Association Between Telomere Length and Risk of Cancer and Non-Neoplastic Diseases: A Mendelian Randomization Study

Deciphering the causal link between gut microbiota and membranous nephropathy: insights into potential inflammatory mechanisms

BACKGROUND

Membranous nephropathy (MN), a leading cause of adult nephrotic syndrome and renal failure, has been linked to gut microbiota (GM) and their metabolites. However, direct causal relationships and therapeutic implications remain unclear.

METHODS

We utilized a comprehensive GWAS dataset that encompasses GM, metabolites, and MN through two-sample Mendelian randomization (MR) analyses, bidirectional MR evaluations, and detailed sensitivity tests.

RESULTS

We identified strong causal associations between nine specific types of GM, including class Clostridia (OR = 1.816, 95%CI: 1.021-3.236, p = .042), class Melainabacteria (OR = 0.661, 95%CI: 0.439-0.996, p = .048), order Gastranaerophilales (OR = 0.689, 95%CI: 0.480-0.996, p = .044), genus Alistipes (OR = 0.480, 95%CI: 0.223-0.998, p = .049), genus Butyricicoccus (OR = 0.464, 95%CI: 0.216-0.995, p = .048), genus Butyrivibrio (OR = 0.799, 95%CI: 0.639-0.998, p = .048), genus Ruminococcaceae UCG003 (OR = 0.563, 95%CI: 0.362-0.877, p = .011), genus Streptococcus (OR = 0.619, 95%CI: 0.393-0.973, p = .038), and genus Oscillibacter (OR = 1.90, 95%CI: 1.06-3.40, p = .031). Additionally, the metabolite tryptophan also exhibited a significant causal influence on MN (OR = 0.852, 95%CI: 0.754-0.963, p = .010). Sensitivity and reverse MR analyses confirmed the robustness of these findings. Further exploration using gutMGene database suggests that GM may influence MN by affecting the release of inflammatory factors and modulating inflammatory pathways.

CONCLUSION

This study offers a comprehensive understanding of the causal links between GM, their metabolites, and MN, which highlight potential pathways for developing new preventive and therapeutic strategies for this condition.

Occupational pesticide use and relative leukocyte telomere length in the biomarkers of exposure and effect in agriculture study

Previous epidemiological studies have reported increased risks of certain cancers in relation to pesticide exposures. Although the biologic mechanisms underlying these associations are not well understood, altered telomere length has been hypothesized to play a role. We examined associations between occupational use of specific pesticides and leukocyte telomere length in the Biomarkers of Exposure and Effect in Agriculture study, a molecular epidemiological investigation of pesticide applicators in Iowa and North Carolina. Relative telomere length (RTL) was measured using quantitative polymerase chain reaction in leukocytes from 1539 male pesticide applicators ≥50 years of age. We evaluated lifetime use of 47 pesticides in terms of self-reported ever use and intensity-weighted lifetime days (IWLDs), a metric integrating lifetime days of use and other factors influencing exposure. Multivariable linear regression was used to estimate percent difference in geometric mean RTL in relation to ever (vs. never) use, IWLDs of use, and timing of use [recent (last 12 months) and former vs. never use]. Mean RTL was significantly longer among ever users of the insecticides lindane (percent difference = 2.20%, 95%CI: 0.45%, 3.99%) and aldicarb (percent difference = 3.27%, 95%CI: 0.23%, 6.40%). Longer RTL was also associated with increasing IWLDs of lindane (highest quartile vs. never use: percent difference = 4.51%, 95%CI: -0.22%, 9.46%; p-trend = 0.048) and the insecticide diazinon (4.77%, 95%CI: 0.17%, 9.58%; p-trend = 0.055), and with recent use of the insecticide dichlorvos (vs. never use: 8.15%, 95%CI: 1.31%, 15.46%). Increasing IWLDs of the insecticide heptachlor and the herbicide 2,4,5-TP and recent use of the herbicide metolachlor were significantly associated with shorter RTL. Our findings provide novel evidence suggesting that use of certain pesticides is associated with altered leukocyte telomere length. Notably, diazinon and lindane have previously been associated with increased risks of lung and lymphoid malignancies, respectively, and longer leukocyte telomere length has been implicated in the development of these cancers.

The Causal Relationship between Telomere Length and Cancer Risk: A Two-Sample Mendelian Randomization

BACKGROUND

Telomere length (TL) shortens with age and is associated with an increased risk of numerous chronic diseases. However, the causal direction of the association between TL and cancer risk remains uncertain. This study aimed to assess the causal impact of TL on cancer risk using Mendelian randomization (MR) analysis.

METHODS

Genome-wide association studies from Singapore and China data, the Korean Cancer Prevention Study II (KCPS-II), the Korean Genome Epidemiologic Study, and the Biobank of Japan were utilized. A two-sample MR study was performed using summary-level genome-wide association study data from individuals of East Asian ancestry. SNPs associated with TL were used as instrumental variables.

RESULTS

Longer TL per 1-SD increase due to germline genetic variants was associated with a higher risk of site-specific cancer. In the KCPS-II and Korean Genome Epidemiologic Study, the strongest association was observed with thyroid cancer {OR, 2.49 [95% confidence interval (CI), 1.79-3.47] and 2.27 (1.49-3.46)}, followed by lung cancer [OR, 2.19 (95% CI, 1.60-3.08) and 1.45 (1.12-1.87)]. Similar results were observed in the Biobank of Japan, with OR, 2.92 (95% CI, 1.75-4.88) for thyroid cancer and 2.04 (1.41-2.94) for lung cancer. In histologic subgroup analysis of KCPS-II, a significant relationship was found with lung adenocarcinoma [OR, 2.26 (95% CI, 1.55-3.31)] but not with lung squamous cell carcinoma (1.21, 0.47-3.06). After removing outlier SNPs in the radial MR analysis, significant associations were identified for both lung adenocarcinoma [OR, 1.88 (95% CI, 1.25-2.82)] and lung squamous cell carcinoma (2.29, 1.05-4.98).

CONCLUSIONS

Our findings suggest that longer TL increases the risk of various cancers in East Asian populations.

IMPACT

Genetically determined longer TL may contribute to a risk of certain cancers.

Causal effect between telomere length and thirteen types of cancer in Asian population: a bidirectional Mendelian randomization study

BACKGROUND

The relationship between leukocyte telomere length (LTL) and the risk of developing various cancers has always been controversial and predominantly focused on European populations. Hence, Mendelian randomization (MR) was applied to the Asian population to explore the causal relationships between LTL and the risk of developing various cancers.

METHODS

We explored the causal connection between LTL and the risk of developing thirteen types of cancer in Asian populations using freely available genetic variation data. The primary analytical method employed was the inverse variance weighted (IVW) method, complemented by sensitivity and validation analyses. Following Bonferroni correction, P < 0.0038 was considered to indicate statistical significance, and P values ranging from 0.0038 to 0.05 were considered to indicate a nominally significant association.

RESULTS

The findings indicated significant positive associations between LTL and the risk of developing lung cancer [odds ratio (OR) = 1.6009, 95% confidence interval (CI) 1.3056-1.9629, P = 6.08 × 10-6] and prostate cancer (OR = 1.4200, 95% CI 1.1489-1.7550, P = 0.0012). Additionally, there was a nominally significant association between LTL and the risk of developing hematological malignancy (OR = 1.5119, 95% CI 1.0810-2.1146, P = 0.0157). No statistically significant relationships between LTL and the risk of developing the other ten kinds of cancer were detected. No causal link between the risk of developing various cancers and LTL was discovered.

CONCLUSIONS

Asians with longer telomeres are more prone to developing lung and prostate cancer. There is also a nominally significant association between longer telomeres and the risk of developing hematological malignancy.

Comprehensive immunogenomic landscape analysis unveils CD33 + myeloid cell-driven immunomodulatory signatures in melanoma development

BACKGROUND

Understanding the causal relationships between immune cell populations and cancer development remains a critical challenge in tumor immunology.

METHODS

We employed Mendelian Randomization analysis leveraging genome-wide association studies of 612 immune cell traits and 91 cancer types to systematically evaluate causal associations. Single-cell RNA sequencing and computational deconvolution analyses were performed to characterize myeloid cell subpopulations in melanoma samples.

FINDINGS

Our analysis revealed significant relationships between specific immune cell subsets and cancer risk, particularly highlighting the role of CD33 + myeloid cells in melanoma pathogenesis. Single-cell RNA sequencing identified distinct CD33high myeloid subpopulations characterized by elevated expression of complement cascade components and chemokine signaling pathways. Through computational deconvolution of The Cancer Genome Atlas melanoma cohort, we demonstrated that elevated CD33high monocyte abundance correlates with increased immune dysfunction scores, reduced CD8 + T cell infiltration, and poor survival outcomes.

