21.   On Thursday, the focus groups found that some doctors mistakenly believe that the disease still occurs naturally.

22.   Others suggest the disease is naturally occurring.

23.   Prion diseases occur when a normal protein called a cellular prion misfolds into an abnormal shape that cannot be broken down by enzymes.

24.   The disease also occurs in Hispanics and people of Mediterranean and western Asian descent.

25.   The disease occurs only if a child inherits a copy of the mutated gene from each parent.

26.   The disease occurs when nerve cells that produce a crucial brain chemical called dopamine deteriorate and die.

27.   The disease usually occurs in puberty and afflicts an estimated half-million to a million Americans.

28.   The disease occurs when a child is born to two parents who carry the Tay-Sachs gene.

29.   The disease occurs most often in the winter and spring.

30.   The cow disease has not occurred in the United States and Americans are not believed to be at risk.