The use of cffDNA in fetal sex determination during the first trimester of pregnancy of female DMD carriers

Abstract

Chorionic villus sampling (CVS) or amniocentesis for fetal sex determination is generally the first step in the prenatal diagnosis of X-linked genetic disorders such as Duchenne muscular dystrophy (DMD). However, non-invasive prenatal diagnostic (NIPD) techniques such as measurement of cell-free fetal DNA (cffDNA) in maternal plasma are preferable given the procedure-related miscarriage rate of CVS. We determined fetal sex during the first trimester using a quantitative real-time polymerase chain reaction (PCR) assay of cffDNA in pregnant carriers of DMD. The fetal sex was confirmed by amniocentesis karyotype analysis and multiplex ligation-dependent probe amplification (MLPA) at 16 weeks. This procedure may avoid unnecessary CVS or amniocentesis of female fetuses.

Keywords: Cell-free fetal DNA (cffDNA); Duchenne muscular dystrophy (DMD); fetal sex determination; non-invasive prenatal diagnostic (NIPD).

Figure 1.

Quantitative real-time PCR. Amplification plots obtained using quantitative real-time PCR for the SRY gene. A: 500GE; B: 100GE; C, D, and E: positive samples; F: negative controls; G: 10GE; H: negative samples. The X-axis denotes the cycle number of a quantitative PCR reaction. The Y-axis denotes ΔRn, which is the fluorescence intensity over the background.

Figure 2.

MLPA analysis of DMD. (A), The result for 034 indicates deletion of exons 3–10, 21, and 22; (B), The result for 035 indicates deletion of exons 11–20; (C), The result for 034 indicates duplication of exons 21–30 and 41–43; (D), The result for 035 indicates duplication of exons 13–20 and 31–40.