Test ID: CAT22
22q11.2 Deletion/Duplication, 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
Aids in the diagnosis of 22q deletion/duplication syndromes, in conjunction with CMS/8696 Chromosome Analysis, for Congenital Disorders, Blood
Detecting cryptic translocations involving 22q11.2 that are not demonstrated by conventional chromosome studies
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)
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
22q Deletion Syndrome
22q Duplication Syndrome
DiGeorge Syndrome
Velo-Cardio-Facial Syndrome
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:
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: Autopsy
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. 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.
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 (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: Fixed cell pellet
Container/Tube: Sterile container with a 3:1 fixative (methanol:glacial acetic acid)
Specimen Volume: Entire specimen
Specimen Type: Products of conception or stillbirth
Container/Tube: Sterile container with sterile Hank's balanced salt solution (Supply T132), Ringer's solution, 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.
Forms: Final Disposition of Fetal/Stillborn Remains (if fetal specimen is sent) in Special Instructions
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
The 22q deletion syndrome and 22q duplication syndrome have overlapping phenotypes. Deletions of 22q are associated with DiGeorge and velocardiofacial syndrome. These syndromes are manifested by the presence of growth deficiency, global developmental delay, heart defect, and hearing loss. The major birth defects include palatal clefting or insufficiency and thymus aplasia. Prominent facial features are widely spread eyes, superior placement of eyebrows, downward slanting palpebral fissures with or without ptosis (droopy upper eyelid), mild micrognathia (small jaw), and a long, narrow face.
FISH studies are highly specific and do not exclude other chromosome abnormalities. For this reason, we recommend that patients suspected of having 22q deletion or duplication syndrome also have conventional chromosome studies (CMS/8696 Chromosome Analysis, for Congenital Disorders, Blood) performed to rule out other chromosome abnormalities or translocations.
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
Any individual with a normal signal pattern in each metaphase is considered negative for this probe.
Any patient with a FISH signal pattern indicating loss of the critical region (1 signal) will be reported as having a deletion of the region tested by this probe. This is consistent with a diagnosis of 22q deletion syndrome.
Any patient with a FISH signal pattern indicating duplication of the critical region (3 signals) will be reported as having a duplication of the region tested by this probe. This is consistent with a diagnosis 22q duplication syndrome.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Because FISH is not approved by the FDA, it is important to confirm 22q deletion/duplication syndrome diagnoses by other established methods, such as clinical history or physical evaluation.
Supportive Data
FISH analysis was performed on a series of patients and results were compared to cytogenetic analyses and the patient's phenotype. Using a probe for the critical region locus (HIRA), FISH analysis of metaphase cells or interphase nuclei identified HIRA deletions or duplications in all patients with a phenotype consistent with 22q deletion or duplication syndromes. In a series of patient samples with normal karyotypes, no deletions or duplications of the HIRA region were identified.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Ensenauer RE, Adeyinka A, Flynn HC, et al: Microduplication 22q11.2 an emerging syndrome: clinical, cytogenetic and molecular analysis of thirteen patients. Am J Hum Genet 2003;73:1027-1040
2. Yobb TM, Sommerville MJ, Willatt L, et al: Microduplication and triplication of 22q11.2: a highly variable syndrome. Am J Hum Genet 2005;76:865-876
3. Bassett AS, Chow EWC, Husted J, et al: Clinical features of 78 adults with 22q11 deletion syndrome. Am J Med Genet 2005;138A:307-313
4. Manji A, Roberson JR, Wiktor A, et al: Prenatal diagnosis of 22q11.2 deletion when ultrasound examination reveals a heart defect. Genet Med 2001;3:65-66
Method Description Describes how the test is performed and provides a method-specific reference
Identification of 22q deletions and duplications is based on FISH analysis of the critical region locus (HIRA) on the long arm of chromosome 22 (22q11.2). Metaphase cells are examined for the presence of HIRA at 22q11.2 (orange signal) and the control probe arylsulfatase-A (ARSA) at 22q13.3 (green signal). In metaphase cells with a deletion, the abnormal (deleted) chromosome 22 will exhibit only a control probe signal, while signals for both the critical region and control probes will be present on the normal chromosome 22 homolog. Since direct 22q duplications of HIRA may be difficult to detect on metaphase cells, interphase nuclei are scored to identify duplications that would be represented by the observation of 3 orange signals. (Crifasi PA, Michels VV, Discoll DJ, et al: DNA fluorescent probes for diagnosis of velocardiofacial and related syndromes. Mayo Clin Proc 1995;195[70]:1148-1153)
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 |
|---|---|---|
| 16254 | Specimen | 31208-2 |
| 16346 | Specimen ID | N/A |
| G_757 | Source | N/A |
| 16255 | Order Date | N/A |
| G_760 | Reason For Referral | 42349-1 |
| 16256 | Method | In Process |
| 16258 | Results | In Process |
| 16259 | Interpretation | 69965-2 |
| 16260 | Amendment | In Process |
| 16261 | Consultant | N/A |
| 16262 | Report Date | N/A |
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