Diagnostic utility of telomere length testing in a hospital-based setting

ATM-dependent DNA damage response constrains cell growth and drives clonal hematopoiesis in telomere biology disorders

Telomere biology disorders (TBDs) are genetic diseases caused by defective telomere maintenance. TBD patients often develop bone marrow failure and have an increased risk of myeloid neoplasms. To better understand the factors underlying hematopoietic outcomes in TBD, we comprehensively evaluated acquired genetic alterations in hematopoietic cells from 166 pediatric and adult TBD patients. Of these patients, 47.6% (28.8% of children, 56.1% of adults) had clonal hematopoiesis. Recurrent somatic alterations involved telomere maintenance genes (7.6%), spliceosome genes (10.4%, mainly U2AF1 p.S34), and chromosomal alterations (20.2%), including 1q gain (5.9%). Somatic variants affecting the DNA damage response (DDR) were identified in 21.5% of patients, including 20 presumed loss-of-function variants in ataxia-telangiectasia mutated (ATM). Using multimodal approaches, including single-cell sequencing, assays of ATM activation, telomere dysfunction-induced foci analysis, and cell-growth assays, we demonstrate telomere dysfunction-induced activation of the ATM-dependent DDR pathway with increased senescence and apoptosis in TBD patient cells. Pharmacologic ATM inhibition, modeling the effects of somatic ATM variants, selectively improved TBD cell fitness by allowing cells to bypass DDR-mediated senescence without detectably inducing chromosomal instability. Our results indicate that ATM-dependent DDR induced by telomere dysfunction is a key contributor to TBD pathogenesis and suggest dampening hyperactive ATM-dependent DDR as a potential therapeutic intervention.

Risk assessment and genetic counseling for hematologic malignancies-Practice resource of the National Society of Genetic Counselors

Hematologic malignancies (HMs) are a heterogeneous group of cancers impacting individuals of all ages that have been increasingly recognized in association with various germline predisposition syndromes. Given the myriad of malignancy subtypes, expanding differential diagnoses, and unique sample selection requirements, evaluation for hereditary predisposition to HM presents both challenges as well as exciting opportunities in the ever-evolving field of genetic counseling. This practice resource has been developed as a foundational resource for genetic counseling approaches to hereditary HMs and aims to empower genetic counselors who encounter individuals and families with HMs in their practice.

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.

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

Canonical and non-canonical functions of the non-coding RNA component (TERC) of telomerase complex

The telomerase complex consists of a protein component (TERT), which has reverse transcriptase activity, and an RNA component (TERC), which serves as a template for telomere synthesis. Evidence is rapidly accumulating regarding the non-canonical functions of these components in both normal or diseased cells. An oligonucleotide-based drug, the first telomerase inhibitor, secured FDA approval in June 2024. We recently summarized the non-canonical functions of TERT in viral infections and cancer. In this review, we expand on these non-canonical functions of TERC beyond telomere maintenance. Specifically, we explore TERC's roles in cellular aging and senescence, immune regulation, genetic diseases, human cancer, as well as involvement in viral infections and host interactions. Finally, we discuss a transcription product of telomere repeats, TERRA, and explore strategies for targeting TERC as a therapeutic approach.

Adult-Onset Presentations of Retinopathy Associated With Short Telomere Syndromes

Purpose: To describe the association between short telomere syndrome and exudative retinopathies in adults. Methods: This case series compared the presentation, course of treatment, and visual outcomes of 2 patients with adult-onset retinopathy associated with short telomere syndrome. Results: In Case 1, a 53-year-old man initially presented with bilateral retinal telangiectasias and preretinal hemorrhage in the left eye, which was followed by multiple vitreous hemorrhages. In the subsequent 15 years, the patient was diagnosed with pulmonary fibrosis, liver cirrhosis, and a RTEL1 gene mutation, consistent with short telomere syndrome. In Case 2, a previously asymptomatic 26-year-old man with paternally inherited short telomere syndrome (TERC gene mutation) presented with floaters, bilateral peripheral retinal capillary nonperfusion, and an aneurysmal lesion with surrounding exudation. Conclusions: Short telomere syndromes, with systemic features that can be life-threatening, can manifest initially in adulthood with retinal telangiectasia, aneurysmal lesions, exudation, or peripheral retinal capillary nonperfusion, preceding systemic manifestations. Because the systemic manifestations of retinal telangiectasia and peripheral retinal capillary nonperfusion are progressive and can be life-threatening, recognizing these findings in adults with retinal telangiectasia is crucial.

A tiered strategy to identify relevant genetic variants in familial pulmonary fibrosis: a proof of concept for the clinical practice

Idiopathic pulmonary fibrosis (IPF) is a progressive, late-onset disease marked by lung scarring and irreversible loss of lung function. Genetic factors significantly contribute to both familial and sporadic cases, yet there are scarce evidence-based studies highlighting the benefits of integrating genetics into the management of IPF patients. In this study, we performed whole-exome sequencing and telomere length (TL) measurements on IPF patients and their relatives. We then identified rare deleterious variants using three virtual gene panels encompassing IPF or TL genes with varying levels of evidence supporting their potential relationship with the disease. We identified 10 candidate variants in well-established disease genes, and these results were validated using two automatic prioritization tools (Exomiser and Franklin). Pathogenic variants were found in two telomere-related genes (RTEL1 and NAF1), and both were associated with severe TL shortening. Our results suggest that this tiered virtual panel strategy is sufficiently robust and serves as a viable solution in clinical practice. It generates valuable genetic data which can be interpreted and validated with the expertise of a multidisciplinary team.

Aging Lung: Molecular Drivers and Impact on Respiratory Diseases-A Narrative Clinical Review

The aging process significantly impacts lung physiology and is a major risk factor for chronic respiratory diseases, including chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis (IPF), asthma, and non-IPF interstitial lung fibrosis. This narrative clinical review explores the molecular and biochemical hallmarks of aging, such as oxidative stress, telomere attrition, genomic instability, epigenetic modifications, proteostasis loss, and impaired macroautophagy, and their roles in lung senescence. Central to this process are senescent cells, which, through the senescence-associated secretory phenotype (SASP), contribute to chronic inflammation and tissue dysfunction. The review highlights parallels between lung aging and pathophysiological changes in respiratory diseases, emphasizing the role of cellular senescence in disease onset and progression. Despite promising research into modulating aging pathways with interventions like caloric restriction, mTOR inhibitors, and SIRT1 activators, clinical evidence for efficacy in reversing or preventing age-related lung diseases remains limited. Understanding the interplay between aging-related mechanisms and environmental factors, such as smoking and pollution, is critical for developing targeted therapies. This review underscores the need for future studies focusing on therapeutic strategies to mitigate aging's detrimental effects on lung health and improve outcomes for patients with chronic respiratory conditions.

Diagnosis and Management of Pulmonary Manifestations of Telomere Biology Disorders

PURPOSE OF REVIEW

Telomere biology disorders (TBD) are a group of genetic disorders characterized by premature shortening of telomeres, resulting in accelerated aging of somatic cells. This often leads to major multisystem organ dysfunction, and TBDs have become increasingly recognized as a significant contributor to numerous disease processes within the past 10-15 years. Both research and clinical practice in this field are rapidly evolving.

