Received on ,
Accepted on ,

Brief Communications

Detection of Increased Amounts of Cell-Free Fetal DNA with Short PCR Amplicons

¹ University Women's Hospital, Department of Biomedicine, Basel, Switzerland
² Fluidigm Corporation, South San Francisco, CA
³ Division of Obstetrics and Gynecology, Drexel University School of Medicine, Philadelphia, PA

^* To whom correspondence should be addressed. E-mail: shahn{at}uhbs.ch; Sinuhe.Hahn.01@gmail.com.

AIM: A digital PCR approach has recently been suggested to detect greater amounts of cell-free fetal DNA in maternal plasma than conventional real-time quantitative PCR (qPCR). Because the digital qPCR approach uses shorter PCR amplicons than the real-time qPCR assay, we investigated whether a real-time qPCR assay appropriately modified for such short amplicons would improve the detection of cell-free fetal DNA.

METHODS: We developed a novel universal-template (UT) real-time qPCR assay that was specific for the DYS14 sequence on Y chromosome and had a short amplicon size of 50 bp. We examined this "short" assay with 50 maternal plasma samples and compared the results with those for a conventional real-time qPCR assay of the same locus but with a longer amplicon (84 bp).

RESULTS: Qualitatively, both assays detected male cell-free fetal DNA with the same specificity and detection capability. Quantitatively, however, the new UT real-time qPCR assay for shorter amplicons detected, on average, almost 1.6-fold more cell-free fetal DNA than the conventional real-time qPCR assay with longer amplicons.

CONCLUSIONS: The use of short PCR amplicons improves the detection of cell-free fetal DNA. This feature may prove useful in attempts to detect cell-free fetal DNA under conditions in which the amount of template is low, such as in samples obtained early in pregnancy.