MAPT and amyotrophic lateral sclerosis: Perhaps the best studied human neurodegenerative disorder—although not the best known or acknowledged—is Western Pacific ALS/PDC, a polyproteinopathy of varying phenotype (ALS, Parkinsonism-dementia (P-D), dementia (GD), and sub-clinical neurofibrillary degeneration comprising hyperphosphorylated tau protein).