RECENT FINDINGS

A subset of patients with TBD suffers from interstitial lung disease, most commonly pulmonary fibrosis. Often, the clinical presentation is indistinguishable from other forms of lung fibrosis. There are no pathognomonic radiographic or histological features, and a high level of suspicion is therefore required. Telomere evaluation is thus crucial to establishing the diagnosis. This review details the clinical presentation, objective evaluation, indicated genetic testing, and recommended management strategies for patients affected by interstitial lung disease associated with TBDs. Our goal is to empower pulmonologists and other healthcare professionals who care for these patients to provide appropriate and personalized care for this population.

Analyzing the role of ferroptosis in ribosome-related bone marrow failure disorders: From pathophysiology to potential pharmacological exploitation

Within the last decade, the scientific community has witnessed the importance of ferroptosis as a novel cascade of molecular events leading to cellular decisions of death distinct from apoptosis and other known forms of cell death. Notably, such non- apoptotic and iron-dependent regulated cell death has been found to be intricately linked to several physiological processes as well as to the pathogenesis of various diseases. To this end, recent data support the notion that a potential molecular connection between ferroptosis and inherited bone marrow failure (IBMF) in individuals with ribosomopathies may exist. In this review, we suggest that in ribosome-related IBMFs the identified mutations in ribosomal proteins lead to changes in the ribosome composition of the hematopoietic progenitors, changes that seem to affect ribosomal function, thus enhancing the expression of some mRNAs subgroups while reducing the expression of others. These events lead to an imbalance inside the cell as some molecular pathways are promoted while others are inhibited. This disturbance is accompanied by ROS production and lipid peroxidation, while an additional finding in most of them is iron accumulation. Once lipid peroxidation and iron accumulation are the two main characteristics of ferroptosis, it is possible that this mechanism plays a key role in the manifestation of IBMF in this type of disease. If this molecular mechanism is further confirmed, new pharmacological targets such as ferroptosis inhibitors that are already exploited for the treatment of other diseases, could be utilized to improve the treatment of ribosomopathies.

Telomere biology disorders: from dyskeratosis congenita and beyond

Defective telomerase function or telomere maintenance causes genomic instability. Alterations in telomere length and/or attrition are the primary features of rare diseases known as telomere biology disorders or telomeropathies. Recent advances in the molecular basis of these disorders and cutting-edge methods assessing telomere length have increased our understanding of this topic. Multiorgan manifestations and different phenotypes have been reported even in carriers within the same family. In this context, apart from dyskeratosis congenita, disorders formerly considered idiopathic (i.e. pulmonary fibrosis, liver cirrhosis) frequently correlate with underlying defective telomere maintenance mechanisms. Moreover, these patients are prone to developing specific cancer types and exhibit exceptional sensitivity and toxicity in standard chemotherapy regimens. The current review describes the diverse spectrum of clinical manifestations of telomere biology disorders in pediatric and adult patients, their correlation with pathogenic variants, and considerations during their management to increase awareness and improve a multidisciplinary approach.

Unveiling immunological signatures and predictors of response to immunosuppressive therapy in acquired aplastic anemia

Acquired aplastic anemia (AA) often results from immune destruction of hematopoietic stem and progenitor cells. However, only 60%-70% of patients with AA respond to immunosuppressive therapy (IST). There is a lack of strong predictive markers for response to IST which can help therapy. Our study sought to pinpoint unique immune markers in AA patients and validate established predictors for response to IST. We enrolled 51 severe AA patients and analyzed 57 immunological parameters via flow cytometry. Additionally, we measured paroxysmal nocturnal hemoglobinuria (PNH) clone, telomere length, and thrombopoietin (TPO) levels prior to IST. After a 6-month follow-up, a response was observed. Patients with AA had a distinct immunological signature characterized by absolute lymphopenia, skewed CD4/CD8 ratio with expansion of CD8 T cells with activated and senescent phenotype. Treg counts were reduced, while the proportion of Treg A and B was comparable to controls. Treatment response was correlated with elevated absolute neutrophil count (ANC), absolute reticulocyte count (ARC), and reduced CD57+ CD8+ naive cells and B cell % before therapy. However, predictors like TPO, telomere length, and PNH did not emerge as indicators of treatment response. Identifying predictors for treatment response in AA is challenging due to abnormal hematopoiesis, genetic mutations, and treatment variables.

Telomeric RNAs, TERRA, as a Potential Biomarker for Spermatozoa Quality

Characterization of long non-coding telomeric repeat-containing RNAs in sperm of normozoospermic and oligoasthenozoospermic men as new biomarker of idiopathic male infertility. We conducted an observational prospective study with two groups of men with normal or orligoasthenozoospermic spermiogram, aged 40 and above. Fertility parameters were analyzed in men undergoing intracytoplasmic sperm injection with donor oocytes, to avoid the female factor. Telomeric RNAs and telomere length were measured by quantitative fluorescent in situ hybridization. Data from seminal parameters and in-vitro fertilization were assessed according to IVIRMA protocols. Patients with oligoasthenozoospermia, who had worse seminal parameters, also obtained embryos with lower inner-cell-mass quality (p = 0.04), despite using donor oocytes. While mean levels of telomeric RNAs were similar for both groups, the percentage of spermatozoa with more than 3 foci was higher in oligoasthenozoospermic men (p = 0.02). Regarding telomere length, oligoasthenozoospermic men had shorter mean, a higher accumulation of short telomeres (15th percentile; p = 0.03) and a lower percentage of very-long telomeres (85th percentile; p = 0.01). Finally, a positive correlation was found between telomeric-RNAs intensity and total progressive motility in the spermatozoa of normozoospermic patients (r = 0.5; p = 0.03). Telomeric parameters were altered in the spermatozoa of the oligoasthenozoospermic group, which also showed lower quality embryos. Interestingly, in the normozoospermic group, a correlation was found between progressive motility and telomeric RNA levels, suggesting that they could be a good biomarker of sperm quality. Further studies are required to confirm these results and translate them into the clinical practice.Trial registration number: 1711-MAD-109-CB, 07/07/2021.

Clinical Impact of Telomere Length Testing for Interstitial Lung Disease

BACKGROUND

Shortened telomere length (TL) is a genomic risk factor for fibrotic interstitial lung disease (ILD), but its role in clinical management is unknown.

RESEARCH QUESTION

What is the clinical impact of TL testing on the management of ILD?

STUDY DESIGN AND METHODS

Patients were evaluated in the Columbia University ILD clinic and underwent Clinical Laboratory Improvement Amendments-certified TL testing by flow cytometry and fluorescence in situ hybridization (FlowFISH) as part of clinical treatment. Short TL was defined as below the 10th age-adjusted percentile for either granulocytes or lymphocytes by FlowFISH. Patients were offered genetic counseling and testing if they had short TL or a family history of ILD. FlowFISH TL was compared with research quantitative polymerase chain reaction (qPCR) TL measurement.

RESULTS

A total of 108 patients underwent TL testing, including those with clinical features of short telomere syndrome such as familial pulmonary fibrosis (50%) or extrapulmonary manifestations in the patient (25%) or a relative (41%). The overall prevalence of short TL was 46% and was similar across clinical ILD diagnoses. The number of short telomere clinical features was independently associated with detecting short TL (OR, 2.00; 95% CI, 1.27-3.32). TL testing led to clinical treatment changes for 35 patients (32%), most commonly resulting in reduction or avoidance of immunosuppression. Of the patients who underwent genetic testing (n = 34), a positive or candidate diagnostic finding in telomere-related genes was identified in 10 patients (29%). Inclusion of TL testing below the 1st percentile helped reclassify eight of nine variants of uncertain significance into actionable findings. The quantitative polymerase chain reaction test correlated with FlowFISH, but age-adjusted percentile cutoffs may not be equivalent between the two assays.

