Parkinson's Disease experts are investigating a 1970s Canadian TV series after four members of the cast and crew - including Michael J. Fox - were found to have the illness. Fox was just 16 when he starred in comedy Leo and Me. And now he, a writer, a cameraman and director Don Williams all suffer from Parkinson's Disease - which attacks the nervous system. Williams admits, "The percentage of people involved is quite amazing to me." Experts fear the disease might have been environmentally caused by toxins or a virus linked to influenza. Pacific Parkinson's Research Center expert Donald Calne says, "This is one in 20,000. It's not a coincidence."