The genetics and clinical manifestations of telomere biology disorders

Telomere dysfunction instigates inflammation in inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic inflammatory condition driven by diverse genetic and nongenetic programs that converge to disrupt immune homeostasis in the intestine. We have reported that, in murine intestinal epithelium with telomere dysfunction, DNA damage-induced activation of ataxia-telangiectasia mutated (ATM) results in ATM-mediated phosphorylation and activation of the YAP1 transcriptional coactivator, which in turn up-regulates pro-IL-18, a pivotal immune regulator in IBD pathogenesis. Moreover, individuals with germline defects in telomere maintenance genes experience increased occurrence of intestinal inflammation and show activation of the ATM/YAP1/pro-IL-18 pathway in the intestinal epithelium. Here, we sought to determine the relevance of the ATM/YAP1/pro-IL-18 pathway as a potential driver of IBD, particularly older-onset IBD. Analysis of intestinal biopsy specimens and organoids from older-onset IBD patients documented the presence of telomere dysfunction and activation of the ATM/YAP1/precursor of interleukin 18 (pro-IL-18) pathway in the intestinal epithelium. Employing intestinal organoids from healthy individuals, we demonstrated that experimental induction of telomere dysfunction activates this inflammatory pathway. In organoid models from ulcerative colitis and Crohn's disease patients, pharmacological interventions of telomerase reactivation, suppression of DNA damage signaling, or YAP1 inhibition reduced pro-IL-18 production. Together, these findings support a model wherein telomere dysfunction in the intestinal epithelium can initiate the inflammatory process in IBD, pointing to therapeutic interventions for this disease.

Fructose Causes Liver Damage, Polyploidy, and Dysplasia in the Setting of Short Telomeres and p53 Loss

Studies in humans and model systems have established an important role of short telomeres in predisposing to liver fibrosis through pathways that are incompletely understood. Recent studies have shown that telomere dysfunction impairs cellular metabolism, but whether and how these metabolic alterations contribute to liver fibrosis is not well understood. Here, we investigated whether short telomeres change the hepatic response to metabolic stress induced by fructose, a sugar that is highly implicated in non-alcoholic fatty liver disease. We find that telomere shortening in telomerase knockout mice (TKO) imparts a pronounced susceptibility to fructose as reflected in the activation of p53, increased apoptosis, and senescence, despite lower hepatic fat accumulation in TKO mice compared to wild type mice with long telomeres. The decreased fat accumulation in TKO is mediated by p53 and deletion of p53 normalizes hepatic fat content but also causes polyploidy, polynuclearization, dysplasia, cell death, and liver damage. Together, these studies suggest that liver tissue with short telomers are highly susceptible to fructose and respond with p53 activation and liver damage that is further exacerbated when p53 is lost resulting in dysplastic changes.

Telomere biology disorder prevalence and phenotypes in adults with familial hematologic and/or pulmonary presentations

Telomere biology disorders (TBDs) present heterogeneously, ranging from infantile bone marrow failure associated with very short telomeres to adult-onset interstitial lung disease (ILD) with normal telomere length. Yield of genetic testing and phenotypic spectra for TBDs caused by the expanding list of telomere genes in adults remain understudied. Thus, we screened adults aged ≥18 years with a personal and/or family history clustering hematologic disorders and/or ILD enrolled on The University of Chicago Inherited Hematologic Disorders Registry for causative variants in 13 TBD genes. Sixteen (10%) of 153 probands carried causative variants distributed among TERT (n = 6), TERC (n = 4), PARN (n = 5), or RTEL1 (n = 1), of which 19% were copy number variants. The highest yield (9 of 22 [41%]) was in families with mixed hematologic and ILD presentations, suggesting that ILD in hematology populations and hematologic abnormalities in ILD populations warrant TBD genetic testing. Four (3%) of 117 familial hematologic disorder families without ILD carried TBD variants, making TBD second to only DDX41 in frequency for genetic diagnoses in this population. Phenotypes of 17 carriers with heterozygous PARN variants included 4 (24%) with hematologic abnormalities, 67% with lymphocyte telomere lengths measured by flow cytometry and fluorescence in situ hybridization at or above the 10th percentile, and a high penetrance for ILD. Alternative etiologies for cytopenias and/or ILD such as autoimmune features were noted in multiple TBD families, emphasizing the need to maintain clinical suspicion for a TBD despite the presence of alternative explanations.

Sex differences in biological aging with a focus on human studies

Aging is a complex biological process characterized by hallmark features accumulating over the life course, shaping the individual's aging trajectory and subsequent disease risks. There is substantial individual variability in the aging process between men and women. In general, women live longer than men, consistent with lower biological ages as assessed by molecular biomarkers, but there is a paradox. Women are frailer and have worse health at the end of life, while men still perform better in physical function examinations. Moreover, many age-related diseases show sex-specific patterns. In this review, we aim to summarize the current knowledge on sexual dimorphism in human studies, with support from animal research, on biological aging and illnesses. We also attempt to place it in the context of the theories of aging, as well as discuss the explanations for the sex differences, for example, the sex-chromosome linked mechanisms and hormonally driven differences.

A novel cause of DKC1-related bone marrow failure: Partial deletion of the 3' untranslated region

Telomere biology disorders (TBDs), including dyskeratosis congenita (DC), are a group of rare inherited diseases characterized by very short telomeres. Mutations in the components of the enzyme telomerase can lead to insufficient telomere maintenance in hematopoietic stem cells, resulting in the bone marrow failure that is characteristic of these disorders. While an increasing number of genes are being linked to TBDs, the causative mutation remains unidentified in 30-40% of patients with DC. There is therefore a need for whole genome sequencing (WGS) in these families to identify novel genes, or mutations in regulatory regions of known disease-causing genes. Here we describe a family in which a partial deletion of the 3' untranslated region (3' UTR) of DKC1, encoding the protein dyskerin, was identified by WGS, despite being missed by whole exome sequencing. The deletion segregated with disease across the family and resulted in reduced levels of DKC1 mRNA in the proband. We demonstrate that the DKC1 3' UTR contains two polyadenylation signals, both of which were removed by this deletion, likely causing mRNA instability. Consistent with the major function of dyskerin in stabilization of the RNA subunit of telomerase, hTR, the level of hTR was also reduced in the proband, providing a molecular basis for his very short telomeres. This study demonstrates that the terminal region of the 3' UTR of the DKC1 gene is essential for gene function and illustrates the importance of analyzing regulatory regions of the genome for molecular diagnosis of inherited disease.

