As an additional supportive finding, our MR sensitivity analyses showed that several CD20- and CD33-expressing leukocytes increase the risk of Alzheimer’s disease and that CD11-expressing leukocytes may increase, and CD27- and CXCR1-expressing leukocytes may decrease, Parkinson’s disease risk. Here, CXCR1 is linked to early-onset autosomal dominant Alzheimer disease.