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Test ID CMAP Chromosomal Microarray, Prenatal, Amniotic Fluid/Chorionic Villus Sampling

Useful For

Prenatal diagnosis of copy number changes (gains or losses) across the entire genome

 

Determining the size, precise breakpoints, gene content, and any unappreciated complexity of abnormalities detected by other methods such as conventional chromosome and fluorescence in situ hybridization (FISH) studies

 

Determining if apparently balanced abnormalities identified by previous conventional chromosome studies have cryptic imbalances, since a proportion of such rearrangements that appear balanced at the resolution of a chromosome study are actually unbalanced when analyzed by higher-resolution chromosomal microarray

 

Assessing regions of homozygosity related to uniparental disomy or identity by descent

Testing Algorithm

Maternal cell contamination (MCC) testing will be performed at no additional charge if a maternal blood sample is received to rule out the presence of maternal cells in the prenatal sample, see Additional Testing Requirements.

 

If an insufficient sample is received or MCC is identified in the prenatal sample, microarray testing will be performed on cultured material.

 

The following algorithms are available in Special Instructions:

-Prenatal Aneuploidy Screening and Diagnostic Testing Options

-High-Risk Pregnancy Based on Fetal Malformations or Positive Serum Screen: Laboratory Testing Algorithm

Method Name

Chromosomal Microarray

Reporting Name

Chromosomal Microarray, Prenatal

Specimen Type

Varies


Advisory Information


This test does not detect balanced chromosome rearrangements such as Robertsonian or other reciprocal translocations, inversions, or balanced insertions. These abnormalities may be identified by chromosome analysis (see CHRAF / Chromosome Analysis, Amniotic Fluid or CHRCV / Chromosome Analysis, Chorionic Villus Sampling).

 

If the reason for testing or specimen type received indicates a fetal demise, the test will be cancelled and CMAPC / Chromosomal Microarray, Autopsy, Products of Conception, or Stillbirth will be added and performed as the appropriate test.



Additional Testing Requirements


A maternal blood sample is requested when ordering this test (see PPAP / Parental Sample Prep for Prenatal Microarray Testing); the PPAP test must be ordered under a different order number than the prenatal specimen.

 

A paternal blood sample is desired but not required (see PPAP / Parental Sample Prep for Prenatal Microarray Testing).

 

Portions of the specimen may be used for other tests such as measuring markers for neural tube defects (eg, AFPA / Alpha-Fetoprotein, Amniotic Fluid), molecular genetic testing, biochemical testing, and chromosome and FISH testing (including CHRAF / Chromosome Analysis, Amniotic Fluid; CHRCV / Chromosome Analysis, Chorionic Villus Sampling; and PADF / Prenatal Aneuploidy Detection, FISH).

 

If additional molecular genetic or biochemical genetic testing is needed, order CULAF / Culture for Genetic Testing, Amniotic Fluid or CULFB / Fibroblast Culture for Genetic Testing so that cultures may be set up specifically for use in these tests.



Shipping Instructions


Advise Express Mail or equivalent if not on courier service.



Necessary Information


1. 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.

2. Notify the laboratory if the pregnancy involves an egg donor or gestational carrier.



Specimen Required


Submit only 1 of the following specimens:

 

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: 20-30 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).

3. Using a stereomicroscope and sterile forceps, assess the quality and quantity of the villi and remove any blood clots and maternal decidua.

 

Supplies: Refrigerate/Ambient Shipping Box, 5 lb (T329)

Specimen Type: Amniotic fluid

Container/Tube: Amniotic fluid container

Specimen Volume: 20-30 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 Shipping Box, 5 lb.

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


Specimen Minimum Volume

Amniotic Fluid: 12 mL
Chorionic Villi: 12 mg; If ordering in conjunction with other testing: If ordered with PADF: 14 mL or 14 mg; with CHRAF: 24 mL; with CHRCV: 24 mg; with PADF and CHRAF/CHRCV: 26 mL or 26 mg

Specimen Stability Information

Specimen Type Temperature Time Special Container
Varies Refrigerated (preferred)
  Ambient 

Reference Values

An interpretive report will be provided.

Day(s) and Time(s) Performed

Specimens are processed Monday through Sunday.

Results reported Monday through Friday, 8 a.m.-5 p.m.

Performing Laboratory

Mayo Clinic Laboratories in Rochester

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

81229

LOINC Code Information

Test ID Test Order Name Order LOINC Value
CMAP Chromosomal Microarray, Prenatal 86611-1

 

Result ID Test Result Name Result LOINC Value
54714 Result Summary 50397-9
54715 Result 62356-1
54716 Nomenclature 62356-1
54717 Interpretation 69965-2
CG900 Reason For Referral 42349-1
CG780 Specimen 31208-2
54718 Source 31208-2
54719 Method 49549-9
53422 Additional Information 48767-8
54720 Released By 18771-6

NY State Approved

Yes

Forms

1. New York Clients-Informed consent is required. Document on the request form or electronic order that a copy is on file. The following documents are available in Special Instructions:

-Informed Consent for Genetic Testing (T576)

-Informed Consent for Genetic Testing-Spanish (T826)

2. Chromosomal Microarray Prenatal Patient Information (T716) in Special Instructions.

Genetics Test Information

Cultures from this specimen will be discarded 10 days after all cytogenetic test results have been reported. If further testing is desired, call the laboratory at 507-284-1668.