For one, it's a genetic disorder that's linked to ancestry.

For another, there's a huge social-justice issue around race in the US. Black people are hugely overrepresented in prisons, and there are vast, ingrained and systemic prejudices and barriers to equality everywhere you look.

This is why ferinstance efforts to enforce photo-ID requirements for voting would significantly disenfranchise Black voters (which is the real reason conservatives keep trying to push for it), because a disproportionate percentage of Black people simply don't have the means to obtain such ID - vastly more than the number of white people in a similar position.

Take centuries of explicitly racist law and policy directly excluding and oppressing Black people. Wind back the explicit racism over the last handful of decades, but quietly replace it with exclusion and oppression based on the socieconomic disparity thus created. Now you can claim to have a colourblind legal/etc system, yet continue to preserve and promote disadvantage that ends up depending on race.

And because social mobility is an absolute joke over there (as it is in most places, tbh), then the opportunities and resources available to you will depend heavily and primarily on the opportunities and resources available to your family and community for many generations back. There's not just generational wealth to deal with, but generational influence and networking; you can't be in with the Right People unless your parents were, and neither could they, rinse and repeat. And when the Right People instantly dismiss you on sight, or even just by seeing your name, then you're fucked.

So when someone says that a hundred thousand people in the US have a crippling and debilitating disease, and the great majority are Black - yeah, it means something. It means that a chunk of the population are getting a raw deal on top of the shit sandwich they've been handed just by being born, and that this is just one more thing that, for the most part, white people don't have to care about. And because the fucked up healthcare system in the US is so profit-driven, that means there's going to be vastly less done about it than if it were equally spread across demographics.