Birdsong-related DNA sequences tied to autism-linked genes | Spectrum
Voice connection: Zebra finches and other birds that learn songs carry mutations near genes that are often mutated in autism.
Courtesy Lomax Boyd
Genes that appear to play a role in song learning in some birds are often mutated in autistic people, according to a new study.
The results show the value of studying the evolution of certain traits in other species, says Sarah London, an adjunct professor of psychology at the University of Chicago who was not involved in the work. “It’s a powerful application of comparative biology. This is work that would not make sense if it were done in the standard rodent models in the laboratory. “
Babies learn to speak by listening to the sounds of those around them and mimicking them. This type of “voice learning” is found only in a few other species, including dolphins, whales, bats, songbirds, hummingbirds and parrots.
To understand the origins of vocal learning, researchers scanned the genomes of 33 species of birds for “accelerated regions” – sequences that are similar in singing birds and have more genetic changes than those of birds lacking vocal learning, suggesting this that these regions have helped develop the skill.
Both humans and birds learning to sing share patterns of different gene expression in speech and language areas of the brain, as the researchers showed in 2014 – patterns that are not seen in birds or mammals that do not imitate sound. The new work shows that accelerated regions associated with vocal learning in birds occur in non-coding areas that regulate the same genes – many of which are often mutated in autistic people.
The results could help researchers better understand the functions of genes associated with autism that could contribute to language difficulties, says lead researcher Erich Jarvis, professor of neuroscience and genomics at Rockefeller University in New York City.
“We’d learn a lot not only about them, but also about ourselves, including health-related topics,” says Jarvis.
Language genes:
The researchers identified 3,608 accelerated regions in songbirds, 3,400 in parrots and 1,795 in hummingbirds.
The regions in songbirds and parrots differed from those in other birds, particularly in non-coding parts of the genome that control genes involved in human language, including FOXP2 and MEF2C, both of which have been linked to autism.
Another 64 regions – many of them near FOXP2 and MEF2C or another autism-associated gene, NR2F1 – are accelerated in both voice-learning birds and humans. And many of the genes involved in syndromic forms of autism overlap with genes that are near an accelerated region in songbirds, Jarvis and colleagues found. The regions are specifically linked to genes that are mutated in autistic children who are minimally verbal, the researchers found in an unpublished analysis, says Jarvis.
The results suggest that these particular genes evolved for spoken language and that mutations in them lead to language difficulties in humans, says Jarvis.
“We haven’t proven that,” he says. “But the correlation is certainly there and quite noticeable.”
The genes that are regulated by accelerated regions in the vowel learners also overlap with a number of genes that are accelerated in humans compared to other vertebrate species, says Jarvis.
The results were published in Genome Research in October.
Feature specificity:
It’s possible that the strategy could be used to identify genes associated with specific autism traits, says Jarvis, and provides targets for genetic screens that could help clinicians find the best therapies for a particular person early on identify in life.
However, researchers should be careful assuming that the genes contribute to language in birds and humans alike, says Emily Casanova, an assistant professor of biomedical science at the University of South Carolina at Greenville who was not involved in the work. Some think of language as an “emergent property” – like consciousness – that can evolve in ways that are specific to the structure of the brain, she says, and the cortical structure of birds is different from ours.
“It can be relevant to autism, but at the same time it can be something unique to birds,” says Casanova. “It’s been so long since we had a common ancestor.”
The study paves a way for researchers to go beyond known autism-related genes and better understand how other parts of the genome contribute to complex behaviors like language, says London.
“So that’s why this study is – it may seem a strange word – but I would say hopeful,” she says. “It paves the way to new ways of research that can be tapped into by a community of humans to break down these different types of biological contributions to behavior.”
Researchers next plan to use animal models to study the genes that appear to play a role in minimally verbal autism, says Jarvis.
Cite this article: https://doi.org/10.53053/AIWD8025
