Pregnancy is one of the most exciting periods in a woman’s life, which brings not only great happiness but also considerations regarding the health of your future baby. Many pregnant women are offered screening in the early pregnancy in order to rule out genetic syndromes, so called trisomies, among which the most common is Downs Syndrome. Testing for trisomies often includes testing of the fetal cells in the amniotic fluid, named amniocentesis. Unfortunately, amniocentesis carries an approximately 1% risk of miscarriage.
Non-invasive prenatal testing is as accurate as amniocentesis and requires only a simple blood test from the expecting parents arm, its carries no risk of miscarriage.
What is Non-Invasive Prenatal Screening (NIPT)?
NIPT is an accurate and comprehensive non-invasive chromosomal screening test to give you the reassurance you need during your pregnancy.
During pregnancy, some of the DNA from the baby crosses into the mother’s bloodstream. DNA carries the baby’s genetic information on chromosomes. A laboratory test that uses a simple blood sample taken from the mother can find the baby’s DNA in the mother’s blood and look for certain chromosome conditions that could affect the baby’s future health.
Most people have 23 pairs of chromosomes; everyone therefore usually carries a total of 46. The NIPT screen is highly effective in determining if there is only one chromosome where there should be a pair, or if there is an extra chromosome, especially for the chromosomes that are responsible for Down’s Syndrome, Edwards Syndrome, Patau Syndrome and certain sex chromosome abnormalities.
Current methods used for genetic diagnosis, i.e. amniocentesis or chorionic villus sampling (CVS), are invasive and carry a risk of miscarriage. The NIPT screen requires only a blood sample from the mother, and is safe for both mother and baby.
An NIPT screen offers you a safe, accurate test for most of the major chromosomal conditions for those pregnant women who want the reassurance that comes from having the most accurate and comprehensive genetic information available.
Currently the NHS offers combined screening between 11 – 13 weeks using ultrasound nuchal measurement and two placental blood markers to detect pregnancies at high risk of being affected by Down’s syndrome.
This type of screening should identify approximately 90% of affected pregnancies but on average 1 in 40 pregnancies will be given a high risk result which means a CVS or amniocentesis test is likely to be suggested.
NIPT however will identify more than 99% of affected pregnancies and screens less than 1 in 1500 pregnancies high risk
NIPT screening brings you:
Access to safe prenatal testing: putting both you and your baby at zero risk
Information in the first trimester – testing can be performed as early as 10 weeks gestation
Accurate results: clinical data shows detection rates over 99%
This is my offer you the choice of two NIPT screens; NIFTY™ from BGI Health and Harmony™ by Ariosa
NIPT screens for trisomies 21, 18, 13 and other types of aneuploidies plus fetal gender if requested.
Based simply on the peripheral blood of the mother, the test is zero risk to the pregnancy.
|this is my: Non Invasive Prenatal Test: NIPT|
|Type of cfDNA analysis||Massively parallel genomic sequencing||Direct Analysis|
|Screen Population||GENERAL & HIGH RISK||GENERAL & HIGH RISK|
|About the test|
|One stop service||YES||YES|
|Result availability||10 – 14 DAYS||14+ DAYS|
|Gestational age||10+ weeks||10+ weeks|
|Fetal DNA analysis||YES||YES|
|Maternal blood mark||NO||NO|
|Ultrasound scan||11+ week anatomy & nuchal+ screen advised|
|Multiples (Twins)||Multiples (Twins)|
|Risk analysis||Individualized risk score & result provided for each patient|
|Result from fetal fraction||>3.5%||>4%|
|Result after 2nd draw||99%||65%|
|Chromosomes anaylsis||DR / FPR / PPV||DR / FPR|
|T21||99.65 / 0.014 / 99.08||>99% / <0.1%|
|T18||99.98 / 0.02 / 96.4||>98% / <0.1%|
|T13||99.98 / 0.018 / 88.64||80% / <0.1%|
|Fetal sex Y(optional)||YES||YES|
|Y aneuploidy (optional)||Y aneuploidy (optional)|
|X0 (Turner syndrome)||YES||YES|
|XXX (Triple X)||NO||YES|
|XYY (Jacob’s syndrome)||NO||YES|
|XXY (Klinefelter syndrome)||NO||YES|
|Micro deletions||Via NIFTY PLUS™||NO|
|Sample turnaround*||10 – 14 days||14+ days|
|Cost (singleton / multiple)||Price from £295||Price from £550|
Frequently Asked Questions About NIPT Screening
How does the NIPT screen work?
