title: Understanding the Limitations of Circulating Cell Free Fetal DNA: An Example of Two Unique Cases.
abstract: Circulating cell free fetal DNA (cffDNA) is an effective screening modality for fetal aneuploidy. We report two cases of false positive results. The first case involves a female, with self-reported Down syndrome. CffDNA returned positive for trisomy 18 leading to a maternal diagnosis of mosaicism chromosome 18 with normal fetal karyotype. The second case involves a patient with an anomalous fetal ultrasound and cffDNA positive for trisomy 13. Amniocentesis demonstrated a chromosome 8p duplication/deletion. False positive cffDNA may arise in clinical scenarios where diagnostic testing is clearly indicated. Practitioners should recognize the limitations of cffDNA.
authors.affiliation: Obstetrics and Gynecology, MedStar Washington Hospital Center, Washington, DC, USA.
authors.forename: Cecily A
authors.initials: CA
authors.lastname: Clark-Ganheart
authors.affiliation: Obstetrics and Gynecology, MedStar Washington Hospital Center, Washington, DC, USA.
authors.forename: Sara N
authors.initials: SN
authors.lastname: Iqbal
authors.affiliation: Obstetrics and Gynecology, MedStar Washington Hospital Center, Washington, DC, USA.
authors.forename: Donna L
authors.initials: DL
authors.lastname: Brown
authors.affiliation: Obstetrics and Gynecology, MedStar Washington Hospital Center, Washington, DC, USA.
authors.forename: Susan
authors.initials: S
authors.lastname: Black
authors.affiliation: Obstetrics and Gynecology, MedStar Washington Hospital Center, Washington, DC, USA.
authors.forename: Melissa H
authors.initials: MH
authors.lastname: Fries
keywords: Cell free fetal DNA; Fetal anomalies; Prenatal diagnosis