Williams syndrome

n. A rare genetic defect of chromosome 7 which leads to a deficit in the production of elastin, a protein which gives strength and elasticity to blood vessels. Persons who have this syndrome have delayed physical development and often have features resembling those of elves or pixies, hoarse voices, abnormal sensitivity to noise, and elevated serum calcium level and are prone to cardiovascular problems. Persons with this syndrome also tend to be mentally delayed in some areas but normal in social skills, verbal ability, and musical skills. Also called hypercalcimea syndrome.