2023-07-03 09:07:44
The discovery opens a new avenue to search for treatments against the disease, initiated by the kissing disease virus.
A study of 10 million military personnel revealed last year that the ubiquitous Epstein-Barr virus, which infects 94% of people and causes the kissing disease, is also the leading cause of multiple sclerosis, a rare disorder that, in the most severe cases, it causes those affected to have trouble speaking and walking. In 36 out of every 100,000 citizens, the virus triggers a process in which the human body’s own defenses destroy the neuron envelope, as if the cables of the brain and spinal cord were peeling. Some patients need a wheelchair, but others are able to reach the summit of Everest, like the American professor Lori Schneider. A new investigation, with 22,000 patients, identifies this Wednesday the first genetic variant associated with a more aggressive evolution of the disease. The researchers believe the discovery opens a path toward treatments that prevent disability.
The authors, from two international consortia with a total of about 150 scientists, have examined seven million genetic variants, until they identified a key region between two genes: DYSF, involved in the repair of damaged cells in muscles, and ZNF638, involved in the control of virus infections. Neurologist Sara Llufriu, from the Hospital Clínic de Barcelona, explains that if a person inherits this variant, both from her mother and her father, “they need the support of a cane more than three and a half years before.” The Clínic has contributed the data of some 300 patients to the macro-study, which is published this Wednesday in the journal Nature, a benchmark for the best science in the world.
The scientific community had already found some 200 genetic variants associated with the risk of multiple sclerosis, but this is the first linked to the rapid progression of the disease, according to neurologist Manuel Comabella, from the Multiple Sclerosis Center of Catalonia. “The disease is very heterogeneous. Many patients first need a crutch to walk, then two crutches, and finally are wheelchair dependent. But there are also more benign forms. There are patients who are even very physically active and run for miles and miles. Obviously, this must be due to possibly genetic factors”, explains Comabella. His center, belonging to the Vall d’Hebron Hospital in Barcelona, 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 disorder is characterized by an inflammatory process, key at the beginning, and a neurodegenerative component, responsible for the progression of the disease. Current treatments only act on inflammation, so they do not 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 illuminates a possible mechanism involved in the progression of the disease, which in the future could be susceptible to being blocked with drugs”, says the neurologist.
The data from the 22,000 patients also suggest that educational level plays a protective role against multiple sclerosis, while smoking aggravates the disease. British neurologist Stephen Sawcer, one of the lead authors of the research, acknowledges that it is difficult to quantify these effects. “We have seen that, on average, each extra year of study reduces severity by about 0.05 points, on a scale of 0 to 10, which is equivalent to 0.5%,” says Sawcer, from the University of Cambridge. The educational level also has a protective role in other neurodegenerative diseases, such as Alzheimer’s.
The work includes patient data from Europe, Australia, the United States and Canada. The neurologist Luis Querol, from the Hospital de la Santa Creu i Sant Pau in Barcelona, applauds the study, in which he did not participate, but points out its limitations. “There are many factors involved in the rapid progression towards disability: the age of the patients, the habits, the treatments used, even geographical variants”, Querol explained to the Science Media Center portal. “Some of these factors do not seem to have been taken into account, so new cohorts would be needed to control these differences, to see if the results are replicated,” he stressed.
The team led by Italian epidemiologist Alberto Ascherio, from Harvard University (USA), discovered last year that the Epstein-Barr virus, responsible for the kissing disease, is also “the main cause” of multiple sclerosis. “Probably, 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 illuminate what happens once this complex autoimmune-inflammatory process is unleashed. Manuel Ansede
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