Learning Objective: By the end of this session, the learner will be able to explain the genetic cause, clinical features, and cardiovascular manifestations of Williams syndrome, and recognize its distinguishing social and metabolic traits.
Overview
Williams syndrome is a congenital microdeletion of the long arm of chromosome 7 (7q11.23), which includes the elastin gene (ELN). The loss of elastin contributes to the connective tissue and vascular abnormalities seen in this condition.
Key Features
| Category | Description |
|---|---|
| Genetics | Microdeletion on chromosome 7 (includes the elastin gene). |
| Inheritance | Sporadic (usually de novo). |
| Facial features | “Elfin” facies — broad forehead, short nose, full cheeks, wide mouth with full lips. |
| Neurological | Intellectual disability; relatively strong verbal skills and musical ability. |
| Behavioral | Overly friendly and outgoing personality (“cocktail party” personality). |
| Metabolic | Hypercalcemia (increased sensitivity to vitamin D). |
| Cardiovascular | Supravalvular aortic stenosis, pulmonary artery stenosis, or renal artery stenosis. |
| Mnemonic | “Will” sing & smile — Williams: friendly, musical, and talkative. |
Pathophysiology Summary
- Loss of elastin gene → vascular stiffness → supravalvular aortic stenosis
- Abnormal calcium metabolism → hypercalcemia (especially in childhood)
- Neurodevelopmental impact → strong verbal skills but low overall IQ
