In my country (not US), I’ve been given a summons by the court in order to appear for Jury Duty (and of course it’s mandatory to show up on the appointed date), but I have Autism (makes it difficult for me to interact with strangers and have distrust towards the authorities). I was last diagnosed when I was around 15 years old whilst the first was since 7.
The only thing I have that somewhat counts as medical proof as a psychological assessment on paper confirming I have Autism (as in on the spectrum) back when I was in 9th grade. Even if I waited through the jury panel, and for some reason the lawyer/s decided I should become a juror (despite not wanting to for medical reasons), could I use that as evidence?
However, will the judge accept that even though it’s an confirmed medical diagnosis from when I was a teen after pleading my case as to why I am ineligible to serve (difficulty on interacting with others, difficulties with understanding social cues or heightened anxiety), although even if excused: will that be considered permanent or temporary?
It will be hard to guess without knowing the specific rules of your country. In my country you can also raise “general hardship” concerns which may not require as formal documentation as a medical exception might (not saying your documents would be invalid, I don’t know!).
I assume your letter does not state what you need to do if you can’t attend on that date? Where I live there is info on who to contact to have it deferred or excused. Is there any contact info on the letter? Maybe you or a helper can contact them and ask these questions. It’s intimidating for sure but it is better for the courts too if people ask these questions in advance so the day goes more smoothly. You may still need to attend the jury selection but you will know what you need to do.
Good luck!