Intellectual disability is frequently caused by non-hereditary genetic problems

Some intellectual disabilities are associated with physical abnormalities that indicate major genetic abnormalities. However, in other cases disabilities are not associated with obvious physical traits "We targeted non-syndromic patients," Michaud said. Together with his colleagues from the Synapse to Disease Project, Michaud analyzed DNA from the patients to identify mutations that were not inherited but were in fact newly formed. These are called de novo mutations. They studied 197 synaptic genes and identified de novo mutations in 10 of the 95 patients. Further studies indicated that all of these mutations affect nerve cell communication, which lead the team to conclude that at least two-thirds of the mutations are the definitive cause of the disorder.

"This finding aligns with our previous work that shows that de novo mutations play important roles in disorders such as autism and schizophrenia," said co-author Guy Rouleau. "Our study indicates that a large fraction of cases with intellectual disability have a genetic origin but are not hereditary. These findings will lead to improved diagnostics," added co-author Fadi Hamdan.

More information: "Excess of De Novo Deleterious Mutations in Genes Associated with Glutamatergic Systems in Nonsyndromic Intellectual Disability" was published in the American Journal of Human Genetics

Provided by University of Montreal