Genes Matter

Non-invasive prenatal test and newborn screening: what are my options?

Pregnancy is a period full of excitement and also doctors’ visits. It’s important to ensure there are no health complications for both mother and unborn child. There are different routine tests and check-ups for pregnant women to make sure everything is going well. However, thanks to advances in technology and science, it is possible to supplement these screenings with genetic tests that will provide even more information about the baby’s health before and after birth. Want to find out more? Keep reading!

The most common pregnancy check-ups

The first test that is carried out on all women who go to the doctor thinking they are pregnant is a blood test. This confirms the high levels of certain hormones that are found in a mother’s blood and provides a definitive confirmation. This analysis also helps to determine the state of the mother’s health in preparation for pregnancy. 

Additional tests and ultrasound scans will be carried out from this point onwards and will be scheduled throughout the different stages of pregnancy to monitor progress. Some of the parameters studied in these checks are:

  • Blood type and Rh: it is important to determine this since the treatment for couples is more specific where the mother is Rh negative, and the father is Rh positive 
  • Hemogram: pregnancy puts more strain on the body and may worsen existing anaemia, so it might be necessary to supplement the blood supply. 
  • Serology (toxoplasmosis, rubella, hepatitis, HIV, etc.): this tells us if the mother has previously had various infections that can cause problems if they occur during pregnancy for the first time. 
  • O’Sullivan’s test: determines blood glucose levels and rules out gestational diabetes 
  • Urine tests: these ensure that the kidneys are functioning properly and can detect urinary infections. 

Although more than 95% of pregnancies result in the birth of a healthy baby, it is important to remember that 5% of babies are born with some kind of abnormality. It is essential for a couple to know as soon as possible if the baby they are expecting is healthy or whether there are any problems. This way they can make decisions and assess special childbirth and postnatal care requirements. 

Practically all women in Spain undergo a combined first-trimester screening, which provides a statistical value for the risk of chromosomal abnormalities. The result is generated by combining (hence the name) the mother’s age, two biochemical parameters and ultrasound data.  Both the blood test and the ultrasound should be performed between weeks 11 and 13+6. During the ultrasound, in addition to checking that everything is in order and that the size of the foetus is normal, they measure the nuchal translucency (NT). 

The NT is the area behind the nape of the foetus and is a necessary ultrasound parameter for combined first-trimester screening. If it is enlarged, there is an increased risk of Down’s syndrome (caused by a trisomy on chromosome 21), Patau syndrome (caused by a trisomy on chromosome 13), or Edwards syndrome (caused by a trisomy on chromosome 18) in the foetus.

If you want to know more about how the trisomies that cause these syndromes are produced, as well as other genetic abnormalities that could affect your baby’s health, you can read our ebook “Disease Prevention for your Child’s Health Using Genetics”, where we explain everything. 

The combined first-trimester screening test examines the levels of two hormones: the pregnancy-associated hormone PPAP-A (a lower value is associated with an increased risk of Down’s syndrome), and the free portion of human chorionic gonadotropin or BhCG (an elevated value is associated with an increased risk of Down’s syndrome). 

Both the NT value and those of both hormones are factored in with the mother’s age to produce a risk index, which indicates the probability of the foetus having Down’s syndrome, e.g. 1/800. This value means that, for every 800 pregnancies with the same ultrasound values, biochemical values and maternal age, one will have Down’s syndrome, which is a low probability. It is considered high risk when the value is greater than 1/250 or 1/270, in these cases doctors will request a diagnostic test to verify the result, in which case an invasive procedure, such as an amniocentesis or a chorionic villus sampling, will be necessary. 

An important point to note is that combined screening has its limitations, with a detection rate of around 95%, i.e. 5 out of every 100 foetuses with abnormalities will not be detected; with a false positive rate of 5%, which means that 5 out of every 100 women will have an unnecessary invasive test, since the foetus will not have a trisomy. 

Non-invasive prenatal tests or NIPT (cell-free DNA tests of maternal blood) are used today to avoid this problem and to obtain more reliable results. NIPTs are more accurate because they analyse genetic material directly from the placenta, which significantly reduces false negative and false positive results.

