Mutations

PSEN1 L424V

Overview

Pathogenicity: Alzheimer's Disease : Pathogenic, Atypical Dementia : Pathogenic
Clinical Phenotype: Atypical Dementia
Reference Assembly: GRCh37 (105)
Position: Chr14:73685863 C>G
dbSNP ID: NA
Coding/Non-Coding: Coding
Mutation Type: Point, Missense
Codon Change: CTC to GTC
Reference Isoform: PSEN1 isoform 1 (467 aa)
Genomic Region: Exon 12

Findings

This mutation has been reported in two individuals with several differences in clinical presentation. It was first documented in a young Spanish woman suffering from an early onset dementia syndrome with a complex clinical phenotype. At the age of 26 she developed symptoms of anorexia nervosa, followed by memory and attention deficits by age 30. Four years later she had developed changes in personality and behavior, including impulsivity and aggression. Her condition deteriorated, and she developed aphasia, stereotyped behaviors, myoclonus, and seizures. Possible diagnoses of Huntington's disease and sporadic Creutzfeldt-Jakob disease were considered and excluded. Her symptoms were indicative of frontal dysfunction reminiscent of frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17). No family members were affected by early onset dementia, although her maternal grandfather developed dementia after age 80. Segregation of the mutation with disease could not be assessed, but it was absent in 178 unrelated individuals (Robles et al., 2009).

A subsequent report described the mutation in a Bulgarian man diagnosed with early onset familial AD (Stoychev et al., 2019). His initial symptoms, surfacing at approximately 38 years of age, included rapid and marked impairment of episodic memory and speech, in addition to slow reactivity and irritability. Aphasic symptoms and episodes of disorientation developed subsequently. Cognitive decline with further deterioration of speech, apraxia, acalculia, and ataxia occurred over the following two years, as well as the emergence of parkinsonian symptoms, bradykinesia and tremor. Unlike the Spanish patient, this individual did not develop myoclonus nor seizures. Of note, the patient also suffered from lupus erythematosus with predominant skin manifestations. The patient's father developed dementia with an approximate age at onset of 44 years. 

Neuropathology

Unknown. CT and SPECT imaging of the Spanish woman's brain showed diffuse cortical and subcortical atrophy as well as hypoperfusion affecting the frontal, temporal, and parietal lobes. Fronto-temporal cortical atrophy was the dominant feature of the Bulgarian case, as revealed by CT and MRI scans.

Biological Effect

Compared with wild-type PSEN1, this mutation increased both Aβ40 and Aβ42 production, and doubled the Aβ42/Aβ40 ratio as assessed by in vitro assays using isolated proteins (Bai et al., 2015; Sun et al., 2017).

Last Updated: 12 Jan 2020

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References

Paper Citations

  1. . Clinical picture of a patient with a novel PSEN1 mutation (L424V). Am J Alzheimers Dis Other Demen. 2009 Feb-Mar;24(1):40-5. PubMed.
  2. . A Clinical Case of Patient Carrying Rare Pathological PSEN1 Gene Mutation (L424V) Demonstrates the Phenotypic Heterogenity of Early Onset Familial AD. Front Psychiatry. 2019;10:857. Epub 2019 Dec 11 PubMed.
  3. . An atomic structure of human γ-secretase. Nature. 2015 Sep 10;525(7568):212-7. Epub 2015 Aug 17 PubMed.
  4. . Analysis of 138 pathogenic mutations in presenilin-1 on the in vitro production of Aβ42 and Aβ40 peptides by γ-secretase. Proc Natl Acad Sci U S A. 2017 Jan 24;114(4):E476-E485. Epub 2016 Dec 5 PubMed.

Further Reading

No Available Further Reading

Protein Diagram

Primary Papers

  1. . Clinical picture of a patient with a novel PSEN1 mutation (L424V). Am J Alzheimers Dis Other Demen. 2009 Feb-Mar;24(1):40-5. PubMed.

Other mutations at this position

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