INTERPRETATION

Incorporating TL testing in ILD impacted clinical management and led to the discovery of new actionable genetic variants.

Haematological features of telomere biology disorders diagnosed in adulthood: A French nationwide study of 127 patients

Data on haematological features of telomere biology disorders (TBD) remain scarce. We describe haematological, extra-haematological characteristics and prognosis of 127 genetically confirmed TBD patients diagnosed after the age of 15. Ninety-three index cases and 34 affected relatives were included. At diagnosis of TBD, 76.3% of index cases had haematological features, half pulmonary features and a third liver features. At diagnosis, bone marrow failure (BMF) was present in 59 (46.5%), myelodysplastic syndrome (MDS) in 22 (17.3%) and acute myeloid leukaemia (AML) in 2 (1.6%) while 13 (10.2%) developed or worsened bone marrow involvement during follow-up. At diagnosis, compared to MDS/AML patients, BMF patients were younger (median 23.1 years vs. 43.8, p = 0.007), and had a better outcome (4-year overall survival 76.3% vs. 31.8%, p < 0.001). While frequencies and burden of cytogenetical and somatic mutations increased significantly in myeloid malignancies, some abnormalities were also observed in patients with normal blood counts and BMF, notably somatic spliceosome variants. Solid cancers developed in 8.7% patients, mainly human papillomavirus-related cancers and hepatocellular carcinomas. TBD is a multiorgan progressive disease. While BMF is the main haematological disorder, high-risk myeloid malignancies are common, and are, together with age, the only factors associated with a worse outcome.

Novel telomerase reverse transcriptase gene mutation in a family with aplastic anaemia

Telomerase Reverse Transcriptase (TERT) encodes the telomerase reverse transcriptase enzyme and is the most frequently mutated gene in patients with telomeropathies. Heterozygous variants impair telomerase activity by haploinsufficiency and pathogenic variants are associated with bone marrow failure syndrome and predisposition to acute myeloid leukaemia. Owing to their rarity, telomeropathies are often unrecognised and misdiagnosed. Herein, we report a novel TERT gene variant, c.2605G > A p.(Asp869Asn) in a family with hereditary aplastic anaemia. This report emphasises the importance of routine deep genetic screening for rare TERT variants in patients with a family history of cytopenia or aplastic anaemia, which could identify clinically inapparent telomere disorders.

T cell exhaustion in human cancers

T cell exhaustion refers to a progressive state in which T cells become functionally impaired due to sustained antigenic stimulation, which is characterized by increased expression of immune inhibitory receptors, but weakened effector functions, reduced self-renewal capacity, altered epigenetics, transcriptional programme and metabolism. T cell exhaustion is one of the major causes leading to immune escape of cancer, creating an environment that supports tumor development and metastatic spread. In addition, T cell exhaustion plays a pivotal role to the efficacy of current immunotherapies for cancer. This review aims to provide a comprehensive view of roles of T cell exhaustion in cancer development and progression. We summerized the regulatory mechanisms that involved in T cell exhaustion, including transcription factors, epigenetic and metabolic reprogramming events, and various microenvironmental factors such as cytokines, microorganisms, and tumor autocrine substances. The paper also discussed the challenges posed by T cell exhaustion to cancer immunotherapies, including immune checkpoint blockade (ICB) therapies and chimeric antigen receptor T cell (CAR-T) therapy, highlightsing the obstacles encountered in ICB therapies and CAR-T therapies due to T cell exhaustion. Finally, the article provides an overview of current therapeutic options aimed to reversing or alleviating T cell exhaustion in ICB and CAR-T therapies. These therapeutic approaches seek to overcome T cell exhaustion and enhance the effectiveness of immunotherapies in treating tumors.

Genetics and Genomics of Pulmonary Fibrosis: Charting the Molecular Landscape and Shaping Precision Medicine

Recent genetic and genomic advancements have elucidated the complex etiology of idiopathic pulmonary fibrosis (IPF) and other progressive fibrotic interstitial lung diseases (ILDs), emphasizing the contribution of heritable factors. This state-of-the-art review synthesizes evidence on significant genetic contributors to pulmonary fibrosis (PF), including rare genetic variants and common SNPs. The MUC5B promoter variant is unusual, a common SNP that markedly elevates the risk of early and established PF. We address the utility of genetic variation in enhancing understanding of disease pathogenesis and clinical phenotypes, improving disease definitions, and informing prognosis and treatment response. Critical research gaps are highlighted, particularly the underrepresentation of non-European ancestries in PF genetic studies and the exploration of PF phenotypes beyond usual interstitial pneumonia/IPF. We discuss the role of telomere length, often critically short in PF, and its link to progression and mortality, underscoring the genetic complexity involving telomere biology genes (TERT, TERC) and others like SFTPC and MUC5B. In addition, we address the potential of gene-by-environment interactions to modulate disease manifestation, advocating for precision medicine in PF. Insights from gene expression profiling studies and multiomic analyses highlight the promise for understanding disease pathogenesis and offer new approaches to clinical care, therapeutic drug development, and biomarker discovery. Finally, we discuss the ethical, legal, and social implications of genomic research and therapies in PF, stressing the need for sound practices and informed clinical genetic discussions. Looking forward, we advocate for comprehensive genetic testing panels and polygenic risk scores to improve the management of PF and related ILDs across diverse populations.

Modified Delphi panel consensus recommendations for management of severe aplastic anemia

ABSTRACT

Severe aplastic anemia (SAA) is a rare hematologic condition for which there is no clear management algorithm. A panel of 11 experts on adult and pediatric aplastic anemia was assembled and, using the RAND/University of California, Los Angeles modified Delphi panel method, evaluated >600 varying patient care scenarios to develop clinical recommendations for the initial and subsequent management of patients of all ages with SAA. Here, we present the panel's recommendations to rule out inherited bone marrow failure syndromes, on supportive care before and during first-line therapy, and on first-line (initial management) and second-line (subsequent management) therapy of acquired SAA, focusing on when transplant vs medical therapy is most appropriate. These recommendations represent the consensus of 11 experts informed by published literature and experience. They are intended only as general guidance for experienced clinicians who treat patients with SAA and are in no way intended to supersede individual physician and patient decision making. Current and future research should validate this consensus using clinical data. Once validated, we hope these expert panel recommendations will improve outcomes for patients with SAA.

Liver disease and transplantation in telomere biology disorders: An international multicenter cohort

BACKGROUND

Patients with telomere biology disorders (TBD) develop hepatic disease, including hepatitis, cirrhosis, and hepatopulmonary syndrome. No specific treatment exists for TBD-related liver disease, and the role of liver transplantation (LT) remains controversial. Our study objectives were to describe the clinical characteristics, management, and outcomes in patients with TBD-related liver disease, and their LT outcomes.

METHODS

Data from 83 patients with TBD-associated liver disease were obtained from 17 participating centers in the Clinical Care Consortium of Telomere-Associated Ailments and by self-report for our retrospective, multicenter, international cohort study.

RESULTS

Group A ("Advanced") included 40 patients with advanced liver disease. Of these, 20 underwent LT (Group AT). Group M ("Mild") included 43 patients not warranting LT evaluation, none of whom were felt to be medically unfit for liver transplantation. Supplemental oxygen requirement, pulmonary arteriovenous malformation, hepatopulmonary syndrome, and higher bilirubin and international normalized ratio values were associated with Group A. Other demographics, clinical manifestations, and laboratory findings were similar between groups. Six group A patients were declined for LT; 3 died on the waitlist. Median follow-up post-LT was 2.9 years (range 0.6-13.2 y). One-year survival post-LT was 73%. Median survival post-LT has not been reached. Group AT patients had improved survival by age compared to all nontransplant patients (log-rank test p = 0.02). Of 14 patients with pretransplant hypoxemia, 8 (57%) had improved oxygenation after transplant.

