Looking at all results, it is apparent that 3 patients initially diagnosed with AD, including one patient with the visual variant of AD (posterior cortical atrophy), are carriers of variants in the FTD genes (MAPT, GRN and C9ORF72) while 5 patients diagnosed with FTD carried mutations in the AD-related PSEN1 gene [15]. This evidence concerns the gene PSEN1 and Alzheimer disease.