Cell-Free DNA Prenatal Screen [A Test in Focus]


The new Cell-Free DNA Prenatal Screen is now available to the Mayo Clinic practice and Mayo Medical Laboratories clients located in the North and South American continents. If you reside outside of this authorized region, please contact an alternative provider to perform similar testing.

This test detects common chromosome abnormalities without the risk of pregnancy loss associated with invasive prenatal procedures. Chromosomal aneuploidy is the leading known genetic cause of miscarriage and congenital birth defects, including Down syndrome, trisomy 13, and trisomy 18.

This fetal DNA screening test is not diagnostic. Abnormal results should be confirmed with invasive prenatal diagnostic testing (such as chorionic villi sampling or amniocentesis). Genetic consultation is recommended.

 

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  • This test detects common chromosome abnormalities without the risk of pregnancy loss associated with invasive prenatal procedures.
  • Chromosomal aneuploidy is the leading known genetic cause of miscarriage and congenital birth defects, including Down syndrome, trisomy 13, trisomy 18, and aneuploidies of chromosomes X and Y.
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How to Use This Test

Chromosomal aneuploidy is the leading known genetic cause of miscarriage and congenital birth defects, including Down syndrome, trisomy 13, trisomy 18, and aneuploidies of chromosomes X and Y.

Prenatal screening of fetal DNA is appropriate for pregnant patients with any of the following:

  • An increased risk for aneuploidy, including maternal age 35 or older at the time of delivery
  • Abnormal fetal ultrasound findings indicating an increased risk for aneuploidy
  • A history of prior pregnancy with aneuploidy
  • Positive maternal serum screening result
  • Known parental balanced Robertsonian translocation
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  • A negative result does not ensure an unaffected pregnancy. The false-negative rate for trisomy 21 is less than 1%, for trisomy 18 is approximately 2%, and for trisomy 13 is approximately 20%.
  • This screening test is not currently recommended for pregnancies at low risk for aneuploidy or multiple gestation pregnancies.
  • Results of this screening test are highly accurate, but false-positive or false-negative results may occur due to placental, maternal, or fetal mosaicism, as well as other causes.
  • Cell-free DNA screening does not replace the accuracy and precision of invasive prenatal cytogenetic testing via chorionic villus sampling or amniocentesis.
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  • Circulating cell-free DNA is purified from the plasma component of anticoagulated maternal whole blood and converted into a genomic DNA library for sequencing. Reads are aligned to the human genome, and a Z-score is generated for chromosomes 13, 18, 21, X and Y. Each sample is also evaluated for the presence or absence of Y chromosome material.(Unpublished Mayo method).
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  • Whole blood
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Day(s) and Time(s) Test Performed:

  • Samples processed Monday through Sunday. Results reported Monday through Friday 8 a.m.-5 p.m. CST.

Analytic Time:

  • 7 days
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Mayo Medical Laboratories

This post was authored by the Marketing Team at Mayo Medical Laboratories.