Mutations

PSEN1 Q223R

Overview

Pathogenicity: Alzheimer's Disease : Pathogenic
Clinical Phenotype: Alzheimer's Disease, Spastic Paraparesis
Reference Assembly: GRCh37 (105)
Position: Chr14:73659471 A>G
dbSNP ID: NA
Coding/Non-Coding: Coding
Mutation Type: Point, Missense
Codon Change: CAG to CGG
Reference Isoform: PSEN1 isoform 1 (467 aa)
Genomic Region: Exon 7

Findings

This mutation was found in a Turkish family with five individuals affected by dementia and spastic paraplegia (Uttner et al., 2010). The proband presented with memory deficits, slurred speech, social disinhibition, a lack of initiative, and emotional blunting at age 34. One year later, he had developed spastic paraparesis and dysphagia, and his cognition had severely declined. Affected family members, spanning three generations, died with similar symptoms in their late 30s or early 40s. The mutation was absent from 192 controls. 

The mutation was also reported in a French family with two affected individuals (Wallon et al., 2012). Age at onset was 31-34 years old, and disease duration was five years. As in the Turkish family, symptoms included spastic paraparesis.

Neuropathology
Neuropathological data from mutation carriers are unavailable, but brain biopsies from the affected mother and brother of the Turkish proband revealed cortical cotton-wool plaques and neurofibrillary tangles (Uttner et al., 2010). In addition, MRI of the proband revealed a few white matter lesions in the frontotemporal region. In the affected brother, MRI showed generalized atrophy and bilateral, frontally pronounced white matter lesions. Moreover, FDG-PET of the proband showed slightly decreased glucose metabolism in the precuneus and part of the posterior cingulate at disease onset. A year later, the reduction had progressed in both areas, and also included bilateral parietal hypometabolism.

Biological Effect
Levels of A42 were drastically decreased in the CSF of two mutation carriers (Uttner et al., 2010; Wallon et al., 2012). In the Turkish proband, the reduction was observed early in the disease, when an FDG-PET scan revealed only minor metabolic alterations and CSF tau levels were normal. In the French proband, CSF tau and phospho-tau levels were increased, consistent with the AD phenotype.

Amyloid-β peptide production in 2EB2 cells transfected with PSEN1 Q223R, while stably overexpressing Swedish APP and BACE1, was altered compared with that of cells transfected with wild-type PSEN1 (Li et al., 2016). Mutant carriers produced less Aβ40, seemingly due to a reduction of Aβ43 cleavage into Aβ40, and more Aβ42, due to decreased Aβ42 cleavage into Aβ38. An in vitro study with purified proteins, however, reported nearly complete ablation of both Aβ40 and Aβ42 production (Sun et al., 2017).

Last Updated: 01 May 2019

Comments

No Available Comments

Make a Comment

To make a comment you must login or register.

References

Paper Citations

  1. . A novel presenilin1 mutation (Q223R) associated with early onset Alzheimer's disease, dysarthria and spastic paraparesis and decreased Abeta levels in CSF. Eur J Neurol. 2010 Apr;17(4):631-3. PubMed.
  2. . 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.
  3. . Effect of Presenilin Mutations on APP Cleavage; Insights into the Pathogenesis of FAD. Front Aging Neurosci. 2016;8:51. Epub 2016 Mar 11 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

Learn More

  1. Alzheimer Disease & Frontotemporal Dementia Mutation Database

Protein Diagram

Primary Papers

  1. . A novel presenilin1 mutation (Q223R) associated with early onset Alzheimer's disease, dysarthria and spastic paraparesis and decreased Abeta levels in CSF. Eur J Neurol. 2010 Apr;17(4):631-3. PubMed.

Alzpedia

Disclaimer: Alzforum does not provide medical advice. The Content is for informational, educational, research and reference purposes only and is not intended to substitute for professional medical advice, diagnosis or treatment. Always seek advice from a qualified physician or health care professional about any medical concern, and do not disregard professional medical advice because of anything you may read on Alzforum.