[Accelerated telomere erosion in schizophrenia: A literature review]

Schizophrenia is associated with a weighted average of 14.5 years of potential life lost according to a recent meta-analysis. This is partly explained by high rates of suicide and a high prevalence of non-psychiatric comorbidity (cardiovascular diseases, diabetes, cancers…). However, all these causes could not fully explain the loss of life expectancy in people suffering from schizophrenia. Life expectancy has been strongly correlated with telomere length (TL). Telomeres are noncoding structures consisting of DNA TTAGGG tandem repeats and associated proteins located at the end of the chromosomes. Their role is to help preserve genome stability by protecting chromosomal ends from the loss of genetic material. The progressive loss of telomeric material during cell divisions has led researchers to consider telomeres as molecular clocks that measure the number of divisions left until cellular death. The fact that both shorter telomeres and schizophrenia have been associated with a decrease in life expectancy has fueled the interest in the study of TL in schizophrenia. In this article, after a detailed review of the literature on the relationships between telomere length and schizophrenia, we discuss the different pathophysiological mechanisms which might explain this association. Based on this analysis, in the last part of the article we discuss potential research, therapeutic and prevention prospects. To date, the majority of the studies and meta-analyses found a decrease in TL in subjects with schizophrenia compared to control subjects. Conversely, all the studies exploring the TL in subjects suffering from first episode psychosis (FEP) have shown no significant difference from TL in control subjects. This suggests that excessive shortening of telomeres occurs during the course of the disease, thus it seems more probable that schizophrenia (or processes associated with it) affects TL rather than telomere erosion being a cause of the disorder. Several pathophysiological, non-mutually exclusive mechanisms have been proposed to explain the observed data. A first hypothesis to explain the acceleration of the physiological process of telomere erosion in schizophrenia is the activation of inflammation processes and oxidative stress as a consequence of schizophrenia per se. However, it seems more probable that reduced TL may be a result of cumulative exposure to chronic stress related to schizophrenia. Indeed, in healthy individuals a growing body of evidence has linked chronic stress to accelerated shortening of TL. This might explain why telomere erosion is too small to be detected in FEP patients who are younger and have a shorter duration of illness than subjects with schizophrenia. Based on these both explanations, telomere alterations may be considered as a biomarker of illness progression and might be useful for illness staging. Identifying processes associated with TL reduction might improve our understanding of the increased mortality and morbidity in schizophrenia, improve reliability of diagnosis, and hopefully suggest means for prevention and/or treatment. Treatments that prevent exposure and/or vulnerability to stressful life events that ameliorate schizophrenia may also prevent or decelerate telomere erosion. In this perspective, engaging subjects suffering from schizophrenia in a healthy diet and regular activity could be both promising strategies to protect telomere maintenance and improve health span at old age. In addition, the inflammatory process and oxidative stress involved in the physiopathology in at least a subgroup of subjects with schizophrenia could also be responsible for telomere erosion. Thus, an efficient anti-inflammatory therapeutic approach that targets these specific pathways could be of interest in this subgroup to limit telomere erosion. Mindfulness-based stress reduction (MBSR) therapies have been shown to reduce telomere erosion by increasing telomerase activity, although these psychological therapies should be used carefully in psychosis. Finally, advancing our understanding of the relationship between stress, inflammation and TL is of great interest for psychiatric research and for understanding stress effects in this population.

Combined lung and liver transplantation for noncirrhotic portal hypertension with severe hepatopulmonary syndrome in a patient with dyskeratosis congenita

DC is caused by defects at the level of telomere maintenance, and cells from patients with this disease have abnormally short telomeres and show premature senescence. One consequence of DC is bone marrow failure. Thus, patients with DC often require HSCT. However, HSCT does not ameliorate other DC-related manifestations. In fact, HSCT can accelerate organ dysfunction due to treatment-related complications, and solid organ transplantation is required in some patients with DC. In this report, we describe the clinical course of a 5-year-old boy who was transferred to our hospital because of progressive dyspnea, 2 years after HSCT. At admission, he had tachypnea and hypoxemia. A liver biopsy was performed for suspected HPS caused by PH, and LT was considered. Eventually, his hypoxemia worsened, and he was transferred to a PICU and started on VA ECMO. He subsequently underwent a CLLT. ECMO was stopped on post-operative day 12, extubation was achieved on post-operative day 29, and the patient recovered well from the surgery. Our results show that CLLT could be a life-saving treatment option for DC patients with very severe HPS in whom a poor outcome is expected after LT.

Telomere length and risk of idiopathic pulmonary fibrosis and chronic obstructive pulmonary disease: a mendelian randomisation study

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a fatal lung disease accounting for 1% of UK deaths. In the familial form of pulmonary fibrosis, causal genes have been identified in about 30% of cases, and a majority of these causal genes are associated with telomere maintenance. Prematurely shortened leukocyte telomere length is associated with IPF and chronic obstructive pulmonary disease (COPD), a disease with similar demographics and shared risk factors. Using mendelian randomisation, we investigated evidence supporting a causal role for short telomeres in IPF and COPD.

METHODS

Mendelian randomisation inference of telomere length causality was done for IPF (up to 1369 cases) and COPD (13 538 cases) against 435 866 controls of European ancestry in UK Biobank. Polygenic risk scores were calculated and two-sample mendelian randomisation analyses were done using seven genetic variants previously associated with telomere length, with replication analysis in an IPF cohort (2668 cases vs 8591 controls) and COPD cohort (15 256 cases vs 47 936 controls).

