Determinación del sexo fetal mediante adn libre fetal en plasma materno

Objective: To validate the use of cell free fetal DNA (ffDNA) in maternal plasma to predict fetal sex in the first half of pregnancy. Method: A prospective observational cohort study of 25 pregnancies between 5 and 15 weeks of gestation was studied (median gestational age of 9+1 weeks). Maternal blood was taken and q-PCR was carried out to detect the multi-copy Y chromosome associated DSY14 gene. The end point was gender as assessed by ultrasound at 20-25 weeks. Results: A Y signal was obtained in 12 patients, so a male fetus was predicted. The earliest signal was at 6+4 weeks. In 9 patients we didn't have any signal, so a female fetus was diagnosed. There were 4 cases where the criterion to define fetal sex was not fulfilled and were classified as equivocal (all of them before 8+3 weeks). The probability to predict fetal sex from the test was 84% (21 of 25 patients). However, when the diagnosis of fetal sex is made, there is a 100% correlation between the ultrasound and Q-PCR. Conclusion: Free fetal DNA in maternal plasma allows prediction of fetal sex in the first half of pregnancy.