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The Genetic Basis of Developmental Language Disorder

Mountford, H. S., Braden, R. O., Newbury, D. F., & Morgan, A. T. (2022). The Genetic and Molecular Basis of Developmental Language Disorder: A Review. Children (Basel), 9(5), 586.


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Key terms in this paper:

  • Heritable: Something that can be passed from parents to their children.

  • Gene: A stretch of DNA that determines a trait (such as speech production).

  • Gene variant: Changes in a gene that make it different from genes in a typical population.

  • Monogenic: When a trait (such as speech production) is caused by a single gene variant.

  • Copy Number Variants (CNVs): Deletions or duplications of regions of genetic material (CNVs can be monogenic but can also occur across multiple genes).


Aim of the paper:

Research suggests that children can inherit DLD from their parents. This may be influenced by complicated interactions between genes and the environment. However, we still do not fully understand how biology influences language. This review looks at many genetic studies on DLD and provides an overview of the findings.


What was found?

  • There is evidence that DLD can be heritable.

The chances of having DLD increase if a parent or sibling also has a DLD diagnosis.

  • DLD can be monogenic.

Technology allows us to examine individual’s genes all at once. As a result, more monogenic variants that explain language difficulties have been discovered. Monogenic variants may have a negative effect on certain cells. This results in a specific difficulty (e.g., problems with producing speech).

  • Some CNVs have been linked to DLD.

CNVs can disrupt the function of a gene. The number and size of CNVs plays a role in DLD. The most important factor is which genes are affected.

  • There are common gene variants that can increase the likelihood of DLD.

Two specific genes have been found that increase the risk of DLD.

  1. One gene has been linked to language, reading and spelling in people with and without DLD. This suggests it contributes to language ability more generally.

  2. The other gene is associated with memory, but only in people with DLD. This suggests it plays a specific role in DLD.

In many other cases, the exact genes and variants are not known. This is because identified regions are very large and contain many hundreds of genes.

  • Different studies disagree on which gene variants are associated with DLD.

This may be because:

  1. There is disagreement over the diagnostic criteria for DLD.

  2. DLD likely involves many variants across many different genes.

  3. Genetic inheritance cannot fully explain DLD. Environmental factors, such as socioeconomic status or smoking during pregnancy, are also suggested to influence DLD.


What does this mean?

Recent progress in genetic studies has improved our understanding of the genes underlying DLD. This can help improve DLD diagnosis. Therapies that target specific genes involved in DLD can now also be developed. This can improve the long-term outcomes for people with DLD.


Where can I read this paper?

This paper is open access, which means everyone can read it. Please click here to find the full paper: https://doi.org/10.3390/children9050586


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