Genetically Predicted Telomere Length and Its Relationship With Alzheimer's Disease.
Level 3 - non-randomized controlled study
Two-sample Mendelian randomization study (observational genetic instrumental variable design).
PubMed 33679878 · doi:10.3389/fgene.2021.595864
What was done
A two-sample Mendelian randomization (MR) analysis was conducted to assess whether leukocyte telomere length is causally related to the risk of Alzheimer's disease (AD). The authors used 20 genome-wide significant single nucleotide polymorphisms as instrumental variables for leukocyte telomere length and obtained summary statistics from an AD genome-wide association study. Primary analyses used the random-effects inverse-variance weighted method, supplemented by weighted median, MR-Egger regression, and weighted mode methods to evaluate horizontal pleiotropy.
What was found
Genetically predicted longer telomeres were significantly associated with lower odds of AD (odds ratio = 0.79, 95% confidence interval: 0.67 to 0.93, P = 0.004). Sensitivity analyses (weighted median, MR-Egger regression, and weighted mode) yielded comparable results, and the MR-Egger intercept was close to zero.
Why it matters
This study provides genetic instrumental variable evidence supporting a putative causal link between shorter telomere length and increased risk of Alzheimer's disease.
Limits
The abstract does not report the sample size or participant characteristics of the underlying GWAS datasets, nor numerical estimates for the sensitivity analyses. Mendelian randomization relies on assumptions regarding absent horizontal pleiotropy and canalization, and leukocyte telomere measurements may not reflect tissue-specific telomere dynamics in the central nervous system.
Cited by
- supports Mendelian randomization studies show that genetic propensity for longer telomeres directly predicts reduced risk of heart disease and dementia.