NIPT (noninvasive prenatal testing)
Noninvasive prenatal testing (NIPT) is a modern screening method used to assess the genetic health of developing babies without the need for invasive procedures. By analyzing DNA from maternal blood, NIPT can screen for various genetic abnormalities, primarily focusing on trisomy disorders such as Down syndrome (trisomy 21), trisomy 13 (Patau syndrome), and trisomy 18 (Edwards syndrome). This technique is especially beneficial as it poses no risk to the mother or fetus, unlike traditional invasive tests that may have a slight risk of miscarriage.
NIPT is typically available after the tenth week of pregnancy and is often recommended for women considered to be at higher risk, including those of advanced maternal age or with previous pregnancies affected by genetic disorders. In addition to detecting chromosomal abnormalities, NIPT can provide information about the fetus's sex and blood type and can screen for other conditions, such as sex chromosome aneuploidies and certain genetic syndromes. While NIPT has shown high accuracy rates, its effectiveness may be reduced in specific circumstances, such as multiple pregnancies or certain maternal health conditions. Overall, NIPT represents a significant advancement in prenatal care, offering expectant parents valuable insights into their baby's health.
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NIPT (noninvasive prenatal testing)
Noninvasive prenatal testing (NIPT) is a technique used by health care providers to screen developing babies for certain genetic abnormalities without the use of invasive and risky tests. NIPT is a relatively new diagnostic tool, and it involves the collection of DNA samples from both the mother and the fetus. These samples are then screened for evidence of one or more genetic disorders and other fetal characteristics that offer insights into the developing baby's health. Prior to administering NIPT, health care providers analyze the situational risk profile of the mother and baby to recommend a specific set of disorders for the screening to attempt to detect.
NIPT is known by several other names, including noninvasive prenatal screening (NIPS) and prenatal cell-free DNA (cfDNA) screening.
Overview
NIPT is primarily used to check developing babies for a range of trisomy chromosomal disorders. Individuals with trisomy have an additional chromosome, meaning that their bodies carry a total of forty-seven chromosomes instead of the usual forty-six. Trisomy disorders are classified by the specific chromosome that has an extra copy. For instance, Down syndrome occurs when a person has three copies of chromosome 21 instead of two, and as such, it is alternately known as trisomy 21. While Down syndrome is the main disorder for which NIPT screens, the testing can also be used to detect trisomy 13 (Patau syndrome), trisomy 18 (Edwards syndrome), trisomy 16, and trisomy 22.
Noninvasive prenatal testing can also detect an increased risk of triploid syndrome, an extraordinarily rare chromosomal disorder in which a fetus has triplicate copies of all forty-six chromosomes. Fetuses with triploid syndrome rarely survive until birth, and mothers may be offered the opportunity to terminate the pregnancy if it is present. Other conditions NIPT can screen for include sex chromosome aneuploidy (Klinefelter syndrome), chromosomal microdeletion syndromes, and single-gene disorders affecting skeleton and bone development. Noninvasive prenatal screenings can also determine the fetus's sex and blood type.
NIPT procedures become available to women after the tenth week of pregnancy, but they are typically reserved for higher-risk situations, including advanced maternal age and a previous history of pregnancies involving trisomy disorders. They may also be offered to expectant mothers with Rh-negative blood types, as this can lead to pregnancy complications if the fetus has an Rh-positive blood type and is not the woman's first child.
The actual test involves the collection of a maternal blood sample that contains the DNA profile of both the mother and the fetus. It carries no risks whatsoever to mother or child, and as such, it represents an improvement over invasive alternatives that screen for Down syndrome but carry a slight chance of triggering a miscarriage.
While NIPT has displayed very high success rates in predicting the aforementioned conditions and chromosomal disorders, it is less effective if the mother is pregnant with multiple babies, is obese, is carrying a fetus on behalf of another person, or was impregnated with a donated egg.
Bibliography
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Michie, M., et al. "Informed Decision-Making about Prenatal cfDNA Screening: An Assessment of Written Materials." Ethics, Medicine and Public Health, vol. 2, no. 3, July–Sept. 2016, pp. 362–71.
"Non-Invasive Prenatal Testing (NIPT) for Down's Syndrome (Also Known as cfDNA Screening)." ARC UK, www.arc-uk.org/tests-explained/non-invasive-prenatal-testing-nipt. Accessed 25 Jan. 2018.
Norwitz, Errol R., et al. "Noninvasive Prenatal Testing: The Future Is Now." Reviews in Obstetrics and Gynecology, vol. 6, no. 2, 2013, pp. 48–62.
"Prenatal Cell-Free DNA (cfDNA) Screening." Genetic Support Foundation, geneticsupportfoundation.org/archive/genetics-and-you/pregnancy-and-genetics/pregnancy-and-genetics-tests/cell-free-dna-cfdna. Accessed 25 Jan. 2018.
"Prenatal Cell-Free DNA Screening." Mayo Clinic, 29 July 2017, www.mayoclinic.org/tests-procedures/noninvasive-prenatal-testing/about/pac-20384574. Accessed 25 Jan. 2018.
Stokowski, Laura A., and Susan Klugman. "The Pros and Cons of Noninvasive Prenatal Screening." Medscape, 7 Nov. 2013, www.medscape.com/viewarticle/813882. Accessed 25 Jan. 2018.
"Trisomy Disorders." Victoria State Government, www.betterhealth.vic.gov.au/health/conditionsandtreatments/trisomy-disorders. Accessed 25 Jan. 2018.