INTERPRETATION

Here we delineate the multifaceted mechanisms through which CD33 + myeloid cell populations orchestrate perturbations in the tumor-immune microenvironmental landscape, manifesting in compromised immunosurveillance and enhanced tumor progression. Our findings illuminate novel therapeutic opportunities through targeted modulation of myeloid cell function, while providing a systematic framework for understanding the complex interplay between immune cell populations and oncogenic processes.

Causal association between dietary factors and telomere length revealed by mendelian randomization

Observational studies have reported associations between dietary factors and telomere length. However, the inherent limitations of observational study designs render them susceptible to confounding and reverse causation biases. Therefore, this study aims to explore the association between dietary factors and telomere length using Mendelian Randomization (MR) to minimize the influence of confounding factors and reverse causality. The IEU Open GWAS project was the source of exposure and outcome datasets. The exposure datasets included 20 dietary factors. We conducted MR analyses to explore the relationship between dietary factors and telomere length. We used MRPRESSO and Radial-MR test to identify any level of multi-effect outliers. Heterogeneity and pleiotropic analysis were performed to ensure the accuracy of the results. The stability of the effect of significant results is assessed using multivariable Mendelian randomization (MVMR) and MR-lap. Two-sample MR analysis revealed a statistically significant association between dried fruit intake and telomere length (β = 0.223, 95% CI 0.091 to 0.356, PIVW=9.089 × 10^-4). After removing outliers and reanalyzing the data, the association remained significant (β = 0.163, 95% CI: 0.163 0.090 to 0.235, PIVW-FE=7.323 × 10^-5), with no significant pleiotropy detected in sensitivity analyses. Following adjustment for confounders, the MVMR results and MR-lap results continued to support a causal relationship between dried fruit intake and telomere length. Other dietary factors' effects on telomere length still need further confirmation. Our findings suggest a potential causal relationship between dried fruit intake and longer telomere length. This finding highlights potential dietary strategies for exploring the beneficial effects of dried fruit intake on preventing diseases and extending lifespan.

Evaluating the Effect of Telomere Length on Oral and Oropharyngeal Cancer Risk Using Mendelian Randomization

INTRODUCTION

The aim of this study was to explore the causal relationship between telomere length and Oral and oropharyngeal cancers by using Mendelian randomization (MR) analysis.

METHODS

We carried out a 2-sample MR to examine the causal association between telomere length and Oral and oropharyngeal cancers. Two large genome-wide association studies (GWAS) were employed to identify single nucleotide polymorphisms (SNPs) as instrumental variables through statistical and biological approaches. The data on SNP-oral and oropharyngeal cancer risk factor associations were sourced from various consortia/UK Biobank. The inverse variance weighted (IVW) method was employed as the primary approach for overall causal estimation in MR, with sensitivity analyses conducted to assess potential confounding by pleiotropy, heterogeneity, and the leave-one-out analysis.

RESULTS

The statistically driven approach indicates limited evidence of a genetically causal effect of telomere length on the risk of oral cavity cancer (OR = 0.999, 95% CI 0.998-1.000, P = .100), oropharyngeal cancer (OR = 0.999, 95% CI 0.998-1.001, P = .650), combined oral and oropharyngeal cancer (OR = 0.999, 95% CI 0.998-1.000, P = .119) in Europeans. The biologically driven approach demonstrated consistent causal effects across all MR methods, thereby further strengthening the reliability of the results. Moreover, the MR-Egger (Q [df] 170.816 [130], P = .009) and inverse variance weighted methods (Q [df] 171.656 [131], P = .010) identified considerable heterogeneity among instrumental variable estimates in Oral cavity cancer, and no evidence of horizontal pleiotropy was detected.

CONCLUSIONS

No significant causal associations between telomere length and Oral and oropharyngeal cancers were found in this study.

Metabolic constraint of human telomere length by nucleotide salvage efficiency

Human telomere length is tightly regulated and associated with diseases at either extreme, but how these bounds are established remains incompletely understood. Here, we developed a rapid cell-based telomere synthesis assay and found that nucleoside salvage bidirectionally constrains human telomere length. Metabolism of deoxyguanosine (dG) or guanosine via purine nucleoside phosphorylase (PNP) and hypoxanthine-guanine phosphoribosyltransferase to form guanine ribonucleotides strongly inhibited telomerase and shortened telomeres. Conversely, salvage of dG to its nucleotide forms via deoxycytidine kinase drove potent telomerase activation, the extent of which was controlled by the dNTPase SAMHD1. Circumventing limits on salvage by expressing Drosophila melanogaster deoxynucleoside kinase or augmenting dG metabolism using the PNP inhibitor ulodesine robustly lengthened telomeres in human cells, including those from patients with lethal telomere diseases. Our results provide an updated paradigm for telomere length control, wherein telomerase reverse transcriptase activity is actively and bidirectionally constrained by the availability of its dNTP substrates, in a manner that may be therapeutically actionable.

Long or short? Telomere length and pancreatic cancer and its precursor lesions, a narrative review

Pancreatic ductal adenocarcinoma (PDAC) is the most common and lethal form of pancreatic cancer, with a survival approaching only 11% at 5 years after diagnosis. In the last 15 years, telomere length (TL) measured in leukocyte (LTL) has been studied in relation to PDAC risk. The majority of the studies reported an association between short LTL and increased PDAC risk, but the results are heterogeneous. Genome-wide association studies have identified several single-nucleotide polymorphisms (SNPs) in the telomerase reverse transcriptase (TERT) gene as susceptibility loci for PDAC. Polygenic risk scores computed using SNPs associated with LTL have been tested in relation to PDAC susceptibility with various methods and giving contrasting results. The aim of this review is to analyze all publications carried out specifically on LTL, considering LTL measured with qPCR and with genetic proxies, and PDAC risk. Additionally, we will give an overview of the most relevant associations between SNPs in telomere-associated genes and PDAC, to answer the question shorter or longer? Which one of the two is associated with PDAC risk?

The relationship between telomere length and aging-related diseases

The intensifying global phenomenon of an aging population has spurred a heightened emphasis on studies on aging and disorders associated with aging. Cellular senescence and aging are known to be caused by telomere shortening. Telomere length (TL) has emerged as a biomarker under intense scrutiny, and its widespread use in investigations of diseases tied to advancing age. This review summarizes the current knowledge of the association between telomeres and aging-related diseases, explores the important contribution of dysfunctional telomeres to the development and progression of these diseases, and aims to provide valuable insights for the development of novel therapeutic strategies.

The Association Between Longer Maternal Leukocyte Telomere Length in the Immediate Postpartum Period and Preterm Birth in a Predominately Latina Cohort of Mothers

OBJECTIVES

We investigated the association between maternal leukocyte telomere length (LTL) in the immediate postpartum period and moderate to late preterm birth (32- < 37 weeks) among Latinas, a population at high risk for preterm birth.

METHODS

Maternal LTL was measured using quantitative polymerase chain reaction at delivery in a prospective San Francisco primarily Latina birth cohort. Logistic regression models were used to investigate the association between postpartum maternal LTL and preterm birth. Maternal LTL was analyzed as a continuous predictor.

RESULTS

Out of 194 participants, 23 (11.9%) had preterm delivery. Longer postnatal maternal LTL was associated with preterm birth (crude OR 4.68; 95% confidence interval (CI) 1.07, 20.6, p = 0.039; adjusted OR 12.8, 95% CI 1.83, 99.9, p = 0.010). Age-stratified analysis showed that being under 35 years increased the effect size of the association between maternal LTL and preterm birth (adjusted OR 32.5, 95% CI 2.58, 597, p < 0.01).

CONCLUSIONS FOR PRACTICE

Latina mothers with moderate to late preterm infants had longer LTL in the immediate postpartum period compared to those with term infants. This association was stronger for mothers under the age of 35 years. LTL may serve as a biomarker to better understand the pathophysiology and risk of preterm birth and could inform targeted interventions for prevention and early detection. Future studies are needed to understand physiological changes in maternal LTL from the prenatal to postnatal period in relation to birth outcomes.

Telomeres in Space

Recent studies have reported that the spaceflight environment lengthens leukocyte telomeres. We propose that this baffling finding reflects changes in the composition of leukocyte subsets rather than an actual increase in telomere length within individual leukocytes. Since leukocyte telomere length is associated with aging-related diseases and longevity in humans, it is crucial to understand the underlying factors driving telomere length changes in space.

Human telomere length detected by quantitative fluorescent in situ hybridization: overlooked importance and application

The technique of Quantitative Fluorescence in Situ Hybridization (Q-FISH) plays a crucial role in determining the length of telomeres for studies in molecular biology and cytogenetics. Throughout the years, the use of Q-FISH for measuring telomere length has made substantial contributions to research in aging, cancer, and stem cells. The objective of this analysis is to delineate the categorization, fundamental concepts, pros and cons, and safety measures of Q-FISH in telomere length analysis, encapsulate, and anticipate its principal uses across diverse human biomedical research fields.

