Test for trisomy 21

Trisomy 21 (Down Syndrome): Diagnosis & Expectations

Trisomy 21, more commonly known as Down syndrome, is a genetic disorder causing developmental and intellectual delays. This disorder affects approximately 1 in every 700 babies.

Normally, a person has 23 pairs of chromosomes. Chromosomes are the packages of genetic information, made of DNA, that contain the instructions the body uses to build a person. Chromosomes come in 23 pairs, with most people having 46 total chromosomes. Trisomy 21 is caused when a person has three copies of chromosome #21 instead of the usual two, for a total of 47 chromosomes.

This extra chromosome affects a baby’s development, resulting in a number of medical issues which may include: a distinct facial appearance, intellectual disability, developmental delays and thyroid/heart disease.

How is Trisomy 21 Diagnosed?

Trisomy 21 can be identified prenatally through screening tests such as non-invasive prenatal testing (NIPT) and ultrasound examinations. The diagnosis can be confirmed prenatally with better than 99% accuracy through chorionic villus sampling (CVS) or amniocentesis. Both of these advanced diagnostics tests are available at the Cardinal Glennon St. Louis Fetal Care Institute. The diagnosis can also be confirmed shortly after birth through blood testing.

Mothers over the age of 35 or with a family history of Down syndrome have a greater risk of having a baby with trisomy 21 and may want to talk with a doctor about genetic counseling and additional screenings.

What Can I Expect When I Visit the SSM Health Cardinal Glennon St. Louis Fetal Care Institute?

At the SSM Health Cardinal Glennon St. Louis Fetal Care Institute, our team has the experience and technology to prenatally diagnosis Trisomy 21, as well as assist families in preparing for delivery and beyond.

Using a multidisciplinary approach, our team will evaluate your baby to determine its specific needs. Ultrasounds will be used to monitor your baby’s growth and development, and a fetal echocardiogram may be used to check for a heart defect, which is more common in babies with Trisomy 21. You will also work with our social worker to learn about the resources available for families of individuals with Down syndrome.

The risk of miscarriage and stillbirth increases in babies with Trisomy 21, but those who are carried to full term can usually be delivered vaginally without incident unless there are other reasons to consider an alternate mode of delivery.

How is Trisomy 21 Treated?

Down syndrome cannot be cured, but early intervention and treatment tailored to each child’s specific situation are helpful in managing this condition. Although babies born with Trisomy 21 will require some amount of care throughout their lifetimes, they can grow up to lead healthy, happy, productive lives.

What Can I Expect After My Baby is Born with Trisomy 21?

Typically, patients at the Cardinal Glennon St. Louis Fetal Care Institute will schedule a visit with a pediatric geneticist at SSM Health Cardinal Glennon Children's Hospital within the first few weeks of life and then follow up at the Down Syndrome Clinic where they will be able to see multiple specialists in one location.

The specialists a particular individual with Down syndrome will see depends on their specific health issues, which can include heart defects, frequent respiratory infections, poor muscle tone, seizures, sleep problems and/or hearing, eye and dental problems. Parents will need to make sure their child has routine medical checkups and be on the lookout for early signs of these issues.

Families are encouraged to work with the Down Syndrome Association of Greater St. Louis or to seek out support from similar organizations where they live. Families who are seen at the Cardinal Glennon St. Louis Fetal Care Institute whose babies are suspected to have Down syndrome will be given resources from appropriate organizations.

We understand that you have a lot of questions if your child has been diagnosed with Trisomy 21. That’s why we’re available to help 24 hours a day, 7 days a week. For more information or to schedule an appointment, call us at 314-268-4037 or toll free at 877-SSM-FETL (877-776-3385).

Patient Stories About Down Syndrome

At the St. Louis Fetal Care Institute, we understand the fear and confusion that come with the diagnosis of a prenatal medical condition. We share these patient stories to offer comfort, hope, and inspiration from other parents who have been where you are. Know that you are not alone - our team is here to support you every step of the way.

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Prenatal Testing for Down Syndrome | Patient Education

Down syndrome is a genetic condition caused by extra genes from the 21st chromosome. It results in certain characteristics, including some degree of cognitive disability and other developmental delays. Common physical traits include an upward slant of the eyes; flattened bridge of the nose; single, deep crease on the palm of the hand; and decreased muscle tone. A child with Down syndrome, however, may not have all these traits.

The incidence of Down syndrome in the United States is about 1 in 1,000 births. There is no association between Down syndrome and culture, ethnic group, socioeconomic status or geographic region.

