In the GCST90027158 dataset, a causal relationship was found between two specific immune cell types and the development of AD: the CD4+ CD8dim T cell leukocyte (OR = 1.020, 95% CI = 1.007–1.033, p = 0.002) and the CD4+ CD8dim T cell lymphocyte (OR = 1.018, 95% CI = 1.005–1.031, p = 0.007). The gene discussed is CD4; the disease is Alzheimer disease.