Reliability of Fetal Sex Determination Using Maternal Plasma

Abstract

III.

Noninvasive fetal sex determination in maternal plasma: a prospective feasibility study

“…32 The drawback of the DYS14 sequence is that it has considerable homology to sequences other than the Y chromosome that could falsely classify female fetuses as male. 33 In comparison with previous studies, 34 we have obtained a high frequency of amplification signals with DYS14 PCR in female fetuses (35% vs. 63.9%). In this sense, the use of centrifugation has been pointed out as a critical step to avoid contamination by residual circulating cells from previous pregnancies.…”

“…39 Despite using a very low volume of plasma (500 µl), no false-negative results were found in our study and we were able to issue results before the 10th week of gestation and without the need for a second maternal blood sample, as distinguished from other groups. 34,40 In our approach, female fetuses are not detected directly but only inferred by a negative result for Y-chromosome-specific sequences. We chose to use a combination of three Y-chromosome sequences to maximize the accuracy of the test.…”

“…36 Some recently published studies used a combination of the DYS14 and SRY sequences to improve sensitivity and specificity of the assay. 34,37 Determination of fetal sex based on the detection of Y-chromosome-specific markers in maternal plasma is prone to false-negative results because female fetuses are not detected directly but instead are inferred by a negative result for Y-chromosome sequences, which could also be caused by undetectable levels of cffDNA. Because of the higher sensitivity of DYS14, testing for only DYS14 has been suggested.…”

Restriction Enzyme–Mediated Enhanced Detection of Circulating Cell-Free Fetal DNA in Maternal Plasma

“…3,4 Noninvasive methods of both rhesus D antigen serotype status and fetal sex determination function by amplifying RHD or Y-chromosomal loci in maternal plasma. 5 The detection of these fetally derived DNA molecules is generally robust, with low detection limits.…”

Chroniques génomiques : On n’arrête pas le progrès…

“…Compte tenu des énormes progrès réali-sés dans l'analyse d'ADN, on pouvait espérer isoler sa contribution propre, au moins dans certains cas. Et effectivement, on procède déjà en clinique au diagnostic du sexe par l'identification de séquences spécifiques au chromosome Y [5], ou au typage des embryons Rhésus-positifs par détection de séquences RHD [6]. On commence à entrevoir la mise en évidence, à partir des mêmes prélèvements, de différentes aneuploïdies, ainsi que celle de mutations responsables d'affections génétiques graves -même si pour ces deux applications la présence de 90 ou 95 % d'ADN maternel dans l'échan-tillon impose le recours à des analyses sophistiquées -nous y reviendrons.…”