Researchers have discovered a new gene called SCN3A which helps us speak and swallow. The discovery of SCN3A came with the help of a handful of families who all have a rare brain disease called polymicrogyria. By looking at genetic similarities across the families, researchers found that a mutated SCN3A gene was the culprit.
The SCN3A gene is primarily active during fetal brain development but when mutated it causes a language area of the brain to develop lots of small folds, like a cauliflower. People with the disease often have impaired oral motor development, resulting in difficulties with swallowing, tongue movement and word articulation.
By linking a new gene with polymicrogyria and speaking and swallowing, researchers are just beginning to understand the role this gene plays in the human brain and in speech development.
We spoke with Richard S Smith from Boston Children's Hospital about the work.
Richard Smith: Polymicrogyria is a brain disease in which the outer regions of the cerebral cortex generate too many peaks and valleys (gyri and sulci). The literal Greek translation is many (poly-), small (-micro), folds (-gyri).
Smith: We discovered a new gene (SCN3A) associated with Polymicrogyria that makes certain regions of the brain’s surface look similar to cauliflower in texture, instead of normal folds. This altered folding in brain areas that contain language and speech centers can result in swallowing and speech problems.
Smith: While the bilateral cortical malformation is rare, swallowing and oral motor problems are relatively common, so we expect the findings might turn out to be helpful for the community at large. Also, every new gene that is annotated to a specific disease, even a rare disease, can help many people around the world find a genetic diagnosis.
Smith: Discovering new genes that are involved in malformations in cortical development provides an opportunity to start investigating novel mechanisms underlying these conditions. For example, SCN3A is an ion channel that conducts sodium, but how sodium ions act within the brains cells to cause structural changes remains unknown.
Smith: The basic steps of brain development have been disrupted in patients who have mutations in this gene, and while we are not yet able to prevent this condition (though future advancements in gene therapy could allow for this), having a better understanding of patients’ genetic backgrounds certainly facilitates a more targeted approach towards therapy to improve oral motor outcomes.
Smith: Every time a new gene involved with the growth of the human cerebral cortex is discovered, we get one step closer to understanding the many genes involved in the evolution of the most complex tissue ever created, the human brain!
Smith: We plan to further explore the mechanisms underlying how the SCN3A gene is able to cause polymicrogyria.
Featured image courtesy of Richard Smith.
