DNA strand
A UHN research team says DNA screening helped to explain 16 per cent of adult cases of unexplained epilepsy. (Photo: iStock)

A research team at UHN has used DNA screening to identify the cause of disease in 16 per cent of adult patients who had previous unexplained cases of epilepsy.

Researchers at Toronto Western Hospital used genome-wide microarray to investigate 143 adult patients with unexplained childhood-onset epilepsy and intellectual disability.

"What we found is that 16 per cent of patients who have undiagnosed epilepsy and some degree of intellectual disability have a genetic abnormality called Copy Number Variation (CNV)," said principal investigator Dr. Danielle Andrade, Medical Director of the Epilepsy Program at UHN, Director of the Epilepsy Genetics Program and a clinician investigator at the Krembil Research Institute.

The findings were published today in the journal JAMA Neurology in a paper titled "Prevalence of Pathogenic Copy Number Variation in Adults with Pediatric-Onset Epilepsy and Intellectual Disability."


Dr. Danielle Andrade, Medical Director of the Epilepsy Program at UHN, used DNA screening to identify the genetic cause of disease in some adult patients with undiagnosed epilepsy.(Photo: UHN)​​

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Copy Number Variations (CNV) are alterations in our DNA that result in cells having an abnormal number of copies of sections of DNA. Often these sections contain genes that are duplicated or deleted. CNVs have been linked to many human diseases.

These latest results should offer a ray of hope for some adults with epilepsy who have lived much of their lives without understanding about why they have the disease. The discovery of CNVs in these patients is expected to assist clinicians in the management of the disease as well as provide further knowledge about genetic counselling for family members who are considering having children.

In order to be included in the study, patients had to have experienced seizures as a child, followed by further seizure activity in adulthood along with an intellectual disability of some degree. These patients did not have any structural brain abnormalities or metabolic conditions to explain their disease.

Researchers say the next steps involve conducting additional studies to better understand how these CNVs lead to brain changes. 

In addition to the new CNVs and genes discovered, this study highlights the need to further investigate adults with epilepsy and intellectual disability.

"Today, children with epilepsy are being offered updated genetic tests such as genome-wide microarray, genetic panels, whole exome sequencing and even whole genome sequencing in order to determine diagnosis and tailor treatment," said Dr. Andrade.

"However, genetic testing is not yet common practice in adult epilepsy clinics," she said. "It is important to keep in mind that when our adult patients started manifesting epilepsy and were investigated in the pediatric world, the tests they had were very rudimentary.

"Adults with epilepsy of unknown cause should be re-investigated with the modern DNA technologies available today." ​

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