X chromosome loss turner syndrome© 2016
By Keith S. Wexler, MBA,
Facilitator of Information, Maternal Fetal Medicine, Prenatal Diagnosis and Biotech Consultant, GENASSIST™, Inc.

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.

Turner Syndrome is characterized by a missing X chromosome in females instead of the expected two X chromosomes.


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 Turner Syndrome.



Turner Syndrome Ultrasound “Markers”:

  • Increased Nuchal Translucency – NT
  • Cystic Hygroma
  • Micrognathia (small jaw)
  • Short 4th metacarpal
  • Differential diagnosis: Noonan Syndrome
  • Differential diagnosis: 4p+ Syndrome

(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”.