Jehovas can actually donate organs if they wish to do so but it's more the blood transfusions and blood donations that is more the thing. Something to do with a verse in their scripture about abstaining from blood. Some choose to donate others don't I guess it's how much they believe in their writings and bible. That's what I can get what I have read.
I am an organ donor and am willing to donate everything they can take. If my death saves another life then why not.