Non-invasive prenatal test (NIPT)

This type of test analyses DNA from the foetus that is freely floating in the mother’s blood; it is therefore also known as the cell-free foetal DNA test. In a puristic sense, the DNA does not come from the foetus, but from the placenta, so these types of tests are considered to be screening tests, not diagnostic tests.

There are both fragments of DNA from the mother and fragments from the placenta’s cells in maternal blood, which can account for between 1 and 20% of the total cell-free DNA in the blood. The percentage of cell-free foetal DNA increases in the first few weeks of pregnancy, so it is best to wait until the tenth week of pregnancy to perform a NIPT test, at which time the concentration is at its highest. If you want to know more about this type of test you can read our article “What is the cell-free foetal DNA screening for?” 

By analysing these small DNA fragments, we can look at the foetus’ genetic information in a non-invasive manner. This greatly improves the efficiency of this prenatal screening, with a 99%+ detection rate and a false positive rate of 0.1%. Therefore, although it is also a screening test, it significantly reduces the number of unnecessary invasive procedures, detecting almost all the cases at risk of Down’s syndrome. Reducing the number of invasive procedures is very important given that they have a small risk of foetal loss. Although this is a small risk, it is better if it can be avoided completely.

Another advantage is that this screening covers other genetic abnormalities that are not examined with the combined screening. Depending on the test, the following abnormalities can be analysed: 

  • Trisomies 21, 13 and 18: these trisomies are covered by the combined screening, but the reliability is considerably higher in this screening
  • Sex of the foetus: you can find out the sex of your baby before the 3-month scan, and even look for abnormalities in the sex chromosomes that could cause syndromes such as monosomy of the X chromosome, triple X or Klinelfelter’s syndrome (XXY chromosome)
  • Aneuploidies in all chromosomes: it is possible to detect an abnormal number of chromosomes in the remaining human chromosomes
  • Microdeletions: these are small deletions that occur in the chromosomes, causing syndromes such as DiGeorge’s syndrome or Angelman’s syndrome. 

Today, it is increasingly common for mothers to take this test for its enormous benefits. There are numerous tests founded on this technology, and consequently their effectiveness and sensitivity are quite similar. 

Since the tests can examine different types of abnormalities, the price varies according to the abnormalities you want investigated. Of course, if you only want to check for the most common trisomies, the price will be lower than if you also wanted check for microdeletions or aneuploidies in all the chromosomes. 

Many companies offer these tests and prices typically range from €400-700. 

Veritas are offering you myPrenatal from €450, with the added value and support of a team of medical and scientific professionals.

What happens postpartum

Once the baby is born, care is also essential. Two routine tests are carried out as soon as the baby is born: 

  • The Apgar test: performed immediately after birth, it analyses the baby’s adaptation and vitality, evaluating breathing, heart rate and reflexes, among other parameters.  
  • The heel prick test: performed 48-72 hours postpartum, it consists of a blood sample soaked in paper, which identifies different types of diseases, mainly metabolic. However, the number of diseases covered varies in each autonomous community, but they all cover at least 7.

This heel prick test is another screening test which requires a follow-up diagnostic test to confirm a positive result. This test is crucial because, thanks to the early detection of these diseases, specific medical treatment can be provided to prevent disease development as much as possible, taking action early and, possibly, even avoiding more serious lifelong implications. 

However, the heel prick test excludes many other diseases that can also seriously impact your baby. These are diseases that can be prevented, or their symptoms alleviated if prompt action is taken. You might now be asking yourself; how can I identify more childhood diseases that are not covered by the heel prick test? At Veritas we have introduced a new test to complement the heel prick test. It is a test that can be performed on your children from birth and throughout their early years. 

myNewborn

It consists of a postnatal genetic test or neonatal screening, which sequences your baby’s entire exome. The exome is the part of our genetic material that codes for proteins. If there is any alteration in these sequences, it is likely that the proteins they code for will not work properly and, therefore, the baby will have some kind of disease. If you want to know more about the concepts “exome” or “proteins”, we recommend reading our article Genes and chromosomes: how do they determine our life and health? 

