According to the CDC, nearly 5.5 million U.S. adults have Autism spectrum disorder (ASD), “a developmental disability caused by differences in the brain.”
Individuals with ASD may communicate and interact differently in social situations. They may also learn, move, and pay attention differently than those who are neurotypical.
And in recent years, scientists have found a strong relationship between ASD prevalence and specific mutated genes.
PTEN, a gene that normally works to control cell growth and regulate neurons’ ability to alter their connection strength, is one of the most common.
When PTEN is mutated, it can cause both ASD, as well as epilepsy and macrocephaly– or an enlarged head.
Just last week, though, a new collaborative study conducted by researchers at Dartmouth’s Geisel School of Medicine and the University of Vermont acquired a further understanding of ASD’s neurobiological basis by focusing on PTEN.
“In previous studies, our lab and many others have shown the PTEN mutations result in an increase in the number of excitatory synaptic connections between neurons in mice– which we believe could be the fundamental basis for the symptoms that are exhibited by ASD patients,” explained Bryan Luikart, one of the study’s authors.
So, in order to replicate the genetic differences found in human ASD patients, the research team first engineered viruses that were able to “knock out” the mouse PTEN gene.
Then, a mutated human PTEN gene was substituted in its place.
sewcream – stock.adobe.com – illustrative purpose only, not the actual person
And finally, the researchers utilized high-power imaging and electrophysiological techniques to analyze how neuronal function was changed among the mice.
They found that mutated PTEN prompts neurons to grow to double the size of a normal neuron. In the process, these larger neurons form quadruple the number of synaptic connections as opposed to normal neurons. This finding only laid the groundwork for the researchers’ next steps, though, in which the team aimed to understand other gene roles in PTEN loss.
“We were able to determine that if you take out the gene known as Raptor, an essential gene in the mTORC1 signaling pathway, it rescues all of the neuronal overgrowth and synapses that occur with normal PTEN loss,” Luikart said.
It is also important to note that the mTORC1 pathway is critical for synapse formation and neuronal growth. And the researchers found that when a drug known as Rapamycin was used to inhibit this pathway, all of the changes to neuronal overgrowth were able to be rescued.
Rapamycin was administered to children during a clinical trial this year and was shown to relieve some symptoms of ASD– a promising new discovery. However, the researchers note that in order for this potential treatment to be effective, they believe the ASD-associated genetic changes will need to be targeted before symptoms begin– which can be a tricky time-sensitive task.
Nonetheless, the team is confident their findings are crucial for gaining a more robust understanding of ASD’s neurological basis and for the future development of patient therapies.
“If we find that treating with a drug like Rapamycin early enough fixes the actual behavior problems of autism in a human patient, then that tells us we are really onto something; that these changes we are seeing and fixing in our model organism are the cellular or physiological basis of autism in humans,” Luikart underscored.
To read the study’s complete findings, which have since been published in Cell Reports, visit the link here.
If true crime defines your free time, this is for you: join Chip Chick’s True Crime Tribe
She Says Her Spirit Guide Saved Her Life After She Almost Fell Out Of A Window
Sign up for Chip Chick’s newsletter and get stories like this delivered to your inbox.