anomalous iris architecture

Williams Syndrome

Clinical Characteristics
Ocular Features: 

Blue irides (77%) and a lacey or stellate pattern (74%) of the iris are characteristic.  The stroma appears coarse with radial or cartwheel striations.  The iris collarette is usually absent or anomalous.  Features of the Peters' anomaly may be present.  The periorbital tissues are described as 'full' and prominent.  Strabismus (usually esotropia) occurs in more than half of patients.  Retinal vessel tortuosity is present in 22% of patients.  Cataracts may be found in younger individuals but are uncommon. Hyperopia is the most common refractive error.  Keratoconus has been described in at least 3 patients.

Systemic Features: 

The phenotype is variable, likely depending upon the size of the deletion.  Cardiovascular disease, primarily hypertension and large vessel stenosis, are among the most important features.  The elastin arteriopathy lead to thickened arterial walls with peripheral pulmonary stenosis and supravalvular aortic stenosis.  The facies is considered unique with bitemporal narrowing, a wide mouth, full lips, malocclusion, small jaw, and prominent earlobes.  The teeth are small and widely spaced.  Connective tissue abnormalities include joint hyperextensibility, hernias, lax skin, hypotonia, and bowel/bladder diverticulae.  Small birth size is common and infants often fail to thrive but at puberty patients can experience a growth spurt.  Ultimate height in adults is usually in the third centile.

Vocal cord anomalies and paralysis can result in a hoarse voice.  A sensorineural hearing loss is common among adults but hyperacusis is often present in young children.

Hypercalcemia and hypercalciuria are common and some (10%) have hypothyroidism.

Most individuals have some cognition difficulties and delays but normal intelligence has also been reported.  Patient personalities consist of anxiety, attention deficit disorder, marked friendliness and a high level of empathy.  Visiospatial construction is often impaired.  Most adults are unable to live independently.

Genetics

This is a deletion syndrome but included in this database because the major features are due to the loss of a single gene (ELN).  The deletion segment consists of 1.4-1.8 Mb at 7q11.23 containing as many as 28 genes.   Most cases occur sporadically but parent-child transmission and affected siblings have been reported.  The recurrence risk is low.

Increased tortuosity of the retinal arterioles is also a feature of Fabry disease (301500) and of a condition known as isolated retinal arteriolar tortuosity (611773, 180000).

Treatment
Treatment Options: 

Feeding issues should be addressed early in infants who fail to thrive.  Early intervention with speech and physical therapy plus special education can be helpful.  Psychological evaluations may help in managing behavioral issues.

Hypertension can often be managed medically but surgery may be required for vascular stenoses.   Hypercalcemia and hypothyroidism often respond to medical therapy. Strabismus, vessel narrowing, and valvular malfunctions can be treated surgically.

References
Article Title: 

The iris in Williams syndrome

Holmstrom G, Almond G, Temple K, Taylor D, Baraitser M. The iris in Williams syndrome. Arch Dis Child. 1990 Sep;65(9):987-9.

PubMed ID: 
2221973

Ocular findings of Williams' syndrome

Hotta Y, Kishishita H, Wakita M, Inagaki Y, Momose T, Kato K. Ocular findings of Williams' syndrome. Acta Paediatr Scand. 1990 Aug-Sep;79(8-9):869-70.

PubMed ID: 
2239289
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