In 29 studies we identified that examined CD4+CD25+Treg either without or with Foxp3/low CD127 expression in MS compared to healthy donors; 12 studies found no difference in MS compared to HD in frequency5,6,9,24,25,27–30,32,34,37 while nine found reduced Treg7,10,11,14–17,19,20, and three found reduced Treg during relapses8,12,19. Here, CD4 is linked to Huntington disease.