Viewpoint: Pre- and post-lung transplant considerations for patients with ultra-short telomere length

Lung transplantation remains the only life-extending procedure for patients with idiopathic pulmonary fibrosis (IPF) and related progressive interstitial lung disease (ILD). Discoveries from recent decades have shown that mutations in telomerase and other telomere maintenance genes are their most common inherited risk factor, identifiable in up to 30–35% of families with pulmonary fibrosis [1]. Mutations in nine telomerase and telomere maintenance genes are confirmed to predispose to adult-onset pulmonary fibrosis by co-segregation in large families and functional studies (table 1) [2–13]. They compromise telomerase abundance, recruitment and function [1, 14].

Patients with ultra-short telomere length develop recurrent complications after lung transplantation; therefore, pre-transplant assessment and individualised post-transplant management may improve outcome in carefully defined high risk patient subsets https://bit.ly/3WvfLC1

Comprehensive analysis of aging-related gene expression patterns and identification of potential intervention targets

PURPOSE

This study aims to understand the molecular mechanisms underlying the aging process and identify potential interventions to mitigate age-related decline and diseases.

METHODS

This study utilized the GSE168753 dataset to conduct comprehensive differential gene expression analysis and co-expression module analysis. Machine learning and Mendelian randomization analyses were employed to identify core aging-associated genes and potential drug targets. Molecular docking simulations and mediation analysis were also performed to explore potential compounds and mediators involved in the aging process.

RESULTS

The analysis identified 4164 differentially expressed genes, with 1893 upregulated and 2271 downregulated genes. Co-expression analysis revealed 21 modules, including both positively and negatively correlated modules between older age and younger age groups. Further exploration identified 509 aging-related genes with distinct biological functions. Machine learning and Mendelian randomization analyses identified eight core genes associated with aging, including DPP9, GNAZ, and RELL2. Molecular docking simulations suggested resveratrol, folic acid, and ethinyl estradiol as potential compounds capable of attenuating aging through modulation of RELL2 expression. Mediation analysis indicated that eosinophil counts and neutrophil count might act as mediators in the causal relationship between genes and aging-related indicators.

CONCLUSION

This comprehensive study provides valuable insights into the molecular mechanisms of aging and offers important implications for the development of anti-aging therapeutics. Key Messages What is already known on this topic - Prior research outlines aging's complexity, necessitating precise molecular targets for intervention. What this study adds - This study identifies novel aging-related genes, potential drug targets, and therapeutic compounds, advancing our understanding of aging mechanisms. How this study might affect research, practice, or policy - Findings may inform targeted therapies for age-related conditions, influencing future research and clinical practices.

Genetic regulation of TERT splicing affects cancer risk by altering cellular longevity and replicative potential

The chromosome 5p15.33 region, which encodes telomerase reverse transcriptase (TERT), harbors multiple germline variants identified by genome-wide association studies (GWAS) as risk for some cancers but protective for others. Here, we characterize a variable number tandem repeat within TERT intron 6, VNTR6-1 (38-bp repeat unit), and detect a strong link between VNTR6-1 alleles (Short: 24-27 repeats, Long: 40.5-66.5 repeats) and GWAS signals rs2242652 and rs10069690 within TERT intron 4. Bioinformatics analyses reveal that rs10069690-T allele increases intron 4 retention while VNTR6-1-Long allele expands a polymorphic G-quadruplex (G4, 35-113 copies) within intron 6, with both variants contributing to variable TERT expression through alternative splicing and nonsense-mediated decay. In two cell lines, CRISPR/Cas9 deletion of VNTR6-1 increases the ratio of TERT-full-length (FL) to the alternative TERT-β isoform, promoting apoptosis and reducing cell proliferation. In contrast, treatment with G4-stabilizing ligands shifts splicing from TERT-FL to TERT-β isoform, implicating VNTR6-1 as a splicing switch. We associate the functional variants VNTR6-1, rs10069690, and their haplotypes with multi-cancer risk and age-related telomere shortening. By regulating TERT splicing, these variants may contribute to fine-tuning cellular longevity and replicative potential in the context of stress due to tissue-specific endogenous and exogenous exposures, thereby influencing the cancer risk conferred by this locus.

Massively parallel variant-to-function mapping determines functional regulatory variants of non-small cell lung cancer

Genome-wide association studies have identified thousands of genetic variants associated with non-small cell lung cancer (NSCLC), however, it is still challenging to determine the causal variants and to improve disease risk prediction. Here, we applied massively parallel reporter assays to perform NSCLC variant-to-function mapping at scale. A total of 1249 candidate variants were evaluated, and 30 potential causal variants within 12 loci were identified. Accordingly, we proposed three genetic architectures underlying NSCLC susceptibility: multiple causal variants in a single haplotype block (e.g. 4q22.1), multiple causal variants in multiple haplotype blocks (e.g. 5p15.33), and a single causal variant (e.g. 20q11.23). We developed a modified polygenic risk score using the potential causal variants from Chinese populations, improving the performance of risk prediction in 450,821 Europeans from the UK Biobank. Our findings not only augment the understanding of the genetic architecture underlying NSCLC susceptibility but also provide strategy to advance NSCLC risk stratification.

Deciphering the bidirectional impact of leukocyte telomere length on multiple sclerosis progression: A Mendelian randomization study

Observational studies have suggested a link between leukocyte telomere length (LTL) and multiple sclerosis (MS) progression, but the causal relationship remains uncertain. This study investigates the causal association between LTL and MS progression using a bidirectional two-sample Mendelian randomization (MR) approach. We analyzed genome-wide association summary statistics data from 472,174 individuals for LTL and 12,584 MS patients for disease progression. The primary method was the inverse variance weighted (IVW) approach, supported by sensitivity analyses to ensure robustness. The forward analysis revealed a significant positive causal relationship between LTL and MS progression (β = 0.107, 95 % CI = 0.006 to 0.209, P = 0.037). Conversely, the reverse analysis indicated a negative causal relationship (β = -0.010, 95 % CI = -0.020 to -0.001, P = 0.037). No heterogeneity or horizontal pleiotropy was found, and the sensitivity analyses confirmed consistent results. These findings suggest that telomere dynamics play a complex role in MS progression and highlight their potential as therapeutic targets. Further research is essential to uncover the biological mechanisms underlying the influence of telomeres on MS progression.

Telomeres, telomerase, and cancer: mechanisms, biomarkers, and therapeutics

Telomeres and telomerase play crucial roles in the initiation and progression of cancer. As biomarkers, they aid in distinguishing benign from malignant tissues. Despite the promising therapeutic potential of targeting telomeres and telomerase for therapy, translating this concept from the laboratory to the clinic remains challenging. Many candidate drugs remain in the experimental stage, with only a few advancing to clinical trials. This review explores the relationship between telomeres, telomerase, and cancer, synthesizing their roles as biomarkers and reviewing the outcomes of completed trials. We propose that changes in telomere length and telomerase activity can be used to stratify cancer stages. Furthermore, we suggest that differential expression of telomere and telomerase components at the subcellular level holds promise as a biomarker. From a therapeutic standpoint, combining telomerase-targeted therapies with drugs that mitigate the adverse effects of telomerase inhibition may offer a viable strategy.

Telomere-based risk models for the early diagnosis of lung cancer

Background

The objective of this study was to evaluate the use of telomere length measurements as diagnostic biomarkers during early screening for lung cancer in high-risk patients.

Methods

This was a prospective study of patients undergoing lung cancer diagnosis at two Spanish hospitals between April 2017 and January 2020. Telomeres from peripheral blood lymphocytes were analysed by Telomere Analysis Technology, which is based in high-throughput quantitative fluorescent in situ hybridization. Analytical predictive models were developed using Random Forest from the dataset of telomere-associated variables (TAV). Receiver Operating Characteristic curves were used to characterize model performance.

Findings

From 233 patients undergoing lung cancer diagnosis, 106 patients aged 55-75 with lung cancer or lung cancer and COPD were selected. A control group (N = 453) included individuals of similar age with COPD or healthy. Telomere analysis showed that patients in the cancer cohort had a higher proportion of short telomeres compared to the control cohort. A TAV-based predictive model assuming a prevalence of 5 % of lung cancer among screened subjects showed an AUC of 0.98 %, a positive predictive value of 0.60 (95 % CI, 0.49-0.70) and a negative predictive value of 0.99 (95 % CI, 0.98-0.99) for prediction of lung cancer.

Interpretation

The results of this study suggest that TAV analysis in peripheral lymphocytes can be considered a useful diagnostic tool during screening for lung cancer in high-risk patients. TAV-based models could improve the predictive power of current initial diagnostic pathways, but further work is needed to integrate them into routine clinical evaluation.

Funding

Life Length SL.

Application of Mendelian randomized research method in oncology research: bibliometric analysis

Background

Cancer has always been a difficult problem in the medical field, and with the gradual deepening of Genome-wide association studies (GWAS), Mendelian randomization methods have been increasingly used to study cancer pathogenesis. In this study, we examine the literature on Mendelian cancer, summarize the status of the research, and analyze the development trends in the field.

