Multiple sclerosis (MS) is an inflammatory disease, which is immune-mediated, and responds to immune-modulating therapies. However, it is uncertain what antigen, or antigens, trigger the immune system to attack the central nervous system's (CNS's) myelin. Could it be iron? The predominantly venotopic location of MS lesions in the CNS has recently been postulated to be a consequence of congenital stenosis of the internal jugular or azygous veins, causing venous congestion and hypertension, and local transmural extravasation of erythrocytes into the white matter. The erythrocytes subsequently degrade, but the residual iron remains an antigenic stimulus for future immune activation …