A study of 10 million military personnel last year found that the ubiquitous Epstein-Barr virus, which infects 94% of people and causes kissing disease, is also the leading cause of multiple sclerosis, a rare condition that leads to It in the most severe cases cause those affected to have difficulty speaking and walking. In 36 out of 100,000 citizens, the virus triggers a process in which the body’s own defenses destroy the neuron sheath, as if the cables from the brain and spinal cord were detaching. Some patients need a wheelchair, but others manage to reach the top of Everest, like American professor Lori Schneider. A new study of 22,000 patients this Wednesday identifies the first genetic variant linked to a more aggressive development of the disease. Researchers believe the discovery paves the way to treatments that prevent disabilities.
The authors, from two international consortia totaling around 150 scientists, studied seven million genetic variants until they identified a key region between two genes: DYSF, which is involved in repairing damaged cells in muscles, and ZNF638, which is involved in repair control from viral infections. Neurologist Sara Llufriu of the Hospital Clínic de Barcelona explains that someone who inherits this variant from both the mother and father “needs the support of a cane more than three and a half years before”. The clinic brought data from around 300 patients into the macro study, which will be published this Wednesday in the journal Nature, a benchmark for the best science in the world.
More information
The scientific community had already found around 200 genetic variants linked to the risk of multiple sclerosis. But this is the first to be linked to the disease’s rapid progression, according to neurologist Manuel Comabella of the Multiple Sclerosis Center of Catalonia. “The disease is very heterogeneous. Many patients first need one crutch to walk, then two crutches, and finally a wheelchair. But there are also more harmless forms. There are patients who are even very physically active and walk for miles. Obviously, this must possibly be due to genetic factors,” explains Comabella. His centre, which is part of Barcelona’s Vall d’Hebron Hospital, has provided information on 173 patients.
There is no cure for multiple sclerosis, but in recent decades there has been a “therapeutic revolution” that has made it possible to reduce and even prevent outbreaks of the disease, according to the authors of the new study. The disease is characterized by an inflammatory process, which is crucial at the beginning, and a neurodegenerative component, which is responsible for the progression of the disease. Current treatments only have an anti-inflammatory effect, so they cannot stop the progression of multiple sclerosis in the long term. Comabella points out that the discovery of the genetic variant points to a new Achilles’ heel. “The finding illustrates a possible mechanism of disease progression that could be blocked with medication in the future,” says the neurologist.
Researchers Sara Llufriu, Albert Saiz and Yolanda Blanco, co-authors of the study at the Hospital Clínic in Barcelona. Hospital Clinic / IDIBAPS
The data from the 22,000 patients also suggest that educational level plays a protective role against multiple sclerosis, while smoking makes the disease worse. British neurologist Stephen Sawcer, one of the study’s lead authors, admits that quantifying these effects is difficult. “We saw that each additional year of study reduced severity by an average of about 0.05 points on a scale of 0 to 10, which is 0.5%,” says Sawcer of the University of Cambridge. The level of education also plays a protective role in other neurodegenerative diseases such as Alzheimer’s.
The work includes patient data from Europe, Australia, the United States and Canada. Neurologist Luis Querol from the Hospital de la Santa Creu i Sant Pau in Barcelona welcomes the study, in which he did not take part, but points out its limitations. “Many factors play a role in the rapid progression of disability: the patient’s age, habits, treatments used and even geographical variations,” Querol told the Science Media Center portal. “Some of these factors do not appear to have been accounted for, so new cohorts would be required to control for these differences and to verify that the results are reproduced,” he stressed.
The team led by the Italian epidemiologist Alberto Ascherio from Harvard University (USA) discovered last year that the Epstein-Barr virus, which is responsible for kissing disease, is also “the main cause” of multiple sclerosis. “Presumably multiple sclerosis does not develop if a person is not infected with the virus,” he explained in an interview with this newspaper. For Ascherio, the disease is “a rare complication of infection.” The new work will serve to shed light on what happens when this complex autoimmune-inflammatory process is triggered.
you can follow THEME on Facebook, Twitter and Instagram, or sign up here to receive our weekly newsletter.