Methods

Publications on "Mendelian Randomization - Cancer" were retrieved and downloaded from the Web of Science Core Collection database. CiteSpace 6.2.R4, VOSviewer 1.6.19, Scimago Graphica 1.0.38, Bibliometrix R-package, and a bibliometric online analysis platform were used for data analysis and visualization. An in-depth analysis of country or region, authors, journals, keywords, and references was performed to provide insights into the content related to the field.

Results

A total of 836 articles were included in the analysis; 643 authors from 72 countries had published articles related to the field. China and Harvard University (among countries and institutions, respectively) had the highest number of articles. Martin, Richard M and Smith, George Davey were the largest contributors. A total of 27 cancers have been studied, with breast, colorectal, and liver cancers being the most studied.

Conclusion

This study is the first to use bibliometric methods to visualize the application of Mendelian randomization analysis in the field of cancer, revealing research trends and research frontiers in the field. This information will provide a strong reference for cancer researchers and epidemiologic researchers.

Non-coding genetic variants underlying higher prostate cancer risk in men of African ancestry

Incidence and severity of prostate cancer (PrCa) substantially varies across ancestries. American men of African ancestry (AA) are more likely to be diagnosed with and die from PrCa than the those of European ancestry (EA). Published polygenic risk scores for developing prostate cancer, even those based on multi-ancestry genome-wide association studies, do not address population-specific genetic mechanisms underlying PrCa risk in men of African ancestry. Specifically, the role of non-coding regulatory polymorphisms in driving inter-ancestry variation in PrCa has not been suficiently explored. Here, by employing a sequence-based deep learning model of prostate regulatory enhancers, we identified ~ 2,000 SNPs with higher alternate allele frequency in AA men that potentially affect enhancer function associated with PrCa susceptibility, as supported by our experimental validation. The identified enhancer SNPs (eSNPs) may influence PrCa development through two complementary mechanisms: 1) the alternate allele that increase enhancer activity result in immune suppression and telomere elongation, and 2) the alternate alleles that decrease enhancer activity, lead to de-differentiation and inhibition of apoptosis. Notably, the eSNPs tend to disrupt the binding of known prostate transcription factors including FOX, AR and HOX families. Lastly, the identified eSNPs can be combined into a polygenic risk score that adds value to current GWAS-based risk variants in assessing PrCa risk in independent cohorts.

Identification of Brain Cell Type-Specific Therapeutic Targets for Glioma From Genetics

BACKGROUND

Previous research has demonstrated correlations between the complex types and functions of brain cells and the etiology of glioma. However, the causal relationship between gene expression regulation in specific brain cell types and glioma risk, along with its therapeutic implications, remains underexplored.

METHODS

Utilizing brain cell type-specific cis-expression quantitative trait loci (cis-eQTLs) and glioma genome-wide association study (GWAS) datasets in conjunction with Mendelian randomization (MR) and colocalization analyses, we conducted a systematic investigation to determine whether an association exists between the gene expression of specific brain cell types and the susceptibility to glioma, including its subtypes. Additionally, the potential pathogenicity was explored utilizing mediation and bioinformatics analyses. This exploration ultimately led to the identification of a series of brain cell-specific therapeutic targets.

RESULTS

A total of 110 statistically significant and robust associations were identified through MR analysis, with most genes exhibiting causal effects exclusively in specific brain cell types or glioma subtypes. Bayesian colocalization analysis validated 36 associations involving 26 genes as potential brain cell-specific therapeutic targets. Mediation analysis revealed genes indirectly influencing glioma risk via telomere length. Bioinformatics analysis highlighted the involvement of these genes in glioma pathogenesis pathways and supported their enrichment in specific brain cell types.

CONCLUSIONS

This study, employing an integrated approach, demonstrated the genetic susceptibility between brain cell-specific gene expression and the risk of glioma and its subtypes. Its findings offer novel insights into glioma etiology and underscore potential therapeutic targets specific to brain cell types.

Longer Telomere Length in Patients with Balkan Endemic Nephropathy Undergoing Chronic Hemodialysis Is Associated with Lower Cardiovascular Mortality

Key Points

Background

Balkan endemic nephropathy (BEN) is characterized with later onset and milder forms of hypertension and lower pulse wave velocity than other ESKD. Longer telomeres are associated with better cardiovascular (CV) prognosis. Therefore, we hypothesized that telomere length (TL) could be longer in patients with BEN compared with other patients with ESKD.

Methods

A total of 124 patients undergoing hemodialysis (68 BEN, 56 non-BEN) were enrolled and followed-up for 72 months. TL was measured in leukocytes by Southern blot at inclusion.

Results

Age- and sex-adjusted TL was significantly longer in the BEN group (P < 0.001). TL was negatively associated with carotid-femoral pulse wave velocity in patients with BEN. Patients with BEN had significantly lower CV mortality than patients with non-BEN ESKD (P < 0.001). In the BEN group, shorter TL (1 kb change) was the only determinant of shorter survival (hazard ratio, 0.11). Using the TL threshold defined by receiver operating characteristic analysis (TL <6.21 kb), we showed in both groups significantly higher CV mortality in the presence of short telomeres (log-rank [Mantel-P < 0.001]).

Conclusions

Longer telomeres are associated with less CV mortality in patients undergoing chronic hemodialysis. Patients with BEN had longer TL and longer survival than that of patients with other ESKD. In patients with BEN, TL was negatively associated with arterial stiffness and positively associated with survival. This study confirmed our hypothesis that BEN is associated with slower vascular aging and that longer TL may partially explain this phenomenon.

Is incident cancer in later life associated with lower incidence of dementia?

Cancer has been associated with lower risk of dementia, although methodological issues raise concerns about the validity of this association. We recruited 31,080 men aged 65-85 years who were free of cancer and dementia, and followed them for up to 22 years. We used health record linkage to identify incident cases of cancer and dementia, and split time span to investigate this association. 18,693 (60.1%) and 6897 (22.2%) participants developed cancer and dementia during follow-up. The hazard ratio (HR) of dementia associated with cancer was 1.13 (95% CI = 1.07, 1.20) and dropped to 0.85 (95% CI = 0.80, 0.91) when 449 participants who developed dementia within 2 years were excluded. The diagnosis of cancer seems to facilitate the early detection of dementia cases. Older participants who survive cancer for 2 or more years have lower risk of receiving the diagnosis of dementia over time. The factors that mediate this association remain unclear.

The causal effects of childhood sunburn occasions on melanoma: A univariable and multivariable Mendelian randomization study

Observational studies have shown an association between childhood sunburn occasions (CSOs) and melanoma in situ (MIS). However, these studies have shown contradictory results. Here, we used a two-sample Mendelian randomization (MR) method to make a causal inference between CSOs and melanoma at the genetic level. Based on the publicly available genome-wide association study summary data, including childhood sunburn (n = 346,955) and MIS (n = 218,792), the inverse-variance weighted (IVW) method of the random effects model was used, supplemented by the MR-Egger method, the weighted median method, and the weighted mode method. IVW results showed a 2.58-fold increased risk of melanoma development for each standard deviation increase in CSOs (odds ratio [OR] = 3.58; 95% confidence interval [CI]: 1.68-7.64; P = 1.00 × 10-3), with the MR-Egger (OR = 4.76, 95% CI: 1.65-13.75, P = 5.60 × 10-3), weighted median (OR = 4.89, 95% CI: 1.62-14.76, P = 4.90 × 10-3), and weighted mode (OR = 6.26, 95% CI: 2.49-15.77, P = 3.00 × 10-4) supporting the results. Furthermore, both the funnel plot and the MR-Egger intercepts showed the absence of directional pleiotropy between childhood sunburn and MIS. Our study confirmed that CSOs increase the risk of melanoma development.

Impact of sociodemographic disparities on sarcopenia, telomere length, and mortality in patients with liver disease in the US population

BACKGROUND & AIMS

Sarcopenia is common in patients with liver disease and both sarcopenia and short telomeres are associated with mortality, however their relationship in patients with liver disease remains unknown.

METHODS

A cohort of 16,072 adults from the National Health and Nutrition Examination Survey from 1999 to 2006 was analyzed. Liver disease was defined by aminotransferases and classified into etiology-based categories. Sarcopenia was defined by dual-energy x-ray absorptiometry. All analyses were conducted separately on each multiple imputation data set and combined via Rubin's rules. P-values for group comparisons were calculated by testing logistic regression parameter estimates. Cox proportional hazards regression was used for mortality analysis with mortality data available until 2015.

RESULTS

Sarcopenia was present in 9.5% of patients with liver disease. Age, race, income, education, physical inactivity, and certain medical comorbidities were associated with sarcopenia. Patients with liver disease and sarcopenia had significantly shorter telomeres than patients with liver disease without sarcopenia when unadjusted for age. The interaction between telomere length and sarcopenia was significantly associated with all-cause mortality.

