I have recently studied how CRISPR works but there is something that I do not understand at all. I have heard a lot of people claiming that with this method it is possible to modify any genome by inactivating, activating, removing or adding genes. However, as far as I have understood, DNA regions can only be modified if they are in the interspaces of short palindromic repeats. So, my question is whether a gene that is not in the interspace of short palindromic repeats can be modified or removed? And if it is possible to do so, how?
When people talk about genome editing with CRISPR, they are really talking about using CRISPR associated nucleases like Cas9 and Cpf1. These nucleases are useful since their sequence specificity is determined by a guide RNA and they can therefore be used to cut at specific sites in the genome. This actually has nothing to do with the repeats themselves.
See this answer for a brief overview of how genome editing with Cas9 works.