RT Journal Article SR Electronic T1 Clinical features and APOE genotype of pathologically proven early-onset Alzheimer disease JF Neurology JO Neurology FD Lippincott Williams & Wilkins SP 1720 OP 1725 DO 10.1212/WNL.0b013e31821a44dd VO 76 IS 20 A1 Balasa, M. A1 Gelpi, E. A1 Antonell, A. A1 Rey, M.J. A1 Sánchez-Valle, R. A1 Molinuevo, J.L. A1 Lladó, A. A1 For the Neurological Tissue Bank/University of Barcelona/Hospital Clínic NTB/UB/HC Collaborative Group YR 2011 UL http://n.neurology.org/content/76/20/1720.abstract AB Objectives:Early-onset Alzheimer disease (EOAD) diagnosis often represents a challenge because of the high frequency of atypical presentations. Our aim was to describe the clinical features, APOE genotype, and its pathologic correlations of neuropathologic confirmed EOAD. Methods:Retrospective review of clinical data (age at onset, family history, clinical presentation, diagnostic delay, diagnosis) and APOE genotype of patients with neuropathologically confirmed EOAD (<60 years). Results:Forty cases were selected. Mean age at onset was 54.5 years (range 46–60). The mean disease duration was 11 years with a mean diagnostic delay of 3.1 years. A total of 37.5% had a nonmemory presentation. Behavioral/executive dysfunction was the most prevalent atypical presentation. Incorrect initial clinical diagnoses were common (53%) in patients with atypical presentations, but rare when anterograde amnesia was the presenting symptom (4%). The incorrect initial clinical diagnoses were 2 behavioral variant frontotemporal lobar degeneration, 2 normal pressure hydrocephalus, 1 semantic dementia, 1 primary progressive aphasia, 1 corticobasal degeneration, 1 pseudodementia with depression, and 1 unclassifiable dementia. APOE genotype was ϵ3/ϵ3 in 59%, with no significant differences between typical and atypical presentations. APOE ϵ4 was 3.3 times more frequent in subjects with family history of AD. A total of 97.5% of the cases presented advanced neurofibrillary pathology. A total of 45% of the patients had concomitant Lewy body pathology although localized in most cases and without a significant clinical correlate. Conclusion:One third of patients with pathologic confirmed EOAD presented with atypical symptoms. Patients with EOAD with nonamnestic presentations often receive incorrect clinical diagnoses.