CONCLUSIONS

LT recipients with TBD do not exhibit excessive posttransplant mortality, and LT improved respiratory status in 57%. A TBD diagnosis should not exclude LT consideration.

Telomere-lengthening germline variants predispose to a syndromic papillary thyroid cancer subtype

Papillary thyroid cancer (PTC) is the most common endocrine malignancy. 10% to 15% of individuals show familial clustering with three or more affected members, but the factors underlying this risk are unknown. In a group of recently studied individuals with POT1 pathogenic variants and ultra-long telomere length, PTC was the second most common solid tumor. We tested whether variants in POT1 and four other telomere-maintenance genes associated with familial cancer underlie PTC susceptibility. Among 470 individuals, we identified pathogenic or likely pathogenic variants in three genes encoding telomere-binding proteins: POT1, TINF2, and ACD. They were found in 4.5% and 1.5% of familial and unselected cases, respectively. Individuals harboring these variants had ultra-long telomere length, and 15 of 18 (83%) developed other cancers, of which melanoma, lymphoma, and sarcoma were most common. Among individuals with PTC and melanoma, 22% carried a deleterious germline variant, suggesting that a long telomere syndrome might be clinically recognizable. Successive generations had longer telomere length than their parents and, at times, developed more cancers at younger ages. Tumor sequencing identified a single oncogenic driver, BRAF p.Val600Glu, in 10 of 10 tumors studied, but no telomere-maintenance mechanism, including at the TERT promoter. These data identify a syndromic subset of PTCs with locus heterogeneity and telomere lengthening as a convergent mechanism. They suggest these germline variants lower the threshold to cancer by obviating the need for an acquired telomere-maintenance mechanism in addition to sustaining the longevity of oncogenic mutations.

Liver disease in germline mutations of telomere-related genes: Prevalence, clinical, radiological, pathological features, outcome, and risk factors

BACKGROUND AND AIM

Germline mutations of telomere-related genes (TRG) induce multiorgan dysfunction, and liver-specific manifestations have not been clearly outlined. We aimed to describe TRG mutations-associated liver diseases.

APPROACH AND RESULTS

Retrospective multicenter analysis of liver disease (transaminases > 30 IU/L and/or abnormal liver imaging) in patients with TRG mutations. Main measurements were characteristics, outcomes, and risk factors of liver disease in a TRG mutations cohort. The prevalence of liver disease was compared to a community-based control group (n = 1190) stratified for age and matched 1:3 for known risk factors of liver disease. Among 132 patients with TRG mutations, 95 (72%) had liver disease, with associated lung, blood, skin, rheumatological, and ophthalmological TRG diseases in 82%, 77%, 55%, 39%, and 30% of cases, respectively. Liver biopsy was performed in 52/95 patients, identifying porto-sinusoidal vascular disease in 48% and advanced fibrosis/cirrhosis in 15%. After a follow-up of 21 months (12-54), ascites, hepato-pulmonary syndrome, variceal bleeding, and HCC occurred in 14%, 13%, 13%, and 2% of cases, respectively. Five-year liver transplantation-free survival was 69%. A FIB-4 score ≥ 3·25 and ≥1 risk factor for cirrhosis were associated with poor liver transplantation-free survival. Liver disease was more frequent in patients with TRG mutations than in the paired control group [80/396, (20%)], OR 12.9 (CI 95%: 7.8-21.3, p < 0.001).

CONCLUSIONS

TRG mutations significantly increase the risk of developing liver disease. Although symptoms may be mild, they may be associated with severe disease. Porto-sinusoidal vascular disease and cirrhosis were the most frequent lesions, suggesting that the mechanism of action is multifactorial.

A persistent variant telomere sequence in a human pedigree

The telomere sequence, TTAGGG, is conserved across all vertebrates and plays an essential role in suppressing the DNA damage response by binding a set of proteins termed shelterin. Changes in the telomere sequence impair shelterin binding, initiate a DNA damage response, and are toxic to cells. Here we identify a family with a variant in the telomere template sequence of telomerase, the enzyme responsible for telomere elongation, that led to a non-canonical telomere sequence. The variant is inherited across at least one generation and one family member reports no significant medical concerns despite ~9% of their telomeres converting to the novel sequence. The variant template disrupts telomerase repeat addition processivity and decreased the binding of the telomere-binding protein POT1. Despite these disruptions, the sequence is readily incorporated into cellular chromosomes. Incorporation of a variant sequence prevents POT1-mediated inhibition of telomerase suggesting that incorporation of a variant sequence may influence telomere addition. These findings demonstrate that telomeres can tolerate substantial degeneracy while remaining functional and provide insights as to how incorporation of a non-canonical telomere sequence might alter telomere length dynamics.

Human telomere length is chromosome end-specific and conserved across individuals

Short telomeres cause age-related disease, and long telomeres contribute to cancer; however, the mechanisms regulating telomere length are unclear. We developed a nanopore-based method, which we call Telomere Profiling, to determine telomere length at nearly single-nucleotide resolution. Mapping telomere reads to chromosome ends showed chromosome end-specific length distributions that could differ by more than six kilobases. Examination of telomere lengths in 147 individuals revealed that certain chromosome ends were consistently longer or shorter. The same rank order was found in newborn cord blood, suggesting that telomere length is determined at birth and that chromosome end-specific telomere length differences are maintained as telomeres shorten with age. Telomere Profiling makes precision investigation of telomere length widely accessible for laboratory, clinical, and drug discovery efforts and will allow deeper insights into telomere biology.

Telomere length and cancer risk: finding Goldilocks

Telomeres are the nucleoprotein complex at chromosome ends essential in genomic stability. Baseline telomere length (TL) is determined by rare and common germline genetic variants but shortens with age and is susceptible to certain environmental exposures. Cellular senescence or apoptosis are normally triggered when telomeres reach a critically short length, but cancer cells overcome these protective mechanisms and continue to divide despite chromosomal instability. Rare germline variants in telomere maintenance genes cause exceedingly short telomeres for age (< 1st percentile) and the telomere biology disorders, which are associated with elevated risks of bone marrow failure, myelodysplastic syndrome, acute myeloid leukemia, and squamous cell carcinoma of the head/neck and anogenital regions. Long telomeres due to rare germline variants in the same or different telomere maintenance genes are associated with elevated risks of other cancers, such as chronic lymphocytic leukemia or sarcoma. Early epidemiology studies of TL in the general population lacked reproducibility but new methods, including creation of a TL polygenic score using common variants, have found longer telomeres associated with excess risks of renal cell carcinoma, glioma, lung cancer, and others. It has become clear that when it comes to TL and cancer etiology, not too short, not too long, but "just right" telomeres are important in minimizing cancer risk.

