system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 : How come we can’t remove the extra chromosome that causes Down syndrome?

You can be born missing parts of a chromosome how come we can’t just recreate this process and remove the extra chromosome?
gpt
A person's DNA is stored independently in every cell of their body. It is thus impossible to execute any sweeping change after a person's cells have multiplied to the point where they are grown.

Even if you could, they are already grown, and so changing their DNA will not cause their body to magically rebuilt itself.