Evidence map›Paper›PMID 41327373›Full record

ArticleAlzheimer's research & therapy2025

Phenotypic variability in early-onset dementia segregating with a novel APP (p.I718M) variant.

Charlotte Johansson, Elena Rodriguez-Vieitez, Marina Bluma, Inger Nennesmo, Håkan Thonberg, Abbe Ullgren, Vesna Jelic, Henrik Zetterberg, Kaj Blennow, Agneta Nordberg and 1 more

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Article in Alzheimer's research & therapy, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

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4 · The record

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5 · Who and what money

Authors and funding

11 authors.

Charlotte JohanssonDivision of Neurogeriatrics, Department of Neurobiology, Center for Alzheimer Disease Research, Care Sciences and Society, Karolinska Institutet, Bioclinicum J10:20 C Graff group, Visionsgatan 4, 171 64, Solna, Sweden. charlotte.johansson@ki.se.
Elena Rodriguez-VieitezDivision of Neurogeriatrics, Department of Neurobiology, Center for Alzheimer Disease Research, Care Sciences and Society, Karolinska Institutet, Bioclinicum J10:20 C Graff group, Visionsgatan 4, 171 64, Solna, Sweden.
Marina BlumaDivision of Clinical Geriatrics, Department of Neurobiology, Center for Alzheimer Research, Care Sciences and Society, Karolinska Institutet, Huddinge, Sweden.
Inger NennesmoDepartment of Oncology-Pathology, Karolinska Institutet, Stockholm, Sweden.
Håkan ThonbergDepartment for Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden.
Abbe UllgrenDivision of Neurogeriatrics, Department of Neurobiology, Center for Alzheimer Disease Research, Care Sciences and Society, Karolinska Institutet, Bioclinicum J10:20 C Graff group, Visionsgatan 4, 171 64, Solna, Sweden.
Vesna JelicTheme Inflammation and Aging, Karolinska University Hospital, Stockholm, Sweden.
Henrik ZetterbergDepartment of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, Mölndal, Sweden.
Kaj BlennowDepartment of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, Mölndal, Sweden.
Agneta NordbergTheme Inflammation and Aging, Karolinska University Hospital, Stockholm, Sweden.
Caroline GraffDivision of Neurogeriatrics, Department of Neurobiology, Center for Alzheimer Disease Research, Care Sciences and Society, Karolinska Institutet, Bioclinicum J10:20 C Graff group, Visionsgatan 4, 171 64, Solna, Sweden.

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

backgroundAutosomal dominant Alzheimer disease (ADAD) is caused by pathogenic variants in the APP, PSEN1 and PSEN2 genes, but a substantial fraction of reported variants is of unknown clinical significance. Here we report a novel variant in the amyloid precursor protein gene (APP p.I718M).

methodsFive siblings from a family with a multi-generational history of cognitive disease were assessed for cognitive impairment at the memory clinic at Karolinska University Hospital. Data were included for genetic analysis, segregation analysis, phenotyping and fluid biomarker analysis. Biomarker analyses were performed in CSF (Aβ38, Aβ40, Aβ42, t-tau, p-tau181, NfL) and plasma (p-tau181, p-tau217, GFAP, NfL). CSF and plasma biomarkers were compared cross-sectionally to non-carrier controls or mutation carriers from other ADAD families. Also, amyloid PET, brain MRI and neuropathological data were included.

resultsThe siblings fulfilled criteria of probable AD (N = 4) or mixed AD and dementia with Lewy bodies (AD/DLB) (N = 1). Median age at onset was 53 years (range 47 to 67). The genetic variant, APP p.I718M, classified as likely pathogenic based on segregation analysis, population frequency and in silico prediction of pathogenicity, was detected in all five siblings. CSF Aβ42/40 and Aβ42/38 ratios were decreased, and the CSF Aβ38/40 ratio was increased compared to controls. Additionally, elevated plasma concentrations of GFAP, NfL and p-tau181 were observed in APP p.I718M and other ADAD mutation carriers. DISCUSSION: The APP p.I718M variant is associated with ADAD. Also, concomitant Lewy body pathology was observed in one sibling. The increase in CSF Aβ38/40 suggests a shift in APP processing product-lines, but functional experiments are needed to characterize further cellular mechanisms of the APP p.I718M variant and to confirm its pathogenicity.

Indexed as

Alzheimer DiseaseAmyloid beta-Protein PrecursorDementiaAge of OnsetAmyloid beta-PeptidesBiomarkersBrainFemaleHumansMagnetic Resonance ImagingMaleMiddle AgedMutationPedigreePhenotypePositron-Emission TomographyAmyloid beta-PeptidesAmyloid beta-Protein PrecursorAPP protein, humanBiomarkerstau ProteinsAmyloid-betaAPPAutosomal dominant Alzheimer diseasePathogenic

Identifiers

PMID41327373
PMCPMC12670831

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.