Overview

Pathogenicity: Alzheimer's Disease : Pathogenic
Clinical Phenotype: Alzheimer's Disease
Reference Assembly: GRCh37/hg19
Position: Chr14:73659502 G>A
dbSNP ID: NA
Coding/Non-Coding: Coding
Mutation Type: Point, Missense
Codon Change: ATG to ATA
Reference Isoform: PSEN1 Isoform 1 (467 aa)
Genomic Region: Exon 7

Findings

This mutation was found in a large French study reporting 56 new families with autosomal-dominant, early onset Alzheimer's disease. All probands met NINCDS-ADRDA criteria for probable AD and had a family history of disease (Wallon et al., 2012).

The M233I (G>A) mutation was detected in a family with two confirmed mutation carriers and two additional affected family members of unknown genotype. The authors reported the mutation segregates with disease, but did not report the identification of unaffected, aged non-carriers. Age of onset was very early in this family, 24 to 30 years, with duration of approximately 11 years. At least one mutation carrier presented with early extrapyramidal signs. 

This variant was absent from the gnomAD variant database (gnomAD v2.1.1, July 2021).

Neuropathology

Unknown.

Biological Effect

A cryo-electron microscopy study of the atomic structure of γ-secretase bound to an APP fragment indicates that, in wild-type PSEN1, this residue is apposed to the APP transmembrane helix, with its side-chain reaching towards the interior of the substrate-binding pore (Zhou et al., 2019; Jan 2019 news). 

Although some in silico algorithms to predict the effects of this variant on protein function yielded conflicting results (Xiao et al., 2021), the CADD-PHRED tool, which integrates diverse information, gave it a high deleteriousness score above 20 (CADD v.1.6, Sep 2021).

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References

News Citations

1. CryoEM γ-Secretase Structures Nail APP, Notch Binding 11 Jan 2019

Paper Citations

1. Wallon D, Rousseau S, Rovelet-Lecrux A, Quillard-Muraine M, Guyant-Maréchal L, Martinaud O, Pariente J, Puel M, Rollin-Sillaire A, Pasquier F, Le Ber I, Sarazin M, Croisile B, Boutoleau-Bretonnière C, Thomas-Antérion C, Paquet C, Moreaud O, Gabelle A, Sellal F, Sauvée M, Laquerrière A, Duyckaerts C, Delisle MB, Streichenberger N, Lannes B, Frebourg T, Hannequin D, Campion D. The French series of autosomal dominant early onset Alzheimer's disease cases: mutation spectrum and cerebrospinal fluid biomarkers. J Alzheimers Dis. 2012 Jan 1;30(4):847-56. PubMed.
2. Zhou R, Yang G, Guo X, Zhou Q, Lei J, Shi Y. Recognition of the amyloid precursor protein by human γ-secretase. Science. 2019 Feb 15;363(6428) Epub 2019 Jan 10 PubMed.
3. Xiao X, Liu H, Liu X, Zhang W, Zhang S, Jiao B. APP, PSEN1, and PSEN2 Variants in Alzheimer's Disease: Systematic Re-evaluation According to ACMG Guidelines. Front Aging Neurosci. 2021;13:695808. Epub 2021 Jun 18 PubMed.

External Citations

1. gnomAD v2.1.1
2. CADD v.1.6

Further Reading

No Available Further Reading