Genetics
Neurodevelopmental disorder caused by a deletion of about 26 genes from the region q11.23 on chromosome 7.

Incidence
Affects between approximately 1 in 7,500 to 1 in 20,000 individuals

Symptoms/Characteristics

• Short stature relative to family
• Mild-to-moderate mental retardation
• Feeding problems including colic, reflux, vomiting (due to low muscle tone and poor gag reflex)
• Unusually cheerful demeanor and ease with strangers
• Unpredictably occurring negative outbursts
• A predisposition to violent outbursts
• Mental retardation coupled with unusual language skills
• A love for music
• Difficulties with visual processing
• Cardiovascular problems, such as supravalvular aortic stenosis and transient hypercalcaemia
• Hyperfocusing on the eyes of others in social engagements
• Higher prevalence of left-handedness and left-eye dominance in those with Williams, and cases of absolute pitch appear to be significantly higher
• People with Williams syndrome often have hyperacusis and phonophobia which resembles noise-induced hearing loss, but may be due to a malfunctioning auditory nerve
• Individuals with William syndrome also report higher levels of fears, which may be associated with hyperacusis

Facial Appearance

• Small upturned nose, with low nasal bridge, long philtrum (upper lip length), wide mouth, full lips, small chin, and puffiness around the eyes
• Blue and green-eyed children with Williams syndrome can have a prominent “starburst” or white lacy pattern on their iris.
• Elfin appearance

Clinical Management
There is no cure for Williams syndrome. Supplemental calcium and vitamin D should be avoided, and it is important to treat high levels of blood calcium if present. Blood vessel narrowing can be a significant health problem and is treated based on severity. Physical therapy is helpful to patients with joint stiffness. Developmental and speech therapy can also help children.