SPAG8 and Infertility: The latter two in particular highlight the cross-over of APECED serum autoreactivities with other pathophysiologies, in that SPAG8 was initially identified as a sperm-associated antigen target of serum of an infertile woman (33), while SPAG16 is expressed in sperm and in reactive astrocytes of lesions in multiple sclerosis patients in whom it has been identified as an autoantibody target (34).