FINDINGS

In the UK Biobank, a genetically instrumented one-SD shorter telomere length was associated with higher odds of IPF (odds ratio [OR] 4·19, 95% CI 2·33-7·55; p=0·0031) but not COPD (1·07, 0·88-1·30; p=0·51). Similarly, an association was found in the IPF replication cohort (12·3, 5·05-30·1; p=0·0015) and not in the COPD replication cohort (1·04, 0·71-1·53; p=0·83). Meta-analysis of the two-sample mendelian randomisation results provided evidence inferring that shorter telomeres cause IPF (5·81 higher odds of IPF, 95% CI 3·56-9·50; p=2·19 × 10-12). There was no evidence to infer that telomere length caused COPD (OR 1·07, 95% CI 0·90-1·27; p=0·46).

INTERPRETATION

Cellular senescence is hypothesised as a major driving force in IPF and COPD; telomere shortening might be a contributory factor in IPF, suggesting divergent mechanisms in COPD. Defining a key role for telomere shortening enables greater focus in telomere-related diagnostics, treatments, and the search for a cure in IPF. Investigation of therapies that improve telomere length is warranted.

FUNDING

Medical Research Council.

Molecular mechanisms of telomere biology disorders

Genetic mutations that affect telomerase function or telomere maintenance result in a variety of diseases collectively called telomeropathies. This wide spectrum of disorders, which include dyskeratosis congenita, pulmonary fibrosis, and aplastic anemia, is characterized by severely short telomeres, often resulting in hematopoietic stem cell failure in the most severe cases. Recent work has focused on understanding the molecular basis of these diseases. Mutations in the catalytic TERT and TR subunits of telomerase compromise activity, while others, such as those found in the telomeric protein TPP1, reduce the recruitment of telomerase to the telomere. Mutant telomerase-associated proteins TCAB1 and dyskerin and the telomerase RNA maturation component poly(A)-specific ribonuclease affect the maturation and stability of telomerase. In contrast, disease-associated mutations in either CTC1 or RTEL1 are more broadly associated with telomere replication defects. Yet even with the recent surge in studies decoding the mechanisms underlying these diseases, a significant proportion of dyskeratosis congenita mutations remain uncharacterized or poorly understood. Here we review the current understanding of the molecular basis of telomeropathies and highlight experimental data that illustrate how genetic mutations drive telomere shortening and dysfunction in these patients. This review connects insights from both clinical and molecular studies to create a comprehensive view of the underlying mechanisms that drive these diseases. Through this, we emphasize recent advances in therapeutics and pinpoint disease-associated variants that remain poorly defined in their mechanism of action. Finally, we suggest future avenues of research that will deepen our understanding of telomere biology and telomere-related disease.

Short telomere length predicts nonrelapse mortality after stem cell transplantation for myelodysplastic syndrome

Allogeneic hematopoietic stem cell transplantation is the only potentially curative treatment for patients with myelodysplastic syndrome (MDS), but long-term survival is limited by the risk of transplant-related complications. Short telomere length, mediated by inherited or acquired factors, impairs cellular response to genotoxic and replicative stress and could identify patients at higher risk for toxicity after transplantation. We measured relative telomere length in pretransplant recipient blood samples in 1514 MDS patients and evaluated the association of telomere length with MDS disease characteristics and transplantation outcomes. Shorter telomere length was significantly associated with older age, male sex, somatic mutations that impair the DNA damage response, and more severe pretransplant cytopenias, but not with bone marrow blast count, MDS treatment history, or history of prior cancer therapy. Among 1267 patients ≥40 years old, telomere length in the shortest quartile was associated with inferior survival (P < .001) because of a high risk of nonrelapse mortality (NRM; P = .001) after adjusting for significant clinical and genetic variables. The adverse impact of shorter telomeres on NRM was independent of recipient comorbidities and was observed selectively among patients receiving more intensive conditioning, including myeloablative regimens and higher dose melphalan-based reduced-intensity regimens. The effect of shorter telomeres on NRM was prominent among patients who developed severe acute graft-versus-host disease, suggesting that short telomere length may limit regenerative potential of mucosal tissues after acute injury. MDS patients with shorter telomere length, who have inferior survival driven by excess toxicity, could be considered for strategies focused on minimizing toxic effects of transplantation.

TINF2 is a haploinsufficient tumor suppressor that limits telomere length

Telomere shortening is a presumed tumor suppressor pathway that imposes a proliferative barrier (the Hayflick limit) during tumorigenesis. This model predicts that excessively long somatic telomeres predispose to cancer. Here, we describe cancer-prone families with two unique TINF2 mutations that truncate TIN2, a shelterin subunit that controls telomere length. Patient lymphocyte telomeres were unusually long. We show that the truncated TIN2 proteins do not localize to telomeres, suggesting that the mutations create loss-of-function alleles. Heterozygous knock-in of the mutations or deletion of one copy of TINF2 resulted in excessive telomere elongation in clonal lines, indicating that TINF2 is haploinsufficient for telomere length control. In contrast, telomere protection and genome stability were maintained in all heterozygous clones. The data establish that the TINF2 truncations predispose to a tumor syndrome. We conclude that TINF2 acts as a haploinsufficient tumor suppressor that limits telomere length to ensure a timely Hayflick limit.

A structurally conserved human and Tetrahymena telomerase catalytic core

Telomerase is a ribonucleoprotein complex that counteracts the shortening of chromosome ends due to incomplete replication. Telomerase contains a catalytic core of telomerase reverse transcriptase (TERT) and telomerase RNA (TER). However, what defines TERT and separates it from other reverse transcriptases remains a subject of debate. A recent cryoelectron microscopy map of Tetrahymena telomerase revealed the structure of a previously uncharacterized TERT domain (TRAP) with unanticipated interactions with the telomerase essential N-terminal (TEN) domain and roles in telomerase activity. Both TEN and TRAP are absent in the putative Tribolium TERT that has been used as a model for telomerase for over a decade. To investigate the conservation of TRAP and TEN across species, we performed multiple sequence alignments and statistical coupling analysis on all identified TERTs and find that TEN and TRAP have coevolved as telomerase-specific domains. Integrating the data from bioinformatic analysis and the structure of Tetrahymena telomerase, we built a pseudoatomic model of human telomerase catalytic core that accounts for almost all of the cryoelectron microscopy density in a published map, including TRAP in previously unassigned density as well as telomerase RNA domains essential for activity. This more complete model of the human telomerase catalytic core illustrates how domains of TER and TERT, including the TEN-TRAP complex, can interact in a conserved manner to regulate telomere synthesis.

