Factors Impacting Autism Spectrum Disorder
In recent years, autism spectrum disorders (ASD) have been more frequently and accurately diagnosed by medical practitioners. As of 2018, the Center for Disease Control found that about one in fifty-nine children is diagnosed with an autism spectrum disorder. With its greater prevalence comes a greater desire to pinpoint a cause of the disease. It is known that genetics play a large role, and parents with one child diagnosed with ASD have a two to eighteen percent chance of having a second child diagnosed with ASD as well. Recent research has focused on genetic causes of autism, and a study published by Zhuchi Tu in October 2018 identified a mutated gene that plays a causative role in autism spectrum disorders.
In the study, Zhuchi Tu and his team utilized CRISPR/Cas9 to disrupt the SHANK3 gene, an ASD causative gene that codes for a postsynaptic scaffold protein. Previous work with this gene in mice failed to show the effects of the mutation; due to the behavioral and brain differences between mice and humans, mutations in SHANK3 in mice did not produce the same characteristic autistic behaviors that are typically observed in humans. Therefore, the researchers used a monkey model to study the mutated SHANK3 gene. One monkey with a two base pair deletion in exon 12 survived, and the researchers longitudinally observed this animal and found that the monkey displayed behaviors characteristic of autism spectrum disorders; the monkey showed repetitive behaviors, stereotypical locomotion, and impaired social interaction.
Dr. Maggie Guy presented her research earlier this semester on infants at high risk of autism spectrum disorders; she and her team studied the ERP responses of the N290, P400, and Nc components in infants diagnosed with Fragile X syndrome and infants with siblings diagnosed with ASD (ASIBs). Fragile X syndrome is the most common known genetic cause of autism, and infants with older siblings diagnosed with ASD have diagnoses that are eighteen to twenty times more prevalent than the general population. When recording the responses of infants looking at their mothers’ faces, strangers’ faces, their own toys, and new toys, Guy found that ASIBs had muted ERP responses in the N290 and Nc components, and they did not differentiate between faces or toys. The results of this study relate to Zhuchi Tu’s findings; Guy found that ASIBs failed to differentiate between familiar and unfamiliar stimuli which relates to the characteristic impaired social interaction that Zu observed in the monkey.
Both Zu and Guy studied factors contributing to autism spectrum disorder symptoms. While Guy focused on the neural correlates of face processing for infants at high risk of an ASD diagnosis, Zu studied the common autistic behaviors observed in the monkey with a SHANK3 mutation. With their research, we are steps closer to pinpointing the causes of ASD and developing more targeted, effective therapies for these patients.
Sources:
https://academic.oup.com/hmg/advance-article/doi/10.1093/hmg/ddy367/5133462
https://www.spectrumnews.org/news/monkey-mutation-top-autism-gene-shows-social-problems/
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