The importance of CD1a in AD was first established through the discovery of peripheral blood and cutaneous house dust mite (HDM)-specific CD1a-reactive T cells, which were enriched in patients with AD compared with controls.41 Interestingly, the presence of null FLG mutations was correlated with an increase in HDM-specific CD1a-reactive T cells. The gene discussed is CD1A; the disease is Alzheimer disease.