Alternatively, based on a recent genetic study that as aforementioned, associates a gain-of-function Kv1.3 gene polymorphism to a more aggressive disease course (Lioudyno et al., 2021), one may propose that the higher Kv1.3 expression in the SPMS group could merely reflect a history of more active disease tending to progress to the SPMS phenotype with a higher frequency. Here, KCNA3 is linked to secondary progressive multiple sclerosis.