To 7-year-old twins Tristan and Tyler Waldner, there are no strangers. The boys have an genetic condition called the Williams syndrome which makes them unusually social.
Scientists think that this may be the key to understanding autism:
Williams syndrome is the perfect test case for studying the link between genes and behavior, Bellugi said. The disorder is very specific, occurring only when a certain cluster of genes is missing from one of two copies of chromosome 7.
“We’re only talking about something like 25 to 28 genes out of 30,000 genes in the brain,” Bellugi said. “And it’s always the same set of genes.”
That genetic deletion creates a well-defined but diverse set of characteristics. People with Williams syndrome have distinctive facial features, often described as “elfin,” including small, upturned noses, wide mouths and lips, a longer span between nose and upper lip and tiny, widely spaced teeth. They often suffer from heart, skeletal and dental problems.
Those with Williams syndrome have a distinctive pattern of intellectual peaks and valleys, including low IQs, developmental delays and learning disabilities, all coupled with rich, imaginative capacity for language — and those exuberantly social personalities.
“The behavior is quite consistent,” Bellugi says. “In terms of their social interest, their social drive, attraction to strangers, looking at faces, looking more intently at faces. We have this kind of social phenotype that we’ve been studying.”
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