What minority in Germany was targeted by the Nuremberg Racial Laws as racially impure, considered unworthy of life, legally required to be reported by the citizenry to the authorities, and especially targeted for extermination by gassing and other cruel methods?
If you answered "the Jews," you're both right and wrong.
A little-known aspect of the infamous Nazi racial legislation is that it targeted three specific groups and the last of these groups is usually unheard of in history lessons. They were the Jews, the Roma/"Gypsies", and the disabled. Very few people know that the first people gassed were the disabled, the gas chambers were created for the T4 euthanasia programme, and the first victim was a severely disabled baby. The disabled were subjected to forced sterilisation, starvation, and killed by lethal injection and gassing at medical facilities that doubled as extermination centres, with the aim of ridding the "pure" and "superior" German race of undesirable genetic traits.
One of these collectives amongst the disabled were the Deaf, of which thousands were unwittingly sterilised and murdered. The survivors never got reparations from the German state, unlike the other collectives of victims (this book is from the 90s, so that might've changed since), and there's always been some resistance to recognise the disabled as victims of Nazism. Sometimes I wonder if it has to do with the fact that aborting babies due to inherited disabilities is still acceptable in many places now? Nobody wants to think it's anything similar to what the Nazis proposed, but this reluctance to recognise the Deaf as victims of racially-driven Nazi eugenics that the survivors quoted in this book is certainly going to be very uncomfortable for many.
The book is written in a very matter-of-fact style, dry and unengaging, very academic in style. It has some outdated details as well and hasn't touched on other aspects it should have. But given the scarcity of books on the T4 programme and specifically on the Deaf as victims of Nazism, this is the best we have for now, so it'll have to do. It's informative enough, though you do need some prior historical context to place the experiences described here.
And it's a very sad read overall, too, in spite of its annoying writing flaws. For me that I have a lifelong connection with the Deaf, it got personal. I've read lots of horrific accounts of the Nazi crimes, but when I think of the Deaf people I know that would've been subjected to this inhumanity, it always hits differently. It's enough WWII for me for the rest of the year, I think!