Navarro et al. [80] described a family with pathologically confirmed cases of early-onset Alzheimer’s disease linked to a mutation of the presenilin-1 gene (PSEN-1); one member of the family developed an atypical phenotype, with left-upper-limb bradykinesia and dystonia, myoclonus, apraxia confined to the left limbs, hemispatial neglect, and frontal dementia, thus mimicking CBS. This evidence concerns the gene PSEN1 and early-onset autosomal dominant Alzheimer disease.