Williams Syndrome - Epidemiology

Epidemiology

Williams syndrome has historically been estimated to occur in roughly 1 in every 20,000 live births. However, more recent epidemiological studies have placed the occurrence rate at closer to 1 in every 7,500 live births, a significantly larger prevalence. As an increasing body of evidence suggests that Williams syndrome is more common than originally noted (approximately 6% of all genetic cases of developmental disability), researchers have begun to theorize past under-diagnosis of the disorder. One theorized reason for the increase in epidemiological estimates is that there exists a substantial minority of individuals with the genetic markers of Williams syndrome who lack the characteristic facial features or the diminished IQ considered to be diagnostic of the disorder, who often are not immediately recognized as people with the syndrome.