Thanks again, everyone. When I was first diagnosed, I read everything I could find concerning PLS. I remember the article about the Canadian family being the only known case where there was evidence of a PLS genetic connection. I feel that knowledge of this disease is extremely limited, so who can say if it's caused by a gene mutation. Also, some researchers still seem to believe ALS and PLS are the same disease.
In my case, knowing what I know now, I think my grandfather had ALS. He died in 1945 and was never seen by a neurologist. The local small town doctor said his problems were a series of small strokes. He lost the use of his legs, then speech, then was completely bedridden until he passed.
My father, following a serious auto accident at age 66, developed symptoms eerily similar to mine, although not as severe. He was not seen by a neurologist after leaving the hospital. He was wheel chair bound the last five years of his life but retained upper body strength. He passed from cancer at age 87.
It's only a theory that there may be a genetic component. I don't know of anyone else in the family that has been affected.