Are NIPT Tests Different?
Yes, NIPT tests are different from each other. Not every NIPT test may offer the same scope, the same technology, the same laboratory quality, and the same clinical performance. Therefore, when choosing a test, attention should be paid not only to the name of the test, but also to its content and reliability.
What are the main differences?
1. Scope
Some NIPT tests only evaluate the most common chromosome abnormalities:
- Trisomy 21 — Down syndrome
- Trisomy 18 — Edwards syndrome
- Trisomy 13 — Patau syndrome
In wider scope tests, in addition to these:
- Sex chromosome abnormalities: Evaluation of number differences in X and Y chromosomes that can affect the baby's male or female development.
- Rare chromosome abnormalities: Investigation of rarer changes in chromosome numbers, other than common conditions like Down syndrome.
- Microdeletions: Screening for certain genetic syndromes that can occur due to the absence of a very small piece of chromosome (<5mb).
- Deletions / Duplications: Evaluation of cases where a part of the chromosome is missing or has extra copies.
- Single-gene hereditary and de novo genetic diseases: Investigation of certain genetic diseases that can occur due to changes in a single gene, can be inherited from the family, or can appear for the first time in the baby.
- Fetal sex or fetal RhD status: Evaluation of baby's sex or RhD blood group information, which can be important in terms of blood incompatibility.
may also be included.
2. Technology Used
The analysis method and bioinformatic algorithms used in NIPT tests may change from laboratory to laboratory. This difference can affect which diseases the test can screen, its performance at low fetal DNA fractions, and the reliability of the result report.
3. Clinical Performance
Scientific performance data of NIPT tests, such as sensitivity, specificity, false positive rate, positive predictive value, and negative predictive value, are not the same.
Therefore, it is not enough for a test to be named simply 'NIPT'; by which clinical studies the test has been validated, on how many samples it has been evaluated, and for which conditions it offers reliable performance should be considered.
4. Test Failure Rate
In some NIPT tests, results cannot be provided due to low fetal DNA fractions or technical reasons. This condition is called 'test failure' or 'no result'. When choosing a test, tests with low failure rates that offer reliable reporting should be preferred.
5. Laboratory Quality and Accreditation
The experience, quality standards, and accreditations of the laboratory where the test is processed are important. Especially for genetic tests, laboratories operating in compliance with international quality standards should be preferred.
6. Genetic Counseling Support
An NIPT result should not always be evaluated alone. Especially in high-risk, suspicious, or comprehensive panel results, specialist physician or genetic counseling support is of great importance.