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Test ID: DD17F Smith-Magenis/Potocki-Lupski Syndromes, 17p11.2 Deletion/Duplication, FISH

Useful For

Establishing a diagnosis of Smith-Magenis syndrome

 

Establishing a diagnosis of Potocki-Lupski syndrome

 

Detecting cryptic rearrangements involving 17p11.2, that are not demonstrated by conventional chromosome studies

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
_PBCT Probe, +2 No, (Bill Only) No
_PADD Probe, +1 No, (Bill Only) No
_PB02 Probe, +2 No, (Bill Only) No
_PB03 Probe, +3 No, (Bill Only) No
_ML10 Metaphases, 1-9 No, (Bill Only) No
_M30 Metaphases, ≥10 No, (Bill Only) No
_IL25 Interphases, <25 No, (Bill Only) No
_I099 Interphases, 25-99 No, (Bill Only) No
_I300 Interphases, ≥100 No, (Bill Only) No

Testing Algorithm

This test includes a charge for application of the first probe set (2 FISH probes) and professional interpretation of results. Additional charges will be incurred for application of all reflex probes performed. Analysis charges will be incurred based on the number of cells analyzed per probe set. If no cells are available for analysis, no analysis charges will be incurred.

Method Name

Fluorescence In Situ Hybridization (FISH)

Reporting Name

17p11.2 Deletion/Duplication, FISH

Specimen Type

Varies


Shipping Instructions


Advise Express Mail or equivalent if not on courier service.



Necessary Information


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.



Specimen Required


Submit only 1 of the following specimens:

 

Supplies: Refrigerate/Ambient Mailer, 5 lb (T329)

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.

3. Place the tubes in a Refrigerate/Ambient Mailer, 5 lb (T329).

4. Fill remaining space with packing material.

Additional Information:

1. Unavoidably, about 1% to 2% of mailed-in specimens are not viable.

2. Bloody specimens are undesirable.

3. If the specimen does not grow in culture, you will be notified within 7 days of receipt.

4. Results will be reported and also telephoned or faxed, if requested.

 

Supplies: Hank's Solution (T132)

Specimen Type: Autopsy

Container/Tube: Sterile container with sterile Hank's solution (T132), Ringer's solution, or normal saline

Specimen Volume: 1 cm(3) biopsy specimen of muscle/fascia from the thigh

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. Biopsy specimens are best taken by punch biopsy to include full thickness of dermis.

 

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.

 

Supplies: CVS Media (RPMI) and Small Dish (T095)

Specimen Type: Chorionic villi

Container/Tube: 15-mL tube containing 15 mL of transport media

Specimen Volume: 20-25 mg

Collection Instructions:

1. Collect specimen by the transabdominal or transcervical method.

2. Transfer chorionic villi to a Petri dish containing transport medium (Such as CVS Media (RPMI) and Small Dish [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: Fixed cell pellet

Container/Tube: Sterile container with a 3:1 fixative (methanol:glacial acetic acid)

Specimen Volume: Entire specimen

 

Supplies: Hank's Solution (T132)

Specimen Type: Products of conception or stillbirth

Container/Tube: Sterile container with sterile Hank's solution (T132), Ringer's solution, sterile RPMI transport media, or normal saline

Specimen Volume: 1 cm(3) of placenta (including 20 mg of chorionic villi) and a 1-cm(3) biopsy specimen of muscle/fascia from the thigh

Collection Instructions: If a fetus cannot be specifically identified, collect villus material or tissue that appears to be of fetal origin.

Additional Information: Do not send entire fetus.

 

Supplies: Hank's Solution (T132)

Specimen Type: Skin biopsy

Container/Tube: Sterile container with sterile Hank's solution (T132), Ringer's solution, or normal saline

Specimen Volume: 1-cm(3) biopsy specimen of muscle/fascia from the thigh

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

Amniotic Fluid: 5 mL; Autopsy, Skin Biopsy: 4 mm; Blood: 2 mL; Chorionic Villi: 5 mg; Fixed Cell Pellet: 1 pellet; Products of Conception: 1 cm(3)

Specimen Stability Information

Specimen Type Temperature Time
Varies Refrigerated (preferred)
  Ambient 

Clinical Information

This test is appropriate for individuals with clinical features suggestive of Smith-Magenis syndrome and Potocki-Lupski syndrome.

