Deep Vein Thrombosis.
The list above contains events or conditions which have stricken friends of mine in the last 12 months: all, to some degree, life-changing. It's very VERY scary - each individual case, in its own right, for obvious reasons: one doesn't ever wish to see such ailments, and their potentially devastating effects, visited upon peers, loved ones...anyone in fact. But what gives additional pause for thought is that all of those conditions (apart from the last one on the list - hardly a condition, but I'll come to that in a moment) have hit people of a similar age to me. In some cases slightly older (throat cancer, heart attack, diabetes). In the remainder, people younger than me.
That shocks me in all sorts of ways. Too close to home. A recognition that I've (we've) reached the age where these things are starting to make themselves known.
The last one in the list is something which I was involved in, earlier this year. In the event, I consider myself lucky: I escaped practically (if not completely) unscathed. I have a few slight residual problems to contend with, but they're fading, minor, little more than an inconvenience. Less than two weeks off work. A few seconds or a few inches either way, and it could have been a very different story. But in the event, I was very, VERY lucky.
I don't take that outcome for granted, and the uncertainties that some of my friends are now facing make me feel that nothing should ever be taken for granted, as such.