21.   He was diagnosed with the degenerative brain condition about six years ago.

22.   Prions are believed to cause a group of degenerative brain diseases, including mad cow disease and scrapie.

23.   Prions are believed to cause a group of degenerative brain diseases, including so-called mad cow disease.

24.   Some scientists believe British cattle developed mad cow disease after eating feed that included offal from sheep infected with scrapie, a degenerative brain disease.

25.   Some believe British cattle developed mad cow disease after eating feed that included offal from sheep infected with scrapie, a degenerative brain disease.

26.   The degenerative brain ailment has been linked to an equally fatal human equivalent, Creutzfeldt-Jakob disease.

27.   New research points to a possible link between BSE and Creutzfeldt-Jakob disease, a degenerative brain disorder in humans.

28.   New research published in March pointed to a possible link between BSE and Creutzfeldt-Jakob disease, the degenerative brain disorder in humans.

29.   New research published in March pointed to a possible link between BSE and Creutzfeldt-Jakob disease, a degenerative brain disorder in humans.

30.   Recent research points to a possible link between bovine BSE and Creutzfeldt-Jakob disease, a degenerative brain disorder in humans.