While the potential pathological role of N2-containing tau is still subjected to preclinical scientific research [84, 172], the absence of N2-containing tau in the 4-repeat specific tauopathy, argyrophilic grain disease (AGD) [124], suggests that N2-specific tau ELISA for CSF might be able to differentiate AGD from other tauopathies. This evidence concerns the gene MAPT and argyrophilic grain disease.