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The scientific miracle of early pregnancy: Why is fetal DNA present in the blood of pregnant women?
In the early stages of pregnancy, an important and surprising phenomenon emerged in the medical community, that is, fetal DNA (cffDNA) freely exists in the blood of pregnant women. As science and technology advance, this phenomenon allows us to learn about the condition of the fetus non-invasively, without having to rely on traditional and risky testing methods.
cffDNA comes from the trophoblast cells of the placenta. When small particles of these cells enter the maternal blood circulation, fetal DNA exists in the form of fragments in the maternal blood.
According to research, fetal DNA fragments are approximately 200 base pairs long, which is smaller than maternal DNA fragments, which allows cffDNA to be effectively distinguished from maternal DNA. As pregnancy progresses, the proportion of cffDNA in the blood gradually increases, but within two hours of delivery, the DNA is no longer detectable. How does this affect pregnancy check-ups and preventive measures?
Detection method of cffDNA
Isolating cffDNA from maternal blood samples is a critical step. This usually requires using a centrifuge to separate plasma from whole blood, followed by extraction and purification of cffDNA. A standardized experimental procedure was developed after evaluating the literature. Using different extraction reagents, it was found that the QIAamp DSP Virus Kit could achieve the highest cffDNA yield.
The addition of formaldehyde can enhance the yield of cffDNA because it stabilizes intact cells and thereby inhibits the release of maternal DNA.
When analyzing cffDNA, real-time polymerase chain reaction (PCR) is a commonly used technology. Here, fluorescent probes are used to monitor the accumulation of amplification products and report the intensity of the fluorescent signal and the generated amplification. Proportional to the number of children. In addition, methods such as digital PCR and high-throughput sequencing are also receiving more and more attention. These methods can detect fetal DNA carefully and accurately, and have obvious advantages in detecting chromosomal abnormalities, fetal blood type or gender determination.
Application Scope
The emergence of cffDNA has opened up a series of new applications in the medical community, including: fetal gender confirmation, congenital disease screening and paternity identification, etc. Especially in the first trimester, fetal gender determination through cffDNA analysis can also provide valuable information to parents.
In the detection of genetic diseases such as congenital adrenal hyperplasia, cffDNA can also provide vital information and help mothers prepare for medical treatment in advance.
In addition, cffDNA can be used for early diagnosis of fetal single-gene diseases, such as cystic fibrosis, β-thalassemia, etc., providing better treatment opportunities for sick children. Its applications even extend to detecting major health problems such as hemolytic disease of the newborn and chromosomal abnormalities such as Down syndrome.
Future Outlook
With the development of next-generation sequencing technology, the application scope of cffDNA will continue to expand. Not only can we detect abnormalities in genes, we may also find clear associations between specific gene variants and disease states. This has triggered profound discussions on data privacy and ethics. How to balance scientific progress and ethics will become a major challenge in the future.
As technology innovates again, the potential application of cffDNA is changing the way pregnant women receive prenatal care. Can we embrace this biomedical revolution and ensure that these advances can be pushed into clinical practice in a safe and responsible way?
