Down's Syndrome Screening

What is Down syndrome?

Down syndrome is a genetic disorder caused by the existence of an extra chromosome, a thread-like structure inside the cell that consists of proteins and DNA that are then arranged in genes. Chromosomes are responsible for creating the baby’s blueprint. In other words, it is the deciding factor in the baby’s functions and form. Down syndrome is associated with growth delays, a certain degree of intellectual disability, and distinctive facial characteristics.

What causes Down syndrome?

Typically, a baby is born with 23 pairs of chromosomes, but a baby with Down syndrome is born with an extra chromosome, i.e., three copies of chromosome 21 instead of the usual two. For this reason, Down syndrome is also called trisomy 21. There’s no particular reason as to what could lead to this. There’s nothing that parents could have done to prevent this or expedite the condition.

The only cause that has been linked to Down syndrome is the age of the mother. A mother is comparatively more prone to bearing a child with Down syndrome when she has hit the age of 35 or more.

Features of Down syndrome

As much as the features of Down Syndrome can be covert, like a poorly functioning immune system, certain qualities could be quite apparent in the condition:

• Flathead, flattened face, especially the bridge of the nose
• Irregular outer ears
• Shortened neck
• Shortened hands
• Extended tongue (comparably longer)
• Slanted eyes 
• Low muscle tone
• Irregular teeth 
• Palmar crease 
• Shorter height 
• Smaller fifth finger, turning towards the thumb.

Down syndrome screening

There are a few ways of knowing whether the newborn child has Down syndrome. Once the child is born, the physical characteristics will give the condition away, but certain tests before the birth could tell with some accuracy whether or not the pregnancy will lead to a child with Down syndrome. The screening can be broken down into a few types:

1. First Trimester Screening: The first screening can be done as early as 10 weeks of pregnancy. There are two ways of doing that:

• Blood test: The blood could show signs of certain proteins that may rule out the possibility of Down syndrome.
• Ultrasound: An ultrasound image could be used to detect fluid in the baby’s neck that is a sign of Down syndrome.

2. Second Trimester Screening: The blood test done during the second trimester is done to detect the levels of four types of proteins in your blood: alpha-fetoprotein, human chorionic gonadotropin, estriol, and inhibin (hormones made by the placenta).
3. Combined/Integrated Tests: As the name suggests, this is where the results of both your previous tests are combined to detect the presence of Down syndrome.
4. Cell-Free Foetal DNA: This test involves taking a blood sample and checking it for large amounts of material from the affected chromosome, i.e., chromosome 21.

Risks involved in tests

There aren’t any major risks involved in screening tests. There may be some bruising from the blood tests or ultrasound, but the symptoms will fade away quickly enough.

What the results mean

• Positive screening result: if the test results come out positive, your child is at a higher than average risk of acquiring Down syndrome. 
• Negative screening result: if the test results come out negative, that means everything is normal and your kid isn’t likely to have Down syndrome.

Conclusion

I hope this article has helped you better understand the nuances of Down syndrome and how to screen for it. But it's very important to know that the test results don't say anything about the child's abilities.

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