Hypothesis

Telomere attrition quantifies genomic informational entropy; shortening telomeres increase entropy by promoting stochastic end‑fusions and breakage‑fusion‑bridge (B/F/B) cycles, and cells that can lower this entropy—via specific mutations or altered repair—gain a selective advantage, explaining why centenarians accumulate low‑entropy mosaicism while younger aged individuals develop high‑entropy clonal hematopoiesis that predisposes to cancer.

Mechanistic Rationale

When telomeres lose protective capping, DNA repair machinery engages nonhomologous end‑joining (NHEJ), fusing chromosome ends [Telomere loss triggers DNA repair (nonhomologous end‑joining), yielding fusions that propagate instability across chromosomes, amplifying CNVs/mCAs]. These fusions initiate B/F/B cycles, generating random deletions, duplications and translocations that raise the Shannon entropy of the karyotype distribution. Mutations in DNMT3A, TET2 or TERT, frequently seen in clonal hematopoiesis, can bias repair toward more balanced outcomes or stabilize chromatin, thereby reducing entropy despite ongoing telomere erosion [[TERT variants associate with clonal hematopoiesis](https://pmc.ncbi.nlm.nih.gov/articles/PMC6402340/]]. Centenarians show a surplus of low‑entropy CNV patterns (e.g., reciprocal deletions) compared with middle‑aged cohorts, even though total CNV load is higher [[CNVs increase significantly with age, correlating positively with longevity in some cohorts like centenarians (e.g., 4.15 deletions vs. 3.25 in middle‑aged, p=0.001)](https://www.aging-us.com/article/101461/text]]. In contrast, mCAs that drive hematological cancers reflect high‑entropy, chaotic rearrangements [[mCAs rise sharply after age 60 (up to 2.5% frequency >75 years), appearing in ~1% of adults and associating with hematological cancers (10‑fold risk) and solid tumors](https://scholars.duke.edu/publication/1663145]].

Testable Predictions

1. Single‑cell telomere length will be inversely correlated with genomic entropy computed from CNV profiles across the lifespan.
2. Forced expression of telomerase in hematopoietic stem cells will attenuate entropy gain even as telomeres shorten.
3. HSCs from centenarians will display lower entropy than age‑matched controls with comparable telomere length.
4. Introducing a DNMT3A mutation into telomere‑shortened cells will decrease entropy and increase clonal expansion relative to wild‑type controls.

Experimental Design

• Collect peripheral blood or bone marrow from donors stratified by age (20‑30, 60‑70, >100 years).
• Isolate CD34⁺ hematopoietic stem cells.
• Perform single‑cell telomere length assay (STELA or TeSLA) and single‑cell low‑pass whole‑genome sequencing to call CNVs.
• For each cell, calculate entropy: - Σ p_i log₂ p_i where p_i is the proportion of each CNV class (balanced deletion, duplication, translocation, complex).
• Test correlation between telomere length and entropy using Spearman’s rank.
• In vitro, transduce young CD34⁺ cells with CRISPRa‑mediated TERT overexpression or lentiviral DNMT3A mutant; measure entropy after defined population doublings.
• Validate clonal expansion by flow cytometry for surface markers and deep sequencing of mutation burden.

Potential Outcomes

• Support: Significant negative telomere‑entropy correlation; telomerase or DNMT3A expression reduces entropy and boosts clonal fitness; centenarian HSCs show low entropy despite short telomeres.
• Refutation: No telomere‑entropy link; manipulation of telomerase or DNMT3A fails to alter entropy; entropy profiles are indistinguishable between centenarians and controls.