Fragile X syndrome, or FXS, a leading genetic cause of autism and affects approximately one in 4,000 men and one in 6,000 women. Its symptoms include increased anxiety, intellectual disability, repetitive behaviors, social communication deficits, and abnormal sensory processing. People living with FXS generally do not have the fragile 1X mental retardation gene, or Fmr1, in their brain cells. If their cells have this gene, it’s silent and doesn’t make a protein called FMRP.
Researchers from the University of California, Riverside revealed they were able to improve symptoms of FXS after inserting Fmr1 into the brains of very young transgenic mice that had been genetically modified to lack this gene. When the scientists measured brain activity for signs of anxiety and hyperactivity in response to stimuli such as stress and sounds, they found that reactivation of the gene Fmr1 in these mice had led them to no longer show symptoms of FXS.
The results of the Research were published in the journal Neurobiology of Disease.
Fragile X Syndrome, or FXS: Here’s what’s new hope for people with autism.
“Our work shows the beneficial effects of reactivating the Fmr1 gene, which would be very welcome news for children living with FXS”, he has declared Iryna M. Ethell, professor of biomedical sciences at theUCR School of Medicine, who led the research.
In their study, the Ethell’s lab, in collaboration with Khaleel A. Razak, professor of psychology, very young mice, less than 3 weeks of age, were selected because the brain is more plastic at the beginning of life; the equivalent in humans is around the first 3-5 years: “For humans, the first 3-5 years are essential for brain development “Ethell said. “It is therefore important that this first period is targeted in FXS ”.
The mouse brain, like the human brain, has excitatory and inhibitory neurons. Unlike excitatory neurons which lead to forward propagation of information, inhibitory neurons function as a brake by suppressing unnecessary activity and tuning brain activity to specific signals.
Ethell and two colleagues recently published a review article on Nature Neuroscience which shows that inhibitory neuron dysfunction is a common pathology in genetic disorders related to autism spectrum disorders, or ASD.
“In this study, we targeted excitatory neurons in the second and third postnatal weeks of mice to insert the gene Fmr1Ethell said. “Our study shows that this period is not too late to manipulate the brain. We targeted these particular neurons because they establish control over inhibitory neurons that are not functioning properly in FXS. At this time, we don’t know if our method would be effective in adults. That research would be a next step in this line of work ”.
How Ethell and her team introduced the Fmr1 gene into mouse brains differs from how the gene might be introduced into a human brain. The end result, however, would be the same, Ethell said. According to her, CRISPR, a powerful tool for editing genomes, would most likely be used to reactivate Fmr1 in the human brain..
“FXS is most often diagnosed early in a person’s life“, has explained: “We cannot stress enough, therefore, that the first few years are the perfect time to reactivate the Fmr1 gene. It offers hope that even if this gene is missing in a child, it can still be introduced, allowing the child to live a daily life free of FXS. As the reactivation of the gene for the treatment of FXS receives increasing attention, our results suggest the benefits of re-expression of Fmr1 during the first period of brain plasticity in mice, which corresponds approximately to the first three years of human life, when the first symptoms of ASD emerge in childhood “.
Next, the research team will work to restore function in the adult FXS brain: “The main challenge is that the adult brain is not that plasticEthell said. “Young brains can do anything. But as an adult, did you try to learn a new language? “
The research paper It is entitled “Functional consequences of postnatal interventions in a mouse model of fragile X syndrome “.
Fragile X syndrome, or FXS, is a genetic condition that causes intellectual disabilities, behavioral and learning problems, and various physical characteristics. Although FXS occurs in both sexes, males are more frequently affected than females and generally more severely.
There have been numerous studies aimed at determining the prevalence of FXS in males and females. The studies were conducted in both the “special needs” population and the general population. The agreed prevalence of FXS: males: approximately 1 in 3,600 to 4,000 .; females: about 1 in 4,000 to 6,000.
Intellectual disabilities in FXS include a range from moderate learning disabilities to more severe intellectual disabilities. Most males with Fragile X syndrome demonstrate significant intellectual disability.
Behavioral characteristics observed in males can also be observed in females, although females often have milder intellectual disability and milder presentation of the behavioral and physical characteristics of the syndrome.
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