Overview

Pathogenicity: Alzheimer's Disease : Uncertain Significance
Clinical Phenotype: Alzheimer's Disease
Reference Assembly: GRCh37/hg19
Position: Chr14:73640406 G>T
dbSNP ID: rs201617677
Coding/Non-Coding: Coding
Mutation Type: Point, Missense
Codon Change: AGG to AGT
Reference Isoform: PSEN1 Isoform 1 (467 aa)
Genomic Region: Exon 5

Findings

This variant has been reported in several Chinese individuals with Alzheimer's disease with a relatively late onset. It was initially found using whole-exome sequencing to screen 15 patients from Chinese families with familial AD (Jiang et al., 2019). The proband was 60 years old at disease onset. His initial symptom was memory loss which progressed slowly, with irritability developing two years later. His mother died at approximately 90 years of age with cognitive impairment.

The variant was also found in a Chinese family in which the proband was diagnosed with AD and six family members, spanning three generations, were affected (Jia et al., 2020). The proband's age at onset was 72 years and the family's mean age at onset was 67.6 years. The variant was identified in four affected members, but its absence was not reported in an aged, unaffected member to demonstrate co-segregation. The proband's APOE genotype was E3/E3.

The variant was also reported in a Han Chinese man in Taiwan with depression and amnesic onset at age 51 (Lin et al., 2020). Family history for this individual was unavailable.

The variant was found in three population-based variant databases: the 1000 Genomes Project (0.0002), ExAC (0.0000659), and gnomAD (0.0000609), as well as in the East Asian subpopulation in ExAC (0.00009244) and Taiwan View (0.00033) (Jiang et al., 2019; Lin et al., 2020).

Neuropathology
Neuropathological data are unavailable, but at age 59, the patient in Taiwan had posterior cortical atrophy and mild medial temporal atrophy, as assessed by MRI (Lin et al., 2020).

Biological Effect
The biological effect of this variant is unknown, but several in silico algorithms (SIFT, Polyphen-2, LRT, MutationTaster, MutationAssessor, FATHMM, PROVEAN, CADD, REVEL, and Reve) predicted this variant is damaging (Lin et al., 2020, Xiao et al., 2021). Both Jiang et al. and Lin et al. classified this variant as of uncertain significance (Jiang et al., 2019; Lin et al., 2020).

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References

Paper Citations

1. Jiang B, Zhou J, Li HL, Chen YG, Cheng HR, Ye LQ, Liu DS, Chen DF, Tao QQ, Wu ZY. Mutation screening in Chinese patients with familial Alzheimer's disease by whole-exome sequencing. Neurobiol Aging. 2019 Apr;76:215.e15-215.e21. Epub 2018 Dec 6 PubMed.
2. Jia L, Fu Y, Shen L, Zhang H, Zhu M, Qiu Q, Wang Q, Yan X, Kong C, Hao J, Wei C, Tang Y, Qin W, Li Y, Wang F, Guo D, Zhou A, Zuo X, Yu Y, Li D, Zhao L, Jin H, Jia J. PSEN1, PSEN2, and APP mutations in 404 Chinese pedigrees with familial Alzheimer's disease. Alzheimers Dement. 2020 Jan;16(1):178-191. PubMed.
3. Lin YS, Cheng CY, Liao YC, Hong CJ, Fuh JL. Mutational analysis in familial Alzheimer's disease of Han Chinese in Taiwan with a predominant mutation PSEN1 p.Met146Ile. Sci Rep. 2020 Nov 13;10(1):19769. PubMed.
4. 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.

Further Reading

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