A rare late-onset neurodegenerative disease with characteristics of supranuclear gaze palsy, postural instability, progressive rigidity, and mild dementia. Five clinical variants have been described with clinicopathological correlations, with Richardson's syndrome the most common clinical variant. The disease has neuropathological manifestations of neuronal loss, gliosis with astrocytic plaques and accumulation of tau-immunoreactive neurofibrillary tangles in specific brain areas. The differences in the rate and areas of accumulation of phosphorylated tau protein correlate with the five clinical variants. The disease is a 4R tauopathy composed of a preponderance of four-repeat (exon 10 positive) tau isoforms and a characteristic biochemical profile (doublet tau 64 and tau 69). The MAPT H1-clade specific sub-haplotype, H1c, is a risk factor for this disease.