Human telomere length is chromosome specific and conserved across individuals

Short telomeres cause age-related disease and long telomeres predispose to cancer; however, the mechanisms regulating telomere length are unclear. To probe these mechanisms, we developed a nanopore sequencing method, Telomere Profiling, that is easy to implement, precise, and cost effective with broad applications in research and the clinic. We sequenced telomeres from individuals with short telomere syndromes and found similar telomere lengths to the clinical FlowFISH assay. We mapped telomere reads to specific chromosome end and identified both chromosome end-specific and haplotype-specific telomere length distributions. In the T2T HG002 genome, where the average telomere length is 5kb, we found a remarkable 6kb difference in lengths between some telomeres. Further, we found that specific chromosome ends were consistently shorter or longer than the average length across 147 individuals. The presence of conserved chromosome end-specific telomere lengths suggests there are new paradigms in telomere biology that are yet to be explored. Understanding the mechanisms regulating length will allow deeper insights into telomere biology that can lead to new approaches to disease.

Clinical manifestations of telomere biology disorders in adults

Telomere biology disorders (TBDs) are a spectrum of inherited bone marrow failure syndromes caused by impaired telomere function due to pathogenic germline variants in genes involved in telomere maintenance. TBDs can affect many organ systems and are often thought of as diseases of childhood. However, TBDs may present in mid- or even late adulthood with features similar to but not always the same as the childhood-onset TBDs. Adult-onset TBDs are often cryptic with isolated pulmonary, liver, or hematologic disease, or cancer, and may lack the classic disease-defining triad of abnormal skin pigmentation, nail dysplasia, and oral leukoplakia. Diagnostics include detection of very short leukocyte telomeres and germline genetic testing. Notably, adult-onset TBDs may show telomeres in the 1st to 10th percentile for age, and some cases may not have an identifiable genetic cause. TBD genetic etiology includes all modes of inheritance, with autosomal dominant the most frequent in adult-onset disease. Variable symptom onset due to incomplete penetrance, variable expressivity, and genetic anticipation add to the diagnostic challenges. Adult-onset TBDs are likely underrecognized, but their correct identification is of utmost importance, since affected patients are faced with numerous clinical complications, including but not limited to an increased risk of malignancies requiring close surveillance for early detection. Currently lung, liver, or hematopoietic cell transplants are the only curative therapeutic approaches but can be complicated by comorbidities, despite improved medical care. This review highlights the challenges of identifying adult-onset TBDs and addresses currently recommended clinical screening measures and therapy options.

Genetic Counseling and Family Screening Recommendations in Patients with Telomere Biology Disorders

PURPOSE OF REVIEW

Telomere biology disorders (TBDs) encompass a spectrum of genetic diseases with a common pathogenesis of defects in telomerase function and telomere maintenance causing extremely short telomere lengths. Here, we review the current literature surrounding genetic testing strategies, cascade testing, reproductive implications, and the role of genetic counseling.

RECENT FINDINGS

The understanding of the genetic causes and clinical symptoms of TBDs continues to expand while genetic testing and telomere length testing are nuanced tools utilized in the diagnosis of this condition. Access to genetic counseling is becoming more abundant and is valuable in supporting patients and their families in making informed decisions. Patient resources and support groups are valuable to this community. Defining which populations should be offered genetic counseling and testing is imperative to provide proper diagnoses and medical management for not only the primary patient, but also their biological relatives.

Telomere biology disorders may manifest as common variable immunodeficiency (CVID)

Telomere biology disorders (TBD) are caused by germline pathogenic variants in genes related to telomere maintenance and are characterized by critically short telomeres. In contrast to classical dyskeratosis congenita (DC), which is typically diagnosed in infancy, adult or late onset TBD frequently lack the typical DC triad and rather show variable organ manifestations and a cryptic disease course, thus complicating its diagnosis. Common variable immunodeficiency (CVID), on the other hand, is a primary antibody deficiency (PAD) syndrome. PADs are a heterogenous group of diseases characterized by hypogammaglobulinemia which occurs due to dysfunctional B lymphocytes and additional autoimmune and autoinflammatory complications. Genetic screening reveals a monogenic cause in a subset of CVID patients (15-35%). In our study, we screened the exomes of 491 CVID patients for the occurrence of TBD-related variants in 13 genes encoding for telomere/telomerase-associated proteins, which had previously been linked to the disease. We found 110/491 patients (22%) carrying 91 rare candidate variants in these 13 genes. Following the American College of Medical Genetics and Genomics (ACMG) guidelines, we classified two variants as benign, two as likely benign, 64 as variants of uncertain significance (VUS), four as likely pathogenic, and one heterozygous variant in an autosomal recessive disease gene as pathogenic. We performed telomere length measurement in 42 of the 110 patients with candidate variants and CVID. Two of these 42 patients showed significantly shorter telomeres compared to controls in both lymphocytes and granulocytes. Following the evaluation of the published literature and the patient's manifestations, we re-classified two VUS as likely pathogenic variants. Thus, 0.5-1% of all CVID patients in our study carry possibly pathogenic variants in telomere/telomerase-associated genes. Our data adds CVID to the broad clinical spectrum of cryptic adult-onset TBD. As the molecular diagnosis greatly impacts patient management and treatment strategies, we advise inclusion of all TBD-associated genes-despite their low prevalence-into the molecular screening of patients with antibody deficiencies.

The distribution and accumulation of the shortest telomeres in telomere biology disorders

Individuals with telomere biology disorders (TBDs) have very short telomeres, high risk of bone marrow failure (BMF), and reduced survival. Using data from TBD patients, a mean leukocyte Southern blot telomere length (TL) of 5 kilobases (kb) was estimated as the 'telomere brink' at which human survival is markedly reduced. However, the shortest telomere, not the mean TL, signals replicative senescence. We used the Telomere Shortest Length Assay (TeSLA) to tally TL of all 46 chromosomes in blood-derived DNA and examined its relationship with TBDs. Patients (n = 18) had much shorter mean TL (TeSmTL) (2.54 ± 0.41 kb vs. 4.48 ± 0.52 kb, p < 0.0001) and more telomeres <3 kb than controls (n = 22) (70.43 ± 8.76% vs. 33.05 ± 6.93%, p < 0.0001). The proportion of ultrashort telomeres (<1.6 kb) was also higher in patients than controls (39.29 ± 10.69% vs. 10.40 ± 4.09%, p < 0.0001). TeS <1.6 kb was associated with severe (n = 11) compared with non-severe (n = 7) BMF (p = 0.027). Patients with multi-organ manifestations (n = 10) had more telomeres <1.6 kb than those with one affected organ system (n = 8) (p = 0.029). Findings suggest that TBD clinical manifestations are associated with a disproportionately higher number of haematopoietic cell telomeres reaching a telomere brink, whose length at the single telomere level is yet to be determined.

Experimental and Computational Approaches to Measure Telomere Length: Recent Advances and Future Directions

PURPOSE OF REVIEW

The length of telomeres, protective structures at the chromosome ends, is a well-established biomarker for pathological conditions including multisystemic syndromes called telomere biology disorders. Approaches to measure telomere length (TL) differ on whether they estimate average, distribution, or chromosome-specific TL, and each presents their own advantages and limitations.

RECENT FINDINGS

The development of long-read sequencing and publication of the telomere-to-telomere human genome reference has allowed for scalable and high-resolution TL estimation in pre-existing sequencing datasets but is still impractical as a dedicated TL test. As sequencing costs continue to fall and strategies for selectively enriching telomere regions prior to sequencing improve, these approaches may become a promising alternative to classic methods. Measurement methods rely on probe hybridization, qPCR or more recently, computational methods using sequencing data. Refinements of existing techniques and new approaches have been recently developed but a test that is accurate, simple, and scalable is still lacking.

