On Jun. 1, 2016, scientists at the University of British Columbia and Vancouver Coastal Health announced proof that multiple sclerosis (MS) can be caused by a single genetic mutation – a rare alteration in DNA that makes it very likely a person will develop the more devastating form of the neurological disease.

The mutation was found in two Canadian families that had several members diagnosed with a rapidly progressive type of MS, in which a person’s symptoms steadily worsen and for which there is no effective treatment. The discovery of this mutation should erase doubts that at least some forms of MS are inherited.