I've seen some posts going around talking about the lists of diagnoses we see for young Steve Rogers in the MCU, and trying to conceptualize them in terms of Steve as a character with disabilities, and while I fully support people writing fic with Steve having any disabilities they want, there's some misconceptions that I'm seeing gain more and more of a foothold in fanon.
So here's my poor attempt at talking about Steve's diagnoses.
I say "diagnoses" rather than illnesses or disabilities deliberately, because the most important thing to keep in mind when thinking about this is that disability and disease are both defined by culture
- the same person with the same symptoms in two different cultures might be seen, by both themself and the culture, as having entirely different problems.
Here's an example: it's easy to say that "a broken leg is a broken leg", but where a broken leg, in today's America, might mean a few weeks in a cast and crutches followed by a while in a walking cast and some annoying medical bureaucracy, the exact same injury in a culture with different medical capabilities might mean months of being unable to get around without help, followed by permanent mobility impairment and chronic pain if the bone heals wrong, and a serious risk of death from blood poisoning. Or a broken leg these days might mean a hairline fracture that's only visible on medical imaging, which a different culture might not classify as the same kind of injury as a broken leg at all. Or maybe in a hundred years, a broken leg will mean a week in a custom power exoskeleton and home regen treatments, and the only reason you have to skip soccer practice is that power armor is cheating, and it's less annoying than a cold. When you get into conditions less straightforward than a broken leg, it gets exponentially more complicated.
The culture Steve Rogers grew up in, 1920s-1940s New York City, had a lot in common with modern American urban culture, but it was very different in a lot of ways, and one of the ways it was very different was in terms of medical culture. The medical advances that came around WWII changed the ways Americans think about illness, disease, and disability in dramatic ways - as two random examples, antibiotics weren't widely used until after the war, and it wasn't shown that DNA contains genetic information until 1943.
So you can't just look at a list of diagnoses made in 1943, and assume they mean at all the same thing that a similar diagnosis would mean today, in terms of what symptoms they're describing, or in terms of what those symptoms meant for the person experiencing them, or in terms of the way the medical establishment and culture responded to them.
The other thing to keep in mind is that most of the information we have comes from Steve Rogers' army intake medical forms, which were not exactly a reliable source even in that 1940s context, given that we know Steve was lying his ass off in them. Even if he wasn't lying, his initial interview and exams would have been hastily done by a doctor who had probably done hundreds of similar exams that day. So we can't assume that the marks we see on the papers are even accurate in terms of describing Steve's health - there could be all sorts of errors, shortcuts, and downright lies on them.
Also, most of this information comes from prop canon, which is legendarily unreliable (Bucky currently has two different birth years based on prop canon!) There are several lists of diagnoses going around, which are all different from each other. I've tried to trace back the actual canon they come from, when I can (mostly using Google Image Search, to be fair.) I'm going to go down them in order of presumed reliability.
First, we've got actual, non-prop canon, which comes down to the two things that were said out loud at Steve's initial exam:( Actual movie canon )
So that's it for non-prop canon, but by itself that's enough to give him a childhood of disability and a solid 4F for quarantine reasons. Then there's the prop canon on top of that. I'm going to go over the stuff from prop canon (and other canon) in vague order of how reliable I consider it.
The most extensive list from prop canon is a Selective Service medical history checklist, which I believe is shown at least partially in the movie though I am not 100% sure, and is available in full as a prop reproduction. It gives his name as "Rodgers, Steve" and his address as Brooklyn, so presumably it was either before he started or after he stopped lying his ass off. This seems to be the list that Marvel's PR/Merch people are treating as canonical - it's been reproduced in several "official" merchandising things and was on the Marvel website for awhile. Here's the list, pulled off the Marvel website:( The first Selective Service list )
There's also a different version of the same form going around, which definitely appeared in the movie, but I've only found as a partial screenshot - it doesn't seem to have been reproduced in full. It contradicts the first checklist in major ways, and from a Doylist POV, my guess is they just had somebody check a bunch of boxes that would show on the film in a nice pattern. If we want to assume it's real, though, presumably it's the medical history screening checklist from one of Steve's other attempts to enlist. We can only see a few lines of it, but there's some interesting differences, especially if we assume the one above is when he wasn't lying, and this is one when he was saying whatever he thought would get him in.( The second checklist )
There's also another list going around, which comes from an SSR intake form that seems to have been distributed with a special edition DVD box set - as far as I know, this is never visible in the movies. It has a list of "medical ailments" and a list of "family history of medical problems", which don't line up well with the other lists, so I'm hesitant to consider it reliable canon. However, this could be due to the fact that Steve is being more honest with Erskine than he ever has previously, or had much more thorough medical exams. So let's look at it anyway. ( The SSR form )
There's also an Army form on the Marvel Look Inside Gallery for Captain America that gives the same list of health issues as the first Selective Service form, and also gives results of an eye and ear exam: his vision is apparently 15/20 in his right eye and 16/20 in his left eye. This, afaik, makes no sense - visual acuity measures in that format should always start with either 20 or 6, and that hasn't changed over time. If they meant 20/15 instead of 15/20, his vision is actually slightly better than normal. If they meant "slightly worse than 20/20", he might have minor blurriness, but he'd still be allowed to drive a car without glasses. For hearing, he's listed as having "ear discharge" - I have no idea what that means in this context, except an ear infection - but, notably, no hearing impairment.
I'm not going to discuss that one in any more depth since it's all duplications, but here's the form:( The Army form )
There's also an exhibit at Disney's Tomorrowland which apparently has a poster about "Skinny Steve" with another list of ailments. It has very little in common with anything from the prop canon. I'm tempted to take this one with a very large grain of salt, because not only is it not even prop canon, but it's not even a medical report - it's in context as a propaganda display, comparing Sick Steve to Captain America Steve, so even if you read it in-universe, it's likely to be exaggerated, or even deliberately falsified for security reasons, or to make a better story. Note, for example, that he's three inches shorter and fifteen pounds lighter here than on either of the medical forms. However there's still some interesting stuff on here, assuming I found the right poster (this required some creative googling and I found it on a photo aggregation site with no attribution).( The Tomorrowland Display )
That basically covers it for the things I've been able to find some sort of canon or semi-canon or hemi-demi-canon for. There's at least one wiki out there that also lists "hypermobility" and "social anxiety", but since I can't find any source for those, I'm just going to leave it that neither of those would have been used as diagnoses in Steve's pre-serum days, as far as I can tell. They may be somebody attempting to translate "trick joint" and "nervous trouble" from the forms into modern terminology, but if so, they're extrapolating far beyond the available data.
Anyway! So that's Young Steve's list of diagnoses. As you can probably tell, I am by no means an expert in any of this, and I welcome corrections and links to sources. And if you're planning on writing about any of this, please, please do your own research - and make sure you research specifically in the 1920-1940s context, not just what the terms and conditions mean today.
Here is Pre-Serum Steve's theme song to play you out. This was a major hit in 1942, you can't tell me Steve didn't listen to it on repeat and cry, and I'm also pretty sure the title of "Star-Spangled Man" was picked to reflect back on it as part of the 4F narrative.( There's a Star-Spangled Banner Waving Somewhere )