GGT1 and tauopathy: Empirically testing the 4R tauopathy samples on the Tau4RD*K317H-YFP cell line, we found that only the CBD (P < 0.0001) and GGT patient samples (P = 0.0046) were able to significantly infect the cells compared to the negative control samples (Fig. 2I; Supplemental Table 3; representative images shown in Fig. S1).