Dr Dianne Newbury is looking for the genes that predispose to Specific Language Impairment, a complex genetic disorder. Two regions, located on chromosomes 16 and 19, are linked with this disorder. Interactions between several normal genetic variants and environmental factors make certain individuals more vulnerable to language problems.
Specific Language Impairment is a disorder in the development of language, despite adequate intelligence and opportunity. Genetic variants have been shown to be correlated with reduced performance on language-related tasks. A better understanding of the underlying biological pathways might help us develop more accurate identification systems and better therapies.
Q: What is Specific Language Impairment?
A: Specific language impairment is a term which is used to describe children who have problems learning to use or understand language for no obvious reason. Lots of children have problems with language development but for a lot of those it's either just the delay which they catch up as they grow a bit older, or they have some other kind of developmental problems which are causing the language impairment. The children who we investigate with specific language impairment they have persistent and quite severe language problems and no apparent problems in any other kind of developmental domains.
Q: What is the contribution of genetics to Specific Language Impairment?
A: We know that specific language impairment runs in families: if you have a brother or a sister who is affected by SLI you are about 8 or 9 times as likely to have a language problem yourself, and the same if your parents are affected, you are more likely to have language problem. We also find that twins, in pairs of twins if one is affected the other is more likely to be affected. That gives us a strong indication that there is some genetic contribution, but we don't think it's caused by a single gene mutation, we think it's combinations of common genetic variants which makes some individuals more susceptible to language problems than other individuals.
Q: What are the most important lines of research that have developed over the past 5 or 10 years?
A: We've been investigating SLI for ten years now and before we started there wasn't any molecular genetic studies done; we knew that SLI ran in families but we didn't have any idea what the genetic contributions were. When we started off, we looked at every single chromosome in a group of affected families and individuals and we narrowed it down to two regions which we believe contained genetic variants which contribute to SLI. At the moment we're looking into what those genetic variants do and how they might contribute to SLI. Over the last ten years, there's been quite a big leap in the research that's been done.
Q: Why does your line of research matter? Why should we put money into it?
A: It's a very common disorder and we don't really understand, even at the level of what is the problem that these children have, why do they have specific language problems. We're hoping that if we come at it from the genetic point of view it will give us an insight into the biological pathways that are causing these problems and the kind of developmental processes that might be underlying the disorder. We hope that this will then have a knock on effect, that we'll be able to intervene with these children earlier to develop better strategies to help them cope with their language problems.
Q: How does your research fit into Translational Medicine within the Department?
A: At the moment our research is more at the molecular level but we're hoping, once we understand these pathways, it will then lead on to translational research. Once we understand the problems that these children have, we can then combine with psychological speech therapy, that kind of research, to develop better therapies for these children. It's not in terms of diagnosing and predicting which children will be effected, it's more developing better therapies for them.