Williams Syndrome is a rare
genetic disorder, occurring in fewer than 1 in every 20,000 live births. It is characterized by a distinctive, "elfin" facial appearance, an unusually cheerful demeanor, ease with strangers,
mental retardation coupled with an unusual facility with
language, a love for music, cardiovascular problems such as
aortic stenosis[?], and
hypercalcemia[?]. Most children with Williams Syndrome are missing genetic material on chromosome 7.