CONCLUSIONS

The implications of telomere length on all-cause mortality in patients with liver disease varied by age and sarcopenia status. Shorter telomeres appear to be more highly associated with increased mortality in older patients without sarcopenia.

Telomere length and chronotype among women in the California Teachers Study (CTS)

While links between certain chronotypes and poorer health outcomes have been well established in previous studies, few studies have examined the relationship between chronotype and cellular aging. Using data from the California Teachers Study (CTS), the present study evaluates the relationship between cellular aging and chronobiology through an analysis of leukocyte telomere length (LTL) and chronotype among 817 predominantly postmenopausal women with no history of cancer and occupations not associated with night-shift work. Unconditional logistic regression models were run to estimate odds ratios (ORs) for each chronotype category, adjusted for age, ethnicity, and smoking status. Analyses were then stratified by potential modifiers to assess whether results varied among specific subgroups within the sample. Women who reported being current evening types and evening types from teen years to now were significantly less likely to have short LTL compared to women who reported being current morning types or morning types from teen years to now (OR = 0.72; 95% CI = 0.53-0.98; OR = 0.57; 95% CI = 0.39-0.84). Our results suggest that women with no history of cancer who identify as evening chronotypes may undergo decreased cellular aging compared to women in the same population who identify as morning types. Further studies on populations of postmenopausal women are warranted.

Associations between historical and contemporary measures of structural racism and leukocyte telomere length: The Multi-Ethnic Study of Atherosclerosis (MESA)

BACKGROUND

We assessed the link between two manifestations of structural racism-historical redlining and contemporary racial residential segregation-and baseline and 10-year changes in leukocyte telomere length (LTL).

METHODS

We used data on Black and Hispanic/Latinx participants from Exams I and V of the Multi-Ethnic Study of Atherosclerosis Stress Ancillary Study (N = 741, age range = 45-84 years). LTL was defined as the ratio of telomeric DNA to a single copy gene (T/S), and 10-year changes were adjusted for regression to the mean. We used 1930s Home Owners' Loan Corporation maps to assign three historical redlining grades (A&B: best/still desirable, C: declining, D: hazardous/redlined) to participants' neighborhoods (census-tracts) at baseline. The Getis-Ord Gi∗ statistic was used to evaluate census-tract level baseline residential segregation (low/moderate/high).

RESULTS

In mixed-effects regression models accounting for neighborhood clustering, individual characteristics, and current neighborhood environments, those living in highly segregated Black neighborhoods had 0.08 shorter baseline LTL (95% CI: -0.13, -0.04), than those residing in the least segregated neighborhoods. We did not find a relationship between residing in segregated neighborhoods and 10-year LTL changes, and associations between residing in historically redlined neighborhoods and both baseline LTL and 10-year changes in LTL were null. Across discriminatory disinvestment trajectories examined, individuals residing in highly segregated but non-redlined neighborhoods had 0.6 shorter baseline LTL than individuals residing in non-redlined neighborhoods with low/moderate segregation (95% CI: -0.12, -0.01).

CONCLUSIONS

Our results highlight the impact of racial segregation on cellular aging and underscore the need to ameliorate structural inequities within segregated neighborhoods.

Annual space weather fluctuations and telomere length dynamics in a longitudinal cohort of older men: the Normative Aging Study

BACKGROUND

Space weather has been associated with increased risk of cardiovascular diseases in space and flight crew. However, limited research has focused on the ground population, particularly among the elderly who are vulnerable to aging-related diseases.

OBJECTIVE

We evaluated the association between space weather alterations and biological aging using leukocyte telomere length as a biomarker in healthy elderly men.

METHODS

We used data from the Normative Aging Study, a longitudinal cohort of healthy elderly men in Massachusetts, USA. Leukocyte telomere length and health information were measured at in-person examinations approximately every three years, contributing to a total of 1,850 visits from 791 participants. Regional space weather information was collected daily, including cosmic ray-induced ionization, neutrons, sunspot number, interplanetary magnetic field, and Kp-index as our exposure of interest. We used mixed-effects models with a random intercept per individual to evaluate the associations between annual averages of space weather indicators and relative telomere length while accounting for participant demographics, environmental parameters, and secular trends.

RESULTS

The mean age at baseline was 72.36 years. A one-year increment in age is associated with a 1.21% reduction in leukocyte telomere length. In the fully adjusted model accounting for individual and environmental factors, an interquartile range (IQR) increase of annual cosmic ray induced ionization (110.0 ion pairs cm-3 sec-1) was associated with a 17.64% (95%CI: -27.73%, -7.55%) decrease in leukocyte telomere length, equivalent to 15-years age increment. Solar and geomagnetic activities were associated with increased leukocyte telomere length, but the association became absent after adjusting for cosmic ray indicators.

IMPACT

Galactic cosmic rays may accelerate the aging process in populations on the Earth, despite the protection by the Earth's atmosphere and magnetic field. This research enhances our understanding of how changes in space weather can impact health, highlights potential risks from space to Earth's inhabitants, and helps inform health strategies for vulnerable populations.

Unraveling the genetic landscape of susceptibility to multiple primary cancers

With advances in cancer screening and treatment, there is a growing population of cancer survivors who may develop subsequent primary cancers. While hereditary cancer syndromes account for only a portion of multiple cancer cases, we sought to explore the role of common genetic variation in susceptibility to multiple primary tumors. We conducted a cross-ancestry genome-wide association study (GWAS) and transcriptome-wide association study (TWAS) of 10,983 individuals with multiple primary cancers, 84,475 individuals with single cancer, and 420,944 cancer-free controls from two large-scale studies. Our GWAS identified six lead variants across five genomic regions that were significantly associated (P<5×10-8) with the risk of developing multiple primary tumors (overall and invasive) relative to cancer-free controls (at 3q26, 8q24, 10q24, 11q13.3, and 17p13). We also found one variant significantly associated with multiple cancers when comparing to single cancer cases (at 22q13.1). Multi-tissue TWAS detected associations with genes involved in telomere maintenance in two of these regions (ACTRT3 in 3q26 and SLK and STN1 in 10q24) and the development of multiple cancers. Additionally, the TWAS also identified several novel genes associated with multiple cancers, including two immune-related genes, IRF4 and TNFRSF6B. Telomere maintenance and immune dysregulation emerge as central, common pathways influencing susceptibility to multiple cancers. These findings underscore the importance of exploring shared mechanisms in carcinogenesis, offering insights for targeted prevention and intervention strategies.

Association of Leukocyte Telomere Length and the Risk of Disease Severity and Metabolic Comorbidities in Arab Patients with Psoriasis

INTRODUCTION

Several studies have related shortened leukocyte telomere length (LTL) with age-related diseases and worse prognosis. Telomere length attrition has recently been associated with inflammatory diseases, including psoriasis (Ps). However, no study has demonstrated an association between LTL and the risk of disease severity and metabolic comorbidities in Arab patients with Ps.

METHODS

68 patients with Ps and 42 normal controls were included. LTL and oxidative damage were determined by quantitative (q) PCR. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using logistic regression. Statistical differences between the groups were determined using χ2 and t tests.

RESULTS

Patients with Ps had significantly shorter LTL (p = 0.032) and higher oxidative damage (p = 0.015) than those without Ps. Patients with moderate-to-severe index (p = 0.03) and metabolic comorbidity showed significantly shorter LTL (p = 0.003) compared to patients with mild index and without metabolic comorbidity, respectively. Patients with short LTL (≤0.9) were correlated with higher risk of moderate-to-severe conditions (OR = 6.98, 95% CI = 2.3-20.8, p = 0.001) and metabolic comorbidities (OR = 2.89, 95% CI = 1.02-8.2, p = 0.04).

CONCLUSION

LTL shortening may be a consequence of increased oxidative damage and is related to the risk of severe Ps and metabolic comorbidities. Therefore, LTL may be a good candidate biomarker for predicting the risk of poor prognosis in patients with Ps.

High-throughput single telomere analysis using DNA microarray and fluorescent in situ hybridization

The human telomere system is highly dynamic. Both short and long leucocyte average telomere lengths (aTL) are associated with an increased risk of cancer and early death, illustrating the complex relationship between TL and human health and the importance of assessing TL distributions with single TL analysis. A DNA microarray and telomere fluorescent in situ hybridization (DNA-array-FISH) approach was developed to measure the base-pair (bp) lengths of single telomeres. On average 32000 telomeres were measured per DNA sample with one microarray chip assaying 96 test DNA samples. Various telomere parameters, i.e. aTL and the frequency of short/long telomeres, were computed to delineate TL distribution. The intra-assay and inter-assay coefficient of variations of aTL ranged from 1.37% to 3.98%. The correlation coefficient (r) of aTL in repeated measurements ranged from 0.91 to 1.00, demonstrating high measurement precision. aTLs measured by DNA-array-FISH predicted aTLs measured by terminal restriction fragment (TRF) analysis with r ranging 0.87-0.99. A new accurate and high-throughput method has been developed to measure the bp lengths of single telomeres. The large number of single TL data provides an opportunity for an in-depth analysis of telomere dynamics and the complex relationship between telomere and age-related diseases.