NIPT screening is a non-invasive prenatal test which means that the test is safe for you and your baby. To have the test done, our team of specialists simply performs a routine ultrasound scan to check your baby’s gestational age and well-being then we draw a small sample of blood from your arm. During pregnancy, some of the DNA from the baby crosses into the mother’s bloodstream. DNA carries the baby’s genetic information on chromosomes. NIPT is a laboratory test that uses this small blood sample from the mother to find the baby’s DNA and to look for certain chromosome conditions that could affect the baby’s health.
The screen looks for certain chromosome conditions in the baby. Humans have 23 pairs of chromosomes for a total of 46. The first 22 pairs are numbered 1 through 22. The last pair determines sex. Girls have two X chromosomes, and boys have one X and one Y chromosome. Health and development problems occur when there are extra or missing chromosomes.
When there is an extra copy of any one chromosome — 3 copies instead of 2 — it is called a trisomy.
When there is a missing copy of any one chromosome — 1 copy instead of 2 — it is called a monosomy.
Trisomy 21: This is caused by an extra copy of chromosome 21 and is also called Down’s syndrome. This is the most common cause of intellectual disability. It may also cause defects of the heart or other organs as well as hearing or vision problems.
Trisomy 18: This is caused by an extra copy of chromosome 18 and is also called Edwards syndrome. This causes severe intellectual disability, as well as serious defects of the heart, brain and other organs. Babies with Edwards syndrome usually pass away before one year of age.
Trisomy 13: This is caused by an extra copy of chromosome 13 and is also called Patau syndrome. This causes severe intellectual disability and many serious birth defects. Babies with Patau syndrome usually pass away before one year of age.
Monosomy X (also called Turner syndrome or 45,X): This is caused by a missing X chromosome and affects only girls. Girls with Monosomy X may have heart defects, hearing problems, minor learning disabilities and are usually shorter than average. As adults, they are often infertile.
What are the alternatives to NIPT screening?
There are other ultrasound and blood screening tests available during pregnancy. These tests can tell you if there is a high chance that your baby has a chromosome condition, such as Down’s syndrome. However, older types of screening tests have a higher chance of incorrect results. This means some pregnancies with a chromosome condition would be missed. It also could mean that some women with healthy babies may be given a result that incorrectly shows an increased chance the baby has a chromosome condition.
To know for sure if the baby has a chromosome condition, tests on the pregnancy itself, like chorionic villus sampling (CVS) or amniocentesis, can be done. Both of these have risks, including the small chance of miscarriage.
When will I get my results?
NIPT screens will give results within 14 days.
What kind of results will I get from my NIPT screen?
The report received will have one of these results:
- LOW RISK RESULTS: A low risk result means the chance that your baby has one of the chromosome conditions we list is very low.
- HIGH RISK RESULTS: A high risk result means there is a very high chance that your baby has that condition. We will at this point advise you that should you so wish an amniocentesis or CVS should be performed to confirm the NIPT findings.
There is also a slim chance that no results will be obtained from your initial sample. In this case we recommend sending another sample.
Who can be tested?
NIPT screens are available to women of any age and ethnicity who are pregnant.
Should I get an NIPT screen?
Many pregnant women have concerns about the health of their baby. If you have concerns, we are more than happy for one of our specialists to talk with you. He or she will advise you as to what tests you might want to have to help give you peace of mind.
Some women have a higher chance for chromosome abnormalities because of their age, family history, or other screening test results. These women may choose to have an NIPT screen to help them decide if they want a CVS or amniocentesis.
Most women who have the NIPT screen will find out their baby is at low risk for the conditions tested. This means that the chance of the baby having one of these conditions is very low, which can be reassuring. When the test result shows a high risk, it is important that we talk with you about your next steps.
How much does NIPT cost?
this is my: understands that prenatal testing is an important decision for expecting mothers and their families. For this reason we strive to make this test affordable for all patients. Our NIPT screens start from £295.
Do I need to have any other tests?