Revesz syndrome revisited

Background

Revesz syndrome (RS) is an extremely rare variant of dyskeratosis congenita (DKC) with only anecdotal reports in the literature.

Methods

To further characterize the typical features and natural course of the disease, we screened the English literature and summarized the clinical and epidemiological features of previously published RS cases. In addition, we herein describe the first recorded patient in central Europe.

Results

The literature review included 18 children. Clinical features are summarized, indicating a low prevalence of the classical DKC triad. All patients experienced early bone marrow failure, in most cases within the second year of life (median age 1.5 years; 95% CI 1.4–1.6). Retinopathy occurred typically between 6 and 18 months of age (median age 1.1 years; 95% CI 0.7–1.5). The incidence of seizures was low and was present in an estimated 20% of patients. The onset of seizures was exclusively during early childhood. The Kaplan–Meier estimate of survival was dismal (median survival 6.5 years; 95% CI 3.6–9.4), and none of the patients survived beyond the age of 12 years. Stem cell transplantation (SCT) was performed in eight children, and after a median of 22 months from SCT four of these patients were alive at the last follow up visit.

Conclusion

RS is a severe variant of DKC with early bone marrow failure and retinopathy in all patients. Survival is dismal, but stem cell transplantation may be performed successfully and might improve prognosis in the future.

Telomere dysfunction activates YAP1 to drive tissue inflammation

Germline telomere maintenance defects are associated with an increased incidence of inflammatory diseases in humans, yet whether and how telomere dysfunction causes inflammation are not known. Here, we show that telomere dysfunction drives pATM/c-ABL-mediated activation of the YAP1 transcription factor, up-regulating the major pro-inflammatory factor, pro-IL-18. The colonic microbiome stimulates cytosolic receptors activating caspase-1 which cleaves pro-IL-18 into mature IL-18, leading to recruitment of interferon (IFN)-γ-secreting T cells and intestinal inflammation. Correspondingly, patients with germline telomere maintenance defects exhibit DNA damage (γH2AX) signaling together with elevated YAP1 and IL-18 expression. In mice with telomere dysfunction, telomerase reactivation in the intestinal epithelium or pharmacological inhibition of ATM, YAP1, or caspase-1 as well as antibiotic treatment, dramatically reduces IL-18 and intestinal inflammation. Thus, telomere dysfunction-induced activation of the ATM-YAP1-pro-IL-18 pathway in epithelium is a key instigator of tissue inflammation.

CD8+ T-cell senescence and skewed lymphocyte subsets in young Dyskeratosis Congenita patients with PARN and DKC1 mutations

BACKGROUND

Dyskeratosis congenita (DC) is a syndrome resulting from defective telomere maintenance. Immunodeficiency associated with DC can cause significant morbidity and lead to premature mortality, but the immunological characteristics and molecular hallmark of DC patients, especially young patients, have not been described in detail.

METHODS

We summarize the clinical data of two juvenile patients with DC. Gene mutations were identified by whole-exome and direct sequencing. Swiss-PdbViewer was used to predict the pathogenicity of identified mutations. The relative telomere length was determined by QPCR, and a comprehensive analysis of lymphocyte subsets and CD57 expression was performed by flow cytometry.

RESULTS

Both patients showed typical features of DC without severe infection. In addition, patient 1 (P1) was diagnosed with Hoyeraal-Hreidarsson syndrome due to cerebellar hypoplasia. Gene sequencing showed P1 had a compound heterozygous mutation (c.204G > T and c.178-245del) in PARN and P2 had a novel hemizygous mutation in DKC1 (c.1051A > G). Lymphocyte subset analysis showed B and NK cytopenia, an inverted CD4:CD8 ratio, and decreased naïve CD4 and CD8 cells. A significant increase in CD21low B cells and skewed numbers of helper T cells (Th), regulatory T cells (Treg), follicular regulatory T cells (Tfr), and follicular helper T cells (Tfh) were also detected. Short telomere lengths, increased CD57 expression, and an expansion of CD8 effector memory T cells re-expressing CD45RA (TEMRA) were also found in both patients.

CONCLUSION

Unique immunologic abnormalities, CD8 T-cell senescence, and shortened telomere together as a hallmark occur in young DC patients before progression to severe disease.

Fibrosing pneumonia – how to diagnose, and how to recognize the etiology?

Background

Fibrosing pneumonias are a group of interstitial lung diseases with a different etiologic background and divergent prognosis. They are differentiated into usual interstitial pneumonia (UIP), non-specific interstitial pneumonia (NSIP), and organizing pneumonia (OP). Some of these entities were initially described by A. Liebow.

Main

In the 90ties the main differences in survival lead to the separation of UIP/IPF as a disease with dismal outcome, from the prognostically better NSIP and OP. Later it was shown that fibrosing NSIP confers an almost identical worse prognosis. Under the heading of pulmologists a classification was created, where the diagnosis has to be established by a multidisciplinary team, based on pattern recognition done by radiologists and pathologists. A clinical diagnosis has to be established based on the patterns: UIP pattern was the basis for IPF, NSIP pattern for the clinical diagnosis NSIP, and organizing pneumonia pattern for the diagnosis of cryptogenic organizing pneumonia. This created confusion, because the pattern UIP was taken almost as synonymous with idiopathic pulmonary fibrosis (IPF). Later on in many articles and classifications the role of the pathologic diagnosis was diminished, because pulmologists based their diagnosis on CT-scan and clinical presentation. This resulted in less tissue biopsies but also delay and misinterpretation of diseases. Even new techniques in tissue biopsies such as cryobiopsy was regarded as unnecessary.

Conclusion

Tissue analysis in fibrosing pneumonias is still the gold standard in making a diagnosis and also evaluating the etiologic background. After an analysis the findings should be discussed in a multidisciplinary board to establish a final diagnosis and a treatment option for the patient.