The test analyses over 400 genes to determine the risk of about 390 childhood and adult diseases that can either be prevented or symptoms mitigated by taking appropriate early measures. Personalised follow-up checks and treatment for the child is provided, even before the onset of symptoms. It is the perfect addition to the heel prick test, since it has the same objectives, but covers more diseases.

It only requires a saliva or blood sample, a simple method to obtain a great deal of information. 

Among the diseases examined are most of those included in the heel prick test, such as cystic fibrosis. Also included are metabolic, cardiovascular, syndromic, endocrine, hearing and neurological conditions, among others, which consequently allow us to tailor the newborn’s medical care to them. Broadly speaking, all these diseases are divided into four groups: actionable diseases that appear during childhood, diseases that appear in adulthood but are actionable during childhood, diseases that also appear in the heel prick test, and non-actionable but common diseases, where the test can facilitate early diagnosis and specific supportive measures and multidisciplinary treatment, thus improving the signs and symptoms of the disease. 

The myNewborn test has been designed by a group of experts, including members of Harvard University, and is based on the BabySeq project, conducted by the US Institute of Health, which sought to sequence the genomes of healthy and sick newborns in order to implement genetic analysis in clinical practice. This study revealed that about 10% of the babies had childhood-onset diseases. 

One of the most essential features of this test is that it includes a genetic counselling consultation. Just like with any medical check-up, for example, when you get a test to check your heart health, a cardiologist will explain the results to you. When you have a genetic test, it is essential that a geneticist explains the results, the consequences, and advises you on the next steps to take depending on the results. It is crucial that you understand what information you will be receiving and how to use it for the medical care of your young ones. 

So you can see how useful it really is, here are some of the diseases covered by this test:

Glucose 6 phosphate dehydrogenase deficiency (G6PD gene)

Glucose 6-phosphate dehydrogenase is an enzyme that is essential for red blood cells (the most abundant components in the blood that are needed to transport oxygen to the various organs and tissues) to perform their function properly.

If there is a deficiency in this enzyme, eating certain foods such as beans or taking drugs such as non-steroidal anti-inflammatory medication, leads to the destruction of red blood cells, also known as haemolysis. Although this usually happens in short episodes, since the body continues to synthesise red blood cells, they can cause shortness of breath, increased heart rate, fever and jaundice, among other symptoms. 

If we know about the presence of this deficiency, the symptoms can be avoided by eliminating the foods and drugs that trigger it, from the diet.

Usher syndrome (USH2A gene)

This syndrome causes hearing loss and retinitis pigmentosa, which is an eye disorder that causes eyesight to deteriorate over time. There is no treatment that prevents this disease from developing, but there are measures that can help mitigate its impact on the child, such as the use of hearing aids and the use of specific devices or aids to enable them to carry out their daily activities. 

Familial hypercholesterolemia (LDLR gene)

With this disease, cholesterol levels in the blood are high from birth because the body cannot remove it properly. The LDLR gene codes for a receptor that captures circulating LDL particles also known as “bad” cholesterol. When the LDLR gene is altered, the receptor does not function properly and LDL cholesterol continues to circulate in the blood without being removed.

Cholesterol level is an essential parameter in our cardiovascular health, and it is estimated that 50% of people suffering from this disease will have cardiovascular disease before the age of 55. However, knowing this information enables us to adapt the child’s lifestyle or start drug treatment from childhood. This is always done at the discretion of the specialist and in order to minimise the cardiovascular impact in adulthood. 

These are just three examples of the 300+ diseases covered by the myNewborn test, the results of which can help you understand which habits to change and even start early treatment for your newborn. 

Nowadays it is possible to obtain useful information that can help you make simple, informed decisions, without putting you or your child’s health at risk. More and more diseases are being analysed in a more reliable way, to make sure that everything is working smoothly both during and after birth. 

At Veritas we are committed to protecting your health, which is why we have developed myBabyHealth, a complete service that includes a non-invasive prenatal test during pregnancy and myNewborn once your baby is born. If you would like more information, please do not hesitate to contact us!

This article is based on the original written by Paula Penedo from the Scientific Department.

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