Age-Related Risks

Generally, the chance of having a Down syndrome birth is related to the mother's age. Under age 25, the odds of having a child with Down syndrome are about 1 in 1,400. At age 35, the odds are about 1 in 350. At age 40, the odds are about 1 in 100.

Causes of Down Syndrome

There are three causes of Down syndrome:

Trisomy 21

An estimated 95 percent of people with Down syndrome have trisomy 21, meaning they have three number 21 chromosomes instead of two. We normally have 23 pairs of chromosomes, each made up of genes. During the formation of the egg and the sperm, a woman's or a man's pair of chromosomes normally split so that only one chromosome is in each egg or sperm. In trisomy 21, the 21st chromosome pair does not split and a double dose goes to the egg or sperm. An estimated 95 to 97 percent of the extra chromosome is of maternal origin.

Translocation

Translocation occurs in about 3 to 4 percent of people with Down syndrome. In this type, an extra part of the 21st chromosome gets stuck onto another chromosome. In about half of these situations, one parent carries the extra 21st chromosome material in a "balanced" or hidden form.

Mosaicism

In mosaicism, the person with Down syndrome has an extra 21st chromosome in some of the cells but not all of them. The other cells have the usual pair of 21st chromosomes. About 1 to 2 percent of people with Down syndrome have this type.

Prenatal Testing

Screening tests can identify women at increased risk of having a baby with Down syndrome. These tests have no risks of miscarriage, but can't determine with certainty whether a fetus is affected. Diagnostic tests, on the other hand, are extremely accurate at identifying certain abnormalities in the fetus, but carry a small — generally less than 1 percent — risk of miscarriage. We offer options for both screening and diagnostic testing.

Screening Tests

Sequential Integrated Screening — Sequential integrated screening is offered to all pregnant women by the state of California. This non-invasive screening is performed in two steps.

In the first step, which is performed between 10 and 14 weeks of pregnancy, a blood sample is taken from the mother and a nuchal translucency ultrasound is performed to measure the amount of fluid at the back of the baby's neck. If the blood test is scheduled prior to the ultrasound, we can provide the results at the end of the ultrasound appointment. The results of the blood test, the nuchal translucency measurement and the mother's age are used to estimate the risk for Down syndrome and trisomy 18.

The second step is a maternal blood test between 15 to 20 weeks of pregnancy. When the results of this blood test are combined with the results from the first trimester blood test and nuchal translucency ultrasound, the detection rate for Down syndrome increases. This test also provides a personal risk assessment for having a fetus with trisomy 18, Smith-Lemli-Opitz syndrome, an open neural tube defect or an abdominal wall defect.

Diagnostic Tests

Amniocentesis, chorionic villus sampling (CVS) and ultrasound are the three primary procedures for diagnostic testing.

Amniocentesis — Amniocentesis is used most commonly to identify chromosomal problems such as Down syndrome. When the fetus is known to be at risk, it can detect other genetic diseases like cystic fibrosis, Tay-Sachs disease and sickle cell disease.

An amniocentesis procedure for genetic testing is typically performed between 15 and 20 weeks of pregnancy. Under ultrasound guidance, a needle is inserted through the abdomen to remove a small amount of amniotic fluid. The cells from the fluid are then cultured and a karyotype analysis — an analysis of the chromosomal make-up of the cells — is performed. It takes about two weeks to receive the results of the test.

Amniocentesis detects most chromosomal disorders, such as Down syndrome, with a high degree of accuracy. Testing for other genetic diseases, such as Tay-Sachs disease, is not routinely performed but can be detected through specialized testing if your fetus is known to be at risk. Testing for neural tube defects, such as spina bifida, also can be performed.

There is a small risk of miscarriage as a result of amniocentesis — about 1 in 100 or less. Miscarriage rates for procedures performed at UCSF Medical Center are less than 1 in 350.

Chorionic Villus Sampling (CVS) — Like amniocentesis, chorionic villus sampling is used most commonly to identify chromosomal problems such as Down syndrome. It can detect other genetic diseases like cystic fibrosis, Tay-Sachs disease and sickle cell disease in at-risk fetuses. The main advantage of CVS over amniocentesis is that it is done much earlier in pregnancy, at 10 to 12 weeks rather than 15 to 20 weeks.

