Successful early fetal sex determination using cell-free fetal DNA isolated from maternal capillary blood: A pilot study

OBJECTIVES: The discovery of cell-free fetal DNA (cffDNA) fragments in maternal plasma made it possible to determine fetal sex at early stages of pregnancy without carrying a risk miscarriage, which is especially important for the management of X-linked genetic abnormalities. The vast majority of studies used cffDNA extracted from maternal venous blood, excluding the possibility of capillary sampling for those who cannot tolerate venipuncture. This study evaluates the possibility of fetal sex determination using cffDNA isolated from capillary blood of women with early gestational pregnancies. STUDY DESIGN: Samples were obtained from 24 pregnant women from the Ukrainian population, whose gestational age varied between 5th to 10th weeks. Sex determination was performed using real-time quantitative PCR of SRY male-specific markers. Results were compared to the known fetal sex (detected by next-generation sequencing during the preimplantation genetic testing procedure) to calculate the test accuracy. RESULTS: Results demonstrated 85.71–100% sensitivity and 100% specificity of the test. Cohen's Kappa coefficient of agreement in sex determination test varied from 0.8 to 1.0 (P < 0.00001). CONCLUSION: This test, which is the first known so far detailed report of successful early fetal sex determination using cffDNA isolated from maternal capillary blood, is a reliable alternative to traditional venipuncture.