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Turnaround Time
8 - 14 days (If culture is needed, an additional 14 - 21 days may be required. Additional culture fee may be applied.)
Use
This test is for fetal testing only. It is not intended for routine sickle cell screening.
This test uses DNA analysis to detect variants known to cause sickle cell anemia and hemoglobin SC disease.
Special Instructions
This test is for fetal testing only. It is not intended for routine sickle cell screening. 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.
Test Includes
This test includes the following gene: HBB.
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
Sickle cell analysis: HbS (c.20A>T, p.Glu7Val) and HbC (c.19G>A, p.Glu7Lys) pathogenic variants are identified by Sanger sequencing, capillary gel electrophoresis and fluorescence detection.
Maternal cell contamination analysis (MCC): Analysis of short tandem repeat markers by multiplex fluorescent polymerase chain reaction (PCR) and capillary electrophoresis.
References
Bender MA, Carlberg K. Sickle Cell Disease. In: GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993. 2003 Sep 15 [updated 2022 Nov 17].20301551
Nagan, M, Faulkner NE, Curtis C, Schrijver I, MCC Guidelines Working Group of the Association for Molecular Pathology Clininical 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
Specimen Requirements
Information on collection, storage, and volume
Specimen
Amniotic fluid or chorionic villus sample (CVS) or cultured cells or cord blood (Direct amniotic fluid or CVS specimen may be submitted; additional culture fee may be applied.)
Volume
Amniotic fluid: 10 mL; CVS: 10 mg; amniotic fluid and CVS culture: 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
Amniotic fluid: 10 mL; CVS: 10 mg; amniotic fluid and CVS culture: 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
Storage Instructions
Maintain specimen at room temperature. Do not freeze.
Causes for Rejection
Frozen or hemolyzed specimen; quantity not sufficient for analysis; improper container
Collection
Standard sterile techniques; transfer aseptically to sterile tubes. Amniotic fluid: Discard first 2 mL of fluid aspirated to avoid maternal cell contamination.