Biological explanations for discordant noninvasive prenatal test results: Preliminary data and lessons learned. (May 2018)

• Record Type: Journal Article
• Authors: Wilkins‐Haug, Louise; Zhang, Chengsheng; Cerveira, Eliza; Ryan, Mallory; Mil‐homens, Adam; Zhu, Qihui; Reddi, Honey; Lee, Charles; Bianchi, Diana W
• Is Part Of: Prenatal diagnosis. Volume 38:Number 6(2018)
• Page Start: 445
• Page End: 458
• Publication Date: 2018-05
• Subjects: Prenatal diagnosis -- Periodicals; Fetus -- Diseases -- Diagnosis -- Periodicals; Electronic journals; 618.32075
• DOI: 10.1002/pd.5260
• Languages: English
• ISSNs: 0197-3851

Abstract

Abstract: Objective: Maternal plasma cell‐free DNA (cfDNA) analysis is a powerful screening tool for Down syndrome. In a pilot series, we examined biologic causes of discordance between the cfDNA test results and the fetal karyotype. We also explored the feasibility of obtaining trio biospecimens by using parental engagement. Methods: A convenience sample of women with discordant cfDNA results were recruited by their care providers. We provided shipping materials and instructions for biospecimen collection. Maternal, newborn, and placental samples were examined with droplet digital PCR. Results: Thirteen of 15 women successfully had biospecimens obtained remotely. High‐quality DNA was extracted in 12 of 13 women. Presumed biologic etiologies for discordance were identified in 7 of 12 women: 3 cases from additional clinical review (male renal transplant, vanishing twin, and colon cancer) and 4 cases from additional laboratory investigation using droplet digital PCR (3 with confined placental mosaicism and 1 with true fetal mosaicism). Conclusions: Understanding the biology behind cfDNA‐fetal karyotype discordancy is useful for follow‐up clinical care. Our study suggests that most cases could be resolved by using a trio biospecimen protocol and parental involvement. To improve accuracy, additional sequencing of biospecimens will be required. Abstract : What's already known about this topic? Up to 10% of maternal plasma cell‐free (cf) DNA results are discordant with the fetal or neonatal karyotype. Minimal scientific evidence is available to guide follow‐up management. This has led to inconsistent clinical care. What does this study add? Presumed biologic etiologies for discordant cfDNA can be identified in over half of the cases by an in‐depth review of clinical records and/or multispecimen genomic examination. Patients and providers are motivated to participate and will be instrumental in expanding assessments to a larger, more diverse obstetric population.