Notable phenotypes of interest for this purpose are so-called atypical variants of AD, including posterior cortical atrophy (PCA: the ‘visual variant of AD’),35 logopenic variant primary progressive aphasia (lvPPA: the ‘language variant of AD’),36 behavioural variant AD (bvAD)37 and corticobasal syndrome (CBS: the ‘motor variant of AD’).38 Each of these variants shows distinct spatial tau patterns that largely correspond to the regions governing the cognitive functions that define each variant. This evidence concerns the gene MAPT and posterior cortical atrophy.