Unique 'Tags' in Male Sperm Could Cause Autism in Children

Unique regulatory "tags" found in male sperm could cause autism in their children, according to a new genetic study.

Autism spectrum disorder affects one in 68 children in the United States. While the root cause of autism continues to elude scientists, it is widely believed that it is inherited, since the condition tends to run in families. That's why Johns Hopkins researchers looked for possible causes for the condition not in genes themselves, but in the "epigenetic tags" that help regulate genes' activity.

"We wondered if we could learn what happens before someone gets autism," Andrew Feinberg, one of the researchers, said in a statement.

"If epigenetic changes are being passed from fathers to their children, we should be able to detect them in sperm," added co-lead investigator Daniele Fallin.

So Feinberg, Fallin and their team assessed the epigenetic tags on DNA from sperm from 44 dads. Not only are sperm easier to sample than female egg cells, but they are also more susceptible to environmental influences that could alter the epigenetic tags on their DNA.

In addition, they study included pregnant mothers who already have a child with autism and collected information and biological samples from these mothers, the new baby's father and the babies themselves after birth. After collecting a sperm sample from fathers early in the pregnancy, the researchers assessed the child one year later for early signs of autism using the Autism Observation Scale for Infants (AOSI).

They collected DNA from each sperm sample and looked for epigenetic tags at 450,000 different positions throughout the genome, comparing the likelihood of a tag being in a particular site with the AOSI scores of each child.

The researchers found 193 different sites where the presence or absence of a tag was statistically related to the AOSI scores.

What's more, many of the epigenetic tags were located close to genes involved in developmental processes, especially neural development. And 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, suggesting that this unique feature of male sperm could lead to the condition.

There is currently no genetic or epigenetic test available to assess autism risk, but researchers plan to study this association further in future studies.

The results were published in the International Journal of Epidemiology.

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