MAPT and frontotemporal dementia: This analysis revealed that the lowest levels of serum TDP-43 were present in the patients with the FTD-MND phenotype (N = 9, 113.3 pg/mL) (i.e., TDP43-positive cases), while the highest levels were found in PSP patients (N = 24, 362.6 pg/mL) (i.e., tau-positive cases).