Genome detectives have done it again by revealing at least three genes which are implicated in the incurable nerve disorder Multiple Sclerosis (MS).
Three team of scientists who have screened the entire human genome also suspect that a dozen more genes might be involved.
MS is caused by the breakdown of the fatty sheath surrounding portions of nerve cells that carry messages from one cell to another; this sheath, known as myelin, is rather like the plastic coating insulating an electrical cord.
Symptoms of the disease include muscle weakness, cognitive impairment, difficulties with balance and coordination and speech and vision problems.
MS is most common in young adults and women are more likely to develop the disease, which affects about 350,000 patients in the United States.
Scientists believe the autoimmune response is triggered as the result of a complex interplay between genetic and environmental factors, and one study suggests subtle changes in the immune system might spur the disease.
The three studies, two published in the journal Nature Genetics and one in the New England Journal of Medicine represent hope to 2.5 million people worldwide with MS, a disabling disease that progressively damages the nervous system.
The researchers say they detected tiny variations in people's genomes by using new tools, called 'snip chips'.
The New England journal study involved teams from the University of California at San Francisco, the University of Miami, Vanderbilt University and the University of Cambridge in the United Kingdom, who led the collection of multiple sclerosis populations.