Implementation of a prospective screening strategy to identify adults with a telomere biology disorder among those undergoing lung transplant evaluation for interstitial lung disease

INTRODUCTION

Patients with interstitial lung disease (ILD) secondary to telomere biology disorders (TBD) experience increased morbidity after lung transplantation. Identifying patients with TBD may allow for personalized management to facilitate better outcomes. However, establishing a TBD diagnosis in adults is challenging.

METHODS

A TBD screening questionnaire was introduced prospectively into the lung transplant evaluation. Patients with ILD screening positive were referred for comprehensive TBD phenotyping and concurrent telomere length measurement and germline genetic testing.

RESULTS

Of 98 patients, 32 (33%) screened positive. Eight patients (8% of total; 25% of patients with a positive screen) met strict TBD diagnostic criteria, requiring either critically short lymphocyte telomeres (<1st percentile) (n = 4), a pathogenic variant in a TBD-associated gene (n = 1), or both (n = 3) along with a TBD clinical phenotype. Additional patients not meeting strict diagnostic criteria had histories consistent with TBD along with telomere lengths <10th percentile and/or rare variants in TBD-associated genes, highlighting a critical need to refine TBD diagnostic criteria for this patient population.

CONCLUSION

A TBD phenotype screening questionnaire in patients with ILD undergoing lung transplant evaluation has a diagnostic yield of 25%. Additional gene discovery, rare variant functional testing, and refined TBD diagnostic criteria are needed to realize the maximum benefit of testing for TBD in patients undergoing lung transplantation.

Telomeres: Dysfunction, Maintenance, Aging and Cancer

Aging has emerged at the forefront of scientific research due to the growing social and economic costs associated with the growing aging global population. The defining features of aging involve a variety of molecular processes and cellular systems, which are interconnected and collaboratively contribute to the aging process. Herein, we analyze how telomere dysfunction potentially amplifies or accelerates the molecular and biochemical mechanisms underpinning each feature of aging and contributes to the emergence of age-associated illnesses, including cancer and neurodegeneration, via the perspective of telomere biology. Furthermore, the recently identified novel mechanistic actions for telomere maintenance offer a fresh viewpoint and approach to the management of telomeres and associated disorders. Telomeres and the defining features of aging are intimately related, which has implications for therapeutic and preventive approaches to slow aging and reduce the prevalence of age-related disorders.

Molecular and Genetic Biomarkers in Idiopathic Pulmonary Fibrosis: Where Are We Now?

Idiopathic pulmonary fibrosis (IPF) represents a chronic progressive fibrotic interstitial lung disease of unknown cause with an ominous prognosis. It remains an unprecedent clinical challenge due to its delayed diagnosis and unpredictable clinical course. The need for accurate diagnostic, prognostic and predisposition biomarkers in everyday clinical practice becomes more necessary than ever to ensure prompt diagnoses and early treatment. The identification of such blood biomarkers may also unravel novel drug targets against IPF development and progression. So far, the role of diverse blood biomarkers, implicated in various pathogenetic pathways, such as in fibrogenesis (S100A4), extracellular matrix remodelling (YKL-40, MMP-7, ICAM-1, LOXL2, periostin), chemotaxis (CCL-18, IL-8), epithelial cell injury (KL-6, SP-A, SP-D), autophagy and unfolded protein response has been investigated in IPF with various results. Moreover, the recent progress in genetics in IPF allows for a better understanding of the underlying disease mechanisms. So far, the causative mutations in pulmonary fibrosis include mutations in telomere-related genes and in surfactant-related genes, markers that could act as predisposition biomarkers in IPF. The aim of this review is to provide a comprehensive overview from the bench to bedside of current knowledge and recent insights on biomarkers in IPF, and to suggest future directions for research. Large-scale studies are still needed to confirm the exact role of these biomarkers.

Lung transplant recipients with telomere-mediated pulmonary fibrosis have increased risk for hematologic complications

Idiopathic pulmonary fibrosis lung transplant recipients (IPF-LTRs) are enriched for short telomere length (TL) and telomere gene rare variants. A subset of patients with nontransplant short-TL are at increased risk for bone marrow (BM) dysfunction. We hypothesized that IPF-LTRs with short-TL and/or rare variants would be at increased risk for posttransplant hematologic complications. Data were extracted from a retrospective cohort of 72 IPF-LTRs and 72 age-matched non-IPF-LTR controls. Genetic assessment was done using whole genome sequencing or targeted sequence panel. TL was measured using flow cytometry and fluorescence in-situ hybridization (FlowFISH) and TelSeq software. The majority of the IPF-LTR cohort had short-TL, and 26% of IPF-LTRs had rare variants. Compared to non-IPF controls, short-TL IPF-LTRs were more likely to have immunosuppression agents discontinued due to cytopenias (P = .0375), and BM dysfunction requiring BM biopsy was more prevalent (29% vs 4%, P = .0003). IPF-LTRs with short-TL and rare variants had increased requirements for transfusion and growth factor support. Multivariable logistic regression demonstrated that short-TL, rare variants, and lower pretransplant platelet counts were associated with BM dysfunction. Pretransplant TL measurement and genetic testing for rare telomere gene variants identified IPF-LTRs at increased risk for hematologic complications. Our findings support stratification for telomere-mediated pulmonary fibrosis in lung transplant candidates.

T cell memory revisited using single telomere length analysis

The fundamental basis of T cell memory remains elusive. It is established that antigen stimulation drives clonal proliferation and differentiation, but the relationship between cellular phenotype, replicative history, and longevity, which is likely essential for durable memory, has proven difficult to elucidate. To address these issues, we used conventional markers of differentiation to identify and isolate various subsets of CD8+ memory T cells and measured telomere lengths in these phenotypically defined populations using the most sensitive technique developed to date, namely single telomere length analysis (STELA). Naive cells were excluded on the basis of dual expression of CCR7 and CD45RA. Memory subsets were sorted as CD27+CD45RA+, CD27intCD45RA+, CD27-CD45RA+, CD27+CD45RAint, CD27-CD45RAint, CD27+CD45RA-, and CD27-CD45RA- at >98% purity. The shortest median telomere lengths were detected among subsets that lacked expression of CD45RA, and the longest median telomere lengths were detected among subsets that expressed CD45RA. Longer median telomere lengths were also a feature of subsets that expressed CD27 in compartments defined by the absence or presence of CD45RA. Collectively, these data suggested a disconnect between replicative history and CD8+ memory T cell differentiation, which is classically thought to be a linear process that culminates with revertant expression of CD45RA.

Comorbidity of Pulmonary Fibrosis and COPD/Emphysema: Research Status, Trends, and Future Directions --------- A Bibliometric Analysis from 2004 to 2023

Objective

The comorbidity of pulmonary fibrosis and COPD/emphysema has garnered increasing attention. However, no bibliometric analysis of this comorbidity has been conducted thus far. This study aims to perform a bibliometric analysis to explore the current status and cutting-edge trends in the field, and to establish new directions for future research.

Methods

Statistical computing, graphics, and data visualization tools such as VOSviewer, CiteSpace, Biblimatrix, and WPS Office were employed.

Results

We identified a total of 1827 original articles and reviews on the comorbidity of pulmonary fibrosis and COPD/emphysema published between 2004 and 2023. There was an observed increasing trend in publications related to this comorbidity. The United States, Japan, and the United Kingdom were the countries with the highest contributions. Professor Athol Wells and the University of Groningen had the highest h-index and the most articles, respectively. Through cluster analysis of co-cited documents, we identified the top 17 major clusters. Keyword analysis predicted that NF-κB, oxidative stress, physical activity, and air pollution might be hot spots in this field in the future.

