Although it’s clear that Down Syndrome is a genetic disorder caused by the occurrence of an extra chromosome, the exact genes, and their functions, related to the condition have remained unknown. A study is shedding new light on these genetic factors: researchers have discovered that a gene related to brain development may also lead to the intellectual disabilities associated with Down Syndrome.

The gene is called 'EURL' or C21ORF91, and it was originally detected as a gene that controls the development of cells in the retina and lens, Medical Xpress reported. However, the new research has uncovered that the gene also serves a second purpose and also controls the formation of neural circuits in the brain, and in the cases of Down Syndrome individuals, leads to intellectual disabilities. It’s for this reason, the study explained, that some individuals with Down Syndrome show only the intellectual disabilities and not the physical characteristics: The different traits assocaited with the condition are not all controlled by the same genes.

Not only have the scientists uncovered a new function of C21ORF91, but they also believe they are able to manipulate its functions.

“Such manipulations might be useful to consider when there are extra copies of the EURL gene in a child, such that we might be able to balance the quantity of functional EURL...,” explained Associate Professor Julian Heng, Head of the Brain Growth and Disease Laboratory at the Harry Perkins Institute of Medical Research, in a statement. “In turn, (this) could lead to improvements in the brain's neural circuitry."

Now that the team has uncovered the role C21ORF91 plays in the development of Down Syndrome, the next step is to uncover exactly how it affects fetal brain development. In doing so they hope the research may eventually lead to medications that could possibly improve mental health and mean a better quality of life for those with certain forms of intellectual disability.

In addition to C21ORF91, earlier this year scientists also identified another gene associated with Down Syndrome, PP2ACdc55. Although the team revealed that this gene controls chromosome segregation, they are still unclear as to what occurs when this process goes wrong.

Source: Li SS, Qu Z, Haas M, et al. The HSA21 gene EURL/C21ORF91 controls neurogenesis within the cerebral cortex and is implicated in the pathogenesis of Down Syndrome. Scientific Reports . 2016

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