In the pilot study, oligomeric Aβ and TDP-43 variants were present in the earliest available plasma samples of patients that later converted to AD up to seven years prior to the initial diagnosis of MCI, indicating promise for a blood-based pre-symptomatic diagnosis of AD, while oligomeric Aβ and tau variants characterized plasma samples taken after a clinical diagnosis of AD had been made [33]. This evidence concerns the gene MAPT and Alzheimer disease.