A Mendelian randomization study of telomere length and blood-cell traits

Whether telomere attrition reducing proliferative reserve in blood-cell progenitors is causal has important public-health implications. Mendelian randomization (MR) is an analytic technique using germline genetic variants as instrumental variables. If certain assumptions are met, estimates from MR should be free from most environmental sources of confounding and reverse causation. Here, two-sample MR is performed to test whether longer telomeres cause changes to hematological traits. Summary statistics for genetic variants strongly associated with telomere length were extracted from a genome-wide association (GWA) study for telomere length in individuals of European ancestry (n = 9190) and from GWA studies of blood-cell traits, also in those of European ancestry (n ~ 173,000 participants). A standard deviation increase in genetically influenced telomere length increased red blood cell and white blood cell counts, decreased mean corpuscular hemoglobinand mean cell volume, and had no observable impact on mean corpuscular hemoglobin concentration, red cell distribution width, hematocrit, or hemoglobin. Sensitivity tests for pleiotropic distortion were mostly inconsistent with glaring violations to the MR assumptions. Similar to germline mutations in telomere biology genes leading to bone-marrow failure, these data provide evidence that genetically influenced common variation in telomere length impacts hematologic traits in the population.

Telomere Attrition in Neurodegenerative Disorders

Telomere attrition is increased in various disorders and is therefore a potential biomarker for diagnosis and/or prognosis of these disorders. The contribution of telomere attrition in the pathogenesis of neurodegenerative disorders is yet to be fully elucidated. We are reviewing the current knowledge regarding the telomere biology in two common neurodegenerative disorders, Alzheimer's disease (AD), and Parkinson's disease (PD). Furthermore, we are discussing future prospective of telomere research in these disorders. The majority of studies reported consistent evidence of the accelerated telomere attrition in AD patients, possibly in association with elevated oxidative stress levels. On the other hand in PD, various studies reported contradictory evidence regarding telomere attrition. Consequently, due to the low specificity and sensitivity, the clinical benefit of telomere length as a biomarker of neurodegenerative disease development and progression is not yet recognized. Nevertheless, longitudinal studies in large carefully selected cohorts might provide further elucidation of the complex involvement of the telomeres in the pathogenesis of neurodegenerative diseases. Telomere length maintenance is a complex process characterized by environmental, genetic, and epigenetic determinants. Thus, in addition to the selection of the study cohort, also the selection of analytical methods and types of biological samples for evaluation of the telomere attrition is of utmost importance.

The future is here: Integrating genetics into the pediatric pulmonary clinic

Recognition of underlying genetic etiologies of disease is increasing at an exponential rate, likely due to greater access to and lower cost of genetic testing. Monogenic causes of disease, or conditions resulting from a mutation or mutations in a single gene, are now well recognized in every subspecialty, including pediatric pulmonary medicine; thus, it is important to consider genetic conditions when evaluating children with respiratory disease. In the pediatric pulmonary clinic, genetic testing should be considered when multiple family members present with similar or related clinical features and when individuals have unusual clinical presentations, such as early-onset disease or complex, syndromic features. This review provides a practical guide for genetic diagnosis in the pediatric pulmonary setting, including a review of genetic concepts, considerations for test selection and results in interpretation, as well as an overview of genetic differential diagnoses for common pediatric pulmonary phenotypes. Genetic conditions that commonly present to the pediatric pulmonary clinic are reviewed in a companion article by Yonker et al.

Recognizing genetic disease: A key aspect of pediatric pulmonary care

Advancement in technology has improved recognition of genetic etiologies of disease, which has impacted diagnosis and management of rare disease patients in the pediatric pulmonary clinic. This review provides an overview of genetic conditions that are likely to present with pulmonary features and require extensive care by the pediatric pulmonologist. Increased familiarity with these conditions allows for improved care of these patients by reducing time to diagnosis, tailoring management, and prompting further investigation into these disorders.

Effect of alcohol use disorder on cellular aging

RATIONALE

Human telomeres consist of tandem repeats at chromosome ends which protect chromosomal DNA from degradation. Telomere shortening occurs as part of natural aging; however, life stressors, smoking, drug use, BMI, and psychiatric disorders could disrupt cell aging and affect telomere length (TL). In this context, studies have evaluated the effects of alcohol consumption on TL; however, results have been inconsistent, which may reflect diverse drinking cut-offs and categorizations.

OBJECTIVES

To help clarify this, the present study addresses the association of TL with alcohol use disorder (AUD), drinking behaviors, lifetime stress, and chronological age.

METHODS

TL was quantified as the telomere to albumin ratio (T/S ratio) obtained from peripheral blood DNA using the quantitative PCR assay, from 260 participants with AUD and 449 non-dependent healthy controls (HC) from an existing National Institute on Alcohol Abuse and Alcoholism (NIAAA) database.

RESULTS

AUD participants showed shorter TL compared to HC with both, age, and AUD, as independent predictors as well as a significant AUD with age interaction effect on TL. TL was also associated with impulsiveness in AUD participants. We did not observe an association between TL and chronicity of alcohol use, alcohol doses ingested, or childhood trauma exposures in either AUD or HC, although very few HC reported a history of childhood trauma.

CONCLUSION

Our results support previous findings of telomere shortening with chronic alcohol exposures and show both an effect of AUD on TL that is independent of age as well as a significant AUD by age interaction on TL. These findings are consistent with accelerated cellular aging in AUD.

Development of metachronous rectal cancers in a young man with dyskeratosis congenita: a case report

BACKGROUND

DKC1 (dyskerin pseudouridine synthase 1) is a causative gene for X-linked dyskeratosis congenita. Approximately 8% of patients with dyskeratosis congenita have malignancy, but information about the development of malignancy in patients with dyskeratosis congenita is limited.

CASE PRESENTATION

A young Japanese patient with bone marrow failure developed metachronous rectal adenocarcinomas at the ages of 16 and 18 years. He had no family history of cancer. Microsatellite instability testing with rectal tumor tissue demonstrated low-level microsatellite instability. To clarify whether any cancer susceptibility genes were involved in the development of rectal cancer, RNA sequencing was performed. Cancer-related genes were assessed, and a c.361A>G (p.Ser121Gly) germline variant was detected in DKC1. The same missense variant was previously reported in two patients with dyskeratosis congenita as a pathogenic variant, but those patients did not develop malignancies.

