What is Williams Syndrome? The rare condition that makes people unusually friendly

Picture striking up a conversation with a stranger on the bus and immediately feeling like they are your best friend or walking down a busy street feeling a wave of warmth, affection, and trust toward every single person you pass.For people withWilliams Syndrome (WS), this isn’t unusual, it's how they experience the world every day.A rare genetic disorder, Williams Syndrome, affects around 1 in 7,500 to 10,000 people worldwide. It is caused by the deletion of a small segment of chromosome 7, which contains 25–27 genes. This deletion not only leads to a unique personality marked by extreme empathy and sociability but also a range of symptoms, including distinctive facial features, developmental delays, and cardiovascular issues.Often described as the 'opposite of autism', people with Williams Syndrome are inclined towards forging instant connections with even strangers. However, on the flip side they fail to maintain friendships and social connections over a long period of time, which leaves them isolated.They are highly verbal, overly trusting, and eager to please. While these traits can be endearing, they can also make them vulnerable to manipulation and social isolation, especially as they struggle to maintain long-term friendships."It's very easy for someone to fool a person with Williams Syndrome and take advantage of them, because they are so trusting," Alysson Muotri, a professor of paediatrics and cellular and molecular medicine at the University of California, San Diego (UCSD) told BBC. "They give themselves to anybody without prejudice, which seems like a lovely trait, but at the end of the day there is a reason why the human brain evolved to be a little bit suspicious of a new person.You don't know if that person is there to hurt you or to love you, and they [a person with WS] cannot make that distinction," he says.WS is usually diagnosed in early childhood, often due to heart problems like supravalvular aortic stenosis (a narrowing of the large blood vessel that carries blood from the heart). Other common features include low muscle tone, delayed milestones like walking or sitting, dental abnormalities, and endocrine issues such as early puberty or hypothyroidism. Many also have mild to moderate intellectual disabilities, although verbal abilities are often strong.Interestingly, researchers have begun to explore what makes people with WS so uniquely social. The gene GTF2I, often missing or altered in those with the condition, may play a central role. Studies on animals and humans suggest that this gene influences sociability. In mice, for example, a lack of GTF2I results in increased social behavior. In contrast, having extra copies of the gene is linked to social withdrawal and traits associated with autism.One theory suggests that the deletion of GTF2I disrupts the brain's myelination process. Myelin acts like insulation for neurons, speeding up communication between brain regions. Without proper myelination, the connection between the amygdala (which processes fear) and the frontal cortex (responsible for decision-making and social judgment) weakens. This may explain why people with WS don’t exhibit the typical hesitation or fear around strangers.Boaz Barak, a professor at Tel Aviv University, is currently studying how clemastine—a common allergy medication that enhances myelination—might help treat WS. Early trials are underway, with results expected in late 2025.Beyond myelin, Muotri’s team has discovered that neurons in people with WS form more synapses—connections between brain cells—than average. This neural “overconnectivity” could explain why they experience such intense social reward from meeting new people. Their brains may release dopamine—the feel-good chemical—more readily in response to social interactions.Other factors may include elevated levels of oxytocin, the so-called “love hormone,” and energy deficits in brain cells due to dysfunctional mitochondria. Together, these biological quirks paint a picture of a brain wired for connection, but not always equipped to navigate its complexities.Still, many families of individuals with WS emphasize the joy their children bring to those around them. “We’re not trying to erase their personalities,” Barak told BBC. “We’re simply offering tools to help them navigate the world more safely.”