Williams syndrome (WS or WMS; also Williams–Beuren syndrome or WBS) is a rare neurodevelopmental disorder characterized by a distinctive, "elfin" facial appearance, along with a low nasal bridge, an unusually cheerful demeanor and ease with strangers; developmental delay coupled with strong language skills; and cardiovascular problems, such as supravalvular aortic stenosis and transient hypercalcaemia.
It is caused by a deletion of about 26 genes from the long arm of chromosome 7. The syndrome was first identified in 1961 by New Zealander Dr. J. C. P. Williams and has an estimated prevalence of 1 in 7,500 to 1 in 20,000 births.
An interesting characteristic of those with Williams Syndrome (from with Williams Syndrome Association):
Most individuals with Williams syndrome have an affinity to music. They are touched by music in ways not usually seen in the general population. It is quite common for those with Williams syndrome to be reduced to tears by classical music, disturbed by music played in minor chords or moved to dance and laugh by playful and "happy" music.
Check out this video from Williams Syndrome Changing Lives Foundation:
The "cheat sheet" about Williams Syndome from the National Library of Medicine is here.
Rare Disease Day is February 28, 2013.