PSEN1 and Alzheimer disease: PSEN1 p.P284L and PSEN1 c.857-1G>A mutations are reported to relate to Alzheimer’s disease with spastic paresis, which is pathologically characterized by large, noncored, weakly neuritic Aβ-amyloid plaques called “cotton-wool” amyloid plaques (CWP) [22-25].