Social behavior genes
Contact: Andrew Porterfield
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Salk Institute
Are there 'social behavior' genes?
La Jolla, Calif. -- A rare genetic disorder may lead scientists to
genes for social behavior, a Salk Institute study has found.

The study zeros in on the genes that may lead to the marked
extroverted behavior seen in children with Williams syndrome,
demonstrating that "hyper-sociability" - especially the drive to
greet and interact with strangers -- follows a unique developmental

The path is not only different from typical children but also from
children with other developmental disorders of the nervous system.
The study appears in the online version of the American Journal of
Medical Genetics.

Teresa Doyle and Ursula Bellugi of the Salk Institute, along with
Julie Korenberg and John Graham of UCLA and Cedars-Sinai Medical
Center, Los Angeles, found that children with Williams syndrome
scored significantly higher on tests measuring behavior in social
situations, including their ability to remember names and faces,
eagerness to please others, empathy with others' emotions and
tendency to approach strangers.

The authors also performed genetic screening on a young girl to look
for genetic underpinnings of this pronounced social behavior.

"We've known for many years that children with Williams syndrome are
markedly more social than other children, in spite of the moderate
mental retardation and physical problems that also are associated
with the disorder," said Doyle. "Here we not only have shown
hyper-social behavior as a hallmark symptom that follows a
characteristic developmental course in Williams syndrome, but we may
be closer to identifying the genes involved in regulating that

Williams syndrome is rare, occurring in only one in every 20,000
people. It arises from the deletion of no more than 20 genes from one
chromosome of the seventh chromosome pair.

Virtually everyone with Williams syndrome has exactly the same set of
genes missing.  People with the disorder have characteristic facial
and physical features, certain cardiovascular problems and mild to
moderate mental retardation.

However, in addition to their very extroverted natures, as adults
Williams patients also possess unusually adept language skills given
their level of general cognitive abilities. Bellugi and her
laboratory have been studying the syndrome for years in an effort to
understand how language is processed in the brain and what genes may
be involved.

Very rarely, an individual with Williams syndrome has a slightly
smaller or larger gene deletion than is typical for the syndrome. The
researchers analyzed the genetic deletion of a two-year-old girl with
Williams syndrome who did not exhibit this especially outgoing

She was shy around strangers, and scored significantly lower on
sociability measures, much more resembling 2-year-old children
without Williams syndrome. It was found that this girl retained at
least one gene that most people with the disorder have missing. This
indicated that the gene (or genes) she retained might be altering the
hyper-sociability usually observed among children with Williams

"We don't know at this point whether these genes are involved in
regulating social behavior in the general population, or whether
their involvement is specific to Williams syndrome," said Bellugi.
"We will need to conduct tests in more patients who do not have all
the gene deletions seen in typical Williams syndrome, and compare and
contrast genetics and behavior."


The research was supported by grants from the National Institutes of
Health, the James S. McDonnell Foundation, the Oak Tree Philanthropic
Foundation, and the U.S. Department of Energy.

The Salk Institute for Biological Studies, located in La Jolla,
Calif., is an independent nonprofit organization dedicated to
fundamental discoveries in the life sciences, the improvement of
human health and conditions, and the training of future generations
of researchers. Jonas Salk, M.D., founded the institute in 1960 with
a gift of land from the City of San Diego and the financial support
of the March of Dimes Birth Defects Foundation.
Jose Morales Ph.D.