Test ID: WSCR
Williams Syndrome, 7q11.23 Deletion, FISH
Secondary ID 
A test code used for billing and in test definitions created prior to November 2011
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Useful For Suggests clinical disorders or settings where the test may be helpful
Detecting deletions of the elastin gene at 7q11.23
Diagnosis of Williams syndrome, when used in combination with high-resolution chromosome studies and clinical evaluation
Special Instructions and Forms Describes specimen collection and preparation information, test algorithms, and other information pertinent to test. Also includes pertinent information and consent forms to be used when requesting a particular test
Method Name A short description of the method used to perform the test
Fluorescence In Situ Hybridization (FISH) with DNA Probes
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Aliases Lists additional common names for a test, as an aid in searching
Chromosome Analysis and Consultation, FISH for Williams Syndrome
Deletion 7
Elastin Williams (Gene)
FISH, Williams Syndrome
Williams Syndrome Chromosome Region (WSCR)
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Provide a reason for referral with each specimen. The laboratory will not reject testing if this information is not provided, but appropriate testing and interpretation may be compromised or delayed.
Forms:
1. New York Clients-Informed consent is required. Please document on the request form or electronic order that a copy is on file. An Informed Consent for Genetic Testing (Supply T576) is available in Special Instructions.
2. If not ordering electronically, submit a Cytogenetics/AFP Congenital Disorders Request Form (Supply T238) with the specimen.
Advise Express Mail or equivalent if not on courier service.
Submit only 1 of the following specimens:
Preferred:
Specimen Type: Blood
Container/Tube: Green top (sodium heparin)
Specimen Volume: 5 mL
Collection Instructions:
1. Invert several times to mix blood.
2. Other anticoagulants are not recommended and are harmful to the viability of the cells.
Acceptable:
Specimen Type: Amniotic fluid
Container/Tube: Amniotic fluid container
Specimen Volume: 20-25 mL
Collection Instructions:
1. Optimal timing for specimen collection is during 14 to 18 weeks of gestation, but specimens collected at other weeks of gestation are also accepted. Provide gestational age at the time of amniocentesis.
2. Discard the first 2 mL of amniotic fluid.
Additional Information:
1. Place the tubes in a Styrofoam container (Supply T329).
2. Fill remaining space with packing material.
3. Unavoidably, about 1% to 2% of mailed-in specimens are not viable.
4. Bloody specimens are undesirable.
5. If the specimen does not grow in culture, you will be notified within 7 days of receipt.
6. Results will be reported and also telephoned or faxed, if requested.
Specimen Type: Chorionic villi
Container/Tube: 15-mL tube containing 15 mL of transport medium
Specimen Volume: 20-30 mg
Collection Instructions:
1. Collect specimen by the transabdominal or transcervical method.
2. Transfer chorionic villi to Petri dish containing transport medium (Supply T095).
3. Using a stereomicroscope and sterile forceps, assess the quality and quantity of the villi and remove any blood clots and maternal decidua.
Specimen Type: Skin biopsy
Container/Tube: Sterile container with sterile Hank's balanced salt solution (Supply T132), Ringer's solution, or normal saline
Specimen Volume: 4 mm diameter
Collection Instructions:
1. Wash biopsy site with an antiseptic soap.
2. Thoroughly rinse area with sterile water.
3. Do not use alcohol or iodine preparations.
4. A local anesthetic may be used.
5. Biopsy specimens are best taken by punch biopsy to include full thickness of dermis.
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected
| Hemolysis | NA |
| Lipemia | NA |
| Icterus | NA |
| Other | Clotted blood |
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
| Specimen Type | Temperature | Time |
|---|---|---|
| Varies | Ambient (preferred) | |
| Refrigerated | ||
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Williams syndrome (WS) is a genetic disorder that occurs in 1/20,000 to 1/50,000 live births. Although WS is typically a sporadic disorder, familial cases have been reported.
WS is characterized by a variable combination of cardiovascular abnormalities, connective tissue abnormalities, distinct facial features, infantile hypercalcemia, mental retardation, and characteristic social interactions such as extreme friendliness and attention-deficit hyperactivity disorder.
