Intellectual disabilities are often caused by a mutation that damages a gene, preventing the associated protein from working properly.
However, a mutation can also change the function of a gene. As a result, the gene in question acts in a completely different way.
Researchers at the Radboud University Medical Center in the Netherlands discovered this mechanism in fifteen genes that play a role in the development of intellectual disabilities.
Genes are responsible for the production of proteins in cells. A common cause of intellectual disability is a de novo mutation (ie, a mutation present in a child, but not in their parents) that damages a gene so severely that it is no longer able to produce functional proteins.
The resulting protein defect will cause disease. In a number of disease-related genes, it is shown that a de novo mutation does not remove the gene, but it probably alters its function. These mutations are localized only in specific parts of the gene.
In order to find out how often this mechanism is involved, researchers combined genetic mutations in Dutch patients with a large international database comprising de novo mutations in patients.
“With our method, we have been able to detect genes in which mutations do not eliminate as much as affect the gene otherwise,” said Christian Gilissen, who led the research.
“We found fifteen genes in which mutations are closely grouped, twelve of which are associated with developmental disorders,” Gilissen said.
“We also found three new genes that are likely to play a role in the development of intellectual disabilities as well,” he said.
De novo mutations found only change a very small part of a protein. The function of the protein remains largely, but not entirely the same.
“Mutations are more likely to affect the surface parts of proteins, which disrupt interactions with other proteins and cause problems,” Gilissen said.
“Although mutations that remove genes are often thought to be the leading cause of intellectual disabilities, mutations that alter the function of genes are now shown to be an important factor as well,” he said.
The three newly discovered genes that play a role in the development of intellectual disabilities provide new diagnostic possibilities for patients.
“It is important that we have discovered a mechanism that has not yet been a focus of study and we expect this mechanism to play a role in a much larger proportion of patients with intellectual disability,” said Gillissen.happy wheels
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