Thymocytes expressing high-affinity TCR for self-peptide/MHC complexes are deleted by apoptosis, a negative selection process critical for self-tolerance, as attested by the multiorgan autoimmune disease associated with autoimmune regulator (AIRE) gene mutations that impair the expression of peripheral self-peptides by thymic epithelial cells (28, 29). The gene discussed is AIRE; the disease is autoimmune disease.