ACD is a type IV hypersensitivity reaction, which is a cell-mediated reaction from the interaction between sensitized T lymphocytes and specific antigens, which leads to an inflammatory reaction from the release of cytokines from CD4+ and CD8+ cells 24 to 72 hours after antigen exposure, ultimately presenting as a delayed-type reaction. The gene discussed is CD8A; the disease is granular corneal dystrophy type II.