How did that extra chromosome get there?

Eating too much greasy foods, drinking, taking drugs, smoking, or doing anything else dangerous while you're pregnant is not a good idea. But, it will NOT cause your child to have Down syndrome. There is nothing you can do to cause Down syndrome.

This is how it happens...


When the egg and sperm meet, they are both prepared with chromsomes that make a person who they are, genetically. The egg usually has 23 chromosomes and the sperm has 23 chromosomes, giving the person-to-be the regular 46 chromosomes in all of her cells.


In a person-to-be with Down syndrome, they have 47 chromosomes in each cell. So, either the sperm or egg gave 24 chromosomes instead of 23. It can be either the sperm or the egg, but not both.

That extra chromosome is the chromosome 21. Usually it just "swims" around with the other chromosomes. This is called Trisomy 21, the most common form of Down syndrome. Sometimes, it attaches itself to another chromosome (like chromosome 14). That's called "Translocation" Down syndrome. And rarely, it only appears in some cells and in other cells there is the usual 46 chromosomes. That's called "Mosaic" Down syndrome.

Want to know more? Pick another question.


What is Down Syndrome?
When a person has DS, what's she/he like?
Why is it called Down syndrome?


When a person has Down syndrome, that's not what they are all about. It's not even the most interesting part about them.

Just see for yourself

People

And if you have a child with DS, don't forget to add him/her.



Anything I missed?
Please, e-mail me and let me know at Basics@DSyndrome.com.


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