The results suggest that a significant increase in cytokines (IL-21, IL-6, and IL-23) and a transcription factor (RORgamma) is associated with the differentiation of Th-17 cells, as well as elevated levels of cytokines (IL-21 and IL-22) produced by these cells and increased levels of IL-9, which is generated by Th-9 cells, in AD [95]. This evidence concerns the gene IL21 and Alzheimer disease.