One study investigating the iron content in a cohort of bvFTD and PPA patients failed to find any difference in the substantia nigra,78 while a post mortem 7 T MRI study found a significant increase of iron deposition in the subthalamic nucleus of the FTLD-FUS, FTLD-TDP-43 and pure ALS groups, but not in the FTD-tau, while there was no difference in the substantia nigra from controls.79 This evidence concerns the gene TARDBP and primary progressive aphasia.