Prenatal Screening: What are Microdeletions & Why Should We Test for Them

prenatal screening for microdeletions

Women who are expecting a baby are no strangers to tests. From their first pregnancy test to the baby’s first hearing test after birth, there is a lot to be screened for and even more to be monitored throughout the course of your pregnancy. While chances are your baby will be born happy and healthy, at your first prenatal appointment your doctor should outline the most important tests and their benefits.

One of those tests, the NIPT, is used to screen for common chromosomal conditions such as Down syndrome as early as the 9th week of pregnancy, but a lot of mums-to-be haven’t yet heard of microdeletions or know how to test for them.

What is a Microdeletion?

Everyone has 46 chromosomes. We receive 23 from our mom and the other 23 from our dad. When a small piece of a chromosome is lost, it is known as a microdeletion.

Some may lead to no physical or mental issues at all, but other more severe deletions could have major impact on a baby’s development. Some of the most common microdeletions to be tested for include DiGeorge syndrome, Angelman syndrome, Prader-Willi and Cri-du-chat syndrome.

Most Common Microdeletion – DiGeorge Syndrome

Also known as 22q11.2 deletion syndrome, DiGeorge syndrome is one of the most common microdeletion conditions. For those who are diagnosed, it is found that a small piece of the middle of chromosome 22 has been deleted. The syndrome can occur in about 1 in every 2,000 births – making the occurrence rate similar to Down syndrome.

There are a wide range of signs and symptoms associated with DiGeorge syndrome. Some of the most common include a cleft palate, congenital heart defects, growth delays, distinct facial features, mental health and psychiatric disorders, and issues with breathing or hearing.

Who is More Likely to Have Baby with Microdeletion?

Certain risk factors, including the mother’s age and family history, can play a major role in the development of a fetus. Chromosomal conditions, such as Down syndrome, are more likely to occur in babies who are subjected to these risks. However, that’s not the cases with microdeletions.

This genetic abnormality normally occurs at random. In fact, it is estimated that many people have chromosomes with a microdeletion, it is just not profound enough to affect their development. Fortunately, there are genetic tests available to detect microdeletions such as DiGeorge syndrome.

Microdeletions Tests – How to Detect the Chromosome Condition

In the past, the only way to thoroughly analyze a baby’s DNA to screen for chromosome abnormalities during pregnancy was with chorionic villus sampling (CVS) or an amniocentesis – both of which come with a slight risk of miscarriage.

Now with modern advancements and more precise technology, the non-invasive prenatal test, also referred to as the NIPT, has made it possible for geneticists to closely examine the baby’s DNA that floats throughout the mother’s blood, providing patients with highly-accurate results.

The NIPT, which is taken by pregnant women as early as their 9th week of gestation, poses no risk for the mother or baby. Additionally, it only requires a small blood sample from the mother and results are usually available within 2 weeks. The NIPT tests for five of the most common microdeletions in addition to screening for other common chromosomal abnormalities like Down syndrome.

What if my NIPT Results are Positive?

The NIPT is a screening test, not a diagnostic test. This means that while the NIPT can screen for genetic abnormalities such as microdeletions during your pregnancy, it cannot tell you with 100% certainty that your baby will be born with a chromosomal condition. The test calculates your odds and helps you determine if a diagnostic test is necessary.  If you do receive a positive result, you can take steps now to improve the quality of life for your diagnosed baby and for your family.

A major benefit to screening for genetic abnormalities during pregnancy is the time and empowerment it allows expecting parents. In addition to educating yourselves, you and your partner can set up appointments with medical specialist who will walk you through the syndrome and the therapies your baby is likely to need. Take advantage of microdeletion testing now to better prepare for your future.

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