What is Trisomy 18? Let's talk about it simply.

It's normal to feel a lot of fear and anxiety when you hear an unfamiliar word like "Trisomy 18" when talking to your doctor about your unborn baby. What kind of condition is this, why is this happening, and did something wrong on my part come to mind? Don't worry. Today, let's understand the condition called Trisomy 18 very simply, as if we were talking to a friend.

What exactly is Trisomy 18?

Simply put, trisomy 18 is a condition caused by a problem with the chromosomes that carry genetic information in our bodies. Another name for this is Edwards syndrome , in honor of the doctor who first described the condition.

Think of our body as a big building. The blueprint for this building is contained in things like books called chromosomes. The genes inside these books are the instructions for how every part of our body, from the color of our hair to the way our heart works, should develop.

Normally, a healthy child receives 23 chromosomes from the mother and 23 from the father. The total is 46. These are arranged in pairs. That means there are two copies of chromosome 1, two copies of chromosome 2, and so on, up to 23.

Are there types of trisomy 18?

Yes, there are mainly three types:

1. Full Trisomy 18 : This is the most common type. Here, every cell in the baby's body has an extra 18th chromosome.

2. Partial Trisomy 18: This is very rare. Instead of a complete extra chromosome, only part of the extra chromosome 18 is present in the cells. This extra part may also be attached to another chromosome (translocation).

3. Mosaic Trisomy 18: This is also a rare condition. Here, only some of the cells in the baby's body have the extra chromosome. The other cells are normal. It's like different cells are mixed together like mosaic tiles.

How common is this condition?

The second most common chromosomal disorder is trisomy 18. The first is the well-known Down syndrome , or trisomy 21.

According to statistics, about one in 5,000 babies born may have trisomy 18. Of these, the most commonly reported are girls. However, in reality, many more fetuses are affected by this condition. However, because the complications associated with this condition are severe, most of the time those babies are lost in the womb during pregnancy.

What are the symptoms of a child with trisomy 18?

Babies born with trisomy 18 are often very small and weak . They can have a number of serious health problems and physical changes. Some of these are listed in the table below.

What causes this? Who is at risk?

This is the question that many parents ask. "Is this my fault?"

However, the risk of these chromosomal defects increases slightly as the mother ages (especially after age 35). However, a mother of any age can have a child with trisomy 18.

If you already have a child with trisomy 18, the risk of having the condition in your next pregnancy is between 0.5% and 1%. However, if you or your partner has the genetic change (translocation) that causes partial trisomy 18, which we talked about, the risk may be even higher. It is very important to talk to your doctor about this and, if necessary, see a genetic counselor.

Can this be detected during pregnancy?

Yes, it is definitely possible. The doctor will first take a blood sample from the mother ( screening test ). Although this cannot be 100% certain, it can tell if the baby is at increased risk of having a chromosomal defect such as trisomy 18.

If this test shows there is a risk, there are further tests to confirm the situation.

• Chorionic Villus Sampling (CVS): A small sample of the placenta is taken and tested during the early weeks of pregnancy (weeks 10-13).
• Amniocentesis: After 15 weeks, a sample of the amniotic fluid surrounding the baby is taken and tested.

Both of these tests can accurately count the child's chromosomes and confirm with certainty whether or not they have trisomy 18.

In addition, an ultrasound scan performed after 12 weeks can also raise suspicions about this condition by looking at things like the baby's growth, heart shape, and position of the limbs.

Is there any treatment? What is the child's future?

This is a very sensitive topic to talk about. There is no cure for trisomy 18 yet . This is because it is a genetic change that is present in every cell of the baby's body.

However, the lack of treatment does not mean that nothing can be done for the child. Supportive care can be provided to ensure that the child is as comfortable and as well-off as possible.

• Surgery for certain things, like heart defects.
• Providing necessary medicines.
• Feeding tubes if there is difficulty in drinking milk.
• Support for breathing difficulties.

Some parents, instead of treating their child with pain, choose to keep them comfortable for a short time, with love and affection. This is called comfort care . These decisions are very personal. It is important to talk openly about all of these options with your doctor.

Unfortunately, due to the serious health problems that come with this condition, many children have a very short lifespan. About half of all babies born die within the first week. Less than 10% live to celebrate their first birthday. Even those babies who survive require constant medical care.

Caring for a child like this can be mentally and physically exhausting for parents, so it's essential to have support for yourself and your family on this journey.