Autism, even in siblings, has different genetic causes: Canadian study

WATCH: A Canadian doctor says each autistic child is different – and that includes siblings who are autistic. Crystal Goomansingh reports.

TORONTO – Canadian doctor Stephen Scherer says each child with autism is like a snowflake. Even if siblings share the disorder, their genetic mutations aren’t the same.

After studying families with children who have autism, Scherer and his team of researchers at the Hospital for Sick Children say that they’ve learned that even siblings can have different ‘forms’ of autism.

“Autism is very, very complex, and there are many different forms of autism. There’s actually hundreds and hundreds of genes involved,” Scherer, a senior scientist at SickKids and University of Toronto professor, told Global News.

His research, published Monday as the cover story in the journal Nature Medicine, has huge implications for the way scientists diagnose and treat the disorder, he suggests.

READ MORE: Scientists find more genes possibly linked to autism with advanced sequencing tool

“It’s very important to understand which form of autism a child has so that the doctors who are treating the children know what are the best treatments for them, what clinics they should see, what tests they should undergo and what their outcome is going to be going forward,” he explained.

The Canadian research is the largest whole genome sequencing study in autism to date. It’s also one of the largest in any disorder, the hospital says.

In this study, Scherer zeroed in on 85 families that each have two children with autism – or 170 patients in total.

Genome sequencing decodes billions of pieces of information in a person’s DNA to help understand genetic makeup. It’s a pricey endeavor but Scherer says the results provide a detailed snapshot that’ll help doctors create a treatment plan. It also catches mutations that would be missed by other techniques, such as exome sequencing and microarrays, which only look at parts of the DNA.

READ MORE: Researchers study how youth with autism learn

The genome sequencing helped the scientists understand that while siblings share a disease, the underpinnings of how autism manifests aren’t the same.

In this case, the siblings and their parents’ genetic code were examined. Mutations present like typos in the human DNA code. While siblings shared autism spectrum disorder and the same parents, the typos in their DNA that led to the neurodevelopmental condition weren’t the same.

The researchers learned that in 70 per cent of the cases, different genes were involved in the siblings’ autism. With this information in hand, Scherer is hopeful that patients will receive individualized treatment.

“We’ve always known that every autistic child, in a way, has their own kind of autism. If you ask parents, and the doctors that see them, they’ll tell you this. I hear this all the time,” he said.

READ MORE: Autism treatment – a system bursting at the seams

Valerie South is the mother of three boys – two of them both have severe autism and are non-verbal, but the disorder presents itself in different ways in the siblings.

Cameron, who is 20, didn’t talk as a toddler. At first, South thought that he may be hearing impaired.

“Cameron seemed to be…almost as though I was speaking a foreign language as what they termed the word deaf…so he could hear the noise and he could hear words coming out but he couldn’t understand what I was saying,” South explained to Global News.

Thomas, 14, isn’t as laid back as his brother. South describes the youngest sibling as mischievous.

“Thomas is more of the sneaky devil with the twinkle in his eye kind of guy…Cameron is more sedate and interested in bottles of things and rattling things and music whereas Thomas has absolutely no interest in music whatsoever,” she said.

South is hopeful that participating in the project will shed light on her sons’ conditions and how to provide them with assistance that’s individual to their needs.

READ MORE: Canada lacks national autism strategy, UBC professor

Scherer didn’t look at identical twins in this study because they share the same genomes, but he concedes it’s an important step to take in the future.

Right now, Scherer’s research is a piece of a larger project he’s leading called MSSNG with Google and advocacy group Autism Speaks. His ultimate goal is to sequence the genomes of 10,000 individuals from families with autism and store this valuable data in an open-source research platform so that it’s accessible to researchers around the globe.

It would be another first – the first time ever that research data is shared on a cloud-based format so that it’s at the fingertips of international scientists who want to collaborate.

carmen.chai@globalnews.ca
Follow @Carmen_Chai