Mutation Specific Sequencing (Prenatal)

CPT 81403
  • Sequencing Follow-up
  • Sequencing, Prenatal

Test Details

Special Instructions

Indicate the specific gene and mutation to be analyzed on the test request form. Failure to indicate the gene and mutation will result in testing delays.


This interpretation is based on the clinical information provided and the current understanding of the molecular genetics of the disease(s) tested. This analysis does not rule out the presence of disease-causing mutations in other regions of the gene(s) analyzed or in other genes, and it does not rule out the presence of large deletion or duplication mutations or complex rearrangements. False-positive or negative results may occur for reasons that include genetic variants, technical handling, blood transfusions, bone marrow transplantation, mislabeling of samples, erroneous representation of family relationships, or contamination of a fetal sample with maternal cells.

This test was developed, and its performance characteristics determined, by LabCorp. It has not been cleared or approved by the US Food and Drug Administration (FDA). The FDA has determined that such clearance or approval is not necessary.


DNA is isolated and specific gene regions amplified by the polymerase chain reaction (PCR). Targeted mutations are detected by direct DNA sequencing using capillary gel electrophoresis and fluorescence detection.

Specimen Requirements

Information on collection, storage, and volume


Amniotic fluid, direct and cultured cells, or chorionic villus (CVS) direct and cultured cells


15 mg CVS, one T-25 confluent flask of fetal cells or 10 mL amniotic fluid


Amniotic fluid: Orange-top polypropylene tube CVS: Laboratory-provided screw-top tubes with sterile transport medium

Storage Instructions

Maintain specimen at room temperature or refrigerate.


Prenatal: Call a laboratory genetic coordinator prior to obtaining any specimens. All prenatal specimens (including cord blood) must be accompanied by a maternal blood specimen for analysis of possible maternal cell contamination.

Amniotic fluid: Discard first 2 mL, then collect 10 mL in 15-mL orange-top polypropylene tube. Additional specimen must be obtained for back-up culture at a LabCorp cytogenetics laboratory or another facility.