Advances in Noninvasive Prenatal Testing For Down Syndrome and Other Trisomies

Author: David J. Moffa, PhD, BCLD
Reviewer: Laurie Bjerklie, MA, MLS(ASCP)CM
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Continuing Education Credits

P.A.C.E.® Contact Hours: 1.5 hour(s)

Florida Board of Clinical Laboratory Science CE Credit Hours

Florida Board of Clinical Laboratory Science CE - General (Molecular Pathology): 1.5 hour(s)

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The development of more sensitive and specific molecular test methods has moved us closer to replacing invasive prenatal procedures that are currently needed to confirm certain chromosomal abnormalities. This course discusses both the prenatal screening tests that are routinely used today and molecular methods that offer hope for noninvasive prenatal testing to diagnose the presence of Down syndrome or other trisomies.

Objectives

  • Define aneuploidy and trisomy and describe the three most common fetal trisomies.
  • Compare prenatal screening tests and diagnostic tests routinely used to detect Down syndrome and other trisomies.
  • Describe the cell-free fetal DNA test (cffDNA) and its application as a noninvasive prenatal testing (NIPT) method for trisomy risk assessment.
  • List various cell-free DNA (cfDNA) tests commercially available for the prenatal assessment of aneuploidy.
  • Discuss recommendations and guidelines for the use of NIPT as a screening tool for fetal aneuploidy.

Course Outline

  • Aneuploidy and Trisomy
    • Aneuploidy and Trisomies
    • Down Syndrome
    • Edwards Syndrome
    • Patau Syndrome
    • Sex Chromosome Aneuploidy
    • Which of the following are true statements?
    • True or False: Turner syndrome is a sex chromosomal condition that affects development in males and is the result of the presence of an extra X chromosome.
  • Down Syndrome (Trisomy 21)
    • Down Syndrome (Trisomy 21)
    • Down Syndrome, continued
    • Which statement best describes the most common cause of Down syndrome?
  • Screening and Diagnostic Tests for Down Syndrome and Other Trisomies
    • Screening Tests: Ultrasound
    • Screening Tests: Maternal Serum Screening
    • Summary of Maternal Serum Screening
    • Patient Information for Prenatal Maternal Serum Screening
    • Laboratory Test Report for Prenatal Screening Panels
    • Prenatal Screening Test Panel Interpretation
    • A maternal serum quadruple screening (quad screen) performed between 16 and 18 weeks of gestation may indicate an increased risk for Down syndrome based on characteristic patterns in the test results. For each marker listed below, select whether the level is expected to be increased or decreased.
    • Diagnostic Tests Overview
    • Diagnostic Tests: Chorionic Villus Sampling
    • Diagnostic Tests: Chorionic Villus Sampling to Diagnose Confined Placental Mosaicism
    • Diagnostic Tests: Amniocentesis
    • Diagnostic Testing Methods Used
    • True or False: A definitive diagnosis of Down syndrome involves the identification of the presence of an extra number 21 chromosome.
  • Noninvasive Prenatal Testing: Cell-Free DNA
    • Noninvasive Prenatal Testing: Cell-Free Fetal DNA
    • Noninvasive Prenatal Testing: Cell-Free Fetal DNA, continued
    • Massively Parallel Sequencing
    • Massively Parallel Signature Sequencing
    • Massively Parallel Signature Sequencing: Cloning of cDNA Fragments on Microbeads
    • Massively Parallel Signature Sequencing: Sequencing Process and Analysis of Sequence Patterns
    • Summary of the MPS and MPSS Procedures
    • Targeted DNA Analysis
    • Commercially Available cfDNA Prenatal Tests for Aneuploidy
    • Commercially Available cfDNA Prenatal Tests for Aneuploidy, continued
    • Commercially Available cfDNA Prenatal Tests for Aneuploidy, continued
    • NIPT Testing Summary
    • Which statement best describes cell-free fetal DNA (cffDNA) testing?
    • Which of the following statements does not describe the currently available commercial cfDNA prenatal tests (NIPT) for fetal aneuploidy?
    • The first step in massively parallel sequencing (MPS) involves preparing DNA or RNA for sequencing and yields DNA fragments that can be amplified and purified. What is this step called?
  • Updated Recommendations on NIPT For Fetal Aneuploidy
    • American College of Obstetricians and Gynecologists Recommendations
    • National Society of Genetic Counselors Recommendations
    • Conclusions
    • According to ACOG recommendations, which statement about noninvasive prenatal testing (NIPT) is correct?
  • References
    • References

Additional Information

Level of Instruction: Intermediate
Intended Audience: Medical laboratory scientists, medical laboratory technicians, laboratory supervisors, and laboratory managers. This course is also appropriate for MLS and MLT students and pathology residents.
Author Information: David Moffa, PhD, has over 30 years of experience in the health care industry as an executive manager, clinical laboratory director, and medical laboratory scientist. He is currently a technical consultant for Kentmere Healthcare in Wilmington, DE, and, until his retirement, was the Regional Director for LabCorp, Inc. He holds a PhD in medical biochemistry from the School of Medicine at West Virginia University.
The author has no conflict of interest to disclose.
Reviewer Information: Laurie Bjerklie, MA, MLS(ASCP)CM, is a Lead Education Developer. She earned a B.S. in Medical Laboratory Science from the University of North Dakota and an M.A. in Curriculum and Instruction from Saint Xavier University. She has over 15 years of experience in higher education and has held program director and faculty positions in both MLT and MLS programs.