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Key Features

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  • Williams syndrome

    • Deletes the gene for elastin and other neighboring genes at 7q11.23

    • Duplication of chromosome 7q11.23 results in a syndrome that includes speech delay and features of autistic spectrum disorders

  • Smith-Magenis syndrome

    • Associated with microdeletion of 17p11

    • Duplication of 17p11 produces Potocki-Lupski syndrome

  • Velocardiofacial syndrome (Deletion 22q11 syndrome)

    • Duplication of the 22q11 region produces a mild and highly variable phenotype that ranges from developmental delays and learning disabilities to functionally normal

    • Also known as DiGeorge syndrome

    • Originally described in newborns with cyanotic congenital heart disease, usually involving

      • Great vessel abnormalities

      • Thymic hypoplasia leading to immunodeficiency

      • Hypocalcemia due to absent parathyroid glands

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Clinical Findings

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  • Williams syndrome

    • Characterized by

      • Short stature

      • Congenital heart disease (supravalvular aortic or pulmonic stenosis)

      • Coarse, elfin-like facies with prominent lips

      • Hypercalcemia or hypercalciuria in infancy

      • Developmental delay

      • Neonatal irritability evolving into an overly friendly personality

    • Natural history includes

      • Progression of cardiac disease

      • Predisposition to hypertension and spinal osteoarthritis in adults

    • Mild to moderate intellectual deficits

  • Smith-Magenis syndrome

    • Characterized by

      • Prominent forehead

      • Deep-set eyes

      • Cupid-shaped upper lip

      • Self-mutilating behavior

      • Sleep disturbance

      • Intellectual disabilities

    • Some patients also have seizure disorders, hearing loss, thyroid disease, and immunological and lipid abnormalities

    • Potocki-Lupski syndrome is characterized by

      • Growth failure

      • Variable levels of cognitive deficiencies

      • Autistic features

      • Structural abnormalities of the heart (occasionally)

  • Velocardiofacial syndrome (Deletion 22q11 syndrome)

    • Characteristics include

      • Mild microcephaly

      • Palatal clefting or incompetence

      • Speech and language delays

      • Congenital heart disease (great vessel abnormalities, tetralogy of Fallot, and a variety of other abnormalities)

    • Some affected individuals are predisposed to psychosis

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Diagnosis

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  • Suspected on the basis of an abnormal phenotype

  • Confirmed via microarray

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Treatment

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  • Williams syndrome

    • Calcium restriction may be necessary in early childhood to prevent nephrocalcinosis

  • Smith-Magenis syndrome

  • Velocardiofacial syndrome (Deletion 22q11 syndrome)

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