Using CRISPR-Cas9 gene editing, researchers were able to reduce autism symptoms in mice with a form of fragile X syndrome or FXS, the most common single-gene cause of autism spectrum disorder.
Reducing Autism Symptoms In Mice With Fragile X Syndrome
Hye Young Lee, from the University of Texas Health Science Center at San Antonio, and colleagues used gold nanoparticles to deliver Cas9 enzyme into the striatum of the brain, a region that mediates habit formation, including that associated with repetitive behaviors common to ASD.
The method, known as CRISPR-Gold, edited out a gene for a neurotransmitter receptor called metabotropic glutamate receptor 5, or mGluR5, involved in communication between neurons and is dysregulated in FXS.
The method reduced repetitive behavior associated with FXS. The mice showed 70 percent less leaping and 30 percent less obsessive digging.
Repetitive and exaggerated behaviors are among the most common characteristics of people with autism spectrum disorders. The results of the experiments that reduced these behaviors in mice with FXS suggests the potentials of using CRISPR-Gold for other types of autism.
"CRISPR-Gold designed to target the metabotropic glutamate receptor 5 (mGluR5) gene can efficiently reduce local mGluR5 levels in the striatum after an intracranial injection," the researchers wrote in their study.
"The effect can also rescue mice from the exaggerated repetitive behaviours caused by fragile X syndrome, a common single-gene form of autism spectrum disorders. "
Autism Spectrum Disorder
People with autism disorders have issues interacting with other people. They are also marked by exaggerated repetitive behavior such as rocking and flapping. ASD affects over one percent of all children. FXS, however, is rare, affecting only one of every 4,000 boys and 6,000 girls.
Autism currently has no treatments or cure. Some parents have already resorted to dangerous and ineffective methods of feeding their children bleach to treat the condition.
Advantage Of Using CRISPR-Gold Method
Many small-molecule treatment trials that target autism-causing proteins have failed.
The study marks the first time when researchers were able to edit a gene that causes autism in the brain and improved behavioral symptoms of the condition.
The researchers said that CRISPR-Gold also has a number of advantages over other ways of delivering Cas9 into the body, such as through viruses because the method allows them to control the amount of Cas9 protein that they inject.
Lee and colleagues published the findings of the animal study in the journal Nature Biomedical engineering on June 25.