Causality between Telomere Length and the Risk of Hematologic Malignancies: A Bidirectional Mendelian Randomization Study

Growing evidence indicates a relationship between telomere length (TL) and the stage, prognosis, and treatment responsiveness of hematopoietic malignancies. However, the relationship between TL and the risk of hematologic malignancies remains unclear, considering the vulnerability of observational studies to potential confounding and reverse causation. A two-sample bidirectional Mendelian randomization (MR) analysis was conducted utilizing publicly available genome-wide association study data to assess whether TL was causally associated with the risk of hematologic malignancies. The inverse variance weighted approach was used as the primary assessment approach to evaluate the effects of the causes, augmented by the weighted median and MR-Egger methods. Cochran's Q test, MR-Egger intercept test, MR-Pleiotropy Residual Sum and Outlier test, and leave-one-out analysis were performed to evaluate sensitivity, heterogeneity, and pleiotropy. According to forward MR estimations, longer TL was related to an increased risk of acute lymphocytic leukemia (OR = 2.690; P = 0.041), chronic lymphocytic leukemia (OR = 2.155; P = 0.005), multiple myeloma (OR = 1.845; P = 0.024), Hodgkin lymphoma (OR = 1.697; P = 0.014), and non-Hodgkin lymphoma (OR = 1.737; P = 0.009). Specific types of non-Hodgkin lymphoma were also associated with TL. The reverse MR results revealed that hematologic malignancies had no effect on TL. This MR analysis revealed an association between longer TL and an increased risk of specific hematologic malignancies, indicating a potential role of TL in risk evaluation and management in hematologic malignancies.

SIGNIFICANCE

In contrast to observational studies, this study uncovered the reliable causal relationships between TL and hematologic malignancies, emphasizing the potential role of telomeres in tumor development. TL maintenance may offer a promising strategy to reduce the risk of hematologic malignancies.

NRF2 signaling pathway and telomere length in aging and age-related diseases

The transcription factor nuclear factor erythroid 2-related factor 2 (NRF2) is well recognized as a critical regulator of redox, metabolic, and protein homeostasis, as well as the regulation of inflammation. An age-associated decline in NRF2 activity may allow oxidative stress to remain unmitigated and affect key features associated with the aging phenotype, including telomere shortening. Telomeres, the protective caps of eukaryotic chromosomes, are highly susceptible to oxidative DNA damage, which can accelerate telomere shortening and, consequently, lead to premature senescence and genomic instability. In this review, we explore how the dysregulation of NRF2, coupled with an increase in oxidative stress, might be a major determinant of telomere shortening and age-related diseases. We discuss the relevance of the connection between NRF2 deficiency in aging and telomere attrition, emphasizing the importance of studying this functional link to enhance our understanding of aging pathologies. Finally, we present a number of compounds that possess the ability to restore NRF2 function, maintain a proper redox balance, and preserve telomere length during aging.

Genetic analysis from multiple cohorts implies causality between 2200 druggable genes, telomere length, and leukemia

BACKGROUND

Clinical therapeutic targets for leukemia remain to be identified and the causality between leukemia and telomere length is unclear.

METHODS

This work employed cis expression quantitative trait locus (eQTL) for 2,200 druggable genes from the eQTLGen Consortium and genome-wide association studies (GWAS) summary data for telomere length in seven blood cell types from the UK Biobank, Netherlands Cohort as exposures. GWAS data for lymphoid leukemia (LL) and myeloid leukemia (ML) from FinnGen and Lee Lab were used as outcomes for discovery and replication cohorts, respectively. Robust Mendelian randomization (MR) findings were generated from seven MR models and a series of sensitivity analyses. Summary-data-based MR (SMR) analysis and transcriptome-wide association studies (TWAS) were further implemented to verify the association between identified druggable genes and leukemia. Single-cell type expression analysis was employed to identify the specific expression of leukemia casual genes on human bone marrow and peripheral blood immune cells. Multivariable MR analysis, linkage disequilibrium score regression (LDSC), and Bayesian colocalization analysis were performed to further validate the relationship between telomere length and leukemia. Mediation analysis was used to assess the effects of identified druggable genes affecting leukemia via telomere length. Phenome-wide MR (Phe-MR) analysis for assessing the effect of leukemia causal genes and telomere length on 1,403 disease phenotypes.

RESULTS

Combining the results of the meta-analysis for MR estimates from two cohorts, SMR and TWAS analysis, we identified five LL causal genes (TYMP, DSTYK, PPIF, GDF15, FAM20A) and three ML causal genes (LY75, ADA, ABCA2) as promising drug targets for leukemia. Univariable MR analysis showed genetically predicted higher leukocyte telomere length increased the risk of LL (odds ratio [OR] = 2.33, 95 % confidence interval [95 % CI] 1.70-3.18; P = 1.33E-07), and there was no heterogeneity and horizontal pleiotropy. Evidence from the meta-analysis of two cohorts strengthened this finding (OR = 1.88, 95 % CI 1.06-3.05; P = 0.01). Multivariable MR analysis showed the causality between leukocyte telomere length and LL without interference from the other six blood cell telomere length (OR = 2.72, 95 % CI 1.88-3.93; P = 1.23E-07). Evidence from LDSC supported the positive genetic correlation between leukocyte telomere length and LL (rg = 0.309, P = 0.0001). Colocalization analysis revealed that the causality from leukocyte telomere length on LL was driven by the genetic variant rs770526 in the TERT region. The mediation analysis via two-step MR showed that the causal effect from TYMP on LL was partly mediated by leukocyte telomere length, with a mediated proportion of 12 %.

CONCLUSION

Our study identified several druggable genes associated with leukemia risk and provided new insights into the etiology and drug development of leukemia. We also found that genetically predicted higher leukocyte telomere length increased LL risk and its potential mechanism of action.

The causal effect of telomere length on the risk of malignant lymphoma: A Mendelian randomization study

Telomere length (TL) has been implicated in the risk assessment of numerous cancers in observational studies. Nevertheless, the relationship between TL and malignant lymphoma remains unclear, displaying inconsistent patterns across different studies. A summary dataset for genome-wide association study of TL and malignant lymphoma was acquired from the OpenGWAS website. An extensive 2-sample Mendelian randomization (MR) analysis was performed, encompassing various methodologies such as MR-Egger, weighted median, weighted mode, simple mode, and the primary method of inverse-variance weighting (IVW). Sensitivity evaluations were performed using the Cochran Q test, MR-Egger regression, and leave-one-out analysis. The main method IVW revealed that TL substantially increased the risk of Hodgkin lymphoma (HL; odds ratio [OR] = 2.135; 95% confidence interval [CI] = 1.181-3.859; P = .012). Both the IVW and weighted median methods indicated statistical associations between genetically predicted TL and other types of non-HL (OR = 1.671, 95% CI = 1.009-2.768, P = .045; OR = 2.310, 95% CI = 1.033-5.169, P = .042). However, there was no association between TL and diffuse large B-cell lymphoma, follicular lymphoma, or mature T/natural Killer-cell lymphoma, and sensitivity analysis revealed no heterogeneity or horizontal pleiotropy, indicating that the causal effect was robust. Our study shows that TL plays different roles in different types of lymphomas. A longer TL significantly increases the risk of HL and other types of non-HL.

Comprehensive analysis of molecular, physiological, and functional biomarkers of aging with neurological diseases using Mendelian randomization

An increasing burden of neurological diseases (NDs) has been a public health challenge in an aging society. Age, especially biological age, is the most important risk factor for NDs. Identification of biomarkers of aging to capture NDs might lead to a better understanding of the underlying mechanisms of pathological brain aging and the implementation of effective intervention. We conducted a comprehensive two-sample Mendelian Randomization (MR) study to investigate the association between various biomarkers of aging and three leading causes of NDs: Alzheimer's disease (AD), vascular dementia (VaD), and ischemic stroke. Publicly available GWAS summary statistics on people from European ancestry were obtained for six molecular biomarkers, two physiological biomarkers, and eight functional biomarkers, and three NDs. Genetic variants serving as instrumental variables (IVs) were identified for each biomarker. The MR analysis included inverse variance weighted (IVW), weighted median, MR-Egger, and MR-PRESSO. We found that short telomere length and decrease in appendicular lean mass were associated with an increased risk for AD (OR IVW = 1.12 per 1SD decrease, 95% confidence interval 1.02-1.22, and OR IVW = 1.11, 1.06-1.16, respectively), whereas high frailty index showed a protective effect for AD. Accelerated BioAge appeared to be associated with increased risk for ischemic stroke (OR IVW = 1.3 per year in BioAge acceleration, 95% CI 1.19-1.41). Our findings implied a causal association of short telomere length and a decrease in appendicular lean mass with an increased risk for AD, while BioAge appeared to be a good biomarker for ischemic stroke. Further studies are needed to validate these associations and explore underlying mechanisms.

