Numerous autoimmune diseases (e.g., insulin-dependent diabetes) and therapy-induced conditions (e.g., allograft transplantation rejection, graft-vs-host disease) adopt a synonymous biochemical pathway.4, 5 An integral part of this biological cascade is perforin oligomerisation in which monomeric perforin binds calcium upon entry into the immune synaptic cleft and forms highly ordered oligomers with 19–24 adjacent perforin monomers. The gene discussed is PRF1; the disease is type 1 diabetes mellitus.