CONCLUSIONS

Our patient developed rectal cancer at an early age of onset compared with the previously reported typical onset age of patients with dyskeratosis congenita. DKC1 might be involved in predisposition to colorectal cancer in young adulthood; therefore, appropriate surveillance may be considered.

Similar telomere attrition rates in androgen-treated and untreated patients with dyskeratosis congenita

Dyskeratosis congenita (DC) is an inherited bone marrow failure syndrome and the prototypic telomere biology disorder (TBD). Leukocyte telomere length (TL) less than the first percentile for age, measured by flow cytometry with in situ hybridization (flow FISH), is diagnostic of DC. Androgens are a therapeutic option for DC/TBD-associated bone marrow failure (BMF). One report has shown an apparent increase in TL in patients while on treatment with the attenuated androgen danazol. The aim of this study was to compare TL over time in 10 androgen-treated and 16 untreated patients with DC. All subjects were enrolled in institutional review board-approved longitudinal cohort studies of inherited BMF. TL in 6-panel leukocyte subsets was measured by flow FISH. Generalized estimating equations (GEE) methodology was used to compare TL changes over time between groups. Unadjusted analyses showed annual median total lymphocyte TL attrition of -62 base pairs/year (bp/y) in androgen-treated patients with DC compared with -76 bp/y in untreated DC patients (P = .71). Longitudinal analysis using a GEE model, adjusted for age at sample collection, showed no statistically significant difference in TL change over time between treated and untreated patients (P = .24). The results were similar for each individual leukocyte subset evaluated. In summary, our data show the expected age-associated longitudinal telomere shortening in patients with DC, irrespective of androgen therapy. Caution is warranted when recommending androgen therapy for non-BMF manifestations of DC or TBDs until the biological mechanisms are better understood.

Neutropenia in the age of genetic testing: Advances and challenges

Identification of genetic causes of neutropenia informs precision medicine approaches to medical management and treatment. Accurate diagnosis of genetic neutropenia disorders informs treatment options, enables risk stratification, cancer surveillance, and attention to associated medical complications. The rapidly expanding genetic testing options for the evaluation of neutropenia have led to exciting advances but also new challenges. This review provides a practical guide to germline genetic testing for neutropenia.

Telomere Length Calibration from qPCR Measurement: Limitations of Current Method

Telomere length (TL) comparisons from different methods are challenging due to differences in laboratory techniques and data configuration. This study aimed to assess the validity of converting the quantitative polymerase chain reaction (qPCR) telomere/single copy gene (T/S) ratio to TL in kilobases (kb). We developed a linear regression equation to predict TL from qPCR T/S using flow cytometry with fluorescence in situ hybridization (flow FISH) TL data from 181 healthy donors (age range = 19⁻53) from the National Marrow Donor Program (NMDP) biorepository. TL measurements by qPCR and flow FISH were modestly correlated (R² = 0.56, p < 0.0001). In Bland-Altman analyses, individuals with the shortest (≤10th percentile) or longest (≥90th) flow FISH TL had an over- or under-estimated qPCR TL (bias = 0.89 and -0.77 kb, respectively). Comparisons of calculated TL from the NMDP samples and 1810 age- and sex-matched individuals from the National Health and Nutrition Examination Survey showed significant differences (median = 7.1 versus 5.8 kb, respectively, p < 0.0001). Differences in annual TL attrition were also noted (31 versus 13 bp/year, respectively, p = 0.02). Our results demonstrate that TL calculated in kb from qPCR T/S may yield biased estimates for individuals with the shortest or longest TL, those often of high clinical interest. We also showed that calculated TL in kb from qPCR data are not comparable across populations and therefore are not necessarily useful.

Subtelomeric methylation distinguishes between subtypes of Immunodeficiency, Centromeric instability and Facial anomalies syndrome

Human telomeres and adjacent subtelomeres are packaged as heterochromatin. Subtelomeric DNA undergoes methylation during development by DNA methyltransferase 3B (DNMT3B), including the CpG-rich promoters of the long non-coding RNA (TERRA) embedded in these regions. The factors that direct DNMT3B methylation to human subtelomeres and maintain this methylation throughout lifetime are yet unknown. The importance of subtelomeric methylation is manifested through the abnormal telomeric phenotype in Immunodeficiency, Centromeric instability and Facial anomalies (ICF) syndrome type 1 patients carrying mutations in DNMT3B. Patient cells demonstrate subtelomeric hypomethylation, accompanied by elevated TERRA transcription, accelerated telomere shortening and premature senescence of fibroblasts. ICF syndrome can arise due to mutations in at least three additional genes, ZBTB24 (ICF2), CDCA7 (ICF3) and HELLS (ICF4). While pericentromeric repeat hypomethylation is evident in all ICF syndrome subtypes, the status of subtelomeric DNA methylation had not been described for patients of subtypes 2-4. Here we explored the telomeric phenotype in cells derived from ICF2-4 patients with the aim to determine whether ZBTB24, CDCA7 and HELLS also play a role in establishing and/or maintaining human subtelomeric methylation. We found normal subtelomeric methylation in ICF2-4 and accordingly low TERRA levels and unperturbed telomere length. Moreover, depleting the ICF2-4-related proteins in normal fibroblasts did not influence subtelomeric methylation. Thus, these gene products are not involved in establishing or maintaining subtelomeric methylation. Our findings indicate that human subtelomeric heterochromatin has specialized methylation regulation and highlight the telomeric phenotype as a characteristic that distinguishes ICF1 from ICF2-4.

