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Print CPT 81229; 88235; 88261; 88280
Synonyms
- Amniotic Fluid Chromosome Five-cell Count Plus Microarray
Test Details
Turnaround Time
10 - 21 days
Use
The test allows prenatal detection of chromosomal aneuploidy, and is used to rule out tetraploidy and rearrangements not detected by array, such as balanced translocations and inversions. It also helps to clarify array abnormalities to determine if a structural rearrangement, marker, or isochromosome is present. Array can only provide copy number imbalances and cannot determine structure of an abnormality. The SNP assay will detect chromosomal imbalances that could be associated with developmental delay/congenital anomalies. It provides detection of possible uniparental disomy of any chromosome, the percent and location of homozygosity, including the degree of identity by descent.
Special Instructions
A completed Clinical Questionnaire for SNP Microarray should accompany specimens. Call 800-345-4363 to request the appropriate form, or photocopy the form from the Genetics Appendix online.
Concurrent maternal contamination (MCC) studies are required.
If prior NIPT studies have been performed, include copy of the report.
If specimens from a twin pregnancy are submitted by request it can be reported if these are DZ or MZ twins.
Test Includes
DNA extraction; interpretation; limited five-cell amniotic sample chromosome analysis (two analyses, one karyotype)
Limitations
This SNP assay does not detect balanced rearrangements, low-level mosaicism (<10%), marker chromosomes that only contain heterochromatin or tetraploidy.
This test was developed and its performance characteristics determined by LabCorp. It has not been cleared or approved by the Food and Drug Administration.
Methodology
Five-cell G-Band Chromosome analysis. SNP microarray analysis is performed using the Cytoscan® HD platform, which uses more than 743,000 SNP probes and 1,953,000 NPCN probes with a median spacing of 0.88 kb.
Related Documents
Specimen Requirements
Information on collection, storage, and volume
Specimen
Amniotic fluid (for direct array and abbreviated amnio chromosome analysis)
Gender by ultrasound is required. Please submit maternal blood (sodium heparin or EDTA) for maternal cell contamination (MCC) studies.
If the specimen does not meet minimum DNA quality and quantity requirements, array testing will be performed on cultured material. If cultures are needed, additional days will be required to complete testing. A notification will be sent to the client if cultures are necessary.
Volume
25 mL amniotic fluid for concurrent array and chromosome analysis
Minimum Volume
12 mL amniotic fluid (minimum volume may delay results; cells would need to be cultured for microarray analysis)
Container
Sterile plastic conical tube
Storage Instructions
Maintain specimen at room temperature.
Causes for Rejection
Quantity not sufficient for analysis (<12 mL of amniotic fluid or DNA quantity <20 ng/μL); bloody sample; gestational age <17 weeks
Collection
Discard first 2 mL of fluid aspirated to avoid maternal cell contamination. Specimen is collected in a 20-mL sterile syringe and transferred aseptically to sterile tubes to be transported to LabCorp.