FOR thousands of parents of autistic children across Britain, the cause of their offspring’s condition remains a mystery.

While their children suffer impairment to varying degrees in social interaction, verbal and non-verbal communication and imagination, scientists are striving to find a genetic basis for their condition.

The Autism Genome Project, an international consortium of geneticists and clinicians, claims that there is strong evidence to link the condition to a number of human chromosomes.

But researchers trying to identify the biological cause have come up with some surprising suspects, including evidence that different genes may be responsible for causing autism in boys than in girls.

The latest research connecting the condition with paternal age may shed light on the possible genetic causes of autistic spectrum disorders (ASDs).

Martin Hewitt was 48 when his autistic son Thomas, 12, was born. Mr Hewitt, a manager of a professional association from Muswell Hill, North London, told The Times yesterday that he felt that the study could link the rise in ASDs to the increasing trend towards older parents, but said that more research would have to be done.

“This research is important in the context of trends in population change but it is specific to the population of Israel, so we need to find out if the structure of father’s ages is the same in other countries,” he said.

Mr Hewitt, who also has two older, non-autistic sons, aged 18 and 36, said yesterday that had he no misgivings about being an older father.

“When Thomas was born I had no idea that he would be autistic and there was no genetic basis in the family history. Older fathers are taking the blame for quite a few things recently there have also been studies linking them to schizophrenia in children but I can’t say I have any regrets.”

Paternal age could also explain the talented but introverted behaviour of famous eccentrics such as Ludwig Wittgenstein, the Cambridge philosopher, who experts suspect had a form of Asperger’s syndrome, a lesser form of autism. His father, Karl, was 42 when Ludwig, the youngest of eight children, was born.

TRAPPED IN CHAOTIC MAELSTROM

• Autism is a lifelong disability that affects the way a person communicates and limits his or her ability to relate to others in a meaningful way
  
• It is often referred to as a spectrum disorder because of the variation in type and severity of problems. Those most able to function normally within the autistic spectrum are said to have Asperger’s syndrome
  
• Autism spectrum disorder (ASD) affects about 50 in 10,000 people, with a male to female ratio of 4:1
  
• Problems associated with ASDs include a failure to develop normal speech, body language and a lack of eye contact; a tendency to spend time alone; a lack of imaginative play; repetitive behaviour, or an obsession with particular objects or routines
  
• People with autism find it hard to make sense of the world, which appears as a chaotic maelstrom lacking boundaries, order or meaning. Up to 75 per cent of those with autism have learning disabilities and up to 30 per cent suffer from seizures
  
• Some autistic children have an exceptional skill, such as an aptitude for drawing, mathematics, or music. A number of famous people thought to have been autistic or had Asperger’s, including Hans Christian Andersen, Sir Isaac Newton, Albert Einstein, Glenn Gould and Andy Warhol
  
• Although autism can run in families, the precise cause remains unknown

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