Conclusion

This bibliometric analysis demonstrates a continuous increasing trend in literature related to the comorbidity of pulmonary fibrosis and COPD/emphysema. The research hotspots and trends identified in this study provide a reference for in-depth research in this field, aiming to promote the development of the comorbidity of pulmonary fibrosis and COPD/emphysema.

Genetic and environmental factors in interstitial lung diseases: current and future perspectives on early diagnosis of high-risk cohorts

Within the wide scope of interstitial lung diseases (ILDs), familial pulmonary fibrosis (FPF) is being increasingly recognized as a specific entity, with earlier onset, faster progression, and suboptimal responses to immunosuppression. FPF is linked to heritable pathogenic variants in telomere-related genes (TRGs), surfactant-related genes (SRGs), telomere shortening (TS), and early cellular senescence. Telomere abnormalities have also been identified in some sporadic cases of fibrotic ILD. Air pollution and other environmental exposures carry additive risk to genetic predisposition in pulmonary fibrosis. We provide a perspective on how these features impact on screening strategies for relatives of FPF patients, interstitial lung abnormalities, ILD multi-disciplinary team (MDT) discussion, and disparities and barriers to genomic testing. We also describe our experience with establishing a familial interstitial pneumonia (FIP) clinic and provide guidance on how to identify patients with telomere dysfunction who would benefit most from genomic testing.

Predicting the number of lifetime divisions for hematopoietic stem cells from telomere length measurements

How many times does a typical hematopoietic stem cell (HSC) divide to maintain a daily production of over 1011 blood cells over a human lifetime? It has been predicted that relatively few, slowly dividing HSCs occupy the top of the hematopoietic hierarchy. However, tracking HSCs directly is extremely challenging due to their rarity. Here, we utilize previously published data documenting the loss of telomeric DNA repeats in granulocytes, to draw inferences about HSC division rates, the timing of major changes in those rates, as well as lifetime division totals. Our method uses segmented regression to identify the best candidate representations of the telomere length data. Our method predicts that, on average, an HSC divides 56 times over an 85-year lifespan (with lower and upper bounds of 36 and 120, respectively), with half of these divisions during the first 24 years of life.

Familial Clonal Hematopoiesis in a Long Telomere Syndrome

BACKGROUND

Telomere shortening is a well-characterized cellular aging mechanism, and short telomere syndromes cause age-related disease. However, whether long telomere length is advantageous is poorly understood.

METHODS

We examined the clinical and molecular features of aging and cancer in persons carrying heterozygous loss-of-function mutations in the telomere-related gene POT1 and noncarrier relatives.

RESULTS

A total of 17 POT1 mutation carriers and 21 noncarrier relatives were initially included in the study, and a validation cohort of 6 additional mutation carriers was subsequently recruited. A majority of the POT1 mutation carriers with telomere length evaluated (9 of 13) had long telomeres (>99th percentile). POT1 mutation carriers had a range of benign and malignant neoplasms involving epithelial, mesenchymal, and neuronal tissues in addition to B- and T-cell lymphoma and myeloid cancers. Five of 18 POT1 mutation carriers (28%) had T-cell clonality, and 8 of 12 (67%) had clonal hematopoiesis of indeterminate potential. A predisposition to clonal hematopoiesis had an autosomal dominant pattern of inheritance, as well as penetrance that increased with age; somatic DNMT3A and JAK2 hotspot mutations were common. These and other somatic driver mutations probably arose in the first decades of life, and their lineages secondarily accumulated a higher mutation burden characterized by a clocklike signature. Successive generations showed genetic anticipation (i.e., an increasingly early onset of disease). In contrast to noncarrier relatives, who had the typical telomere shortening with age, POT1 mutation carriers maintained telomere length over the course of 2 years.

CONCLUSIONS

POT1 mutations associated with long telomere length conferred a predisposition to a familial clonal hematopoiesis syndrome that was associated with a range of benign and malignant solid neoplasms. The risk of these phenotypes was mediated by extended cellular longevity and by the capacity to maintain telomeres over time. (Funded by the National Institutes of Health and others.).

COPD Patients Exhibit Distinct Gene Expression, Accelerated Cellular Aging, and Bias to M2 Macrophages

COPD, one of world's leading contributors to morbidity and mortality, is characterized by airflow limitation and heterogeneous clinical features. Three main phenotypes are proposed: overlapping asthma/COPD (ACO), exacerbator, and emphysema. Disease severity can be classified as mild, moderate, severe, and very severe. The molecular basis of inflammatory amplification, cellular aging, and immune response are critical to COPD pathogenesis. Our aim was to investigate EP300 (histone acetylase, HAT), HDAC 2 (histone deacetylase), HDAC3, and HDAC4 gene expression, telomere length, and differentiation ability to M1/M2 macrophages. For this investigation, 105 COPD patients, 42 smokers, and 73 non-smoker controls were evaluated. We identified a reduced HDAC2 expression in patients with mild, moderate, and severe severity; a reduced HDAC3 expression in patients with moderate and severe severity; an increased HDAC4 expression in patients with mild severity; and a reduced EP300 expression in patients with severe severity. Additionally, HDAC2 expression was reduced in patients with emphysema and exacerbator, along with a reduced HDAC3 expression in patients with emphysema. Surprisingly, smokers and all COPD patients showed telomere shortening. COPD patients showed a higher tendency toward M2 markers. Our data implicate genetic changes in COPD phenotypes and severity, in addition to M2 prevalence, that might influence future treatments and personalized therapies.

Size matters in telomere biology disorders ‒ expanding phenotypic spectrum in patients with long or short telomeres

The end of each chromosome consists of a DNA region termed the telomeres. The telomeres serve as a protective shield against degradation of the coding DNA sequence, as the DNA strand inevitably ‒ with each cell division ‒ is shortened. Inherited genetic variants cause telomere biology disorders when located in genes (e.g. DKC1, RTEL1, TERC, TERT) playing a role in the function and maintenance of the telomeres. Subsequently patients with telomere biology disorders associated with both too short or too long telomeres have been recognized. Patients with telomere biology disorders associated with short telomeres are at increased risk of dyskeratosis congenita (nail dystrophy, oral leukoplakia, and hyper- or hypo-pigmentation of the skin), pulmonary fibrosis, hematologic disease (ranging from cytopenia to leukemia) and in rare cases very severe multiorgan manifestations and early death. Patients with telomere biology disorders associated with too long telomeres have in recent years been found to confer an increased risk of melanoma and chronic lymphocytic leukemia. Despite this, many patients have an apparently isolated manifestation rendering telomere biology disorders most likely underdiagnosed. The complexity of telomere biology disorders and many causative genes makes it difficult to design a surveillance program which will ensure identification of early onset disease manifestation without overtreatment.

