A Non Invasive Screening Test for Fetal Genetic Anomalies: Cell-Free DNA Testing

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Highlights:

• Cell-free DNA (cfDNA) analysis is a non-invasive prenatal screening test that can detect chromosomal abnormalities in a fetus
• The test involves analyzing the DNA fragments present in the mother's blood, which are thought to come from the placenta
• The test can also detect certain sex chromosome abnormalities and be used to determine the sex of the fetus with high accuracy

Prenatal testing is crucial to detect fetal anomalies and genetic disorders in the early stages of pregnancy. The traditional methods for prenatal testing, such as amniocentesis and chorionic villus sampling, have some limitations, including the risk of miscarriage and fetal injury. Advances in genetic technology, on the other hand, have paved the way for new, non-invasive testing methods, such as cell-free DNA analysis in maternal plasma.

Cell-free DNA analysis in maternal plasma is a non-invasive prenatal testing (NIPT) method that detects fetal DNA in maternal blood. The test measures the fragments of fetal DNA in the maternal plasma and screens for common genetic disorders and chromosomal abnormalities. The technology has a high sensitivity and specificity, which can provide accurate results with a low false-positive rate.

‘Cell-free DNA analysis in maternal plasma is a non-invasive prenatal testing method that can provide early detection of fetal abnormalities and genetic disorders. The technology has several benefits over traditional prenatal testing methods, including reduced risk of miscarriage and fetal injury, early detection of fetal abnormalities, and high accuracy’

Studies have shown that cell-free DNA analysis can be used for the early detection of fetal abnormalities in cases where the ultrasound examination shows suspicious results. In these cases, cell-free DNA analysis can provide a non-invasive method for detecting genetic disorders, including trisomy 21 (Down syndrome), trisomy 18 (Edwards syndrome), and trisomy 13 (Patau syndrome) (1^✔). The technology can also detect other genetic abnormalities, such as sex chromosome anomalies and microdeletions.

Benefits of Cell-Free DNA Analysis

Cell-free DNA analysis has several benefits over traditional prenatal testing methods. Firstly, the test is non-invasive and does not carry the risk of miscarriage or fetal injury. Secondly, the test can be performed as early as 10 weeks of gestation, which allows for early detection of fetal abnormalities. Thirdly, the test has a high accuracy rate, which reduces the need for further invasive testing methods, such as or chorionic villus sampling.

Detection of Common Genetic Disorders and Chromosomal Abnormalities

Perinatal screening for genetic disorders is important because early detection can lead to early intervention, which can improve the outcome of the pregnancy. Common genetic disorders detected perinatally include Down syndrome, Edwards syndrome, and Patau syndrome.

Down syndrome, also known as trisomy 21, is a chromosomal abnormality caused by an extra copy of chromosome 21. Down syndrome is associated with intellectual disability, heart defects, and other health problems. According to the Centers for Disease Control and Prevention (CDC), the prevalence of Down syndrome in the United States is approximately 1 in every 700 births (2^✔).

Edwards syndrome, also known as trisomy 18, is a chromosomal abnormality caused by an extra copy of chromosome 18. Edwards syndrome is associated with severe intellectual disability, congenital heart defects, and other health problems. The prevalence of Edwards syndrome is approximately 1 in every 5,000 live births.

Patau syndrome, also known as trisomy 13, is a chromosomal abnormality caused by an extra copy of chromosome 13. Patau syndrome is associated with severe intellectual disability, congenital heart defects, and other health problems. The prevalence of Patau syndrome is approximately 1 in every 10,000 live births.

Cell-free DNA testing has a high detection accuracy rate for common fetal chromosomal abnormalities, such as trisomy 21, trisomy 18, and trisomy 13. In a meta-analysis of 31 studies that included a total of 88,677 pregnancies, the detection rates for these three chromosomal abnormalities were as follows: 99.2% for trisomy 21, 97.4% for trisomy 18, and 92.5% for trisomy 13 (3^✔).

However, it is important to note that cell-free DNA testing is a screening test, and a positive result does not necessarily mean that the fetus has the chromosomal abnormality in question. Further diagnostic testing, such as amniocentesis or chorionic villus sampling, may be necessary to confirm the diagnosis. Cell-free diagnostic testing is now being used by the majority of obstetricians and geneticists to guide antenatal parents correctly. This test is non- invasive and less cumbersome, and highly accurate. It is recommended for antenatals whose ultrasound images showed some abnormalities on the routine ultrasound screening. It is also done in high risk pregnancies. It can also be done to predict the outcome of the pregnancy if there is already a pre-existing family history of chromosomal abnormalities.

References :

1. Women's Health: Racial and Ethnic Health Inequities - (https:www.ncbi.nlm.nih.gov/pmc/articles/PMC3833574/)
2. Data and Statistics on Down Syndrome - (https:www.cdc.gov/ncbddd/birthdefects/downsyndrome/data.html)
3. Analysis of cell-free DNA in maternal blood in screening for fetal aneuploidies: updated meta-analysis - (https:obgyn.onlinelibrary.wiley.com/doi/10.1002/uog.14791)

Source: Medindia

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