Collectively rare diseases are very common when you add them all up because there are many thousands of them and 80% of those rare diseases have a genetic basis.
A solution works in a similar way to the Covid vaccine made by AstraZeneca. It uses a harmless virus to take a genetic message into the body.
And that vector system is used to then ferry that genetic payload intravenously to the liver where it takes up residence, and hopefully, after a single injection, corrects that person's genetic abnormality for the rest of their life.
https://www.abc.net.au/radionational/programs/healthreport/gene-therapy-rare-diseases/101405506