Table 1

Characteristics of the presenile dementia syndromes

TypeAbnormal proteinPredisposing genetic mutationsSusceptibility genesPer cent of predisposition mutations
AlzheimerAmyloid β-42Amyloid precursor protein, presenilin 1, presenilin 2Apolipoprotein E4<5%
Frontotemporal dementiaTauTau introns and exonsUnknown<10%
Dementia with Lewy bodiesα Synucleinα Synuclein, 4p locusApolipoprotein E4<1%
Creutzfeldt–JakobPrionPrion proteinPrion protein codon 129<15%