Scientists announced on Wednesday that they had identified 29 new genes linked to multiple sclerosis, offering clues about how to potentially treat the debilitating disease.

Multiple sclerosis ravages the nervous system, and scientists believe that it is caused by a combination of environmental factors and inherited factors. In the new study, whose results were published in the journal Nature, an international team of researchers identified 29 genes whose variants are linked to multiple sclerosis, adding to 23 genes already believed to be associated with the disease.

Most of the genes in some way affected immunity, either through controlling interleukins, messenger chemicals that that help immune defenses communicate, or by affecting T-cells, which attack intruders. That bolsters the theory that multiple sclerosis begins by undermining the immune system.

"It is now clear that multiple sclerosis is primarily an immunological disease," Alastair Compston of Cambridge University, who co-led the study, told Reuters. "This is the way to nail this disease and get on top of it."

The study compared the genes of 9,772 people afflicted by multiple sclerosis with 17,376 people who did not have the disease. About 2.5 million people worldwide suffer from multiple sclerosis.

Some of the genes identified have also been linked in earlier research to other auto-immune diseases like diabetes and Crohn's. That suggests that existing drugs could be effective in treating multiple sclerosis.

"We have known for some time that many devastating diseases of the immune system must have common genetic causes," said Chris Cotsapas of Yale University in the United States. "Now we have the outline of a map that tells us where we can look for common treatments."