to me, the question is not whether the program's internal rules require a given hurdle to be jumped (staying in hospital, for example). it is more whether such rules are /always/ completely necessary in every case, for the mission of the program. i.e. can a reasonable accommodation be made.
this isn't hypothetical. among the sickest cannot travel. it therefore directly impacts the mission if reasonable accommodations /can/ be made (such as running most but not all tests, allowing local tests, using open-tech-standards communications tech like email, etc.) but /are not/.
so it is not "merely" that it is potentially discriminatory, but that it is, /on top of "mere" discrimination/, potentially discriminatory toward those who could potentially contribute /the most/ to knowledge of rare diseases by being tested. /and/ toward many of those who potentially need it the most.
this is not to show ingratitude for the program. it is to point out that there is a population out there. they quite possibly do not know that!
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pwme are manifestly systematically discriminated against, and this is widespread. very often it is institutional. for example, hospitals have no idea what they are supposed to do for pwme or they get it completely wrong from start (place to lie down for those who most need it) to finish (treatment that isn't "graded smirk therapy").
sometimes it is an oversight. nobody thinks "oh yeah, there is a sick population, with really serious problems, a huge percentage of which cannot travel, and a huge percentage of which are misdiagnosed! as OUR VERY MISSION is to pay attention to sick populations that need but are not getting correct diagnoses, we can consider making reasonable accommodations!"
in fact, they might not know anything accurate about m.e.
whether this program can provide reasonable accommodations, idk. but i think we should all get tired of being special exceptions, /even/ when those exceptions are oversights buried within rules in institutional settings. and /even when/ those rules seem normal for relatively healthy people or diseases popularly considered normal. i include all severity levels. as ben franklin said, we hang together or we hang separately.