Identification of Adult Patients With Classical Dyskeratosis Congenita or Cryptic Telomere Biology Disorder by Telomere Length Screening Using Age-modified Criteria

Telomere biology disorders (TBD) result from premature telomere shortening due to pathogenic germline variants in telomere maintenance-associated genes. In adults, TBD are characterized by mono/oligosymptomatic clinical manifestations (cryptic TBD) contributing to severe underdiagnosis. We present a prospective multi-institutional cohort study where telomere length (TL) screening was performed in either newly diagnosed patients with aplastic anemia (AA) or if TBD was clinically suspected by the treating physician. TL of 262 samples was measured via flow-fluorescence in situ hybridization (FISH). TL was considered suspicious once below the 10th percentile of normal individuals (standard screening) or if below 6.5 kb in patients >40 years (extended screening). In cases with shortened TL, next generation sequencing (NGS) for TBD-associated genes was performed. The patients referred fell into 6 different screening categories: (1) AA/paroxysmal nocturnal hemoglobinuria, (2) unexplained cytopenia, (3) dyskeratosis congenita, (4) myelodysplastic syndrome/acute myeloid leukemia, (5) interstitial lung disease, and (6) others. Overall, TL was found to be shortened in 120 patients (n = 86 standard and n = 34 extended screening). In 17 of the 76 (22.4%) standard patients with sufficient material for NGS, a pathogenic/likely pathogenic TBD-associated gene variant was identified. Variants of uncertain significance were detected in 17 of 76 (22.4%) standard and 6 of 29 (20.7%) extended screened patients. Expectedly, mutations were mainly found in TERT and TERC. In conclusion, TL measured by flow-FISH represents a powerful functional in vivo screening for an underlying TBD and should be performed in every newly diagnosed patient with AA as well as other patients with clinical suspicion for an underlying TBD in both children and adults.

The effects of exercise and diet on oxidative stress and telomere length in breast cancer survivors

PURPOSE

Cancer and its treatments accelerate biological aging. This analysis tested the hypothesis that exercise and diet reduce oxidative stress and prevent telomere shortening in breast cancer survivors.

METHODS

In a 2 × 2 factorial design, 342 breast cancer survivors who were insufficiently physically active and had overweight or obesity at enrollment were randomized to one of four treatment groups for 52 weeks: control, exercise alone, diet alone, or exercise plus diet. The endpoints of this analysis were the change from baseline to week 52 in 8-iso-prostaglandin F2α (8-iso-PGF2α) and lymphocyte telomere length.

RESULTS

Baseline telomere length was shorter than age-adjusted normative values (median difference: - 1.8 kilobases; 95% CI - 2.4, - 1.1); equivalent to 21 years (95% CI 17, 25) of accelerated chronological aging. Compared to control, exercise alone did not change 8-iso-PGF2α [9.9%; 95% confidence interval (CI) - 1.0, 20.8] or telomere length (13.8%; 95% CI - 15.6, 43.3). Compared to control, diet alone was associated with reduced 8-iso-PGF2α (- 10.5%; 95% CI - 19.5, - 1.5) but did not change telomere length (12.1%; 95% CI - 17.2, 41.3). Compared to control, exercise plus diet was associated with reduced 8-iso-PGF2α (- 9.8%; 95% CI - 18.7, - 0.9) but did not change telomere length (- 8.5%; 95% CI - 32.1, 15.2). Change in 8-iso-PGF2α did not correlate with change in telomere length (r = 0.07; 95% CI - 0.07, 0.20).

CONCLUSION

In breast cancer survivors, diet alone or exercise plus diet were associated with reduced oxidative stress but did not change telomere length. This analysis may inform future trials that aim to optimize healthy aging in cancer survivors.

Short Telomere Syndrome presenting with pulmonary fibrosis, liver cirrhosis and hepatopulmonary syndrome: a case report

BACKGROUND

Idiopathic pulmonary fibrosis is thought to result from aberrant post-injury activation of epithelial cells leading to fibroblast proliferation and activation. A number of genetic aetiologies have been implicated in this disease process, including, among others, the short telomere syndromes. Short telomere syndromes follow an autosomal dominant pattern of inheritance resulting in shortened telomere length, which consequently leads to accelerated cell death. Organs with rapid cell turnover are most affected.

CASE PRESENTATION

We describe a case of a 53-year-old man with a chief complaint of cough and dyspnea on exertion. His presentation was otherwise significant for features of accelerated aging, including a history of osteoporosis and early greying, and a family history of pulmonary fibrosis in his father. Pulmonary function testing revealed a restrictive pattern with severely reduced diffusion capacity and high resolution CT of the chest showed diffuse lung disease with mild fibrosis, in pattern suggesting an alternative diagnosis to IPF. Biopsy of the lung was in keeping with chronic fibrosing interstitial pneumonia. Imaging of the abdomen showed splenomegaly, hepatic cirrhosis and portal hypertension. Transthoracic contrast echocardiogram showed intrapulmonary shunting consistent with hepatopulmonary syndrome. Given the constellation of early aging, idiopathic pulmonary fibrosis, cryptogenic cirrhosis and a family history of pulmonary fibrosis in this patient, the Short Telomere Syndrome was suspected. Peripheral blood was sent for Flow-cytometry FISH, which demonstrated granulocyte telomere length below the 10^th percentile for the patient's age, consistent with a diagnosis of Short Telomere Syndrome in this clinical context. Targeted genetic testing of mutations known to be associated with short telomere was negative though it was acknowledged that the full spectrum of disease-causing mutations remains unknown. Given the extensive fibrosis on biopsy and his progressive hypoxemia he was treated with mycophenolate and prednisone. Ultimately, he developed progressive respiratory failure and underwent double lung and concurrent liver transplant 18 months after the initial diagnosis was made.

CONCLUSIONS

Short Telomere Syndrome is a rare cause of end stage organ disease and testing lacks sensitivity making diagnosis challenging. Organ transplant is still the mainstay of treatment. Nevertheless, disease identification is important because of implications for family member screening and the possibility of future treatment options.

T cell immune deficiency rather than chromosome instability predisposes patients with short telomere syndromes to squamous cancers

Patients with short telomere syndromes (STS) are predisposed to developing cancer, believed to stem from chromosome instability in neoplastic cells. We tested this hypothesis in a large cohort assembled over the last 20 years. We found that the only solid cancers to which patients with STS are predisposed are squamous cell carcinomas of the head and neck, anus, or skin, a spectrum reminiscent of cancers seen in patients with immunodeficiency. Whole-genome sequencing showed no increase in chromosome instability, such as translocations or chromothripsis. Moreover, STS-associated cancers acquired telomere maintenance mechanisms, including telomerase reverse transcriptase (TERT) promoter mutations. A detailed study of the immune status of patients with STS revealed a striking T cell immunodeficiency at the time of cancer diagnosis. A similar immunodeficiency that impaired tumor surveillance was documented in mice with short telomeres. We conclude that STS patients’ predisposition to solid cancers is due to T cell exhaustion rather than autonomous defects in the neoplastic cells themselves.

Thymidine nucleotide metabolism controls human telomere length

Telomere length in humans is associated with lifespan and severe diseases, yet the genetic determinants of telomere length remain incompletely defined. Here we performed genome-wide CRISPR-Cas9 functional telomere length screening and identified thymidine (dT) nucleotide metabolism as a limiting factor in human telomere maintenance. Targeted genetic disruption using CRISPR-Cas9 revealed multiple telomere length control points across the thymidine nucleotide metabolism pathway: decreasing dT nucleotide salvage via deletion of the gene encoding nuclear thymidine kinase (TK1) or de novo production by knockout of the thymidylate synthase gene (TYMS) decreased telomere length, whereas inactivation of the deoxynucleoside triphosphohydrolase-encoding gene SAMHD1 lengthened telomeres. Remarkably, supplementation with dT alone drove robust telomere elongation by telomerase in cells, and thymidine triphosphate stimulated telomerase activity in a substrate-independent manner in vitro. In induced pluripotent stem cells derived from patients with genetic telomere biology disorders, dT supplementation or inhibition of SAMHD1 promoted telomere restoration. Our results demonstrate a critical role of thymidine metabolism in controlling human telomerase and telomere length, which may be therapeutically actionable in patients with fatal degenerative diseases.