MAPT and Alzheimer disease: Nonetheless, similar mean seed concentrations for AD brain samples were obtained with Spearman-Kärber analyses of end-point dilution data the two assays, i.e., 8.7 +/− 0.2 and 8.4 +/− 0.2 log SD50/mg with AD tau RT-QuIC and K12 RT-QuIC, respectively.