Variability of ffDNA in maternal plasma does not prevent correct classification of trisomy 21 using MeDIP‐qPCR methodology

Abstract

Overall, the variability of ffDNA and total DNA among maternal samples does not affect the correct trisomy 21 classification using MeDIP-qPCR methodology applied in peripheral blood.

The Epigenome View: An Effort towards Non-Invasive Prenatal Diagnosis

“…Our group also investigated whether the variability of the fetal fraction present in maternal plasma has a negative effect in our assay’s diagnostic efficiency. Although previous reports demonstrated an effect of different fetal amounts present in maternal plasma [73,74,75], our study has shown no significant association between cffDNA fraction, absolute fetal amount or the concentration present in maternal plasma with the test result classification using our diagnostic formula [20,72]. We speculate that this is due to the fact that maternal blood contains <1% of fetal DNA [20,72] in contrast to maternal plasma, which contains ~10%–15% fetal DNA [10,76].…”

“…The efficiency of the MRED assays depends on the purity of the sample, and for this reason, they require high purity and high integrity samples [90]. Additionally, MRED assays require fairly high quantities of starting material, which is a restriction to its implementation in plasma samples, because not only the target fetal DNA sequences are of a low amount, but also the total plasma DNA is very low (around 10 ng/4 mL plasma) [20]. An additional drawback of the assay is that it can only evaluate the methylation status of a specific and very limited number of genomic sequences.…”

“…Such markers were Y-chromosome-specific loci for fetal sex determination, such as DYS14 [1,20], as well as fetal Rhesus D found in maternal circulation in pregnancies in which the mother was Rhesus D negative [21,22]. These methods were readily and rapidly introduced in the clinical setting of diagnostic laboratories worldwide [23], and within a few years, the field of NIPT evolved even further with the use of Y-chromosome-specific markers or paternally inherited polymorphic loci for the NIPT of X-linked inherited diseases, as well as through the identification of fetal-specific chromosomal translocations [24] and trinucleotide repeats in muscular dystrophy (DMPK) [25].…”

Analysis of cell‐free DNA in maternal blood in screening for fetal aneuploidies: updated meta‐analysis

“…In the fourth study 64 , cfDNA testing was performed prospectively in 333 singleton pregnancies at 14 (range, [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] weeks. The test did not provide a result in 1.2% of cases and there was no follow-up in 5.5% of cases.…”

Non-invasive prenatal testing (NIPT): limitations on the way to become diagnosis

“…The MeDIP assay can tolerate sample impuritiesand thus, no prior sample purification is required -and is not affected by the amount of ccffDNA or fetal gender or the presence of informative polymorphic sites as it may happen to SNP-related methods [50,51]. It can be applicable for low starting DNA templates, generating sufficiently enriched outputs, a development that renders possible its implementation with plasma samples [52].…”