Father's Age Linked to Autism

A new study published in the journal, Nature, found that a man’s age may affect his child’s chances of developing autism or schizophrenia.  This is because random mutations in the chromosomes provided by the father become more prevalent as the man gets older.

 

The research was prompted by the belief that increasing cases of autism in the last few years may be due to the increasing age at which couples are starting families. However, it also noted that the age of the mother had little or nothing to do with the outcome of her child developing autistic traits.

 

How many cases of autism can be attributed to the father’s age?  The study claims that roughly 30 percent of all autistic cases can be traced back to the father being 40 years old or older. 

 

Children born to a 20 year-old father would have an average of 25 chromosomal mutations. Researchers found that every year, the number of mutations provided by the father increases by 2, topping off at an average of 65 mutations by the age of 40. In comparison, the average number of mutations provided by the mother is 15.

 

“This study provides some of the first solid scientific evidence for a true increase in the condition of autism, “ the director of the Child Study Center at the Yale School of Medicine, Dr. Fred Volkmar, told the New York Times

 

In response to questions of the study’s validity (especially in light of certain “studies” that have overlooked  other variables), he added, “It is extremely well done and the sample meticulously characterized.”

 

The study was conducted in Iceland by the firm deCODE Genetics.  They looked at 78 couples who were parents with no signs of mental disorders but that had a child with autism or schizophrenia.  Blood samples were taken for all three members, which allowed the researchers to isolate mutations in the child’s genes that were not present in the parents’ DNA.

 

So why does the father's age contribute to the risk of autism?

 

Well, sperm cells are constantly being developed and divide every 15 days.  Continual copying leads to errors and mutations in the DNA.  The study’s senior author, Dr. Kari Stefansson said, “It is absolutely stunning that the father’s age accounted for all this added risk, given the possibility of environmental factors and the diversity of the population.  And it’s stunning that so little is contributed by the age of the mother.”

 

Evan E. Eichler, professor of genome sciences at the University of Washington in Seattle responded to the study saying, “You are going to have guys who look at this and say, ‘Oh no, you mean I have to have all my kids when I’m 20 and stupid?’ Well, of course not.  You have to understand that the vast majority of these mutations have no consequences, and that there are tons of guys in their 50s who have healthy children.”