Interestingly, individuals with MHC‐I deficiencies, caused by deleterious mutations in the complex TAP (transporter associated with antigen processing) or β‐2‐microglobulin, which are associated with very low levels of conventional CD8+ T cells, are susceptible to several infections caused by extracellular bacteria, underscoring the critical role of CD8+ T cells against these pathogens.29 The gene discussed is CD8A; the disease is infection.