Difficulty communicating with others is one of the defining features of autism spectrum disorder (ASD). For a large subset of individuals with ASD, language disorders or delays contribute to these communication problems. The causes of these communication impairments are not yet known.
A recent study at the Children’s Hospital of Philadelphia (CHOP), led by Dr. Timothy L. Roberts, investigated the possible link between genetics, language disorder, and ASD. Previous research had found that DNA mutations on chromosome 16 – specifically, deletions or duplications of DNA information at the genetic site 16p11.2 – were associated both with ASD and with language impairment. In order to explore how these genetic changes might be related to problems with language and social communication, Dr. Roberts looked at how people with mutations at 16p11.2 process sounds in the brain. This study enrolled children with 16p11.2 deletions, 16p11.2 duplications, and typical development. While all of the participants with genetic differences at 16p11.2 had some neurological or learning disabilities, only a portion had diagnoses of ASD.
The study looked at how children’s brains responded to a series of simple tones. A magnetoencephalography machine was used to measure brain activity. Researchers for this study analyzed a very early brain response to processing a sound. This early response reflects how the brain takes in and processes auditory information from the world around it.
Results showed that the brains of children with a 16p11.2 deletion were significantly delayed in responding to sounds compared to typically developing children. This delay was not found among children with 16p11.2 duplication. Though the delay seems small (23 ms), it is very large when it comes to fast-changing sounds like speech. A 23 ms delay means that a child hearing the word ‘elephant’ would still be processing the ‘el’ sound while other children moved on to processing ‘phant’. Over the course of a conversation, these delays can lead to children falling behind by full words and phrases.
This study shows a clear connection between the 16p11.2 gene and how our brain processes auditory information. Because this gene is also related to ASD, it could be an underlying cause of language problems for some people with ASD.
Dr. Roberts and his team are continuing their research into the relationship between genetics and the brain’s delay in processing sound. This includes a new study on minimally verbal children with ASD. His team’s goal is to shed light on the possible underlying genetic and biologic causes of language impairment in ASD.
Jenkins, J., Chow, V., Blaskey, L., Kuschner, E., Qasmieh, S., Gaetz, L., Edgar, J.C., Mukherjee, P., Buckner, R., Nagarajan, S.S., Chung, W.K., Spiro, J.E., Sherr, E.H., Berman, J.I., & Roberts, T. P. (2015). Auditory Evoked M100 Response Latency is Delayed in Children with 16p11.2 Deletion but not 16p11.2 Duplication. Cerebral Cortex, http://doi.org/10.1093/cercor/bhv008.