They've been occasionally been referred to as “mutates”, as opposite to “natural” x-gene carrying mutants.

Also if their powers (or some form of power) can be inherited by their children (or clones), there's probably been some genetic change.

This is definitely the case for Spider-Man (so many clones! 😩) or the Hulk (though that could be radiation poisoning), and might be the case for the Fantastic Four (though it depends on the writer, and one of their children is a mutant, not a mutate, and radiation poisoning is also a possibility in their case).