London, February 19: Scientists have developed new blood and urine tests that can diagnose autism in children, allowing patients to get appropriate treatment much earlier in their lives.

Autism spectrum disorders (ASD) are defined as developmental disorders mainly affecting social interaction and they can include a wide spectrum of behavioural problems. These include speech disturbances, repetitive and/or compulsive behaviour, hyperactivity, anxiety, and difficulty to adapt to new environments, some with or without cognitive impairment.

Since there is a wide range of ASD symptoms diagnosis can be difficult and uncertain, particularly at the early stages of development. "Our discovery could lead to earlier diagnosis and intervention," said Naila Rabbani, at the University of Warwick in the UK. "We hope the tests will also reveal new causative factors.

With further testing we may reveal specific plasma and urinary profiles or "fingerprints" of compounds with damaging modifications," said Rabbani. "This may help us improve the diagnosis of ASD and point the way to new causes of ASD," she said. The study published in the journal Molecular Autism found a link between ASD and damage to proteins in blood plasma by oxidation and glycation - processes where reactive oxygen species (ROS) and sugar molecules spontaneously modify proteins.

They found the most reliable of the tests they developed was examining protein in blood plasma where, when tested, children with ASD were found to have higher levels of the oxidation marker dityrosine (DT) and certain sugar-modified compounds called "advanced glycation endproducts" (AGEs).

Genetic causes have been found in 30-35 per cent of cases of ASD and the remaining 65-70 per cent of cases are thought to be caused by a combination of environmental factors, multiple mutations, and rare genetic variants. However the research team also believe that the new tests could reveal yet to be identified causes of ASD.

The research also confirmed the previously held belief that mutations of amino acid transporters are a genetic variant associated with ASD. Researchers, including those from the University of Bologna in Italy, recruited 38 children who were diagnosed with ASD (29 boys and nine girls) and a control group of 31 healthy children (23 boys and eight girls) between the ages of five and 12. Blood and urine samples were taken from the children for analysis. The team discovered that there were chemical differences between the two groups.

The changes in multiple compounds were combined together using artificial intelligence algorithms techniques to develop a mathematical equation or "algorithm" to distinguish between ASD and healthy controls. The outcome was a diagnostic test better than any method currently available.