Blood Transfusion and AIDS question

Following from a thread about blood groups -

Many of us pre-dx will have donated blood, wonder if anyone has ever claimed that they have developed m.s. because of getting an ‘infected’ blood transfusion.

Some years ago recall reading that no one with AIDS has ever gone on to have m.s. - wonder if that is still the case.

Also read that no one with Downs Syndrome has ever developed m.s.

Not sure what the relevance of these points !! but I wonder if the medics have ever identified some people who have ‘immunity’ from developing m.s.?