Differences in the risk association of TERT-CLPTM1L rs4975616 (A>G) with lung cancer between Caucasian and Asian populations: A meta-analysis

BACKGROUND

Although the G allele variant of TERT-CLPTM1L rs4975616 has been confirmed to be negatively associated to the risk of lung cancer (LC), some other studies haven't found this negative association. The purpose of this study is to clarify the association of the rs4975616 with the risk of developing LC and the differences of this association among patients with different ethnicities (Caucasians and Asians), different subtypes of LC, and different smoking status.

METHODS

Relevant literatures published before July 20, 2023 in PubMed, EMbase, Web of Science, MEDLINE databases were searched through the Internet. Statistical analysis of data was performed in Revman5.3, including drawing forest plots, funnel plots and so on. Sensitivity and publication bias were performed in Stata 14.0. The stability of the results was assessed using Test Sequence Analysis (TSA) software. Registration number: CRD42024568348.

RESULTS

The G allele variant of rs4975616 was negatively associated with the risk of LC ([OR] = 0.86, 95%CI [0.84, 0.88]), and that this negative association was present in both Caucasians ([OR] = 0.85, 95%CI [0.83, 0.87]) and Asians ([OR] = 0.91, 95%CI [0.86, 0.95]), and the strength of the negative association was higher in Caucasians than in Asians (subgroup differences: P = 0.02, I2 = 80.3%). Across LC subtypes, rs4975616[G] was negatively associated with the risk of NSCLC (LUAD, LUSC) in both Caucasians and Asians (P<0.05) and the strength of the association with NSCLC (LUAD) was higher in Caucasians than in Asians (Subgroup differences: I2>50%). In Caucasians, rs4975616[G] was negatively associated with the risk of LC in both smokers and non-smokers (P<0.05), and the strength of the association did not differ between smokers and non-smokers (Subgroup differences: P = 0.18, I2 = 45.0%). In Asians, rs4975616[G] was mainly negatively associated with the risk of LC in smokers (P<0.05) but not in non-smokers ([OR] = 0.97, 95%CI [0.78, 1.20]). Comparisons between the two populations showed that the strength of this negative association was higher in Caucasian non-smokers than in Asian non-smokers (Subgroup differences: P = 0.04, I2 = 75.3%), whereas the strength of this negative association was the same for Caucasian smokers as for Asian smokers (Subgroup differences: P = 0.42, I2 = 0%). Among the different LC subtypes, rs4975616[G] was negatively associated with the risk of NSCLC (LUAD) incidence in both Asian smokers and Caucasian non-smokers (P<0.05), whereas it was not associated with the risk of NSCLC development in Asian non-smokers (P>0.05). Comparisons between the two populations showed that the strength of the association was higher in Caucasian non-smokers than in Asian non-smokers (Subgroup differences: I2>50%).

CONCLUSION

The G allele variant of rs4975616 is negatively associated with the risk of LC and NSCLC (LUAD, LUSC). Compared with Asians, Caucasians are more likely to have a higher risk of LC and NSCLC (LUAD) due to the rs4975616 variant. In Caucasians, smoking and other factors like non-smoking contribute to rs4975616 variations leading to LC, and other factors like non-smoking also induce rs4975616 variations leading to NSCLC (LUAD). In Asians, smoking is the major risk factor for the induction of rs4975616 variations leading to LC and NSCLC(LUAD).

Effect of polygenic scores of telomere length alleles on telomere length in newborns and parents

In adults, polygenic scores (PGSs) of telomere length (TL) alleles explain about 4.5% of the variance in TL, as measured by quantitative polymerase chain reaction (qPCR). Yet, these PGSs strongly infer a causal role of telomeres in aging-related diseases. To better understand the determinants of TL through the lifespan, it is essential to examine to what extent these PGSs explain TL in newborns. This study investigates the effect of PGSs on TL in both newborns and their parents, with TL measured by Southern blotting and expressed in base-pairs (bp). Additionally, the study explores the impact of PGSs related to transmitted or non-transmitted alleles on TL in newborns. For parents and newborns, the PGS effects on TL were 172 bp (p =  2.03 × 10-15) and 161 bp (p =  3.06 × 10-8), explaining 6.6% and 5.2% of the TL variance, respectively. The strongest PGS effect was shown for maternally transmitted alleles in newborn girls, amounting to 214 bp (p =  3.77 × 10-6) and explaining 7.8% of the TL variance. The PGS effect of non-transmitted alleles was 56 bp (p = 0.0593) and explained 0.6% of the TL variance. Our findings highlight the importance of TL genetics in understanding early-life determinants of TL. They point to the potential utility of PGSs composed of TL alleles in identifying susceptibility to aging-related diseases from birth and reveal the presence of sexual dimorphism in the effect of TL alleles on TL in newborns. Finally, we attribute the higher TL variance explained by PGSs in our study to TL measurement by Southern blotting.

A metabolome-wide Mendelian randomization study prioritizes causal circulating metabolites for reproductive disorders including primary ovarian insufficiency, polycystic ovary syndrome, and abnormal spermatozoa

BACKGROUND

Accumulating studies have highlighted the significant role of circulating metabolomics in the etiology of reproductive system disorders. However, the causal effects between genetically determined metabolites (GDMs) and reproductive diseases, including primary ovarian insufficiency (POI), polycystic ovary syndrome (PCOS), and abnormal spermatozoa (AS), still await thorough clarification.

METHODS

With the currently most comprehensive genome-wide association studies (GWAS) data of metabolomics, systematic two-sample Mendelian randomization (MR) analyses were conducted to disclose causal associations between 1,091 blood metabolites and 309 metabolite ratios with reproductive disorders. The inverse-variance weighted (IVW) method served as the primary analysis approach, and multiple effective MR methods were employed as complementary analyses including MR-Egger, weighted median, constrained maximum likelihood (cML-MA), contamination mixture method, robust adjusted profile score (MR-RAPS), and debiased inverse-variance weighted method. Heterogeneity and pleiotropy were assessed via MR-Egger intercept and Cochran's Q statistical analysis. Outliers were detected by Radial MR and MR-PRESSO methods. External replication and metabolic pathway analysis were also conducted.

RESULTS

Potential causal associations of 63 GDMs with POI were unearthed, and five metabolites with strong causal links to POI were emphasized. Two metabolic pathways related to the pathogenesis of POI were pinpointed. Suggestive causal effects of 70 GDMs on PCOS were detected, among which 7 metabolites stood out for strong causality with elevated PCOS risk. Four metabolic pathways associated with PCOS mechanisms were recognized. For AS, 64 GDMs as potential predictive biomarkers were identified, particularly highlighting two metabolites for their strong causal connections with AS. Three pathways underneath the AS mechanism were identified. Multiple assessments were conducted to further confirm the reliability and robustness of our causal inferences.

CONCLUSION

By extensively assessing the causal implications of circulating GDMs on reproductive system disorders, our study underscores the intricate and pivotal role of metabolomics in reproductive ill-health, laying a theoretical foundation for clinical strategies from metabolic insights.

The role of herpes simplex virus infection in the etiology of head and neck cancer-a Mendelian randomization study

Introduction

Head and neck cancer (HNC) is a complex disease, and multiple risk factors can lead to its progression. Observational studies indicated that herpes simplex virus (HSV) may be correlated with the risk of HNC. However, the causal effects and direction between them were still unclear.

Methods

This study utilized a Mendelian randomization (MR) approach for causality assessment between HSV infection and Head and neck cancer based on the latest public health data and Genome-Wide Association Study (GWAS) data. The causal effects were estimated using IVW, weighted median, and MR-Egger. A reverse MR analysis was subsequently performed. Cochrans Q test, MR-Egger intercept test, leave one out analysis, and the funnel plot were all used in sensitivity analyses.

Results

Genetically predicted higher level of HSV-1 IgG was causally related to HNC (OR=1.0019, 95%CI=1.0003-1.0036, p=0.0186, IVW) and oral and oropharyngeal cancer (OR=1.0018, 95%CI=1.0004-1.0033, p=0.0105, IVW). The reverse MR analysis did not demonstrate a reverse causal relationship between HSV and HNC. However, HSV-2 infection was not causally related to HNC data and oropharyngeal cancer data. Sensitivity analysis was performed and revealed no heterogeneity and horizontal pleiotropy.

Conclusion

Collectively, a significant association was noted between HSV infection and increased risk of HNC, providing valuable insights into the etiology of this malignancy. Further in-depth study is needed to validate these findings and elucidate the underpinning mechanisms.

