The study could also broaden understanding of how environmental influences alter genes to cause a wide range of diseases.

The causes of multiple sclerosis (MS) are not well understood, but experts have long suspected that environmental factors trigger the disease in people who are genetically susceptible.

In the newly published study, researchers found that women with MS were more likely than men with MS to have a specific genetic mutation that has been linked to the disease.

More about Women With MS More Likely to Have Gene Mutation

Marek Michalak and Allison Kraus, scientists from the University of Alberta’s faculty of medicine and dentistry, were lead investigators on an international research team which identified a gene that plays a key role in the normal function of nerve cells and their ability to relay messages in the body. They discovered that shutting off an important gene causes mobility issues much like those seen in MS patients. The finding helps in the understanding of complex neurological diseases such as MS and Charcot Marie Tooth, both of which involve something called myelin impairment. Myelin is the protective coating around neurons which allow messages to travel quickly within the nervous system.

Using extremely fine-grained analytical tools, scientists compared genetic information in three sets of identical twins. Of each pair, one twin had MS, and the other didn’t — yet their genes proved essentially identical.

“We find no smoking gun on the genetic level,” said National Center for Genome Resources geneticist Stephen Kingsmore, coauthor of the study published April 28 in Nature.

The research cost $1.5 million, and the scientists took 18 months to sequence 2.8 billion DNA units in each twin, and determine whether they came from the mother or father. Most genomic comparisons look for differences in a just handful of suspect gene, and even whole-genome approaches don’t differentiate between parental contributions.