Healthy Living

Autism Spectrum Disorder: Sex & Gender Differences in Children

Having one child with autism is a well-known risk factor for having another one with the same type of disorder, but whether and how a sibling's gender influences this risk has remained largely unknown. Until now New research driven by a team of scientists at Harvard Medical School looked at gender and siblings differences and has successfully quantified the likelihood that a family who has one child with autism would have another one with the same disorder based on the siblings' gender.

Did you know that statistics show that autism is more prevalent among boys than girls? But the latest research has also determined that sibling gender also plays a crucial role in other siblings being diagnosed with Autism. There has been a significant link between autism and gender that, until now, was unknown.

Autism-spectrum disorders (ASD) are neurodevelopmental conditions that typically emerge in the first few years and affect 1 in 68 children in the U.S., per the CDC. Past research has found that males are at far higher risk for autism spectrum disorder (ASD) than females. In fact, boys, on average, are five times more likely to have autism than girls — but why is autism more common in boys?

In Leo Kanner’s 1943 study of a small group of children with autism there were four times as many boys as girls.

The Key Factor Between Autism & Gender

Genetics may be a critical factor in the link between the disorder and gender, according to a 2014 study published in the American Journal of Human Genetics. Researchers in the study found that girls have a higher tolerance for genetic mutations and therefore require a more significant number of them than boys to be diagnosed with a developmental disorder. Simply put, even with identical genetic mutations, a boy could display symptoms of ASD while a girl could show none.

“Overall, females function a lot better than males with a similar mutation affecting brain development,” described study author Dr. Sébastien Jacquemont of the University Hospital of Lausanne. “Our findings may lead to the development of more sensitive, gender-specific approaches for the diagnostic screening of neurodevelopmental disorders.”

Differences in the Brain May Impact Autism and Gender

Structural differences in the male brain may also hold a connection between autism and gender, says a recent JAMA study. The study’s findings point to women being three times more likely to have ASD if their brain anatomy resembled more closely what is typically seen in male brains.

In other words, this means there’s something about the way the male brain is structured that makes men more apt to develop the disorder, although the study did not prove that these anatomical differences cause the disorder.

It May Greatly Depend on A Sibling’s Gender/Sex

A recent study in JAMA Pediatrics revealed an unusual pattern of frequency based on gender. Researchers found that that having an older female child diagnosed with autism actually elevated the risk for younger siblings and that the liability was highest among younger siblings who were male.

In other words, boys with older female siblings with autism had the highest risk for developing autism themselves, while female siblings with older brothers with autism have the lowest chance of incidence.

These new findings could help doctors and geneticists explain the risk for younger siblings in families who already have one child who has the disorder.

“Our results give us a fair degree of confidence to gauge the risk of autism recurrence in families affected by it based on a child’s gender,” noted study author Nathan Palmer, instructor in biomedical informatics at Harvard Medical School. (HMS) “It is important to be able to provide worried parents who have one child with the condition some sense of what they can expect with their next child.”