Loss of Notch1 predisposes oro-esophageal epithelium to tumorigenesis

Notch signaling functions in diverse developmental and homeostatic processes, including stem cell self-renewal and cell fate determination. Notch1-inactivating mutations are frequently detected in skin and oro-esophageal cancers, suggesting a role for Notch1 as a tumor suppressor. Here, we clarify the contribution of Notch1 deficiency to oro-esophageal tumorigenesis using a physiological experimental model. Tongue and esophageal tumors induced in mice by 4-nitroquinoline-1-oxide (4-NQO) showed pathophysiological similarities to human tumors, including decreased Notch1 expression in the basal cells. We created mutant mice (N1cKO), in which the Notch1 gene was disrupted specifically in the squamous epithelium. The epithelium formed normally in N1cKO mice, and although multiple skin tumors were detected at 65 weeks, no tumors developed in the tongue and esophagus. However, 4-NQO-induced tumorigenesis assays revealed that tumor onset occurred earlier in N1cKO mice than in wild-type littermates, and the tumors arose preferentially from the Notch1-negative epithelium, indicating the tumor susceptibility of Notch1-deficient epithelium. Notch1 regulates the expression of TERT, and age-related telomere erosion was more rapid in Notch1-deficient basal cells. Our results indicated that although Notch1 deficiency had little effect on squamous epithelium formation, it predisposed the affected epithelium to tumor development, at least in part through accelerated telomere erosion.

Telomeropathies: rare disease syndromes

Telomeres are located at the end of the chromosomes. They protect chromosomes from fusion and degradation. Every cell division causes a shortening of the telomeres. A special enzymatic complex called telomerase is responsible for maintaining telomere length in intensively dividing cells, such as epithelial cells and bone marrow cells. The enzymatic complex includes the TERT subunit, which has reverse transcriptase activity, and the TERC subunit, which acts as a template. Other important components of telomerase are the proteins that are responsible for structural stability. Telomerase remains active only in the dividing cells of the body. The rate of telomere shortening depends on many factors including age, sex, and comorbidities. Faster shortening of telomeres is caused by gene defects, which have an impact on telomerase action. Collectively, these are called telomeropathies. Common causes of telomeropathies are mutations in the TERT and TERC telomerase genes. Types of telemeropathies include dyskeratosis congenita, idiopathic pulmonary fibrosis, and aplastic anaemia, among others. Clinical manifestations and prognoses depend on the type and quantity of mutated genes. Diagnosis of telomeropathies is often problematic because they present with the same symptoms as other diseases. So far, no effective therapeutic methods have been developed for telomeropathies. A therapeutic method for patients with bone marrow failure may be the transplantation of hematopoietic stem cells. For patients with idiopathic pulmonary fibrosis, treatments include immunosuppressive therapy, lung transplantation, or palliative care. In the future, gene therapy may be an effective treatment strategy for telomeropathies. Lifestyle changes may also have a positive impact on the person. Physical activity combined with a healthy diet rich in antioxidants and unsaturated fatty acids can decrease the oxidative stress levels in cells and lead to a slower shortening of the telomeres.

Leukocyte Telomere Length Shortening, hTERT Genetic Polymorphisms and Risk of Childhood Acute Lymphoblastic Leukemia

Background: Telomeres are involved in chromosomal stability, cellular immortality and tumorigenesis. Human telomerase reverse transcriptase (TERT) is essential for the maintenance of telomere DNA length. Recently, a variable tandem-repeats polymorphism, MNS16A, located in the downstream region of the TERT gene, was reported to have an effect on TERT expression and telomerase activity. Previous studies have linked both relative telomere length (RTL) and TERT variants with cancer. Therefore, we evaluated associations between RTL, TERT gene polymorphisms (hTERT, rs2735940 C/T and MNS16A Ins/Del) and risk of childhood acute lymphoblastic leukemia (ALL) in an Iranian population. Methods: RTL was determined by a multiplex quantitative PCR-based method, and variants of the hTERT, rs2735940 C/T and MNS16A Ins/Del, were genotyped by amplification refractory mutation system PCR (ARMS-PCR), and PCR, respectively. Results: Our results indicated that RTL was shorter in ALL patients (1.53±0.12) compared to the control group (2.04±0.19) (P=0.029). However, no associations between hTERT gene variants or haplotypes and the risk of childhood ALL were observed (P>0.05). Also hTERT polymorphisms were not associated with RTL or patient clinicopathological characteristics, including age (P=0.304), sex (P=0.061) organomegally (P=0.212) CSF involvement (P=0.966) or response to treatment (P=0.58). Conclusions: We found that telomere attrition may be related to the pathogenesis of childhood ALL, irrespective to TERT variants.

Attachment and telomere length: more evidence for psychobiological connections between close relationships, health, and aging

Individuals with a history of poor interpersonal relationships are more likely to demonstrate negative health outcomes than those who have had high quality relationships. We sought to evaluate how attachment orientations, stress-induced respiratory sinus arrhythmia (RSA), and self-reported stress were associated with length of telomeres measured from peripheral blood mononuclear cells. Participants (N = 213) completed self-report measures of attachment and stress. Measurement of RSA was conducted before and after a stressful task and a blood draw was completed for analysis of telomere length. Attachment orientations were not directly associated with telomere length; however, we found that high attachment anxiety was associated with shorter length of telomeres via high self-reported stress. Attachment avoidance was also associated with telomere length via self-reported stress, but only among those with high stress-induced RSA. Exploratory analyses of T cell subsets indicated that stress was most strongly associated with telomeres from CD8CD28+ cells in comparison to CD8CD28- and CD4 cells. Study findings indicate that attachment orientations are associated with telomere length via stress, providing novel insights into the mechanisms through which close relationships can impact health and aging.

Dyskeratosis congenita with a novel genetic variant in the DKC1 gene: a case report

Background

Dyskeratosis congenita (DC) is a rare genetic disorder of bone marrow failure inherited in an X-linked, autosomal dominant or autosomal recessive pattern. It has a wide array of clinical features and patients may be cared for by many medical sub specialties. The typical clinical features consist of lacy reticular skin pigmentation, nail dystrophy and oral leukoplakia. As the disease advances, patients may develop progressive bone marrow failure, pulmonary fibrosis, oesophageal stenosis, urethral stenosis, liver cirrhosis as well as haematological and solid malignancies. Several genes have been implicated in the pathogenesis of dyskeratosis congenita, with the dyskerin pseudouridine synthase 1 (DKC1) gene mutations being the X-linked recessive gene.

