Doctors discover more clues signalling risk of autism
Published Saturday, July 13, 2013 10:06PM EDT
Last Updated Sunday, July 14, 2013 12:10AM EDT
Scientists might soon have a few more tools to help spot young children at risk of autism spectrum disorder.
A Canadian-led research team this week identified several new genetic mutations that appear to be linked to autism.
As well, another study released this week found 23 per cent of all autism cases might be due to antibodies in the mother's blood that interfere with fetal brain development.
And finally, researchers in California have discovered that babies who are later diagnosed with autism are more likely to have higher levels of cerebral spinal fluid around their brain when they are just six months old -- long before any symptoms of the condition emerge.
Autism spectrum disorder (ASD) affects about one in every 88 children in North America, leading to problems with communication and behavioural disabilities.
But identifying the children with the condition takes time and requires lots of behaviour testing once the child reaches the preschool age. Many believe that being able to spot the condition earlier could allow for earlier and more effective treatments.
In the first discovery, scientists at Toronto's Hospital for Sick Children conducted whole genome sequencing of 32 Canadians with ASD, their parents, and in some cases siblings and other relatives. They used the sequencing to "read" the DNA of the volunteers, including an estimated 30,000 genes.
The team found mutations in nine genes previously linked to autism, four newly recognized genes, and eight genes that might be candidates for raising one's autism risk.
The researchers say that with whole genome sequencing, doctors are able to find genetic problems in 50 per cent in those with autism that explains their condition. Previous technologies, which sequence targeted snippets of a person's DNA, had only been able to identify genetic alterations in about 20 per cent of autism patients tested.
The research team says their ultimate goal is to find all the genetic mutations that appear to lead to ASD. That could one day allow families with one child affected by ASD to decide whether it makes sense for them to have more children.
In the second study, researchers with the UC Davis MIND Institute discovered a group of antibodies called "autoantibodies" are common in mothers of children with ASD. The researchers think these autobodies slip into the placenta and attack proteins that are necessary for a baby's brain development.
The study compared 246 autistic children and their mothers, to 149 typically developing children. They found that 23 per cent of mothers of autistic children had the autobodies in their blood, compared to only one per cent of the mothers whose children did not have autism.
They are now working on a blood test for the antibodies that they believe could predict with 99 per cent certainty which children are at highest risk of developing autism.
Finally, in another study by researchers at UC Davis' MIND Institute, researchers studied 55 infants between 6 months and three years of age to test their brain fluid levels. Thirty-three of the babies were considered at high risk for autism because they had an older sibling with autism, and 22 had no family history of the condition.
The researchers periodically measured the infants' brain growth by conducting MRIs. Ten of the children were eventually diagnosed with autism; all were in the high-risk group.
The researchers found that by 6 to 9 months of age, the children who developed autism had elevated cerebrospinal fluid levels in the space above and surrounding their brains.
Those fluid levels remained abnormally high when they were scanned again between 18 to 24 months of age.
In the infants who went on to be diagnosed with autism, the extra fluid volume was, on average, 33 per cent greater at 12 to 15 months and 22 per cent greater at 18 to 24 months, when compared with typically developing infants.
The more fluid that was found during early infancy, the more severe did the child's autism symptoms become as they grew.
The researchers say that if their results can be replicated in a larger study, it's possible that one day, spinal fluid levels in the brain could become a useful biomarker for the early detection of ASD risk.
That could help identify children with the condition earlier which many involved in autism say it crucial, since children who get intensive therapy early typically go on to have less disability.
With a report from CTV medical specialist Avis Favaro and producer Elizabeth St. Philip