© 2017, GENASSIST, Inc.     

By Keith S. Wexler, MBA, Maternal Fetal Medicine, Prenatal Diagnosis and Biotech Consultant/Life Sciences, GENASSIST, Inc.

Paul Wexler, M.D., F.A.C.O.G., Medical Director, GENASSIST, Inc.

Clinical Professor, Department of OB/GYN, University of Colorado Health Sciences Center

Clinical Professor, Division of Genetics/Dept. of Pediatrics, Univ. of Colorado/The Children’s Hospital

Background: The breakdown of fetal cells in the maternal circulation make it possible for laboratories to screen for Fetal DNA during pregnancy.

When fetal cells break down Cell Free DNA (cf DNA) is released. It is possible to duplicate many copies of this DNA so that testing is possible.

This prenatal non-invasive testing can be performed as early as the 10th week of pregnancy.

Maternal Fetal DNA testing of chromosomes has helped uncover some chromosomal abnormalities in pregnancy.

Edward Syndrome (Trisomy 18) is characterized by three copies of chromosome 18 instead of the expected

two copies.

The incidence of Trisomy 18 (Edward Syndrome) is approximately 1 in 2500 pregnancies.

If a Maternal Fetal DNA test result comes back as “High Risk” for a chromosomal abnormality, the recommendation (1) is to confirm the diagnosis by amniocentesis.

Ultrasound performed in pregnancy after 15 weeks gestation can help identify some babies with Trisomy 18.Edward Syndrome(Trisomy 18) Ultrasound “Markers”:

  • Small Jaw
  • Clenched Fists/Overlapping Fingers
  • Rocker Bottom Feet
  • Low Set Ears
  • Choroid Plexus Cysts – Fluid Cysts in the Fetal Brain
  • Hydronephrosis – Fluid in the Fetal Kidneys
  • Heart Defect(s)

(1)The American College of Obstetricians & Gynecologists, Committee Opinion Number 545 December 2012, The American College of Obstetricians and Gynecologists Committee on Genetics The Society For Maternal-Fetal Medicine Publications Committee, “NonInvasive Prenatal Testing for Fetal Aneuploidy”.