WEDNESDAY, May 1 (HealthDay News) -- With four to five times
more males affected by autism spectrum disorders than females, much
less is known about girls with autism.
Fortunately, more research is beginning to focus on autism in
girls, said Geraldine Dawson, chief science officer of Autism
Speaks, with two such studies set to be presented Saturday at the
International Meeting for Autism Research in San Sebastian,
"Autism affects boys much more frequently than girls. But, we
may be missing some girls. The diagnostic criteria were developed
using symptoms in boys, and symptoms in girls and boys may be
different," Dawson explained.
"Because of this difference in incidence, researchers may end up
with a small number of girls in studies," she said, adding that
differences in symptoms or reactions to treatments may lead to the
girls' data being excluded from studies. But, it's just those
differences that may really need to be researched, to make sure
girls are being diagnosed and treated correctly.
"Other neuropsychiatric disorders have already made the
discovery that symptoms can be different in girls and may require
different treatments for girls," said Dawson, who is also a
research professor in the department of psychiatry at the
University of North Carolina, Chapel Hill. One such example is
attention-deficit/hyperactivity disorder. Girls tend to be less
hyperactive than boys, and may instead appear as if they're
In the latest autism research, the first study compared visual
scanning patterns in boys and girls with autism spectrum disorders.
Scanning patterns were also collected for typically developing
"We used eye-tracking technology while the participants in these
studies watched videotapes of social scenes that presented
naturalistic stimuli," said study co-author Ami Klin, director of
the Marcus Autism Center, in Atlanta.
The study, which was led by Klin's student, Jennifer Moriuchi,
included 116 school-aged children with autism spectrum disorders.
Eighty-one were boys and 35 were girls. The children with autism
had varying degrees of social disability. The study also included
36 typically developing children.
"On a surface level, it appears that boys and girls with autism
appear to spend equal time learning from the eyes. They did look
less than other children," Klin said. But, when the researchers
correlated the youngsters' eye tracking with their level of
disability, a much different picture emerged.
"In boys, the more they looked at the eyes, the less socially
disabled they are. In girls, the more they looked at the eyes, the
more disabled they are," said Klin, chief of the division of autism
and related disorders at Emory University School of Medicine and
Children's Healthcare of Atlanta.
"What the study is suggesting is that we should not
automatically assume that boys and girls learn about the world in
the same way," Klin said, adding, "we have to take gender as a
Dawson said "the study found that there are differences in the
way girls and boys look at the eyes, so there may be differences in
the way autism is manifested in girls than in boys." She noted that
an important criterion right now for diagnosing autism is a lack of
eye contact and using the eyes for social cues.
The second study looked at the genetics involved in autism, and
potential differences in boys and girls. Yale University
researchers analyzed samples from 2,326 families. Included in those
samples were those of 2,017 boys and 309 girls with an autism
The Yale team found differences between the boys' and girls'
"The fact that autism does affect boys so much more frequently
has been staring us in the face for decades. There's been a
hypothesis that there's something in the extra X chromosome that
girls have that may be protective," Dawson explained. "The idea is
that if you have this protective mechanism in place you may need
more risk factors to overwhelm that protective effect and cause
autism, and that's exactly what they found."
"To develop autism in a girl requires more genetic mutations,"
Dawson said. The type of mutations they found are called "de novo"
mutations, she added. This means that the genetic change occurs in
the sperm or the egg. It isn't a gene that's passed down from the
parents. These mutations can occur randomly, or they can be caused
by an environmental trigger.
Because these studies are being presented at a medical meeting,
the data and conclusions should be viewed as preliminary until
published in a peer-reviewed journal.
Learn more about autism from the
U.S. National Institute of Neurological Disorders and