Autism in siblings do not share the same genetic factors: Study

By Staff Reporter - 26 Jan '15 16:48PM

A new study suggests that most siblings diagnosed of autism do not share the same genetic factors that predispose them to developing the disorder.

Children who do share genetic mutations, however, also tend to display the same types of symptoms. The findings suggests that the condition may be related to different factors, even in siblings. And figuring out what those factors are for each individual child, the researchers say, may be important for diagnosis - as well as management.

The researchers found that these sibling pairs shared the same autism-relevant gene variations only about 31% of the time, according to the study published online Monday in the journal Nature Medicine.

"It isn't really autism; it's autisms," said the study's lead investigator, Dr. Stephen W. Scherer, head of the Center for Applied Genomics, Genetics and Genome Biology at the Hospital for Sick Children in Toronto. In some cases, he added, "it's like lightning striking twice in the same family."

The technique reads every one of the six billion letters that comprise an individual's genetic code, including those that make up more than 20,000 of a person's genes. Mutations are like typos in the massive encyclopedic tome that is human DNA.

"When we looked at the data, we were really surprised to see that when we could find mutations in genes that are known to be involved in autism, more often than not the siblings were carrying different mutations in different genes," said principal investigator Stephen Scherer, director of the Centre for Applied Genomics at Toronto's Hospital for Sick Children.

"I would have expected that more than one sibling would have carried the same sets of mutations because they both have autism."

"This study makes us step back and realize we're not necessarily going to get as much predictive value out of genetic mapping as we thought, "Helen Tager-Flusberg, a developmental neuroscientist at Boston University who didn't participate in the study, told The New York Times.