#Screening #CreutzfeldtJakob #disease #Israel
An Israeli hospital has become the first in the country to introduce a cutting-edge test for a notoriously difficult brain disease to diagnose.
Creutzfeldt-Jakob disease (CJD) is caused by an abnormal infectious protein in the brain called a prion. This protein has unique properties that make it act like a virus or bacteria, and cause other prions to mimic their behavior. The abnormal protein deposits spread throughout the brain, causing widespread damage that progresses rapidly. Symptoms include decreased intellectual faculties, memory loss, slurred speech, and personality changes.
This disease is incurable and usually kills the patient within a year of its onset. But the diagnosis is considered important because it would avoid subjecting patients to often painful treatments, which are suitable for other degenerative diseases but not for CJD, giving them false hope and tempting parents with a genetic risk to take preventive measures by screening of their embryos.
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CJD is disproportionately present in Jews of Libyan and Tunisian descent. It is estimated that thousands of carriers of the E200K mutation responsible for CJD live in Israel, and children of only one parent are at risk of developing this incurable disease. A small minority of children of carriers develop the disease, but it is fatal to them.
There is no commonly used laboratory test for CJD, which is particularly notorious because it can be caused by eating beef infected with bovine spongiform encephalopathy, known colloquially as bovine spongiform encephalopathy.
Diagnosis is complex and often based on a combination of tests. Brain biopsies are not performed on living patients due to the contagious nature of the disease and an MRI is never completely conclusive.
People whose genetic background increases their risk of being a carrier are encouraged to get tested, but many don’t. When a person develops CJD but the family is not informed, its members are unaware that they themselves are at risk and therefore have the opportunity to take steps to test the embryos of their offspring.
Tel Aviv’s Sourasky Hospital is now one of a dozen hospitals internationally that perform this test, allowing highly accurate diagnosis based on analysis of cerebrospinal fluid. It joins a few hospitals in the United States, but it is the first in Israel. “This method is the world’s first independent test that can diagnose CJD with a very high accuracy (92% confidence),” said Dr. Yifat Alkalai, Director of the Sourasky Clinical Immunology Laboratory.
She predicts her lab will now test hundreds of samples a year, using the method that was pioneered in Japan 11 years ago but has not been widely used due to the high level of expertise needed to put it into practice.
Since CJD is characterized by specific interactions between prions, the test can be performed by observing the interaction of prions from one patient with prions from another source. The tremor-induced real-time conversion (RT-QUIC) technique, currently used in Tel Aviv, uses prions from hamsters.
Human and hamster prions are observed simultaneously under laboratory conditions for five days, and certain patterns of interaction, mimicking the behavior of prions in the brain, will confirm CJD.
Alkalai told the israeli times “It is a difficult test to learn and perform, and we consider it very important for the detection of CJD that we have introduced it in Israel. We hope it will allow for earlier diagnosis and for families who don’t know they have a gene that puts them at risk to find out and have the opportunity to get the right information.”