Mutations

PSEN1 P242H

Overview

Pathogenicity: Alzheimer's Disease : Not Classified
ACMG/AMP Pathogenicity Criteria: PS3, PM2, PP2, BP4
Clinical Phenotype: Alzheimer's Disease
Position: (GRCh37/hg19):Chr14:73659528 C>A
Position: (GRCh38/hg38):Chr14:73192820 C>A
dbSNP ID: NA
Coding/Non-Coding: Coding
DNA Change: Substitution
Expected RNA Consequence: Substitution
Expected Protein Consequence: Missense
Codon Change: CCT to CAT
Reference Isoform: PSEN1 Isoform 1 (467 aa)
Genomic Region: Exon 7

Findings

Detailed information on carriers of this variant, identified in Australia and/or the U.S., is unavailable. However, it was classified as “Likely Pathogenic” and eligible for inclusion in clinical trials organized by the Dominantly Inherited Alzheimer Network Trials Unit (DIAN-TU) to test disease-modifying treatments for Alzheimer’s disease (Liu et al., 2025). Data used to determine DIAN-TU eligibility include family history suggesting an autosomal dominant pattern of inheritance, documentation of amnestic-predominant, progressive cognitive impairment leading to AD dementia (preferably with AD biomarkers and/or neuropathological confirmation of AD in at least one family member), low frequency of the variant in a large population database such as the gnomAD, evidence of co-segregation with disease within a family, and assessment of Aβ42 and Aβ40 levels in a cell-based assay. Additional supportive criteria include conservation of the affected amino acid between PSEN1 and PSEN2, presence of other AD pathogenic variants at the same amino acid site, and in silico prediction of damaging effects.

This variant was absent from the gnomAD variant database (gnomAD v4.1.0).

Neuropathology
Neuropathological data are unavailable.

Biological Effect
In a cell-based assay, this variant increased the Aβ42/Aβ40 ratio compared to wildtype PSEN1, but decreased production of both Aβ40 and Aβ42 (Marsh et al., 2025). The variant’s PHRED-scaled CADD score, which integrates diverse information in silico, was 15.13, below the commonly used deleteriousness threshold of 20 (CADD v.1.7, March 2025).

Pathogenicity

Alzheimer's Disease : Not Classified*

*Carriers of this variant are eligible for inclusion in clinical trials organized by the Dominantly Inherited Alzheimer Network Trials Unit (DIAN-TU) to test disease-modifying treatments for Alzheimer’s disease (Liu et al., 2025). Alzforum has not yet classified this variant because carrier data are not yet published.

This variant fulfilled the following criteria based on the ACMG/AMP guidelines. See a full list of the criteria in the Methods page.

PS3-M

Well-established in vitro or in vivo functional studies supportive of a damaging effect on the gene or gene product. P242H: This variant resulted in an increased Aβ42/Aβ40 ratio, but the levels of both peptides were reduced.

PM2-M

Absent from controls (or at extremely low frequency if recessive) in Exome Sequencing Project, 1000 Genomes Project, or Exome Aggregation Consortium. *Alzforum uses the gnomAD variant database.

PP2-P

Missense variant in a gene that has a low rate of benign missense variation and where missense variants are a common mechanism of disease.

BP4-P

Multiple lines of computational evidence suggest no impact on gene or gene product (conservation, evolutionary, splicing impact, etc). *In most cases, Alzforum applies this criterion when the variant’s PHRED-scaled CADD score is less than 20.

Pathogenic (PS, PM, PP) Benign (BA, BS, BP)
Criteria Weighting Strong (-S) Moderate (-M) Supporting (-P) Supporting (-P) Strong (-S) Strongest (BA)

Last Updated: 10 Mar 2025

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References

Paper Citations

  1. . The landscape of autosomal-dominant Alzheimer's disease: global distribution and age of onset. Brain. 2025 Feb 4; Epub 2025 Feb 4 PubMed.
  2. . Evaluating pathogenicity of variants of unknown significance in APP, PSEN1, and PSEN2. Neurotherapeutics. 2025 Jan 27;:e00527. Epub 2025 Jan 27 PubMed.

Further Reading

No Available Further Reading

Protein Diagram

Primary Papers

  1. . The landscape of autosomal-dominant Alzheimer's disease: global distribution and age of onset. Brain. 2025 Feb 4; Epub 2025 Feb 4 PubMed.
  2. . Evaluating pathogenicity of variants of unknown significance in APP, PSEN1, and PSEN2. Neurotherapeutics. 2025 Jan 27;:e00527. Epub 2025 Jan 27 PubMed.

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