“…Nine studies included a healthy control arm [15,21,23,27,32,40,[48][49][50]. A majority of the studies (N = 20) recruited only relapsing-remitting (RR) MS patients [14,[16][17][18]20,23,[26][27][28]31,33,35,37,[39][40][41][42]47,48,51]. Sixteen studies recruited primary progressive (PP) MS and secondary progressive (SP) MS patients [15,21,22,24,25,29,30,32,34,36,38,[43][44][45][46]49].…”