Compare prion diseases

Prion diseases share one process but differ in cause, in who they affect and in how fast they move. These cards put them side by side.

  • Sporadic

    Sporadic CJD

    Cause
    No known cause. Prion protein misfolds for reasons not understood.
    When it starts
    Average in the late 60s. About 9 in 10 are between 45 and 85.
    First signs
    Memory lapses, confusion, mood change, poor balance.
    How long it lasts
    Often about 4 to 5 months. Most people live months to about a year.
    Runs in families?
    No

  • Sporadic

    VPSPr

    Cause
    No known change in the prion protein gene.
    When it starts
    Average age 70.
    First signs
    Psychiatric symptoms, speech problems, memory and thinking problems.
    How long it lasts
    About 24 months, from small numbers of patients.
    Runs in families?
    Not shown to be

  • Inherited

    Genetic CJD

    Cause
    An inherited change in the PRNP gene.
    When it starts
    Differs by gene change and by person.
    First signs
    Much like sporadic CJD.
    How long it lasts
    Often slower than sporadic CJD. Inherited forms often run around 2 years.
    Runs in families?
    Yes, 50% chance for each child

  • Inherited

    Fatal familial insomnia

    Cause
    An inherited change in the PRNP gene. Damage falls mainly on the thalamus.
    When it starts
    Usually in the 30s, 40s or 50s.
    First signs
    Sleeplessness that keeps getting worse, often with confusion or unsteadiness.
    How long it lasts
    Typically longer than a year.
    Runs in families?
    Yes, 50% chance for each child

  • Inherited

    GSS

    Cause
    An inherited change in the PRNP gene. Damage falls first on the cerebellum.
    When it starts
    Usually in the 30s, 40s or 50s, occasionally the 20s.
    First signs
    Unsteadiness and poor coordination.
    How long it lasts
    2 to 10 years. Published reviews give a mean of about 5.
    Runs in families?
    Yes, 50% chance for each child

  • Acquired

    Variant CJD

    Cause
    Linked to eating beef from cattle with BSE.
    When it starts
    Median age at death 28.
    First signs
    Low mood, anxiety, withdrawal, painful sensations in the limbs.
    How long it lasts
    Median 13 to 14 months.
    Runs in families?
    No
    Today
    Very few cases now occur anywhere.

  • Acquired

    Iatrogenic CJD

    Cause
    Past medical treatment, mainly human growth hormone and dura mater grafts.
    When it starts
    Years after exposure: on average 17 for growth hormone and 12 for grafts.
    How long it lasts
    See the full page.
    Runs in families?
    No
    Today
    Both main sources stopped in the 1980s.

  • Acquired

    Kuru

    Cause
    Spread through funeral practices among the Fore people of Papua New Guinea.
    When it starts
    Decades after exposure in the last cases.
    First signs
    Headache and aching limbs, then worsening unsteadiness.
    How long it lasts
    10 to 25 months in a group of 11 patients.
    Runs in families?
    No
    Today
    The practices ended by around 1960. It does not occur now.
Age when the illness starts
Sporadic CJD
VPSPr
Fatal familial insomnia
GSS
Variant CJD
0306090

Years of age. Variant CJD shows median age at death. VPSPr shows the average age at onset.

How long the illness lasts
Sporadic CJD
VPSPr
Genetic CJD
GSS
Variant CJD
Kuru
02460120

Months from first symptoms. These are group figures from the pages above, not a forecast for any person.

Nothing here can tell you what is happening to a particular person. A neurologist is the person to ask about symptoms and results, and a genetic counsellor about inheritance.

Last checked 1 November 2026