Causal effects of omega-6 and LDL-C on androgenetic alopecia: A Mendelian randomization study

BACKGROUND

Increasing studies have reported a causal relationship between androgenetic alopecia (AGA) and lipid-related metabolites. However, the relationships between HDL-C, LDL-C, Omega-6, and Omega-3 with AGA remain unclear. Some research findings are even contradictory. Therefore, we designed this study to explore this issue.

METHODS

In this study, we selected seven exposure factors, screened SNPs with significant associations, removed linkage disequilibrium and weak instrumental variables, and conducted bidirectional MR analysis.

RESULTS

The study found that omega-6 and LDL-C, especially total cholesterol in medium LDL and total cholesterol in small LDL, are risk factors for the occurrence of androgenetic alopecia.

CONCLUSION

In summary, we found that various lipid-related metabolites have a causal relationship with the occurrence of androgenetic alopecia, providing new insights into the pathogenesis of androgenetic alopecia and offering references for clinical treatment of androgenetic alopecia.

Peripheral blood leukocyte Telomere length and endometriosis: A Mendelian randomization study

Background

The link between peripheral blood leukocyte telomere length (LTL) and endometriosis has remained uncertain. In order to investigate this association, a two-sample Mendelian randomization(MR) analysis was performed.

Methods

We extracted Single-nucleotide polymorphisms (SNPs) associated with LTL from a published genome-wide association study (GWAS) comprising 472,174 individuals. Data on endometriosis, including its seven subtypes, were sourced from the iue open gwas project. Four methods were employed for MR: Inverse-variance weighted analysis (IVW), Mendelian randomization-Egger regression (MR Egger), weighted-median analysis, and Weighted Mode.

Results

Genetically determined LTL was identified as a factor that can promote the occurrence of endometriosis. With every 1-SD increase in LTL, the risk of endometriosis increased by 26 % (OR = 1.260, 95 % CI = 1.073 to 1.479; P = 0.005). Genetically determined LTL also contributed to endometriosis subtypes: intestine (OR = 3.584, 95 % CI = 1.597 to 8.041; P = 0.002), ovary (OR = 1.308, 95 % CI = 1.033 to 1.655; P = 0.026), rectovaginal septum and vagina (OR = 1.360, 95 % CI = 1.000 to 1.851; P = 0.049). There was no observed causal relationship between LTL and the other four subtypes.

Conclusion

This study, utilizing genetic data, offers evidence that longer LTL may cause increased risks of endometriosis, specifically endometriosis of the intestine, ovary, rectovaginal septum and vagina. These findings not only suggest that LTL may serve as a predictive factor for assessing the prevalence of three endometriosis subtypes but also provide new insights into the study of endometriosis pathogenesis.

Causal association between telomere length and female reproductive endocrine diseases: a univariable and multivariable Mendelian randomization analysis

BACKGROUND

The relationship between leukocyte telomere length (LTL) and female reproductive endocrine diseases has gained significant attention and research interest in recent years. However, there is still limited understanding of the exact impacts of LTL on these diseases. Therefore, the primary objective of this study was to investigate the genetic causal association between LTL and female reproductive endocrine diseases by employing Mendelian randomization (MR) analysis.

METHODS

Instruments for assessing genetic variation associated with exposure and outcome were derived from summary data of published genome-wide association studies (GWAS). Inverse-variance weighted (IVW) was utilized as the main analysis method to investigate the causal relationship between LTL and female reproductive endocrine diseases. The exposure data were obtained from the UK Biobanks GWAS dataset, comprising 472,174 participants of European ancestry. The outcome data were acquired from the FinnGen consortium, including abnormal uterine bleeding (menorrhagia and oligomenorrhea), endometriosis (ovarian endometrioma and adenomyosis), infertility, polycystic ovary syndrome (PCOS), premature ovarian insufficiency (POI) and premenstrual syndrome (PMS). Furthermore, to account for potential confounding factors such as smoking, alcohol consumption, insomnia, body mass index (BMI) and a history of pelvic inflammatory disease (PID), multivariable MR (MVMR) analysis was also conducted. Lastly, a series of pleiotropy tests and sensitivity analyses were performed to ensure the reliability and robustness of our findings. P < 0.0063 was considered to indicate statistically significant causality following Bonferroni correction.

RESULTS

Our univariable MR analysis demonstrated that longer LTL was causally associated with an increased risk of menorrhagia (IVW: odds ratio [OR]: 1.1803; 95% confidence interval [CI]: 1.0880-1.2804; P = 0.0001) and ovarian endometrioma (IVW: OR: 1.2946; 95%CI: 1.0970-1.5278; P = 0.0022) at the Bonferroni significance level. However, no significant correlation was observed between LTL and oligomenorrhea (IVW: OR: 1.0124; 95%CI: 0.7350-1.3946; P = 0.9398), adenomyosis (IVW: OR: 1.1978; 95%CI: 0.9983-1.4372; P = 0.0522), infertility (IVW: OR: 1.0735; 95%CI: 0.9671-1.1915; P = 0.1828), PCOS (IVW: OR: 1.0633; 95%CI: 0.7919-1.4278; P = 0.6829), POI (IVW: OR: 0.8971; 95%CI: 0.5644-1.4257; P = 0.6459) or PMS (IVW: OR: 0.7749; 95%CI: 0.4137-1.4513; P = 0.4256). Reverse MR analysis indicated that female reproductive endocrine diseases have no causal effect on LTL. MVMR analysis suggested that the causal effect of LTL on menorrhagia and ovarian endometrioma remained significant after accounting for smoking, alcohol consumption, insomnia, BMI and a history of PID. Pleiotropic and sensitivity analyses also showed robustness of our results.

CONCLUSION

The results of our bidirectional two-sample MR analysis revealed that genetically predicted longer LTL significantly increased the risk of menorrhagia and ovarian endometrioma, which is consistent with the findings from MVMR studies. However, we did not notice any significant effects of LTL on oligomenorrhea, adenomyosis, infertility, PCOS, POI or PMS. Additionally, reproductive endocrine disorders were found to have no impact on LTL. To enhance our understanding of the effect and underlying mechanism of LTL on female reproductive endocrine diseases, further large-scale studies are warranted in the future.

Genetic susceptibility to chronic diseases leads to heart failure among Europeans: the influence of leukocyte telomere length

BACKGROUND

Genetic susceptibility to various chronic diseases has been shown to influence heart failure (HF) risk. However, the underlying biological pathways, particularly the role of leukocyte telomere length (LTL), are largely unknown. We investigated the impact of genetic susceptibility to chronic diseases and various traits on HF risk, and whether LTL mediates or modifies the pathways.

METHODS

We conducted prospective cohort analyses on 404 883 European participants from the UK Biobank, including 9989 incident HF cases. Multivariable Cox regression was used to estimate associations between HF risk and 24 polygenic risk scores (PRSs) for various diseases or traits previously generated using a Bayesian approach. We assessed multiplicative interactions between the PRSs and LTL previously measured in the UK Biobank using quantitative PCR. Causal mediation analyses were conducted to estimate the proportion of the total effect of PRSs acting indirectly through LTL, an integrative marker of biological aging.

RESULTS

We identified 9 PRSs associated with HF risk, including those for various cardiovascular diseases or traits, rheumatoid arthritis (P = 1.3E-04), and asthma (P = 1.8E-08). Additionally, longer LTL was strongly associated with decreased HF risk (P-trend = 1.7E-08). Notably, LTL strengthened the asthma-HF relationship significantly (P-interaction = 2.8E-03). However, LTL mediated only 1.13% (P < 0.001) of the total effect of the asthma PRS on HF risk.

CONCLUSIONS

Our findings shed light onto the shared genetic susceptibility between HF risk, asthma, rheumatoid arthritis, and other traits. Longer LTL strengthened the genetic effect of asthma in the pathway to HF. These results support consideration of LTL and PRSs in HF risk prediction.

Choice of gDNA isolation method has a significant impact on average murine Telomere Length estimates

Telomere Length (TL) and integrity is significantly associated with age-related disease, multiple genetic and environmental factors. We observe mouse genomic DNA (gDNA) isolation methods to have a significant impact on average TL estimates. The canonical qPCR method does not measure TL directly but via the ratio of telomere repeats to a single copy gene (SCG) generating a T/S ratio. We use a monochromatic-multiplex-qPCR (mmqPCR) method which multiplexes the PCR and enables quantification of the target and the single copy gene within the same qPCR reaction. We demonstrate that TL measurements, from murine gDNA, isolated via Spin Columns (SC) and Magnetic Beads (MB), generate significantly smaller T/S ratios compared to gDNA isolated via traditional phenol/chloroform methods. The former methods may impede correct TL estimation by producing non representative fragment sets and reducing qPCR efficacy. This work highlights discrepancies in TL measurements due to different extraction techniques. We recommend the use of gDNA isolation methods that are shown to preserve DNA length and integrity, such as phenol/chloroform isolation. We propose that widely used high throughput DNA isolation methodologies can create spurious associations within a sample set, thus creating misleading data. We suggest that published TL associations should be revisited in the light of these data.