It takes many gene bricks to build the language wall

#freshfromthelab: Dr Dianne Newbury on how genetics studies help us reveal the sophisticated machinery behind language development.

When Dr Dianne Newbury started studying language, she was more often than not wearing a long white coat to carry out her experiments in a lab, patiently testing variations of candidate genes to find those responsible for a particular language disorder.

She is now a reader at Oxford Brookes University, where her lab coat is most of the time left hanging at the door while she sits in front of her computer. She found that going through gigantic databases of DNA actually better serves her quest to understand language development and its impairment. This way, she can screen millions of variations in the DNA to link a multitude of genes together and get a broader picture of what is happening. In the seminar she gave at the CBCD, she explained to us her journey to thinking of language as an aptitude that comes about when a wealth of different genes all work together, each adding their small brick to the edifice, rather than a few key genes doing most of the job.

Why are genetics helpful for understanding language? What can genetics of language impairments tell us about how these difficulties (and language in general) develop? And why is the study of language impairments so important?

A large study of 5- to 8-year-old children in 180 schools in Surrey (SCALES) found that on average, about 3 children in every UK classroom present a language impairment. However, only 50% of the children that showed language difficulties were receiving specific educational support. Every child grows up following their own unique path, which luckily means that some kids will catch up on delayed language acquisition and grow into adults who are very skilled at language, while others will keep some language difficulties while growing up. It is therefore essential to gain a better understanding of their difficulties and how the fantastic ability to acquire and use language develops, so we can make education for all as fruitful as possible.

Dianne’s take on this was to try and find which set of genes play a role in which language impairment. As living beings, we all have cells that contain our very own DNA, a collection of information that makes us unique individuals. In our DNA, some bits called genes contain specific information for our body to create our own proteins, key molecules that make up our body – including our brain. We are made from a huge variety of proteins and they assume a multitude of different roles. Together, they represent the backbone of all the extraordinary functions our bodies are able to perform, like seeing, digesting, thinking... Because we belong to humankind, we share similarities and all have very similar proteins that give us a particular set of human traits and abilities. Still, we also have variations in our DNA, and eventually in our proteins, that make each of us a unique person. While we are unique, we share some variations, in particular with our family, but also with unrelated people who share traits with us, like the colour of our eyes. Dianne’s work builds on this and looks for the DNA variations that are shared by children with a given language skill or impairment. Indeed, language impairments have been described as highly heritable, which tells us that genes are probably important here.

Dianne began by looking at a few genes in relation to single specific disorders, but soon, she started wondering whether genes of, say, dyslexia, could also have an effect in other language difficulties. Could the role of genes be studied more generally, looking at their influence on one aspect of language (such as oral vs. written language), rather than at a single disorder? This led Dianne to become more interested in the genes expressed in the whole population, and not only in children who had developed a language impairment. This approach is very central to the idea that every child has a unique way of growing up and developing skills. Instead of studying disorders limited to a set of particular symptoms, Dianne’s approach can give information on language as a whole: when it is impaired in some way and when it develops without an impairment. Dianne’s work, comparing the DNA variations of thousands of people, shows that the genes that can account for variations in language abilities are manifold. Lots of genes assuming small functions work together to make this very complex skill develop. Instead of looking at a few genes, she recommends taking large numbers of genes into account when assessing language abilities and risk factors.

Genes give us crucial information on what is a fertile foundation for language to develop but they do not give a full picture of how children develop language: they do not take a child’s environment into account. Just as every child’s DNA is unique, so is their environment, which makes their developmental path even more complex but also exciting! As parents, you can’t change your baby’s DNA, but you can build a fertile environment for them to grow up in. Maybe you remember some of the ideas we shared here for you and your child to play with or our interview with the amazing Evelyne Mercure on this topic. And of course, our app is always here for you to find related games. It has a “Have a Chat” section dedicated just to this theme!

Author: Cécile Gal

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