Find Locations
For hours, walk-ins and appointments.Synonyms
- Arthrogryposis multiplex congenita
- SMA testing
- SMN1 copy number analysis
Test Includes
This test includes the following gene: SMN1.
Special Instructions
Labcorp clients with 8-digit client account numbers should call 800-345-4363 and Labcorp Genetics & Women's Health clients with 6-digit client/subclient account numbers should call 800-255-7357 to speak with a laboratory genetic coordinator before collecting specimens. In some circumstances, specimens from both parents and other family members may be required. All fetal specimens, including cord blood, must be accompanied by a maternal blood, PurFlock buccal swab kit or Oragene Dx 500 saliva kit for maternal cell contamination (MCC). A separate requisition should be submitted with the maternal specimen.
Expected Turnaround Time
8 - 14 days (If culture is needed, an additional 14 - 21 days may be required. Additional culture fee may be applied.)
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Specimen Requirements
Specimen
Cultured amniotic fluid or cultured chorionic (CVS) cells or cord blood is required for testing. (Direct amniotic fluid or CVS specimen may be submitted; additional culture fee may be applied.)
Volume
One confluent T-25 flask or 4 mL cord blood (If amniotic fluid or CVS are cultured at another facility, please maintain back-up cultures.)
Minimum Volume
One confluent T-25 flask or 3 mL cord blood
Container
Amniotic fluid or CVS: sterile plastic conical tube or T-25 flask; cord blood: yellow-top (ACD-A) or lavender-top (EDTA) tubes
Collection
Standard sterile techniques; transfer aseptically to sterile tubes. Amniotic fluid: Discard first 2 mL of fluid aspirated to avoid maternal cell contamination.
Storage Instructions
Maintain specimen at room temperature. Do not freeze.
Stability Requirements
Please ship expedited at room temperature.
Causes for Rejection
Frozen or hemolyzed specimen; quantity not sufficient for analysis; improper container
Test Details
Use
This test is used for prenatal diagnosis for pregnancies at risk for spinal muscular atrophy.
Limitations
Technologies used do not detect germline mosaicism and do not rule out the presence of large chromosomal aberrations including rearrangements and gene fusions, or variants in regions or genes not included in this test, or possible inter/intragenic interactions between variants or repeat expansions.
Variant classification and/or interpretation may change over time if more information becomes available. False positive or false negative results may occur for reasons that include: rare genetic variants, sex chromosome abnormalities, pseudogene interference, blood transfusions, bone marrow transplantation, somatic or tissue-specific mosaicism, mislabeled samples or erroneous representation of family relationships.
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
Spinal muscular atrophy (SMA): Copy number assessment of SMN1 exon 7 by quantitative polymerase chain reaction (qPCR). Reflex testing to SMN2 copy number analysis is performed for affected fetus with 0 copies of SMN1.
Maternal cell contamination analysis (MCC): Analysis of short tandem repeat markers by multiplex fluorescent polymerase chain reaction (PCR) and capillary electrophoresis.
References
Deignan JL, Astbury C, Behlmann A, et al. Addendum: Technical standards and guidelines for spinal muscular atrophy testing. Genet Med. 2021 Dec;23(12):2462.33046848
Nagan, M, Faulkner NE, Curtis C, Schrijver I, MCC Guidelines Working Group of the Association for Molecular Pathology Clinical Practice Committee. Laboratory guidelines for detection, interpretation, and reporting of maternal cell contamination in prenatal analyses: a report of the association for molecular pathology. J Mol Diagn. 2011 Jan;13(1):7-11.21227389
Prior TW, Leach ME, Finanger E. Spinal Muscular Atrophy. In: GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993.2000 Feb 24 [updated 2020 Dec 3].20301526
LOINC® Map
| Order Code | Order Code Name | Order Loinc | Result Code | Result Code Name | UofM | Result LOINC |
|---|---|---|---|---|---|---|
| 481651 | Spinal Muscular Atrophy, Fetal | 481631 | Ethnicity | 42784-9 | ||
| 481651 | Spinal Muscular Atrophy, Fetal | 481632 | Specimen Type | 31208-2 | ||
| 481651 | Spinal Muscular Atrophy, Fetal | 481633 | Genetic Counselor | 89993-0 | ||
| 481651 | Spinal Muscular Atrophy, Fetal | 481634 | Indication | 42349-1 | ||
| 481651 | Spinal Muscular Atrophy, Fetal | 481635 | Fetal ID | 11951-1 | ||
| 481651 | Spinal Muscular Atrophy, Fetal | 481636 | Result: | 41053-0 | ||
| 481651 | Spinal Muscular Atrophy, Fetal | 482026 | SMN2 Copy Number Reflex | 54449-4 | ||
| 481651 | Spinal Muscular Atrophy, Fetal | 481637 | Interpretation | 53039-4 | ||
| 481651 | Spinal Muscular Atrophy, Fetal | 481638 | General Comments | 8262-8 | ||
| 481651 | Spinal Muscular Atrophy, Fetal | 482029 | MCC, Maternal Control | 59266-7 | ||
| 481651 | Spinal Muscular Atrophy, Fetal | 481639 | Recommendations | 62385-0 | ||
| 481651 | Spinal Muscular Atrophy, Fetal | 481640 | Additional ClinicalInformation | 55752-0 | ||
| 481651 | Spinal Muscular Atrophy, Fetal | 481642 | Comments | 8251-1 | ||
| 481651 | Spinal Muscular Atrophy, Fetal | 481643 | Methods/Limitations | 49549-9 | ||
| 481651 | Spinal Muscular Atrophy, Fetal | 481644 | Information Table | 36908-2 | ||
| 481651 | Spinal Muscular Atrophy, Fetal | 481645 | References | 75608-0 | ||
| 481651 | Spinal Muscular Atrophy, Fetal | 481648 | Director Review/Release | 72486-4 | ||
| 481651 | Spinal Muscular Atrophy, Fetal | 481649 | 51969-4 |
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The LOINC® codes are copyright © 1994-2021, Regenstrief Institute, Inc. and the Logical Observation Identifiers Names and Codes (LOINC) Committee. Permission is granted in perpetuity, without payment of license fees or royalties, to use, copy, or distribute the LOINC® codes for any commercial or non-commercial purpose, subject to the terms under the license agreement found at https://loinc.org/license/. Additional information regarding LOINC® codes can be found at LOINC.org, including the LOINC Manual, which can be downloaded at LOINC.org/downloads/files/LOINCManual.pdf