Leukocyte Disease, also known as leukocyte disorders, is related to neutrophilia, hereditary and chronic granulomatous disease. An important gene associated with Leukocyte Disease is MIR21 (MicroRNA 21), and among its related pathways/superpathways are T-cell activation SARS-CoV-2 and Th17 Differentiation. The drugs Prednisone and glucocorticoids have been mentioned in the context of this disorder. Affiliated tissues include white blood cells, and related phenotype is immune system.