Williams Syndrome is a inherited form of mental retardation is manifest in both males and females. It is characterized by mild mental retardation but with striking retention and even precocity or superiority of musical aptitude and social amiability. The child is physically slow and has minor but distinctive somatic changes (wide mouth, almond-shaped eyes, upturned nose, small pointed ears), together impaing an "elfin appearance." By the use of high-resolution cytogenetics, the disease has been traced in 90 percent of cases to a microdeletion on chromosome 7 in the region of the gene that controls the production of elastin (Nickerson et al). Ref: Ropper A.H., Samuels M.A. (2009). Chapter 38. Developmental Diseases of the Nervous System. In A.H. Ropper, M.A. Samuels (Eds), Adams and Victor's Principles of Neurology, 9e.