THREE MAJOR studies have for the first time pinpointed the genetic mechanisms underlying some autistic disorders, which may enhance understanding of what causes them and eventually help point the way towards a cure.
The research has been described as hopeful by Prof Michael Fitzgerald, professor of child psychiatry at Dublin’s Trinity College, but he said it would be unfair to suggest a cure is around the corner.
“Autism is a very complex disorder both in description and genetics . . . there are many, many genes involved . . . we might be able to be more hopeful about certain subtypes where we might be able to make more progress from a therapeutic point of view because of this,” he said.
The new research involved screening the DNA of many thousands of volunteers.
Two of the studies were American-led and were reported yesterday in an early online edition of the journal Nature.
The third was conducted by British scientists at Oxford University and appears in the journal Molecular Psychiatry.
The largest investigation, conducted in the US, involved analysing the DNA of almost 13,000 including many from families affected by autism. Comparing the entire genetic code of these individuals enabled scientists to focus on a “hotspot” on chromosome five – one of the coiled up “packets” of DNA within the nuclei of cells that contain the genes.
Study leader Dr Hakon Hakonarson, director of the centre for applied genomics at The Children’s Hospital of Philadelphia, said: “Although a particular gene variant may contribute a small risk for an autism spectrum disorder (ASD) in a particular individual, we estimate that the variants we discovered may contribute to as many as 15 per cent of ASD cases in a population typically referred to as the population-attributed risk of the variant.”
The British scientists, who analysed the DNA of more than 500 people, looked for single-letter changes in the genetic code in two particular chromosomes as well as copy number variations. They pinpointed a gene on chromosome 7 called Dock4 that appeared to be significantly associated with autism.
Tara Matthews, spokeswoman for the Irish Society for Autism, said the research was another step forward in trying to find an answer to what caused autism. “Autism is a complex condition and there may be more than one answer.”