CVS involves removing a tiny piece of tissue from the placenta. Under ultrasound guidance, the tissue is obtained either with a needle inserted through the abdomen or a catheter inserted through the cervix. The tissue is then cultured and a karyotype analysis of the chromosomal make-up of the cells is performed. It takes about two weeks to receive the results.

The advantage of CVS over amniocentesis is that the test is performed much earlier in pregnancy, so results are typically available by the end of the third month. A disadvantage is that spinal cord defects cannot be detected. Expanded alpha fetoprotein (AFP) blood testing or ultrasound can be performed later in the pregnancy to screen for spinal cord defects.

There is a small risk of miscarriage as a result of CVS — 1 in 100 or less. Miscarriage rates for procedures performed at UCSF Medical Center are less than 1 in 350.

Ultrasound — The primary purpose of ultrasound is to determine the status of a pregnancy — the due date, size of the fetus and if the mother is carrying multiples. Ultrasound also can provide some information about possible birth defects in a fetus. All patients at UCSF Medical Center undergo a comprehensive ultrasound examination before any invasive tests are performed. Results of the ultrasound are explained at the time of the visit.

In some patients, an ultrasound raises concern of a possible abnormality in the fetus. We have extensive experience in performing and interpreting ultrasounds in pregnancy.

If You Receive a Positive Result

If you receive positive results on a screening test, we recommend that you discuss this with your doctor and a genetic counselor. Options for further diagnostic testing will be explained. The decision as to whether to have invasive genetic testing is up to you.

If a diagnostic test finds a genetic abnormality, the significance of such results should be discussed with experts familiar with the condition, including a medical geneticist and a genetic counselor, as well as your own doctor.

Trisomy test (13,18 and 21)

TRISOMY test is a quick, easy and safe method to learn more about the health of your unborn child.

The TRISOMY test is designed to rule out the most common genetic disorders (trisomy) of chromosomes 21, 18 and 13 that cause Down, Edwards and Patau syndromes. Before taking the test, you should consult a specialist in gynecology and obstetrics or a clinical geneticist.

Non-Invasive Prenatal Testing (NIPT) offered by various laboratories detects specific chromosome 21, 18 and 13 abnormalities and sex chromosome abnormalities. The tests give results that do not reveal any information about genetic or morphological fetal or maternal disorders other than those for which they are intended. Positive test results obtained with NIPT require confirmation by an invasive method.

Trisomy 21 (Down syndrome)

NIPT screening can detect more than 99% of cases of trisomy 21. Overall, only 1 in 1650 trisomy 21 as part of NIPT results based on normal pregnancy (0.06%)* was identified as false positive. With respect to the TRISOMY test, only 1 out of 1,842 results based on normal pregnancy was found to be false positive (i. e., less than 0.05%). The results of the latest validation study, which included a set of samples obtained from pregnant women and a set of samples containing embryonic trisomy 21, showed that the TRISOMY test is very sensitive.

Trisomy 18 (Edwards syndrome)

The sensitivity of NIPT in detecting trisomy 18 is lower than the sensitivity in detecting trisomy 21, namely in the amount of 90%*. The false positive rate of the TRISOMY test is 0.01%*. The false negative rate of the TRISOMY test (1 in 9 cases*) is comparable to the global rate (1 in 10 cases*).

Trisomy 13 (Patau syndrome)

Cases of trisomy 13 are rare in prospective studies, making calculations of the sensitivity and specificity of NIPT for this type of syndrome quite complex. In a recent international study based on 11,185 samples, 2 out of 2 positive cases* were successfully identified. The false positive rate for this type of trisomy in this particular study reached 0. 02%*. With regard to the TRISOMY test screening test, 3 out of 3 trisomies were correctly identified within 13 cases, with a false positive rate of 0.05%.

TRISOMY test is a non-invasive maternal blood test that, due to its high sensitivity and specificity, can exclude the presence of chromosomal abnormalities already after the 11th week of pregnancy. The test can also determine the sex of the unborn child if the mother-to-be wishes to know.

The TRISOMY test is suitable for any pregnant woman as early as the 11th week of pregnancy.
Compared to traditional screening methods, the TRISOMY test has higher sensitivity and specificity for the types of trisomy for which it is intended. As a result, it provides a significantly lower number of false positives.

