One of the authors (LK) reviewed all published studies (1756 in November 2015) resulting from a PubMed search using the keywords “Alzheimer’s disease,” “cerebrospinal fluid,” and “tau.” Similar to our findings, the vast majority of the cross-sectional studies described no association between tau levels and disease stage. The gene discussed is MAPT; the disease is early-onset autosomal dominant Alzheimer disease.