Objective: To describe the novel phenotype of a patient with an amyloid precursur protein (APP) mutation presenting with dementia and symptoms of both progressive supranulcear palsy (PSP) and multisystem atropy (MSA).

Background: Early dementia of AD phenotype is the most common presenting feature of patients with APP mutations. In human subjects, overlapping features of APP, PSP, and MSA have not previously been decribed in the literature.

Methods: We examined a 70 yo man with a history of four years of dementia, presenting with three years of akinetic-rigid parkinsonism and one year of autonomic dysfunction of urinary incontinence and orthostatic hypotension respectively. He had a family history of early onset (EOD) dementia in two out of four of his siblings and his mother. Mini-mental status exam was 2/30, During his clinic visit, he was orthostatic. MRI of the brain revealed moderate midbrain atrophy, but no hot-cross bun sign. B12 and TSH were WNL, and RPR negative. Gene testing revealed negative Presenillin 1 and 2, but he was positive for an APP disease-associated known mutation, G>A, nucleotide position 2149, codon 717, valine>isoleucine.

Results: This patient’s APP mutation has been characterized in several patients prior, but soley associated with the typical early AD features. This is the first case reported with parkinsonism, supranuclear palsy, and dysautonomia.

Conclusions: Features of PSP and MSA may be included to the expanded phenotypic range associated with mutations of APP.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/a-novel-phenotype-of-amyloid-precursor-protein-app-mutation-presenting-with-dementia-and-symptoms-of-both-progressive-supranulcear-palsy-psp-and-multisystem-atrophy-msa/