The first blood test for autism can detect one-in-six children with the disorder.
Until now there has not been a biological test for children on the spectrum and the disorder affects about one in every 100 people in the UK with more boys diagnosed than girls.
Children have previously been diagnosed based on their altered behaviours, which may not become evident until children are two to four years old.
And families often have to wait to see a specialist for a more in-depth assessment, which should be started within three months of the referral but can take longer.
But now American scientists have identified a group of blood metabolites that could help detect some children with autism spectrum disorder (ASD)
The new biomarker panel could accelerate autism diagnoses as about 17 per cent of kids with autism we re identified with the metabolic blood test. This could speed up children having intensive behavioural therapy at an earlier age.
Professor David Amaral, of the University of California Davis MIND Institute, said: “With this panel of alterations in amino acid metabolism, we can detect about 17 per cent of kids with ASD
“This is the first of hopefully many panels that will identify other subsets of kids with autism.”
The findings were based on the largest metabolomic ASD study ever attempted – the Children’s Autism Metabolome Project (CAMP).
CAMP researchers believed the answer lies in the metabolome – the molecules that remain after larger molecules have been broken down (metabolised).
Metabolomics has the advantage of monitoring both genetic and environmental contributions to the development of autism.
The professor of psychiatry and behavioural sciences explained: “By the time you’re getting to metabolomics, you’re looking at how the body is working, not just the genes it has.”
Prof Amaral said: “It is unlikely that a single marker will detect all autism.
“This paper demonstrates that alterations in metabolic profiles can detect sizable subsets of individuals with autism.
“The hope is that we will be able to generate a panel of biomarkers that will detect a large proportion of people at risk.
“Moreover, this approach highlights metabolic pathways that may be targets of intervention.”
The study collected blood samples from 1,100 children between 18 months and 4 years old, of which two-thirds were diagnosed with ASD.
Researchers compared blood metabolites – specifically, amino acids – in 516 kids with ASD and 164 children showing typical development.
They found that 17 per cent of the ASD children had unique concentrations of specific amino acids (metabotypes) in their blood.
Though a 17 per cent subgroup may seem small, it is actually quite significant.
ASD encompasses a complex array of symptoms, and no one expected to find a single group of markers that would diagnose all subsets.
Prof Amaral said it is hoped to create a number of metabolomic assays that cover all variations.
He said: “The long-term vision is, once we’ve been able to analyse all the data from CAMP, we would have a series of panels.
“Each of these would be able to detect a subset of kids with autism.
“Ultimately, metabolomics may be able to identify most children with autism.”
In addition to enabling earlier diagnosis, this work also could help generate targeted interventions for specific ASD groups.”
Prof Amaral points to phenylketonuria (PKU) as a possible template.
PKU is a rare disease in which the amino acid phenylalanine builds up, causing brain damage however, relatively small dietary adjustments can make a big difference.
He concluded: “With just a simple dietary modification, a child can move from being profoundly disabled to one who lives a reasonably normal life
“That’s the hope with autism as well.”
“I’m optimistic this is not a one-off. There are going to be other panels that can detect other groups of kids with ASD.”
The study was published in the journal Biological Psychiatry.