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Williams Syndrome deletion 7q11.2 by FISH*

Test Code


Test Synonyms



Fluorescence in situ Hybridization (FISH)
*performed by affiliate laboratory

Turnaround Time

5-7 days

Specimen Requirements

5.0 mL whole blood, sodium heparin (EDTA)

Specimen Stability
Stable at 4-25°C for 72 hours.
Storage & Handling

Protect from extreme temperature. Ship with cool pack (refrigerated). Ship on Saturday for Monday delivery.

Causes for Rejection

Clotted specimen; Specimen exposed to extreme temperature; Anticoagulant toxic to cells; Insufficient number of cells; Improper fixative

Reference Range

See report

It is recommended that all FISH studies be done in conjunction with routine cytogenetic studies. If the FISH result is normal, a chromosome analysis allows identification of more complex abnormalities.


Williams syndrome is a rare genetic disorder found in approximately 1 in 7,500-20,000 people. A deletion on chromosome 7 is the cause for the disorder. This region includes several genes that most likely contribute to the characteristic features. Usually this disorder is seen as a random event and not inherited.


Elçioglu N et al. (1998). FISH analysis in patients with clinical diagnosis of Williams syndrome. Acta Paediatr. 87(1):48-53.