 Since 2016, a special clinical variant of "rapidly progressive" MS has been found to be different from RRMS and other kinds of PPMS.It is due to a mutation inside the gene NR1H3, an arginine to glutamine mutation in the position p.Arg415Gln, in an area that codifies the protein LXRA.For the rest of the progressive cases, it has been found that the lesions are diffuse instead of the normal focal ones, and are different under MR spectroscopy.