Creutzfeldt-Jakob disease
A rare, fatal disease of the brain caused by a misfolded protein called a prion.
What it is
In CJD, the prion protein takes on an abnormal shape and spreads through brain cells, killing them and leaving small holes that give the brain a sponge-like look. Decline is fast, often over a few months. It usually starts after age 30 and affects one or two people per million each year.
Symptoms depend on which part of the brain is affected first. They can include memory loss and dementia, changes in behaviour, loss of balance and coordination, muscle jerks, problems with vision and hearing, and finally loss of consciousness.
Three forms
| Form | Cause | Notes |
|---|---|---|
| Sporadic | Unknown | The most common form worldwide. |
| Genetic | A mutation in the PRNP gene | E200K is the most common mutation. It is dominant, so one carrier parent can pass it on, but not every carrier becomes ill. |
| Acquired | Infected beef (variant CJD) or a medical procedure (iatrogenic CJD) | Very rare. Iatrogenic cases are about 1% of the total. |
Genetic CJD is not contagious between people, including between spouses. As a precaution, close relatives of patients are asked not to donate blood.
Why one community matters
The E200K mutation is found at an unusually high rate among families of Libyan and Tunisian Jewish origin, and also in Italy, Slovakia and elsewhere. Many affected families live close together, which makes it possible to follow carriers for years. Worldwide, the genetic form is 10 to 15% of cases.
How it is diagnosed
For a long time CJD could only be confirmed after death. Today doctors combine several tests and rule out other causes:
- Clinical picture: fast neurological decline that few other diseases match.
- Tau and neurofilament light (NfL): markers of nerve-cell damage, now measurable in blood as well as spinal fluid.
- RT-QuIC: a specific spinal-fluid test for the abnormal prion. It is less reliable for genetic cases, where false negatives have been reported.
- MRI and EEG: read by a physician experienced in CJD.
- PRNP gene test: a blood test that tells genetic from sporadic disease. Family history or origin alone is not enough. The whole gene should be sequenced, since more than 60 mutations are known.
Treatments in research
No treatment yet prevents or stops CJD, but several are being studied, some already in people:
- Lowering the prion protein: antisense oligonucleotides and siRNA in early human trials, plus gene editing, zinc-finger repressors and oral small molecules in the lab.
- Antibodies: a first-in-human antibody study showed the approach was safe. Researchers believe it needs testing earlier in the disease.
- Lifestyle and resilience: studies suggest chronic stress may play a part in when the disease begins, and that diet may matter. These leads need more research.
Treatments will work best when given early. That is why finding the first biological signs in carriers, years before symptoms, is the biobank's main goal.
This page is general information and does not replace advice from your own physician or genetic counsellor.