Pinpointing ASD's Key Factors

The case of finding a cause for Autism Spectrum Disorder (ASD) has been a long and complex one. It is extremely widespread, and its diversity in the the effect can range from extremely severe to almost unnoticeable. As more research has come out about the success in early treatment on severity of symptoms for those living with autism, it has become more and more important to find and pinpoint the key causes as a way to target and identify them for future people at risk.

Dr. Maggie Guy conducted research on just one of the pieces that may contribute to the cause and help lead to early identification of ASD. In her research, she looked at three different populations: low-risk controls (LR), siblings of children with ASD (ASIBs), and infants with fragile X syndrome (FXS). ASIBs are shown to be 18-20 times more likely to receive diagnosis, and they show the broader autism phenotype. Infants with FXS are at high risk, as FXS is the most common known genetic cause of ASD, and 60-74% of those with FXS meet criterion for ASD. Dr. Guy’s research was conducted with the question of looking at the neural correlates of face-processing across these groups, but on a broader level, looking at the heterogeneous pathways to ASD emergence.

In this particular study, Dr. Guy used a series of different brief stimuli presentations (pictures of toys or faces) and looked at both Event-Related Potential (ERP) results and used cortical source analysis. The negative ERP component N290 shows a greater response or activation to faces than toys in all groups, however there were more muted responses in ASIBs to faces than the other two groups, and the strongest responses were from those participants in the FXS group. In addition to the N290, the negative central (Nc) shows responses to visual stimuli with its greatest amplitude being in response to novel stimuli. In these results, both LR and ASIB infants showed a higher amplitude Nc response to novel stimuli than to their mother’s face, while FXS infants showed a higher amplitude Nc response to familiar stimuli than the novel stimuli presented. The results of Dr. Guy’s study could help show just one way to potentially target early indicators of ASD.

Another study led by Christopher Walsh, chief of genetics at Boston Children’s Hospital, focused on the importance of de novo, non-inherited, or mosaic mutations in those with ASD. In this particular study, the researchers relied on DNA from blood and saliva to identify these potential neural correlates for ASD known as mosaic mutations. Many of these mosaic mutations happen to be highly expressed in the amygdala. Some of the genes that were targeted in this study that have mosaic mutations were SCN2A, one of the top autism risk genes, and SMARCA4, which regulates the expression of another leading autism risk gene. The results of this study indicated that mosaic mutations have milder effects on ASD than those affecting the entire body, but this is not to say that the results are not significant. Both the findings of Dr. Guy and Dr. Walsh have helped progress the identification of ASD’s key factors. Whether the results indicated a gene or factor of a key factor or as a smaller contributing factor, it helped narrow down those potential factors to hopefully help future research.

Works Cited:

https://www.spectrumnews.org/news/sizeable-fraction-autism-risk-traced-mosaic-mutations/

Guy, M. W., Richards, J. E., Tonnsen, B. L., & Roberts, J. E. (2018). Neural correlates of face processing in etiologically-distinct 12-month-old infants at high-risk of autism spectrum disorder. Developmental Cognitive Neuroscience, 29, 61-71. doi:10.1016/j.dcn.2017.03.002