If your child has Down syndrome, you likely already know many facts about them. You know that your child is loving and trusting. You know that their facial features may not look like every other child’s, but that doesn’t make them any less capable in this world. And you know that parenting a child with Down syndrome comes with as many rewards and challenges as parenting any child does.
What you might not know is the genetic side of Down syndrome. Let’s explore a few facts about Down syndrome so that you have a scientific context for your wonderful child.
Down syndrome revolves around chromosome 21
As a current or expectant parent of a newborn baby with Down syndrome, you might know that an extra chromosome is what causes the condition. Chromosomes live in the body’s cells and are what house a person’s genes. Each cell of a developing baby is supposed to receive 23 pairs of chromosomes, with one set coming from the mother and the other from the father, for a total of 46 chromosomes. In the case of a baby with Down syndrome, one of the chromosomes doesn’t separate properly and the baby ends up having three copies of chromosome 21 instead of two. This extra copy is what causes the differences in the development of physical features and cognition in people with Down syndrome.
There are three types of Down syndrome
While the above explanation of chromosomes is the general genetic reason behind Down syndrome, it doesn’t happen like that for every individual. In fact, there are three types of Down syndrome that differ based on exactly what happens to the chromosomes during development. The first type is called trisomy 21 and is caused by the extra copy of chromosome 21 in every cell, as explained above. This is the most common form of Down syndrome.
Another one of the types of Down syndrome is known as mosaicism. This type happens when a child has an extra chromosome in some of their cells, but not all of them. People who have mosaic Down syndrome typically have fewer symptoms of Down syndrome than people who have trisomy 21. The final type of Down syndrome is translocation. With translocation, a person will only have an extra partial copy of chromosome 21. They still have 46 total chromosomes, but one of them has an extra piece of chromosome 21 attached to it.
Prenatal screening can detect the extra chromosome
In the United States, doctors often offer to screen for Down syndrome as a routine part of prenatal care. This screening has resulted in a decrease of 30% in the population of people with Down syndrome. However, for many expectant parents, learning that their child will have Down syndrome through a prenatal screening is simply a way to help them better prepare for their baby.
At the end of the day, your child is going to be characterized by their kindness and love for life, not by their chromosomes. While understanding the chromosomal reasoning behind why your child has Down syndrome can answer some of your questions, it ultimately doesn’t change the wonderful person that they are. If you have any additional questions about Down syndrome or prenatal screening, be sure to consult your doctor.
