UC Davis researchers develop new test for fragile X syndrome

Fragile X syndrome is the number one cause of inherited mental retardation in humans. People with Fragile X syndrome experience deficits in learning, behavior, motor skills, sensory systems, and speech. The extent to which each individual will be affected depends largely on how extensive the mutation is on their X chromosome and the affected person’s gender. Additionally, most individuals with the syndrome are screened for whether or not they also have autism as the two disorders are commonly found to be comorbid.

Fragile X syndrome is caused by the slipped mispairing of three nucleotides CGG in the FMR1 gene. This mutation leads to a deficit in the FMR1 Protein as the expanded mutation silences the gene. Lacking this protein, normal communication between nerve cells cannot occur and people with the syndrome often have substantial cognitive delays as a result. Because the FMR1 gene is on the X chromosome, boys are more likely to be affected than girls as a result of inheriting a mother’s affected X chromosome. Likewise, because these mothers pass on the affected X chromosome to their sons, the mothers themselves are often mildly affected with increased anxiety and slight behavioral abnormalities. Girls who inherit one affected X chromosome from either parent will often have mild effects as the other X chromosome can make up for some of the deficit.

At UC Davis, both the MIND Institute and the Center for the Mind and Brain do research on the behavioral and molecular abnormalities associated with the syndrome. A new genetic test, developed by Paul Hagerman at the MIND Institute, is called ELISA and was created to measure the level of FMR1 protein expressed in individuals who carry the gene mutation. This test will better allow individuals to be diagnosed with the syndrome so they may therefore receive earlier treatment for the disorder. Decreased FMRP levels have already been associated with other disorders in development, behavior, anxiety, Fragile-X associated tremor/ataxia syndrome, ovarian deficiencies, and ADHD. It is being discussed whether testing for Fragile X syndrome would be beneficial to add to the standard neonatal tests which are already administered at birth.

The fact that UC Davis is associated with the MIND institute is invaluable to students who are interested in genetic disorders. People come from all over the world to visit Drs. Paul and Randi Hagerman as they are experts in the study of Fragile X syndrome and are directors of the Fragile X Syndrome Treatment and Research Center. I have personally been involved in research on fragile X syndrome as a research assistant at the Center for the Mind and Brain and have been able to apply a lot of what I have learned in genetics and psychology to the internship.

References:

Brown, Phyllis. UC Davis researchers develop new test for fragile X syndrome. Insciences Organisation. 2009 [8 June 2010]. <http://insciences.org/article.php?article_id=5897>

Iwahashi, C., Tassone, F., Hagerman, R.J., Yasui, D., Parrott, G., Nguyen, D., Mayeur, G., Hagerman, P.J. A Quantitative ELISA Assay for the Fragile X Mental Retardation 1 Protein. The Journal of Molecular Diagnostics. 2009 [8 June 2010] Vol. 11(4). <http://jmd.amjpathol.org/cgi/content/short/11/4/281>