Williams syndrome, also known as Williams-Beuren syndrome, occurs when people are missing of a chunk of DNA containing about 27 genes. The syndrome affects about one in 10,000 people, and it is associated with a suite of mental and physical traits, including bubbly, extroverted personalities, a broad forehead, full cheeks, heart defects, intellectual disability and an affinity for music.
The first hint of a link between dogs and Williams syndrome came in 2010, when evolutionary biologist Bridgett vonHoldt and her colleagues examined DNA from 225 wolves and 912 dogs from 85 breeds. They were looking for parts of the genome that have been shaped by selection since dogs diverged from wolves.
One gene that popped out was WBSCR17, suggesting that it or other genes near it were important in dog evolution. This region of the genome is similar in dogs and humans, and the human version of WBSCR17 is located near the sequence that is deleted in people with Williams syndrome.