Mice in which the gene that causes Fragile X syndrome —- the most common form of inherited mental retardation — in humans had been knocked out, showed reduced long-term potentiation in neurons due to abnormalities in the channels that regulate the flow of calcium into neurons. Excitingly, exposure to an enriched environment restored normal neuronal plasticity, suggesting that mechanisms for synaptic plasticity are in place, they just require stronger neuronal activity to be triggered.

[638] Meredith, R. M., Holmgren C. D., Weidum M., Burnashev N., & Mansvelder H. D.
(2007).  Increased Threshold for Spike-Timing-Dependent Plasticity Is Caused by Unreliable Calcium Signaling in Mice Lacking Fragile X Gene Fmr1.
Neuron. 54(4), 627 - 638.