In addition, they have been discovered to have a close connection with immune-related diseases; for instance, Cheng J et al. found increased expression of miR-451a in the thymus, and deficiency in miR-451a also decreased the numbers of CD4 + CD69 + and CD4 + /CD8 + T cells28, which provides a theoretical basis for subsequent experimental confirmation of MG. The gene discussed is CD8A; the disease is myasthenia gravis.