Home
HelpTest ID D15F 15q11.2 Duplication, FISH
Useful For
Evaluating patients with autistic spectrum disorders for 15q11.1-11.3 region
Confirming the origin of supernumerary marker chromosomes suspected of being derived from chromosome 15
Resolving the origin when duplication of 15q11.1-11.3 is identified via molecular multiplex ligation-dependent probe amplification analysis
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.
Special Instructions
Method Name
Fluorescence In Situ Hybridization (FISH)
Reporting Name
15q11.2 Duplication, FISHSpecimen Type
VariesProvide 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: 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.
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 (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 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 (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 (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 Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Varies | Refrigerated (preferred) | |
| Ambient | ||
Clinical Information
Individuals with autism spectrum disorders, individuals with supernumerary chromosomes suspicious for a chromosome 15 origin, individuals with duplications of 15q11-q13 detected by multiplex ligation-dependent probe amplification (MLPA) or other testing methodologies (to distinguish between interstitial tandem duplication and supernumerary marker).
Cytogenetic abnormalities at the 15q11-q13 locus are reported in up to 4% of patients with autism spectrum disorders. Duplications in this chromosome region can occur as an interstitial tandem repeat or as a supernumerary isodicentric chromosome 15, leading to trisomy or tetrasomy of genes at the 15q11-q13 locus. The majority of interstitial tandem repeats in this region are not detectable by conventional chromosome analysis but can be identified by FISH. Supernumerary chromosomes can often be identified by conventional chromosome analysis but their origin must be confirmed by FISH analysis. Molecular analysis by MLPA can also detect duplications of chromosome 15q, but FISH analysis is necessary to distinguish between interstitial tandem duplication and a supernumerary marker.
The phenotype associated with these abnormalities depends largely on the amount of duplicated material, as well as parent of origin. Small dicentric markers with little 15q material duplicated are often familial and result in a normal phenotype. Larger dicentric 15 markers are usually new mutations and result in mild dysmorphic features, mental retardation, and behavioral abnormalities consistent with autism. Interstitial tandem duplications are associated with autistic spectrum disorders when maternally inherited, but paternally inherited duplications are less likely to cause phenotypic effects.
Cautions
Because this FISH test is not approved by the US Food and Drug Administration, it is important to correlate 15q11.2 duplications by other established methods, such as clinical history or physical evaluation.
This test is not designed to identify 15q deletions or diagnose Prader-Willi/Angelman syndromes
Interfering factors:
-Cell lysis caused by forcing the blood quickly through the needle
-Use of an improper anticoagulant or improperly mixing the blood with the anticoagulant
-Excessive transport time
-Inadequate amount of specimen may not permit adequate analysis
-Improper packaging may result in broken, leaky, and contaminated specimen during transport
-Exposure of the specimen to temperature extremes (freezing or >30° C) may kill cells and interfere with attempts to culture cells
-In prenatal specimens, a bloody specimen may interfere with attempts to culture cells and contamination by maternal cells may cause interpretive problems
Day(s) Performed
Samples processed Monday through Sunday. Results reported Monday through Friday, 8 a.m.-5 p.m.
Report Available
12 daysPerforming Laboratory
Mayo Medical Laboratories in Rochester
Test Classification
This test was developed using an analyte specific reagent. Its performance characteristics were 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
88271x2, 88291 – DNA probe, each (first probe set), Interpretation and report
88271x2 – DNA probe, each; each additional probe set (if appropriate)
88271x1 – DNA probe, each; coverage for sets containing 3 probes (if appropriate)
88271x2 – DNA probe, each; coverage for sets containing 4 probes (if appropriate)
88271x3 – 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)