“A child with fragile X may not have any really, truly connected social conversations,” says Linmarie Sikich, who runs clinical trials for developmental disorders and autism at UNC. (Photo by Donn Young)
Signal to noise
In the quest to solve the autism puzzle, we know more about fragile X syndrome than any other piece. How close are we to a cure?
- In recognition of World Autism Awareness Day, UNC-Chapel Hill presents this Endeavors article about Adam Strom and how some UNC researchers are searching for a cure for fragile X.
Imagine you’re listening to the radio. You hear music. But there’s a lot of static, too—noise that butts in from all over the place and muddies the signal. The static is distracting and frustrating and no matter how you mess with the dial, it won’t go away. Now imagine you can’t turn the radio off. That’s sort of what it’s like inside Adam Strom’s brain.
Adam has fragile X syndrome, a genetic condition that can be synonymous with a lot of things: learning disabilities, intellectual disability, seizure disorders. A third of children diagnosed with fragile X, including Adam, also have autism.
One of Adam’s symptoms is the static—the unending zap of stimulation from the sights and sounds around him, each of which demands the same attention from his brain regardless of importance. A typical human brain can tune out unimportant things in favor of more immediate concerns—an ongoing conversation, for example, rather than a squeaky door in the other room or a fly buzzing at the window.
Each of those things is a stimulus, a signal to the brain that sets off a flurry of synaptic activity and forges connections between nerve cells. When the brain recognizes a signal as something it doesn’t need to pay attention to, the nerve cells calm down and stop producing the pay-attention protein they had begun to pump out. This synaptic activity is how we learn throughout our lives, and it’s especially crucial for young, developing brains. But for children with fragile X syndrome, the cells don’t calm down. The result is overstimulation, under-connectivity between nerve cells, and incessant static.
The autism link
The “fragile X gene” that scientists talk about wasn’t discovered until 1991, just a few years before Adam was born. “For many years in this business, we just sort of lumped children and people together as having developmental delay or intellectual disability,” says Joe Piven, who studies the neural mechanisms involved in autism. “Being able to identify a gene that’s responsible for this whole set of behavioral, cognitive, and medical problems really catapulted the whole field forward. Fragile X is a huge window of opportunity for understanding not only intellectual disability but also autism.”
Researchers all over the world think a fragile X cure—or the nearest thing to it—could be as little as ten years away. And researchers at UNC are getting closer to it.No one really knows all the various causes of autism. But the discovery of the fragile X gene in 1991 changed everything for researchers all over the world. Suddenly they had an indisputable culprit for up to 6 percent of autism cases. Fragile X is now the most common known cause of autism.
“The issue with autism is that it’s not one thing,” Piven says. “We call it autism, but some people in the field are starting to call it ‘the autisms.’ Say somebody shows up at your doorstep and they’re short of breath. You don’t know if they’ve just run a race, or they just smoked a carton of cigarettes, or they have pneumonia, or they’re having a heart attack. That’s the situation with autism. We’re now discovering that they don’t all have the same thing.”
Piven and his colleagues at UNC and Stanford just finished a study of brain images that show the differences between the developing brains of toddlers with autism caused by fragile X syndrome (like Adam) and toddlers who have autism with no known cause.
Published April 2, 2012.