MAPT and early-onset autosomal dominant Alzheimer disease: We read with great interest the paper by Hart de Ruyter et al. [5] in the February issue of Acta Neuropathologica assessing the presence of p-tau (total tau (HT7), p-tau Ser202/Thr205, and p-tau Thr217) in the retina in relation to tau pathology in the brain in primary tauopathies and Alzheimer’s disease compared with non-tau-associated pathologies.