APA Dictionary of Psychology

a rare autosomal dominant disorder caused by deletion of a segment of chromosome 7. In addition to the symptom of mild to moderate intellectual developmental disorder, it is characterized by failure to thrive, high concentrations of calcium in the blood, narrowing of blood vessels (particularly the aorta, which restricts blood flow from the heart), and unusual facial features (e.g., short nose with a broad tip, wide mouth, small chin). Individuals with Williams syndrome are highly sociable and, although their ability to perform visual–spatial tasks is typically impaired, their verbal skills are superior. Most cases are not inherited but occur randomly during the development of reproductive cells (eggs or sperm) in a parent of an affected individual. [described in the 1960s by J. C. P. Williams, 20th-century New Zealand cardiologist; Brian Gerald Barratt-Boyes (1924–2006), New Zealand cardiologist; and Alois J. Beuren (1919–1984), German cardiologist]