NIPT does not replace your first trimester nuchal scan. If you have opted to screen prior to 11 weeks gestation you are strongly advised to have an ultrasound scan to check your baby’s anatomy.
NIPT does not replace diagnostic genetic testing such as CVS or amniocentesis. If you are not reassured by your NIPT screen the result can only be absolutely verified by having an invasive diagnostic test but this does carry a small risk of miscarriage
The NIPT screen does not provide information on other rare chromosomal abnormalities. If the ultrasound scan shows a high nuchal translucency or other major physical defects such as brain or heart abnormalities, the risk for some rare chromosomal defects may be high. In such cases, you may choose to have a CVS or an amniocentesis.
The non-invasive prenatal test does not provide information on other physical defects such spina bifida, or information on fetal growth. It is therefore advisable that you have all the usual ultrasound scans during your pregnancy.
How accurate is the BGI Health NIFTY screen?
The clinical validation study of BGI Health NIFTY test has been finished by a multi-centered collaboration. This non-invasive screening for fetal aneuploidies has shown over 99% consistency with the result of the golden standard of the prenatal diagnosis, karyotyping. 3464 NIFTY test in phase I clinical validation with fetal karyotyping analysis indicated that it is highly accurate. Table 1 shows the comparative results of our NIFTY test of trisomies 21, 18 and 13 with fetal karyotyping analysis.
In 2009-2011, BGI performed phase II clinical testing on 11105 patients. The result strongly proved that NIFTY test is highly sensitive and accurate.
Table 1 shows comparative results of our NIFTY Test and fetal karyotyping analysis for Trisomy 21, Trisomy 18 and Trisomy 13 with fetal karyotyping analysis on phase I and II.
NIFTY website visit http://niftytest.com
How accurate is the Ariosa Harmony™ screen?
The Harmony Prenatal Test is intended to be used for women with singleton pregnancies of at least 10 weeks’ gestation and can be ordered for IVF singleton pregnancies including self-donor, unrelated egg donor and surrogate pregnancies.
DNA from the fetus circulates in the mother’s blood. Cell-free DNA (cfDNA) results from the natural breakdown of fetal cells (presumed to be mostly placental) and clears from the maternal system within hours of giving birth. During a pregnancy, cfDNA can be tested to give the most accurate screening approach in estimating the risk of a fetus having a common chromosome condition sometimes called a trisomy. This occurs when there are three copies of a particular chromosome instead of the expected two. The test looks to detect the following trisomies:
• Trisomy 21 is the most common trisomy at the time of birth. Also called Down syndrome, it is associated with moderate to severe intellectual disabilities and may also lead to digestive disease, congenital heart defects and other malformations.
• Trisomy 18 (Edwards syndrome) and Trisomy 13 (Patau syndrome) are associated with a high rate of miscarriage. These babies are born with severe brain abnormalities and often have congenital heart defects as well as other birth defects. Most affected individuals die before or soon after birth and very few survive beyond the first year of life.
The testing is non-invasive: it involves taking a blood sample from the mother. The pregnancy is not put at risk of miscarriage, or from other adverse outcomes that are associated with invasive testing procedures such as amniocentesis.
Clinical studies have shown that the Ariosa Harmony™ Prenatal Test has exceptional accuracy for detecting fetal trisomy.
A ‘high risk’ result is indicative of a high risk for a trisomy. The test identifies more than 99% of fetuses with trisomy 21, 97% of fetuses with trisomy 18, and 80% of fetuses with trisomy 13. After the test, the number of women screening high risk where a CVS or an amniocentesis is strongly recommended is less than 1%.
It is important to note that if the test results show there is a high risk that the fetus has trisomy 21, 18 or 13, it does not mean that the fetus definitely has one of these conditions, although it is highly likely. For this reason, in the event of a ‘high risk’ (or positive) result, follow-up testing by an invasive procedure is recommended.
In the same way if the test results show that there is a ‘low risk’ that the fetus has trisomy 21, 18 or 13, it is unlikely that the fetus has one of these conditions. However, there is a very small risk that not all trisomy fetuses will be detected.
All results should be interpreted by a clinician in the context of clinical and familial data.
Patients should continue with their usual scan appointments following testing.
Harmony™ website visit http://www.ariosadx.com/
Articles from the Press