An Israeli hospital has become the first in the country to introduce a cutting-edge test to detect a notoriously hard-to-diagnose brain disorder.
Creutzfeldt-Jakob disease is caused by an abnormal infectious protein in the brain called a prion. This protein has unique properties that make it act similarly to a virus or bacteria, and it causes other prions to mimic its conduct. Abnormal protein deposits spread in the brain, causing widespread damage that progresses rapidly. Symptoms include loss of intellect and memory, slurred speech and personality changes.
The disease is incurable and usually kills the sufferer within a year of onset. But diagnosis is considered important, as it avoids subjecting patients to often-painful treatments that fit other degenerative diseases but not CJD, giving them false hope, and prompts relatives who are at genetic risk to take preventative steps like screening their embryos.
CJD is disproportionately found among Jews of Libyan and Tunisian origin. It is estimated that there are thousands of carriers of the CJD-causing E200K mutation living in Israel, and children with just one carrier-parent can develop the incurable disease. A small minority of children of carriers develop the disease, but when it does develop, it is fatal.
There is no single commonly-used lab test that detects CJD, which is particularly well-known because it can be caused by eating beef infected by bovine spongiform encephalopathy, known colloquially as mad cow disease.
Diagnosis is complex, often relying on a combination of tests. Brain biopsies aren’t used on living patients because of the contagious nature of the disease and even an MRI scan is not fully conclusive.
And while people whose heritage raises the risk of being a carrier are encouraged to screen, many don’t. When somebody develops CJD but the family never learns the identity of their disease, family members fail to learn they are at risk themselves, and that they have the option of taking measures to screen embryos of their offspring.
Tel Aviv Sourasky Medical Center has now become one of a dozen hospitals internationally to run a test that gives high-accuracy diagnosis based on analysis of spinal fluid. It joins a few hospitals in the US, but is the first in Israel. “This method is the world’s first standalone test to give diagnoses of CJD with very high accuracy — sensitivity of 92 percent,” said Dr. Yifat Alkalai, director of Sourasky’s Clinical Immunology Laboratory.
She expects that her lab will now analyze hundreds of samples per year, using the method that was developed in Japan 11 years ago, but which hasn’t become widely used due to the high level of expertise needed to put it into practice.
As CJD is characterized by specific interactions between prions, testing can be carried out by observing a patient’s prions interacting with prions from another source. The real-time quaking-induced conversion (RT-QUIC) technique, now in use in Tel Aviv, uses prions from hamsters.
The human and hamster prions are observed together in lab conditions for five days, and certain patterns of interaction, which mimic how the prions would behave on the brain, confirm CJD.
Alkalai told The Times of Israel: “This is a hard-to-learn and hard-to-perform test, and we see it as very important for the detection of CJD that we have brought it to Israel. We hope it will lead to earlier diagnosis, and lead to families that don’t know they have a gene that puts them at risk finding out, and having the ability to have the right information.”