 

Smith-Magenis syndrome is associated with a deletion of the proximal short arm of chromosome 17, including the critical RAI1 gene region. Although the phenotype is variable, the syndrome can be suspected in patients with failure to thrive, brachycephaly (short head), prominent forehead, microcephaly (small head), flat and broad midface, broad nasal bridge, strabismus, myopia, malformed ears, high and cleft palate, prognathism (protruding mandible), short and broad hands and feet, scoliosis (laterally curved spine), and cryptorchidism (undescended testes). Unusual features of the syndrome include specific self-destructive behavior, including insertion of foreign objects into bodily orifices, pulling out fingernails and toenails, and sleep abnormalities (especially disturbed rapid eye movement sleep). Mental retardation is variable but usually severe with seizures and hyperactivity.

 

Patients with duplications of this region (Potocki-Lupski syndrome) tend to have a milder but overlapping phenotype.

 

FISH studies are highly specific and do not exclude other chromosome abnormalities.

Reference Values

An interpretive report will be provided.

Interpretation

Any individual with a normal signal pattern (2 signals for RAI1) in each metaphase is considered negative for a deletion or duplication in the region tested by this probe.

 

Any patient with a FISH signal pattern indicating loss of the RAI1 critical region will be reported as having a deletion of the regions tested by this probe. This is consistent with a diagnosis of 17p11.2 deletion (Smith-Magenis) syndrome.

 

Any patient with a FISH signal pattern indicating additional critical region signals will be reported as having a duplication of the regions tested by this probe. This is consistent with a diagnosis of 17p11.2 duplication (Potocki-Lupski) syndrome.

Clinical Reference

1. Potocki L, Chen KS, Park SS, et al: Molecular mechanism for duplication 17p11.2-the homologous recombination reciprocal of the Smith-Magenis microdeletion. Nat Genet 2000;24:84-87

2. Elsea SH, Girirajan S: Smith-Magenis Syndrome. Eur J Hum Genet 2008;16:412-421

3. Smith ACM, Boyd KE, Elsea SH, et al. Smith-Magenis Syndrome. 2001 Oct 22 [Updated 2012 Jun 28]. In: Pagon RA, Adam MP, Ardinger HH, et al, editors. GeneReviews (Internet). Seattle (WA): University of Washington, Seattle; 1993-2014. Available at http://www.ncbi.nlm.nih.gov/books/NBK1310/Accessed 05/27/2013

Day(s) and Time(s) Performed

Samples processed Monday through Sunday. Results reported Monday through Friday, 8 a.m.-5 p.m. CST.

Analytic Time

7 days

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

88271 x 2, 88291-DNA probe, each (first probe set), Interpretation and report

88271 x 2-DNA probe, each; each additional probe set (if appropriate)

88271 x 1-DNA probe, each; coverage for sets containing 3 probes (if appropriate)

88271 x 2-DNA probe, each; coverage for sets containing 4 probes (if appropriate)

88271 x 3-DNA probe, each; coverage for sets containing 5 probes (if appropriate)

88273 w/modifier 52-Chromosomal in situ hybridization, less than 10 cells (if appropriate)

88273-Chromosomal in situ hybridization, 10-30 cells (if appropriate)

88274 w/modifier 52-Interphase in situ hybridization, <25 cells, each probe set (if appropriate)

88274-Interphase in situ hybridization, 25 to 99 cells, each probe set (if appropriate)

88275-Interphase in situ hybridization, 100 to 300 cells, each probe set (if appropriate)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
DD17F 17p11.2 Deletion/Duplication, FISH In Process

 

Result ID Test Result Name Result LOINC Value
51991 Result Summary 50397-9
51993 Interpretation In Process
54563 Result In Process
CG713 Reason for Referral 42349-1
CG714 Specimen 31208-2
51994 Source 31208-2
51995 Method 49549-9
51992 Additional Information 48767-8
53852 Disclaimer 62364-5
51996 Released By No LOINC Needed

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 (T576) is available in Special Instructions.

2. Final Disposition of Fetal/Stillborn Remains form (if fetal specimen is sent) in Special Instructions (Only for products of conception or stillbirth specimen).

Mayo Medical Laboratories | Genetics and Pharmacogenomics Catalog Additional Information:

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