Maternal Blood Collection: The mother’s blood is drawn, and the cfDNA (cell-free DNA) contained within it is analyzed. This cfDNA originates from the placenta and contains the fetus’s genetic information.
Chromosomal Abnormality Screening: Primarily, abnormalities in chromosome 21 (Down syndrome), chromosome 18 (Edwards syndrome), and chromosome 13 (Patau syndrome) are examined.
Advantages
Safety: Since the procedure is non-invasive, it poses no risk to the mother or fetus (unlike amniocentesis or chorionic villus sampling, which carry a risk of miscarriage).
Early Testing: The test can be performed from the 10th week of pregnancy, allowing early assessment of the fetus’s condition.
Accuracy: It boasts an accuracy rate close to 99% for detecting chromosomal abnormalities such as Down syndrome.
Disadvantages
Screening, Not Diagnosis: NIPT is strictly a screening test; if a positive result is obtained, a diagnostic test such as amniocentesis is required for confirmation.
Limited Scope: Standard NIPT primarily detects chromosomal number abnormalities and cannot identify other genetic disorders such as single-gene diseases.
Cost: It is relatively expensive and often not covered by insurance.
2. NIPPT (Non-Invasive Paternity Testing)
Method
Maternal Blood Collection: The mother’s blood is drawn, and the fetal cfDNA (cell-free DNA) contained within it is isolated.
Collection of the Alleged Father’s DNA: DNA is collected from the alleged father through saliva or blood samples, and compared with the fetal DNA.
Determination of Paternity: The degree of match between the alleged father’s DNA and the fetal DNA is analyzed to determine paternity.
Advantages
Safety: Paternity can be determined during pregnancy without any risk to the mother or fetus, as the test is non-invasive.
Early Paternity Determination: Testing can be performed from the 10th week of pregnancy, allowing paternity to be established without waiting for the birth.
Disadvantages
Cost: Like NIPT, NIPPT is relatively expensive, and it is rarely covered by insurance.
Potential for Inconclusive Results: Although advanced DNA separation techniques are used, if the proportion of fetal cfDNA is low, the results may be inconclusive.
3. Parentage Test
Method
DNA Collection: DNA samples are collected from the parent and child, typically using saliva, buccal (inner cheek) swabs, or blood.
DNA Analysis: Specific DNA markers (STRs: Short Tandem Repeats) are analyzed to confirm the biological relationship. The DNA patterns of the parent and child are compared for matches.
Advantages
High Accuracy: Parentage can be confirmed with an accuracy of over 99%.
Simple and Quick: DNA collection is usually done via saliva or buccal swabs rather than blood draws, making the process painless and easy.
Disadvantages
Cost: If legal documentation is required, the cost may be higher.
Ethical Considerations: Because parentage testing can have emotional and ethical implications, careful consideration is necessary before proceeding.
4. Sibling Test
Method
DNA Collection: DNA is collected from siblings using saliva, blood, or buccal (inner cheek) swabs.
DNA Comparison: Similar to parentage testing, DNA markers between siblings are compared to determine whether they share one or both biological parents.
Advantages
Relationship Confirmation Without Parental DNA: Even if a parent’s DNA sample is unavailable, genetic similarity between siblings can still be analyzed to determine their relationship.
Non-Invasive and Simple: The test is painless, typically using buccal swabs or saliva samples.
Disadvantages
Limitations in Accuracy: Compared to parentage testing, sibling testing may have slightly lower accuracy, especially in cases involving half-siblings.
Potential for Inconclusive Results: When siblings share only one biological parent (such as in half-sibling relationships), the DNA match may be incomplete, leading to less definitive results.
Summary of Genetic Testing
Advantages
High Accuracy: Genetic testing can confirm parentage, sibling relationships, and fetal chromosomal abnormalities with very high precision.
Non-Invasive Methods: Tests such as NIPT and NIPPT are much safer and less risky compared to invasive procedures.
Early Diagnosis: It is possible to assess the fetus’s condition and determine paternity even during pregnancy.
Legal Documentation: Parentage and sibling tests can be used as legal evidence.
Disadvantages
High Cost: Many genetic tests are expensive and often not covered by insurance.
Emotional Burden: Testing for parentage or sibling relationships can cause emotional and ethical issues within families.
Limitations of Testing: NIPT is limited to screening for chromosomal abnormalities and may not detect other types of genetic disorders.
