Mutations in a father's sperm could predict risk of autism in children, study finds

Mutations in a father’s sperm could predict the risk of a child being diagnosed with autism, a new study suggests. 

The genetic flaws, known as ‘de novo mutations’, can appear in a child’s DNA through problems with sperm production.

Researchers found that 15 percent of men with autistic children had these disease-causing mutations in their sperm.

The team, from the University of California San Diego School of Medicine, says the findings could lead to test in which fathers have their sperm screened to determine their future children’s risk of the developmental disorder.  

A new study from the University of California San Diego School of Medicine has found that ‘de novo mutations’ in a father’s sperm can predict the risk of autism in a child (file image)

Autism spectrum disorder (ASD) is a developmental disorder in which sufferers have a hard time communicating and with behavior.

It encompasses several conditions – including autism and Asperger’s syndrome – and symptoms can range from mild to severe.

Children are usually diagnosed by age two after they exhibit signs such as reduced eye contact, not responding to their name and performing repetitive movements.

According to the Centers for Disease Control and Prevention, about one in 59 children has ASD.

Boys are much more likely – up to four times – to have the condition than girls. 

Despite decades of research, the causes of ASD remain a mystery. Both genetics and environmental factors are believed to play a role. 

However, recent studies have suggested that de novo mutations may be the cause of between 10 and 30 percent of ASD cases.

These mutations occur for the first time in a family member as the result of a mutation in the sperm or egg of a parent. 

For the study, published in the journal Nature Medicine, the team looked at the sperm of eight fathers who had children already diagnosed with ASD.

The sperm was analyzed for mosaicism, a condition in which a person has genetically different sets of cells within their body. 

‘While medical textbooks teach us that every cell in the body has an identical copy of DNA, this is fundamentally not correct,’ said first author Dr Martin Breuss, an assistant project scientist at UC San Diego Health Sciences.

‘Mutations occur every time a cell divides, so no two cells in the body are genetically identical.’   

Mosaicism occurs in an unborn baby’s early developmental stages after an error in cell division. 

‘[It] can cause cancer or can be silent in the body. If a mutation occurs early in development, then it will be shared by many cells within the body,’ said Dr Breuss. 

‘But if a mutation happens just in sperm, then it can show up in a future child but not cause any disease in the father.’

Disease-causing mutations were found in about 15 percent of the fathers’ sperm cells, the researchers said. 

‘My laboratory has a long-standing interest in understanding the origins of pediatric brain disease, and how mutations contributes to disease in a child,’ said co-senior study author Dr Joseph Gleeson, a professor of neuroscience at UC San Diego School of Medicine.  

‘We previously showed that mosaicism in a child can lead to diseases like epilepsy. Here, we show that mosaicism in one of parents is at least as important when thinking about genetic counseling.’

The researchers say their findings could be developed into a clinical test that fathers could undergo to test the risk of recurrence in future children or for men who haven’t had children yet but want to know the risk.