An international study has discovered 29 new genetic variants of multiple sclerosis, bringing the total number of variants that underlie the disease to 57.

Twenty-three research groups working in 15 countries studied the differences in DNA between 9,772 European patients with multiple sclerosis and 17,400 healthy control subjects.

The research, published in scientific journal Nature, also confirmed 26 mutations suspected previously from smaller studies.

The results, gathered by The International Multiple Sclerosis Genetics Consortium and The Wellcome Trust Case Control Consortium 2 prove that multiple sclerosis is primarily a disorder of the immune system, which then attacks the central nervous system, reports the Financial Times.

The research also shows that drugs to treat multiple sclerosis should focus on preventing the initial faulty immune response.

Organisations involved in the research include the UK’ University of Cambridge, US-based Harvard Medical School and the Danish Multiple Sclerosis Center, among others.

Multiple sclerosis, which affects 2.5 million people worldwide, is an inflammatory disease in which the fatty myelin sheaths around the brain and spinal cord are damaged.