Study Identifies Putative Causal Association Between Latent Epigenetic Ageing and Bone Mineral Density

A Mendelian randomization study of 426,824 individuals suggests a potential causal link between latent epigenetic ageing and estimated bone mineral density via monocyte-specific regulation of the TRIM59-IFT80 locus.

Researchers constructed a latent epigenetic ageing factor using Genomic structural equation modelling across four DNA methylation clocks: GrimAge, Hannum, PhenoAge, and intrinsic epigenetic age acceleration.

Two-sample Mendelian randomization (MR) on a cohort of 426,824 individuals demonstrated a potential causal effect of the latent ageing factor on heel estimated bone mineral density (eBMD) (inverse-variance weighted β = 0.067, P = 3.6 × 10-4), while reverse MR showed no causal association.

Integrative genomic analyses converged on chromosome 3, identifying IFT80 (posterior probability of hypothesis 4 = 0.769) and TRIM59 (posterior probability of hypothesis 4 = 0.886) as key monocyte-specific mediating genes.

Causal transcriptome-wide association study fine-mapping nominated 45 high-confidence eBMD genes, independently confirming IFT80 (PIP = 0.981) and TRIM59 (PIP = 0.936) as top-ranked candidates.

In vitro Western blot analysis confirmed significant IFT80 downregulation and TRIM59 upregulation during RANKL-induced THP-1 osteoclast differentiation, validating the computational predictions.

The findings provide a direct link between systemic epigenetic clocks and a concrete clinical endpoint (bone mineral density), helping resolve whether epigenetic drift actively drives or merely correlates with age-related functional decline.

Identifying monocyte-specific genes offers a highly targeted therapeutic window, allowing developers to focus on the immune-bone axis rather than attempting systemic, tissue-agnostic epigenetic rejuvenation.

The identification of 45 high-confidence candidate genes expands the IP landscape for preclinical musculoskeletal pipelines, offering novel targets for gene therapy and small-molecule discovery engines.

Because the study represents early-stage target identification, commercial translation will require extensive preclinical validation in primary human cells before clinical-stage assets can be realized.

Preclinical validation of the identified 45 candidate genes and the specific modulation of the TRIM59-IFT80 locus in primary human monocyte-derived osteoclasts.