Noninvasive prenatal testing (NIPT) allows doctors to detect chromosomal abnormalities, including Down syndrome and aneuploidies of the sex chromosomes (trisomy 21, trisomy 18 and trisomy 13). NIPT also screens for microdeletions in chromosomes that can cause conditions such as Turner syndrome, Klinefelter syndrome, and triple X and XYY syndromes.
NIPT is a useful tool that can help women and couples make informed decisions about their pregnancies. However, the test results can also lead to anxiety and stress for some patients.
Prenatal Screening for Rare Genetic Disorders
NIPT is an increasingly common screening method for chromosomal abnormalities that can cause genetic disorders. It uses a sample of the mother’s blood to detect small missing pieces of DNA (microdeletions) in specific chromosome regions.
Advanced NIPT tests use sequencing technologies that can also pick up on microduplications and insertions. This can screen for more rare chromosomal abnormalities including certain syndromic conditions like DiGeorge syndrome or deletions in the X chromosome, which can lead to Turner and Klinefelter syndromes.
The NIPT test can detect Down syndrome and other common trisomies including trisomy 18 (Edwards) and trisomy 13 (Patau). It can also screen for aneuploidies of the X or Y chromosomes, such as Turner syndrome or XXY (Klinefelter syndrome). NIPT can also determine the sex of the fetus at an early stage in pregnancy.
Non Invasive Prenatal Testing for Rare Conditions
The test, based on the analysis of circulating cell-free fetal DNA (cff-DNA) in the mother’s bloodstream, is a safe alternative to the invasive prenatal tests known as amniocentesis and chorionic villus sampling. These procedures have a 1-2% risk of miscarriage.
The NIPT is able to detect aneuploidies, such as trisomies that cause Down syndrome and Edwards syndrome, and chromosome microdeletions that cause Patau and Kleinfelter syndrome. It can also determine sex from nine weeks gestation, much earlier than ultrasound.
For those women whose NIPT results suggest a high risk for a rare condition, the results can be followed up with chorionic villus sampling. However, the test has a low false positive rate. Moreover, the detection of some rare conditions may be complicated by a low fetal fraction result or other factors, such as maternal obesity or certain autoimmune disorders, that affect the availability of placental cf-DNA.
Detecting Rare Genetic Disorders with NIPT
NIPT currently detects chromosomal anomalies, such as trisomy 21 (Down syndrome), trisomy 18, and trisomy 13, which are caused by extra or missing copies of specific chromosomes. It is also beginning to be used to test for genetic disorders that are caused by changes in single genes.
These alterations are caused by small deletions and duplications in certain parts of the genome, so they are among the easiest to detect. Some advanced NIPTs can also screen for more rare conditions, such as Turner syndrome and 22q 11.2 deletion syndrome.
Because of its relatively low cost and noninvasive nature, NIPT could potentially be used in LMICs alongside maternal serum screening and ultrasound exams. However, implementing this strategy will require technological innovation directed toward low-resource settings and training for community health workers to perform blood draws and interpret ultrasound images.
NIPT Benefits for Expectant Parents
For pregnant women, NIPT xet nghiem nipt ha noi is usually recommended based on OB-GYN and midwifery guidelines. It is a good idea to check with your insurance provider to learn whether NIPT is covered and what the out-of-pocket costs are.
NIPT is a screening test that can tell if an individual is at higher risk for certain genetic disorders. However, it can’t diagnose the condition. A 2016 study found that NIPT has high sensitivity for trisomy 21 and other common chromosomal abnormalities.
It can also detect rare genetic conditions that either run in the family, such as cystic fibrosis and Duchenne muscular dystrophy, or arise at conception, such as thanatophoric dysplasia. Until recently, these conditions could only be diagnosed with invasive tests such as amniocentesis or CVS. NIPT can avoid these invasive procedures and increase the likelihood of a positive diagnosis.
Challenges in NIPT for Rare Genetic Disorders
Noninvasive prenatal screening (NIPT) analyzes cell-free fetal DNA in maternal blood. It has gained popularity since it allows detection of chromosomal aneuploidies and determination of sex with a low risk of miscarriage. NIPT has improved in recent years and now includes detection of microdeletions >= 7 Mb as well as single gene disorders caused by mutations or autosomal dominant inheritance.
Nevertheless, there is still a great deal of work to be done to improve the accuracy of NIPT. In particular, the PPVs of different aneuploidies and single gene disorders vary widely across studies and patient cohorts, making counseling challenging.
NIPT is currently too expensive for LMICs, but continued sequencing cost declines could make the test cheaper and more accessible. Community health workers are already able to draw blood, so it should be relatively simple for them to implement NIPT.