. Link is found between father's DNA and symptoms

. DNA in men's sperm linked to tags that influence the way genes act

. Researchers say finding could offer clues as to causes of the condition 

 

The origins of a child's autism could be found in their father's sperm, it has emerged. A new study has found links between DNA in sperm and distinct patterns of indicators that could contribute to the condition.

 

While some past studies have identified specific genes thought to cause the condition, most cases remain unexplained. However, the consensus remains that autism is usually inherited, since the condition typically runs in families.

 

In this study, researchers from Johns Hopkins University looked for possible causes for the condition, not in the genes themselves, but in the epigenetic tags that help regulate genes' activity.

Andrew Feinberg, said: 'We wondered if we could learn what happens before someone gets autism. If epigenetic changes are being passed from fathers to their children, we should be able to detect them in sperm,' added Professor Daniele Fallin, one of the lead investigators."

 

Sperm are not only easier to sample than a woman's eggs, but are more susceptible to environmental influences that could alter the epigenetic tags on their DNA.

 

Researchers examined the epigenetic tags on DNA from the sperm of 44 fathers.  The men were part of an ongoing study to assess the factors that influence a child early on, before he or she is diagnosed with autism.  The study enrolls pregnant mothers who already have a child with autism and collects information and biological samples from these mothers, the new baby’s father and the babies themselves after birth. Early in the pregnancy, a sperm sample was collected from fathers enrolled in the study. 

 

One year after the child was born, he or she was assessed for early signs of autism using the Autism Observation Scale for Infants (AOSI). The researchers collected DNA from each sperm sample and looked for epigenetic tags at 450,000 different positions throughout the genome. 

 

They then compared the likelihood of a tag being in a particular site with the AOSI scores of each child. They found 193 different sites where the presence or absence of a tag was statistically related to the AOSI scores. When they looked at which genes were near the identified sites, they found many of them were close to genes involved in developmental processes, especially neural development.

 

Of particular interest was that four of the 10 sites most strongly linked to the AOSI scores were located near genes linked to Prader-Willi syndrome, a genetic disorder that shares some behavioral symptoms with autism. 

 

Several of the altered epigenetic patterns were also found in the brains of individuals with autism, giving credence to the idea that they might be related to autism.

The team plans to confirm its results in a study of more families and to look at the occupations and environmental exposures of the dads involved.  There is currently no genetic or epigenetic test available to assess autism risk.

 

The study was published in the International Journal of Epidemiology.

 

By Lizzie Parry

Dailymail