People with autism spectrum disorder (ASD) often have unusual or disordered sleep habits. Understanding what causes disordered sleep for people with ASD is important because insufficient sleep exacerbates ASD’s symptoms like repetitive behaviors. A new study from Jichi Medical University in Shimotsuke, Japan reports that gene mutations may be the root of autism’s sleep problems. The findings may help researchers identify treatments for disordered sleep in ASD.
The researchers sequenced 18 genes associated with the body’s sleep-wake cycles. The genes were from 23 people without ASD and 28 children and adults with ASD. Half of the participants with ASD had a sleep disorder. After sequencing the genes, they analyzed the impact of the mutations they found. Some mutations were “silent,” which means the mutation has no effect on the gene. The rest of the mutations were “missense” mutations, which means the mutation disrupts the gene’s protein sequence. The researchers also used three computer algorithms to predict whether the mutations would impact the genes’ functions.
In 15 of the sequenced genes, there were 68 mutations, split about evenly between silent and missense mutations. Nine of the missense mutations were not previously documented. The participants with ASD—both the participants with and without sleep disorders—had twice as many mutations in these circadian genes than participants in the control group. All of the ASD participants had seven missense mutations, but only one participant in the control group had a missense mutation. According to the analysis by the computer algorithms, the majority of the missense mutations are benign, but eight appear to be damaging.
“We detected many mutations only in the patients with autism, but almost nothing in the control group. So I think these genes relate to some pathophysiology of autism,” explained lead researcher Takanori Yamagata, professor of pediatric developmental medicine. “It is not clear yet what the basis of this interaction is.”
This research is published in the journal Brain and Development.
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