IIRC this has already happened with Tay-Sachs, although not by editing, just by testing (either before marriage, or of embryos). I think the disease is now more

IIRC this has already happened with Tay-Sachs, although not by editing, just by testing (either before marriage, or of embryos). I think the disease is now more common among non-Ashkenazim, who are unlikely to be tested. Seems like a useful test case to think about, and read about, rather than relying only on imagination.