I don't really dwell on all those who may have it, but not yet know. In some ways I think it's good not to know everything that will happen to us. I don't think I would have liked to know earlier than I did, as I think it would have blighted what turned out to be many relatively well years.
But I do get what you're saying about the history going back much farther than the diagnosis. I think this is really common.
I can remember having a strange episode - 10 years ago? 20? when my neck wouldn't support the weight of my head. I remember travelling home on the bus - from town, I think - and having a job to stop my head lolling forward onto my chest. My neck muscles were so tired - I was having to prop up my head with one hand! I remember being like this for about a couple of days. There was no pain, and it cleared up by itself, so I never went to the doctor's. Thought I'd just pulled a muscle.
Then there were the times I got a completely dead arm during the night, and just thought I'd slept awkwardly. Woke up to find the arm completely useless, and a dead weight. When I tried to move, the arm flailed about uselessly, bashing into things and knocking them over! Because it wore off relatively fast once I was up and about, again, I never thought of going to the doctor's.
Then the same with a leg. I remember having a really bad cramp, and not being able to stand, let alone go upstairs. I remember it was cold, and I was on the floor of the living room. I hadn't fallen, but had sat down when the pain was so bad. I was worried I may be spending the night on the floor, and it crossed my mind that I might need to call an ambulance. But at the same time, I knew it was "only" cramp, and had never heard of anyone calling an ambulance for cramp, and thought it would be ridiculous. So I just sat on the floor and waited for it to pass - which it did, eventually. But nowadays, severe cramps, during which I can't walk are not uncommon. They hardly ever interefere with daily life, fortunately - I've never had one in public. It tends to be late at night, when I'm alone.
Loads of other stuff. Shoes have been a problem for years. I actually blamed quality of the shoes going downhill, moaning that: "You can never get a comfy pair these days!" Never suspecting that my health was deteriorating, not the standard of shoes.