The TRISOMY test is suitable for pregnant women who:

are anxious about possible health problems for the unborn child caused by the presence of one of the studied types of trisomy;
who are 35 or older at birth and have a negative biochemical screening test;
conceived as a result of IVF,
had a positive biochemical screening*,
received an ultrasound screening result indicating a higher risk of traceable trisomy types,*
have had a fetal chromosomal abnormality in the past,*
their parent(s) have been diagnosed with a Robertsonian translocation (increased risk of trisomy 13 or 21),*
suffer from recurrent miscarriage. *
*Medical genetic counseling should be done prior to the test.

TRISOMY test is also useful in case of gynecological and obstetrical contraindications that may complicate invasive prenatal testing (amniocentesis), for example:

increased risk of miscarriage,
current anticoagulant therapy (low blood clotting),
immune risk due to Rh incompatibility (Rhesus negative),
gestational age from 14 to 16 weeks of gestation (increased risk of complications due to amniocentesis),
placenta previa,
uterine fibroids.

Consult your gynecologist/obstetrician for any obstetric contraindications.

Consultation with an OB/GYN or clinical geneticist is required prior to non-invasive prenatal testing.

TRISOMY test results

Non-invasive prenatal testing results provide information on a selected number of the most common genetic chromosomal disorders (up to 85% of all fetal genetic disorders). It should also be remembered that testing cannot detect all existing genetic or developmental disorders.

If your NIPT test is negative, it will help you avoid invasive diagnostic tests such as amniocentesis, which carry certain risks associated with taking amniotic fluid.

The sensitivity and specificity of the TRISOMY test are over 99%.

Attention: Despite the high sensitivity and specificity in the detection of fetal trisomy on the 21st, 18th and 13th chromosomes, the TRISOMY test is considered a type of screening and not a diagnostic method. Therefore, a positive result should always be confirmed by taking amniotic fluid or chorionic villi.

A negative TRISOMY test result does not need to be confirmed by diagnostic amniocentesis, which means that in most cases the mother-to-be can avoid invasive tests and their associated risks.

If the TRISOMY test is positive, you should consult with a geneticist who will refer you for the examination required in this situation.

ᐈ Analysis for the presence of Down syndrome (trisomy 21 chromosomes), sex determination in Kyiv, prices

A non-invasive test that can reliably determine the presence of Down syndrome in a fetus and determine its gender. The clinical test is completely safe for both the fetus and the expectant mother. Down syndrome is the most well-known chromosomal disorder - it is diagnosed in one in 700-900 babies born worldwide. A medical diagnosis is made on the basis of a laboratory test and a doctor.

Each human cell contains 46 chromosomes, whose DNA determines appearance and development. Down syndrome results when there is an extra partial or complete copy of chromosome 21 (trisomy 21). There may be several reasons for this, the most common of which is an error in cell distribution, which results in an embryo with three copies of chromosome 21 instead of the usual two, which is why a laboratory test for this syndrome is so important.

As the embryo develops, an extra chromosome is replicated in every cell of the body. This type of development of Down syndrome is 95% of cases. About 4% of cases of this disease are due to translocation - while the total number of chromosomes in cells is 46, but an additional complete or partial copy of chromosome 21 is attached to another chromosome. Sometimes an additional examination is required to make a diagnosis. In addition, in very rare cases, there may be mosaic Down syndrome. It is diagnosed if there are two types of cells in the body: some contain the usual chromosomes 46, and some 47 (in them they find an additional chromosome 21). An additional partial or complete copy of the 21st chromosome, the embryo most often receives from the mother. If a woman gave birth to a child with trisomy 21, then it is believed that the probability of her having a second child with the same pathology is 1 to 100. By carefully studying the biological material of the study, it is possible to determine the exact indicators of the analysis. The non-invasive prenatal test for trisomy 21 in a fetus is a new and improved prenatal test capable of detecting the chromosomal material of a fetus circulating in the maternal blood. Also, this test determines the sex of the child with an accuracy of> 99.9%. Gender is optional. The possibility of passing the test with a quality guarantee is provided by the ADONIS clinic, where you can take the material in any convenient laboratory.

Non-invasive prenatal test for the presence of Down's syndrome, sex determination, is indicated for the diagnosis of women over 35 years of age with chromosomal abnormalities in relatives, with a history of reproductive losses, with 2 or more IVF failures, with changes in biochemical markers by screening. The exact diagnosis is determined by the doctor.

The conclusion of the study can be presented in two versions:

"Low risk" - the child is unlikely to have Down syndrome.

"High risk" - Evidence of trisomy 21 was found. This test result may indicate that the fetus has Down syndrome.

The price of the study is indicated on the website.

DNA sex determination reveals the Y chromosome.