Recent atomic structures of human lysozyme amyloid fibrils have revealed polymorphism.[26] Unlike the in vitro fibrils formed by the WT lysozyme under harsh conditions (85 °C, 300 rpm),[26a]ex vivo fibrils from patients with the D87G mutation retain all four native disulfide bonds.[26b] This suggests that the amyloid fibrils responsible for systemic amyloidosis are formed by partially unfolded protein intermediates with intact disulfide bonds, rather than by fully denatured proteins. The gene discussed is LYZ; the disease is primary systemic amyloidosis.