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

Prenatal diagnosis and in utero treatment of congenital adrenal hyperplasia: An up-to-date comprehensive review

Congenital adrenal hyperplasia (CAH) is a term that encompasses a wide range of conditions that affect the adrenals. Diagnosis and treatment before birth are important as irreparable birth defects can be avoided, decreasing the need for surgical intervention later in life, especially regarding genitalia anomalies. Although early implementation of dexamethasone in the prenatal treatment of CAH has been controversial, there is recent evidence that this treatment can reduce long-term complications.

DNA Hyperstructure

This study presents a new procedure to condense DNA molecules and precipitate them onto a glass slide. The resulting DNA molecules undergo autonomous self-assembly, creating closed superstructures on the micrometer scale, which are called DNA hyperstructures. These structures can be observed using low-magnification (4×) light microscopy. Precisely controlling the alcohol/glacial acetic acid ratio and DNA concentration during precipitation enabled the regulation of structure compaction on the slide. The alcohol/glacial acetic acid ratio is inversely proportional to the DNA concentration to achieve optimal compaction on the slide. Confocal microscopy fluorescence analysis of DNA extracts stained with DAPI shows that nucleic acids self-assemble to form structures during precipitation on the slide. This methodology is relevant since it facilitates the precipitation and visualization of DNA, regardless of its origin or molecular weight. To confirm its versatility, results with DNA extracted from human peripheral blood, the Lambda virus, and plasmid pBR322 are presented. The study examined the morphological features of DNA hyperstructures in both healthy individuals and those diagnosed with different medical conditions or illnesses, revealing distinct patterns specific to each case. This innovative technology has potential for disease detection in peripheral blood samples, ranging from cancer and Alzheimer's disease to determining the gender of the gestational product at an early stage.

Identifying the minimum concentrations of cell-free fetal DNA in maternal blood required for bovine fetal sexing using PCR

We evaluated the feasibility of cffDNA extraction from the maternal blood samples regarding the threshold concentrations required for fetal sexing in pregnant cattle by PCR. In four trials, we 1) compared the extraction efficiency of seven methods using freshly harvested plasma/blood of cows carrying male fetii (150-240 d gestation) bovine amelogenin (bAML) and Y-specific gene sequences, 2) identified the minimum amounts of spiked cffDNA needed for a PCR for fetal sexing, 3) determined the most optimal protocol among three commercial kits for cffDNA extraction from neat and spiked plasma samples (181-240 d gestation) for PCR detection of Y-specific sequence and 4) tested Y-specific sequence PCR on pregnant cows at different stages of gestation (60-150 versus 151-240 d pregnant). In these experiments, blood samples from unbred dairy heifers (Canadian Holstein, n = 10), pregnant dairy cows (Canadian Holstein, 60-240 d gestation, n = 25 with male fetii), and aborting beef cows (Angus cross, n = 5, 100-150 d pregnant) were used for DNA extraction, spiking, and PCR. Extracted DNA from the blood samples of unbred heifers (n = 5) and bull calves (n = 5) served as controls in all trials. In the first trial, DNeasy Blood and Tissue, Qiagen DSP Virus, and NucleoMag cfDNA isolation kits were relatively successful among seven methods to isolate cffDNA from freshly harvested maternal plasma/blood of pregnant cows. In trial 2, using serial dilutions of cffDNA from male fetii spiked in cow plasma samples, a positive and unambiguous detection by PCR targeting Y-specific sequence and bAML gene was observed when spiked cffDNA concentration in plasma was >31.3 pg/ml and >2 ng/ml, respectively. In the third trial, the DNeasy Blood and Tissue kit was most successful in extracting cffDNA spiked at the minimum concentrations in maternal plasma and subsequent PCR for Y-specific sequence. In our fourth trial, more cows in the second half (9/10) of gestation showed a positive Y-specific PCR outcome than those in the first half (3/9, Fischer's exact test; P < 0.05, 90%; CI: 55.5-99.75 vs 33%; CI: 7.5-70.1). In conclusion, we observed variability between different DNA extraction methodologies and stages of gestation results in the PCR for prenatal sexing. Thus, the current PCR methodologies are unreliable for detecting cffDNA in pregnant cows. Additionally, ≥10 (≥31.3 pg/ml of cffDNA) and ≥648 (≥2 ng/ml of cffDNA) copies of the whole fetal genome in bovine maternal plasma are needed for Y-specific PCR and bAML PCR, respectively.

Fetal Nucleated Red Blood Cells Preferable Than Cell-Free Fetal DNA for Early Determination of Gender Among Invasive and Non-Invasive Source Using Novel Four Genes Multiplex PCR

Background

Deoxyribonucleic acid from invasive, non-invasive and 9th week embryo can be a resource for the determination of fetal sex using highly sensitive and specific multiplex PCR.

Methods

A total of 402 DNA samples were used to test the newly developed novel multiplex PCR including male specific (3 genes: SRY, DAZ2 and TSPY1) Y-biomarkers and internal control, ACTB. The study isolated cffDNA (Cell-free fetal DNA; n = 73) from mother’s plasma, serum and urine, fetal DNA from 9th week embryo and cord blood, and fetal DNA from CD71^+ve nucleated red blood cells (fNRBC; n = 73). Paternal and maternal DNA from buccal cells (n = 20) and blood (n = 232) used for male and female confirmation.

Results

The study observed that SRY alone cannot be a suitable Y-biomarker. Confirmation from any two Y-biomarkers is mandatory for male fetus identification. Direct sequencing of the gel eluted multiplex and single amplicons confirmed the specific sequences. Presence of two out of 3 Y-biomarkers OR single Y-biomarker with >1,000,000 intensity is considered positive for male. The multiplex PCR is suitable for determining sex from all source of fetal DNA including highly degraded cffDNA and can detect the sex using 0.5ng DNA. Individual marker-based real-time qPCR followed by combined melt curve analysis showed distinguished melt curve peaks for the markers.

Conclusion

The multiplex PCR achieved 100% accuracy on fetal DNA from fNRBC for early determinations (<13 weeks) of gender. The developed novel and simple multiplex PCR and individual qPCR can be adopted in all types of laboratories for determining human fetal gender using fetal DNA from fNRBC. Early identification of gender can support to prepare for possible X-linked analysis, reduce anxiety in mother, strengthen a bond between mother and fetus, and effective decision making. Non-invasive source of fetal DNA from fNRBC preferred for identifying gender to reduce the risk of invasive procedures in early (8–13 weeks) pregnancy.