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The Kleberg Cytogenetics Laboratory offers a fluorescence in situ hybridization (FISH)-based assay for identifying the deletion on 7q11.23 associated with Williams syndrome. Clinical Features:Williams syndrome is characterized by "elfin" facies, mental retardation, growth deficiency, gregarious personality, intermittent infantile hypercalcemia and cardiovascular disease. The most common cardiovascular anomaly associated with Williams syndrome is supravalvular aortic stenosis, although patients may have peripheral or valvular pulmonic stenosis, ventricular septal defects, patent ductus arteriosus and renal artery stenosis. Reason for Referral:Patients with clinical features suggestive of Williams syndrome may be tested for deletions of 7q11.23 by FISH simultaneously with high-resolution chromosomal analysis (if not previously performed). Prenatal diagnosis may be performed if an affected family member has been studied in our laboratory and shown to have a deletion detectable by FISH. Please call regarding all prenatal samples. Testing Methodology:FISH is the application of fluorescently labeled DNA molecules to metaphase chromosomes and interphase nuclei for the detection of chromosome abnormalities and alterations. It is a rapid, reliable and direct approach for identifying patients with microdeletions or microduplications. FISH analysis for Williams syndrome is performed on metaphase chromosomes. The absence of a hybridization signal indicates a deletion. Greater than 90% of individuals with Williams syndrome have a deletion of the elastin gene on the long arm of chromosome 7 detectable with this FISH assay. Specimen Requirements:Whole blood in sodium heparin (green-top) tubes: Shipping and Handling:All tubes must be labeled with the patient's testname and date of birth, and a completed requisition form must accompany each sample. If the laboratory is billing the patient's insurance, please enclose a copy of the insurance card. Ship specimens for overnight delivery at ambient temperature. Please notify the laboratory of incoming samples. Turnaround Time:7-10 days CPT Codes and Prices:88230, 88271, 88273, 88291 References:1. Nickerson, et al. (1995) Am. J. Hum. Genet. 56: 1156-1161. Forms: >> Cytogenetics
Requisition Test Code:8483 |