What scientists haven't understood is what they have in common. But now, they may be closer to an answer. A new study suggests that many autism-linked genes are connected through a shared biological network and this could help explain why autism is diagnosed much more often in males than females.
The research, published in the journal Nature, focused on autism spectrum disorder (ASD), a neurodevelopmental condition characterized by differences in social communication as well as restricted or repetitive behaviors. Although autism is highly heritable, researchers have identified hundreds of genes that can increase a person's risk of developing it, leaving a longstanding question: how can so many different genetic changes result in similar outcomes? A team led by researchers at Boston Children's Hospital discovered that many of these seemingly unrelated genes may converge on the same genetic pathways.
By studying autism-associated genes in human cell models, the researchers found that disrupting a single autism-linked gene often triggered changes in many others. Lead author Rebecca Andersen, Ph.D., described the phenomenon as "transcriptomic convergence," referring to the tendency of different autism-related mutations to produce similar patterns of genetic activity. "When I started this project, I thought that by disrupting several autism-associated genes one at a time, we would be able to group subsets of them together based on how similar or different the effects were," Andersen told Newsweek.
Instead, nearly all the gene disruptions tested produced similar effects on overall gene expression, particularly affecting other genes linked to autism. "This suggests that autism-associated genes are tightly interconnected with one another, such that disrupting one of them can have rippling effects that disrupt many others, and this begins to explain how so many different genes can play a role in autism," Andersen said. Osanmoh, a board-certified psychiatric mental health nurse practitioner at Savant Care who was not involved in the study, said the findings could help explain why people with different genetic mutations can share similar autism characteristics.
"It does not, however, tell us how [a] child may progress or what kind of interventions they may require," Osanmoh told Newsweek. The study also explored another enduring mystery in autism research: the so-called "female protective effect." Autism is diagnosed approximately four to five times more frequently in males than females, leading scientists to suspect there may be biological factors that help protect females from developing the condition, even when they carry autism-associated genetic variants. The researchers identified a gene called ZFX as a potential key player.
Located on the X chromosome, ZFX belongs to a small group of genes that escape a process known as X chromosome inactivation. While most genes on one of a female's two X chromosomes are effectively switched off, escapee genes such as ZFX remain active on both chromosomes. As a result, females generally produce higher levels of the ZFX protein than males.
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