Seriously, hard-headedness and red hair are not diseases.
Well we’re certainly prone to alcoholism for sure.
And many of the problems that go with it.
“What is that about?”
Frequently a gene was discovered when a mutant copy of it turned up causing an affliction. Thus the gene that, if it works it means you do NOT get cystic fibrosis; gets called the “cystic fibrosis gene” - as if the gene was there to either cause or prevent cystic fibrosis.
It is thought that any diseases that are common to a particular population and/or culture might have a genetic component making them more susceptible (or causing) the affliction.
But genes are NOT there to cause genetic disease!
Sort of like a mechanic telling you your cars carburetor is there to flood the engine. Because he discovered the carburetor when the engine started flooding!