As Alzheimer's disease is a complex neurodegenerative disorder in which many different pathophysiological processes have been implicated (e.g. tau and amyloid deposition, abnormalities of cholesterol metabolism, inflammation, oxidative damage and lysosomal dysfunction) it is not surprising that many different candidate biomarkers for disease progression in Alzheimer's disease have been studied. The gene discussed is MAPT; the disease is early-onset autosomal dominant Alzheimer disease.