Form: Sporadic CJD (sCJD)
Cause: Unknown
Distinguishing Features: Affects mainly people over the age of 60. Common symptoms include ataxia and dementia. Short course. Upon tissue examination there is spongiform change, but plaques are rarely present.

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Form: Sporadic Fatal Insomnia (sFI)
Cause: Unknown
Distinguishing Features: Has clinical and histopathologic features indistinguishable from those of Fatal Familial Insomnia (FFI), but does not have the mutation on the prion gene that characterizes FFI.

To learn more about FFI, click here.