Isolated congenital narrowing of the ascending aorta is common in WS patients and results in a separate syndrome called supravalvular aortic stenosis (SVAS).
WS is a contiguous gene deletion syndrome, caused by deletion of several genes on chromosome 7q. One gene that often is deleted in WS is the elastin gene, which causes SVAS and other cardiovascular disease in these patients. This association was described by Ewart et al (1993) who identified hemizygosity of the elastin gene in WS and SVAS.
The elastin gene, ELN, has been mapped to 7q11.23 (Williams syndrome chromosome region, and is reportedly hemizygous in up to 96% of patients with WS. The deletion of an elastin gene locus cannot be detected by conventional high-resolution chromosome analysis in the vast majority of cases due to the small size of this deletion. Nickerson et al used molecular methods to detect a deletion of the elastin gene in 91% (39/43) of WS patients.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
An interpretive report will be provided.
Interpretation Provides information to assist in interpretation of the test results
An interpretive report is provided.
The use of high-resolution chromosome studies and FISH for Williams syndrome chromosome region should diagnose about 96% of Williams syndrome patients and, at the same time, identify any other chromosome anomalies.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Because this FISH test is not approved by the Food and Drug Administration it is important to confirm Williams syndrome (WS) by other established methods, such as clinical evaluation.
In up to 1% of patients, WS is caused by a gene mutation within or near the elastin gene. These mutations would not be detected by this FISH test. FISH testing involves a DNA probe that detects only large deletions including this entire gene and the DNA probe, small deletions or mutations may give normal results by FISH.
Patients with a deletion outside of the elastin gene could display normal development of connective tissue, including the heart, but have other features of WS.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Ewart AK, Morris CA, Atkinson D, et al: Hemizygosity at the elastin locus in a developmental disorder, Williams syndrome. Nature Genet 1993;5:11-16
2. Jalal SM, Crifasi PA, Karnes PS, Michels VV: Cytogenetic testing for Williams syndrome. Mayo Clin Proc 1996;71:67-68
3. Lowery MC, Morris CA, Ewart AK, et al: Strong correlation of elastin deletions, detected by FISH, with Williams syndrome, evaluation of 235 patients. Am J Hum Genet 1995;57:49-53
4. Morris CA, Demsey SA, Leonar CO, et al: Natural history of Williams syndrome. J Pediatr 1988;113:318-326
5. Olson TM, Michels VV, Lindor NM, et al: Autosomal dominant aortic stenosis: localization to chromosome 7. Hum Mol Genet 1993;2:869-873
Method Description Describes how the test is performed and provides a method-specific reference
The FISH test to diagnose Williams syndrome (WS) involves a commercial DNA probe for the elastin WS chromosome region (WSCR) that hybridizes to 7q11.23. The WSCR probe is used in conjunction with a control probe that maps to the terminal region of chromosome 7 (7q36). Ten of 10 metaphases with 2 ELN signals is considered normal, and 10 of 10 metaphases with 1 ELN signal is consistent with microdeletion of the WS critical region. (Ewart AK, Morris CA, Atkinson D, et al: Hemizygosity at the elastin locus in a developmental disorder, Williams syndrome. Nature Genet 1993:5:11-16; Nickerson E, Greenberg F, Keating MT, et al: Deletion of elastin gene at 7q11.23 occur in approximately 90% of patients with Williams syndrome. Am J Hum Genet 1995;56:1156-1161)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Samples processed Monday through Sunday. Results reported Monday through Friday, 8 a.m.-5 p.m. CST.
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
Test Classification Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
CPT Code Information Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
88271 x 2-DNA probe, each
88273-Chromosomal in situ hybridization
88291-Interpretation and report
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
| Result ID | Reporting Name | LOINC Code |
|---|---|---|
| 16263 | Specimen | 31208-2 |
| 16347 | Specimen ID | N/A |
| CG389 | Source | N/A |
| 16264 | Order Date | N/A |
| CG392 | Reason For Referral | 42349-1 |
| 16265 | Method | In Process |
| 16267 | Results | 48970-8 |
| 16268 | Interpretation | 69965-2 |
| 16269 | Amendment | In Process |
| 16270 | Consultant | N/A |
| 16271 | Report Date | N/A |
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