Overview

Pathogenicity: Alzheimer's Disease : Pathogenic
Clinical Phenotype: Alzheimer's Disease
Reference Assembly: GRCh37 (105)
Position: Chr14:73653577 T>G
dbSNP ID: rs63750265
Coding/Non-Coding: Coding
Mutation Type: Point, Missense
Codon Change: CTT to CGT
Reference Isoform: PSEN1 isoform 1 (467 aa)
Genomic Region: Exon 6

Findings

This mutation is associated with early onset Alzheimer’s disease in a family of Spanish origin. The reported pedigree contains six affected individuals over three generations. In this family, symptoms became apparent between the ages of 32 and 44. The proband began to experience memory decline at age 32. A neurological exam also showed a grasping reflex and bradykinesia. The proband’s mother was also affected, but her age of onset is unknown. His maternal aunt experienced memory loss at age 44, along with irritability and depression. She also developed aphasia and akinetic movements. The mutation was found to segregate with disease; it was present in the proband but absent in two healthy family members aged 37 and 60. The L166R mutation was also detected in two healthy individuals, who, at age 25 and 28, were below the average age of onset in this family (Ezquerra et al., 2000). This family was included in a later mutation-prevalence study conducted in Spain (Lleó et al., 2002).

Neuropathology

Unknown. MRI of the proband showed cortical atrophy and PET showed parietal hypoperfusion (Ezquerra et al., 2000).

Biological Effect

Unknown. Several mutations tied to dementia have been reported at this site. Moreover, a cryo-electron microscopy study of the atomic structure of γ-secretase bound to an APP fragment indicates 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).

Comments

No Available Comments

Make a Comment

To make a comment you must login or register.

References

News Citations

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

Paper Citations

1. Ezquerra M, Carnero C, Blesa R, Oliva R. A novel presenilin 1 mutation (Leu166Arg) associated with early-onset Alzheimer disease. Arch Neurol. 2000 Apr;57(4):485-8. PubMed.
2. Lleó A, Blesa R, Queralt R, Ezquerra M, Molinuevo JL, Peña-Casanova J, Rojo A, Oliva R. Frequency of mutations in the presenilin and amyloid precursor protein genes in early-onset Alzheimer disease in Spain. Arch Neurol. 2002 Nov;59(11):1759-63. PubMed.
3. 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.

Further Reading

Learn More

1. Alzheimer Disease & Frontotemporal Dementia Mutation Database