Newspaper article The Canadian Press

Some Cerebral Palsy Cases Caused by Genetic Anomalies, Not Just Brain Injury: Study

Newspaper article The Canadian Press

Some Cerebral Palsy Cases Caused by Genetic Anomalies, Not Just Brain Injury: Study

Article excerpt

Some cerebral palsy caused by genetics: study


TORONTO - Cerebral palsy, the most common cause of physical disability in children, has long been thought to result from brain injury in the fetus. But new Canadian research is challenging that notion, finding that at least one in 10 cases likely has an underlying genetic cause.

"Our findings were shocking, actually," said principal investigator Stephen Scherer, director of the Centre for Applied Genomics at Toronto's Hospital for Sick Children.

So ingrained has medical dogma been around the root causes of cerebral palsy that "when I showed the results to our clinical geneticists, initially they didn't believe it," he said.

About two in every 1,000 babies born are affected by cerebral palsy. An estimated 50,000 Canadian children and adults have the condition, which leads to varying degrees of motor impairment, including muscle spasticity and involuntary movements.

Symptoms can include epilepsy as well as learning, speech, hearing and visual impairments. Some with the disorder are mildly affected, while others can't walk or communicate.

Traditionally, cerebral palsy was believed to be caused by a stroke or infection of the brain in the developing fetus, or by birth asphyxia -- a lack of oxygen to the infant during delivery.

But genetic testing of a group of affected children from across Canada found that in 10 per cent of cases, structural changes to the DNA appear to have given rise to the condition.

The research team, which includes physicians at the McGill University Health Centre in Montreal, performed genome sequencing tests on 115 children with cerebral palsy and their parents.

Ten per cent of the children were found to have DNA alterations known as copy number variations, or CNVs, that affect clinically relevant genes. CNVs can be present as deletions, additions or reorganized segments of DNA that can lead to disease.

"In five per cent, we found these spontaneous, massive changes," affecting dozens or even hundreds of genes in some children, said Scherer. "For five per cent, these big changes are the cause of their CP.

"The other five per cent were smaller changes, but affect lots of genes and in some cases were inherited from the parents. And we think they're involved in the medical complexities these kids have."

The study, published Monday in the journal Nature Communications, also shows there are many different genes involved in cerebral palsy, just as there are in autism spectrum disorder and other neurodevelopmental conditions.

"I think what's really interesting here is that what was thought to be an almost entirely environmental disorder (caused by fetal injury or infection) has a significant genetic component," said Scherer.

"I can't imagine having a child who's got any disorder and not having some type of an explanation (as to why)," he said. …

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