there 'social behavior' genes?
La Jolla, Calif. -- A rare genetic disorder may lead
scientists to genes for social behavior, a Salk Institute study has
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
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
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
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
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
Jose Morales Ph.D.