A new gene linked to autism has been identified by UCLA researchers, who were able to break down the complexity of the developmental disorder by simultaneously working in different fields of research.
“By bringing geneticists, neuroscientists and clinicians together for one goal, we were able to make the link from genetics, to the brain, to behavior,” said Maricela Alarcon, an assistant professor-in-residence of neurology and author of a recently released study that found a new genetic link to autism.
“This is the first study that has been able to make these kinds of connections,” she said.
The study simplified the problem of studying autism by exploring one component at a time. Autism encompasses a pattern of symptoms, but the researchers chose to break down the disorder into its component parts.
Classical autism impairs language, communication and social interaction, and causes repetitive behaviors. By isolating one of these symptoms, impaired language and communication, UCLA scientists were able to identify the gene responsible for the trait. Alarcon said that such a technique had never been employed before.
The gene was found to be most active in regions of the brain such as the prefrontal cortex, which is responsible for language and higher abstract thought, Alarcon said.
But even though the gene was identified, researchers still needs to be done to determine how the gene works or what it really does, Alarcon added, pointing out the complex genetics of autism.
Susan Bookheimer, a professor of psychiatry and biobehavioral sciences, said about 11 to 15 genes associated with the development of autism have been identified. Since autism is about 70 percent genetically determined, the study of individual genes can lead to a better understanding of the syndrome itself, she added.
But Bookheimer added that environmental factors also play a role, though the interaction is not yet understood.
By studying the development of different brain regions to find the precise area where problem genes are expressed, researchers have gained helpful clues about the underlying functions the genes are controlling, said Brett Abrahams, a postdoctoral student of neurology.
“Once we find the genes and pathways, we will better understand the mechanisms of the behaviors,” Abrahams said.
Brain imaging studies are currently being conducted to address these sorts of questions and to try to understand how the brain functions of a child with autism differs from those of other children, Bookheimer said.
The same approach of breaking down the complexity was used in targeting a single symptom to study, instead of the entire syndrome. The major symptoms being studied include language, social communication, joint attention and emotion, she added.
Bookheimer said some theories point to the possibility of autism being a problem of the circuit connectivity of the brain, meaning that long-distance connections within the brain from one region to another are not well formed, but the local connections are abundant.
In addition, Bookheimer said, the mirror neuron system, which connects to limbic structures that rule emotion are also not functioning in the same way in children with and without autism.
“We feel rewarded when we see a smiling face and have automatic responses that go off in the limbic system,” Bookheimer said. “Autistic kids do not respond the same way. While they are able to physically imitate the faces, they lack limbic reward activity.”
However, children with autism are capable of feeling pleasure, and those who are higher functioning can be very intelligent but lack social skills, she said.
“They are unable to put themselves in another’s shoes,” Bookheimer said.
Some, Alarcon said, may even develop special skills in one field, such as music, complex mathematics or calendar counting tricks, while still scoring low on IQ tests.
However, these scores may not reflect their actual intelligence level, but may be due instead to a lack of compliance in engaging with the test itself, Alarcon said.
The bodies of children with autism do not seem to respond to what their minds tell them, accounting for symptoms such as repetitive behaviors and focused attention on a single subject.
The latter has been linked to the over-connectivity of local brain regions, while repetitive behaviors are linked to possible overuse of the brain’s sensory cortex, which is responsible for coordinated movements, according to Bookheimer.
The multiple dimensions of the disorder make it difficult to study as a single disease, said Dr. Daniel Geschwind, professor of human genetics.
Geschwind also said that it is easier to view autism as an array of symptoms occurring together.
New approaches to studying developmental disorders have converted autism research into a more dynamic field in recent years, he added.
Many experts believe that breakthroughs in understanding autism have accelerated in recent years as a result of the collaboration between different heads of science, Geschwind said.