In 1933, the nazis passed a law called "Law for the prevention of Progeny of hereditary disease" the law affected the mentally ill, physically handicapped and alcoholics by

The 1933 Law for the Prevention of Progeny of Hereditary Disease required that persons such as those you listed had to be sterilized. In other words, they would make them incapable of sexual reproduction.

That's not the only horrible things the Nazis did in their campaign for a "master race" as well as their World War effort. They used Jewish persons and others they deemed undesirable essentially as laboratory rats for doing unethical medical experiments on them. For example, they'd put persons in a pressure chamber to find out how high an altitude they could let their pilots fly before they'd become unconscious from the altitude and pressure. Others of their experiments were even more gruesome. And then there was the Holocaust, an even greater and more widespread atrocity.