Is the ban on genetic modification a Federation thing, or is it just a Starfleet thing? They may not be the same thing.

How about DS9’s “The Wire”. A powerful story of isolation, suffering, addiction, and the power of friendship coupled with medical professionalism. I have to admit I don’t recall anyone else’s role other than Dr. Bashir’s and Garak’s (and some momentary spots with Quark and some random nurse). I don’t remember what the B plot was.