Mad cow disease (Creutzfeldt-Jakob disease)is a fatal acquired brain disorder caused by prions (a protein-based unusual structure smaller than a virus). They also alter nearby protein structures and consequently their functions. When diagnosed CJD has caused enough damage to produce progressive dementia and involuntary jerking muscle movements called myoclonus. About more than half of cases of CJD are from sporadic mutations, the rest may be hereditary or transmitted from an animal to a person, or from person to person (eg. transfusions). It’s very rare to make a diagnosis, as the condition continues undetected they will eventually develop strong muscle spasms, paralysis, and coma. The prognosis is very poor, about 90% of people with CJD die within 1 year.