PSEN1 and early-onset autosomal dominant Alzheimer disease: The M93V variant in PSEN1, so far never described, is very interesting as localized in a mutational hot spot in a critical region for the protein function, the transmembrane domain 1: in fact, the adjacent mutations C92S (Zhang et al., 2000; Tedde et al., 2003) and V94M (Arango et al., 2001; Somavarapu and Kepp, 2016) are associated with Alzheimer’s disease (AD).