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The curious case of a heterozygous loss-of-function PSEN1 variant associated with early-onset Alzheimer’s disease

Sanjuan-Ruiz, Inmaculada; Serneels, Lutgarde; Craessaerts, Katleen; Goate, Alison; Annaert, Wim; Chávez-Gutiérrez, Lucía; Shi, Yonggang; ... De Strooper, Bart; + view all (2025) The curious case of a heterozygous loss-of-function PSEN1 variant associated with early-onset Alzheimer’s disease. Molecular Neurodegeneration Advances , 1 , Article 4. 10.1186/s44477-025-00004-x. Green open access

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Abstract

BACKGROUND: Over 300 mutations in PSEN1 have been identified as causes of early-onset Alzheimer's disease (EOAD). While these include missense mutations and a few insertions, deletions, or duplications, none result in open reading frame shifts, and all alter γ-secretase function to increase the long/short Aβ ratio. METHODS: We identified a novel heterozygous PSEN1 nonsense variant, c.325A > T, in a patient and his father, both presenting with EOAD, resulting in the substitution of lysine 109 with a premature stop codon at position (p.K109*). This produces a truncated 109 amino acid (aa) N-terminal PSEN1 fragment. Functional characterization was performed using overexpression models and a heterozygous mouse model (Psen1K109*/+). RESULTS: In overexpression models, downstream ATGs serve as alternative starting codons, generating a > 37 kDa and a > 27 kDa PSEN1 C-terminal fragment (PSEN1-CTFA and PSEN1-CTFB, respectively) that retain the two catalytic aspartates of γ-secretase. Heterozygous Psen1K109*/+ mice exhibited subtle phenotypic defects, including reduced Pen2 expression and mild APP-CTF accumulation. Notably, aged mice demonstrated significantly increased Psen2 protein expression, potentially contributing to an elevated Aβ42/Aβ38 ratio. CONCLUSIONS: These findings indicate that PSEN1 c.325A > T (p.K109*) is not a complete loss-of-function mutation. However, to what extent and by what mechanism it contributes to EOAD pathogenesis remains unclear. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s44477-025-00004-x.

Type: Article
Title: The curious case of a heterozygous loss-of-function PSEN1 variant associated with early-onset Alzheimer’s disease
Location: England
Open access status: An open access version is available from UCL Discovery
DOI: 10.1186/s44477-025-00004-x
Publisher version: https://doi.org/10.1186/s44477-025-00004-x
Language: English
Additional information: This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/.
Keywords: Alzheimer’s disease, PSEN1, loss-of-function, γ-secretase
UCL classification: UCL
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > UCL Queen Square Institute of Neurology
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > UCL Queen Square Institute of Neurology > UK Dementia Research Institute
URI: https://discovery.ucl.ac.uk/id/eprint/10216322
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