Autism's Genetic Roots
Our genes provides the framework of who we are and what we will become. New research relating to developmental disorders has found that gene activity can affect how developmental delays manifest. The data plays a pivotal role in identifying how autism can be expressed throughout one’s life.
We already know that autism is attached to genes. Autism, as well as schizophrenia and bipolar disorder can be heritable*. During part of this ongoing study, when comparing autism to the other neuropsychological disorders, researchers found that certain autism-related genes are responsible for increasing gene activity and forming unique brain patterns.
The large-scale research involved 15 institutions analyzing over 2,000 postmortem brains. About 50 of these brains belonged to individuals with autism. These brains would be used throughout the series of studies examining which cell types and biological processes are affected in autism and other neuropsychiatric disorders related to gene expression.
Through previous findings, researchers confirmed that schizophrenia, bipolar disorder, and autism shared similar genetic variants and patterns. All three disorders displayed an implication of the prefrontal and temporal cortices, which are parts of the cerebral cortex.
The prefrontal cortex is related to complex cognitive behavior, personality expression, and social behavior. The temporal cortex is involved with the cognitive processing of language, comprehension, emotion, and memory. Researchers link a dysfunction of these activities with autism. In the current study, researchers wanted to uncover the source of these irregularities by replicating specific patterns that were identified in the cerebral cortex. They also profiled the expression of isoforms – alternate and varied sequences of RNA that stem from the same gene.
This discovery revealed that isoform dysregulations seem to be the hallmark of schizophrenia, bipolar disorder, and autism. Although these disorders shared similarities, only autism showed the activation of specific brain immune cells that are called microglia.
The next phase of the research was to categorize genes and isoforms, which show patterns of expression in the brain, into groups called modules. The researchers noted overlap between all three disorders in 5 of the 90 studied modules, but found three other modules that showed alterations in autistic brains only.
Autistic brains exhibited 767 isoforms produced at different levels. Though the research originally suggested a shared irregularity of these isoforms among neuropsychological disorders, most were unique to autism.
In the distinctly autistic modules, researchers looked at the genes and molecules that cause the irregular functions associated with the disorder. One, called interferon, which is particularly crucial in autism research, becomes the most active in the brain about the same time as symptoms related to autism begin to show up in children.
According to Michael Gandal, a co-leader of the study and Assistant Professor of Psychiatry and Biobehavioral Sciences at the University of California, Los Angeles, "The interferon response is very intriguing to me in autism, because it really seems to peak as early as we have samples, around age 2 or 3. That suggests to us that [it] may be related to the disease onset.”
What this research has uncovered is not an answer or solution to autism, but rather more data from which future research can benefit. Understanding when genes activate and begin to transform can lead to a better sense of how and when autism occurs in individuals. The researchers plan to update with further findings every six months, shading more light on the molecular data that can be directly traced to autism.
Read more about this study here.