Case presentation

Herein, we report a 31-year-old male with history of recurrent febrile episodes who was found to have reticulate skin pigmentation interspersed with hypopigmented macules involving the face, neck and extremities, hyperkeratosis of palms and soles, nail dystrophy, leukoplakia of the tongue, premature graying of hair, watery eyes and dental caries. Several of his male relatives, including two maternal uncles and three maternal cousins were affected with a similar type of disease condition. Pedigree analysis suggested a possible X-linked pattern of inheritance. Genetic testing in the proband showed a novel hemizygous, non-synonymous likely pathogenic variant [NM_001363.4: c.1054A > G: p.Thr352Ala] in the PUA domain of the DKC1 gene. Quantitative polymerase chain reaction for relative telomere length measurements performed in the proband showed that he had very short telomeres [0.38, compared to a control median of 0.71 (range 0.44–1.19)], which is consistent with the DC diagnosis. Co-segregation analysis of the novel mutation and telomere length measurements in the extended family members could not be performed as they were unwilling to provide consent for testing.

Conclusions

The novel variant detected in the DKC1 gene adds further to the existing scientific literature on the genotype-phenotype correlation of DC, and has important implications for the clinical and molecular characterization of the disease.

Beginning at the ends: telomeres and human disease

Studies of rare and common illnesses have led to remarkable progress in the understanding of the role of telomeres (nucleoprotein complexes at chromosome ends essential for chromosomal integrity) in human disease. Telomere biology disorders encompass a growing spectrum of conditions caused by rare pathogenic germline variants in genes encoding essential aspects of telomere function. Dyskeratosis congenita, a disorder at the severe end of this spectrum, typically presents in childhood with the classic triad of abnormal skin pigmentation, nail dystrophy, and oral leukoplakia, accompanied by a very high risk of bone marrow failure, cancer, pulmonary fibrosis, and other medical problems. In contrast, the less severe end of the telomere biology disorder spectrum consists of middle-age or older adults with just one feature typically seen in dyskeratosis congenita, such as pulmonary fibrosis or bone marrow failure. In the common disease realm, large-scale molecular epidemiology studies have discovered novel associations between illnesses, such as cancer, heart disease, and mental health, and both telomere length and common genetic variants in telomere biology genes. This review highlights recent findings of telomere biology in human disease from both the rare and common disease perspectives. Multi-disciplinary collaborations between clinicians, basic scientists, and epidemiologist are essential as we seek to incorporate new telomere biology discoveries to improve health outcomes.

Telomerase Reverse Transcriptase Polymorphism rs2736100: A Balancing Act between Cancer and Non-Cancer Disease, a Meta-Analysis

The enzyme telomerase reverse transcriptase (TERT) is essential for telomere maintenance. In replicating cells, maintenance of telomere length is important for the preservation of vital genetic information and prevention of genomic instability. A common genetic variant in TERT, rs2736100 C/A, is associated with both telomere length and multiple diseases. Carriage of the C allele is associated with longer telomere length, while carriage of the A allele is associated with shorter telomere length. Furthermore, some diseases have a positive association with the C and some with the A allele. In this study, meta-analyses were performed for two groups of diseases, cancerous diseases, e.g., lung cancer and non-cancerous diseases, e.g., pulmonary fibrosis, using data from genome-wide association studies and case-control studies. In the meta-analysis it was found that cancer positively associated with the C allele (pooled OR 1.16 [95% CI 1.09–1.23]) and non-cancerous diseases negatively associated with the C allele (pooled OR 0.81 [95% CI 0.65–0.99]). This observation illustrates that the ambiguous role of telomere maintenance in disease hinges, at least in part, on a single locus in telomerase genes. The dual role of this single nucleotide polymorphism also emphasizes that therapeutic agents aimed at influencing telomere maintenance should be used with caution.

Cytomegalovirus Retinitis as a Presenting Feature of Multisystem Disorder: Dyskeratosis Congenita

Cytomegalovirus (CMV) retinitis is an opportunistic infection commonly seen in disorders that affect the immune system of the body such as acquired immunodeficiency syndrome and hematological malignancies such as leukemia/lymphoma or organ transplantation. The occurrence of CMV retinitis in the absence of such condition should be thoroughly investigated, as it is a strong indicator of poor immune competence. We here report an interesting case of CMV retinitis as a presenting feature of rare multisystem disorder “Dyskeratosis congenita.”

Uncoding the genetic heterogeneity of myelodysplastic syndrome

Myelodysplastic syndrome (MDS) is a clinically heterogeneous disease characterized by functional impairment of hematopoiesis and abnormal bone marrow morphology. The type and severity of hematopoietic dysfunction in MDS are highly variable, and the kinetics of disease progression are difficult to predict. Genomic studies have shown that MDS is typically driven by a multistep somatic genetic process affecting a core set of genes. By definition, recurrent MDS driver mutations all drive clonal dominance, although they can have stereotyped positions in the clonal hierarchy or patterns of comutation association and exclusivity. Furthermore, environmental context, such as exposures to cytotoxic chemotherapy or the presence of germ-line predisposition, can influence disease pathogenesis and clinical outcomes. This review will address how an enhanced understanding of MDS genetics may enable refinement of current diagnostic schema, improve understanding of the pathogenesis of therapy-related MDS, and identify germ-line predispositions to development of MDS that are more common than recognized by standard clinical evaluation.

Progressive reticulate skin pigmentation and anonychia in a patient with bone marrow failure

KEY TEACHING POINTS.

A landscape of germ line mutations in a cohort of inherited bone marrow failure patients

Bone marrow (BM) failure (BMF) in children and young adults is often suspected to be inherited, but in many cases diagnosis remains uncertain. We studied a cohort of 179 patients (from 173 families) with BMF of suspected inherited origin but unresolved diagnosis after medical evaluation and Fanconi anemia exclusion. All patients had cytopenias, and 12.0% presented ≥5% BM blast cells. Median age at genetic evaluation was 11 years; 20.7% of patients were aged ≤2 years and 36.9% were ≥18 years. We analyzed genomic DNA from skin fibroblasts using whole-exome sequencing, and were able to assign a causal or likely causal germ line mutation in 86 patients (48.0%), involving a total of 28 genes. These included genes in familial hematopoietic disorders (GATA2, RUNX1), telomeropathies (TERC, TERT, RTEL1), ribosome disorders (SBDS, DNAJC21, RPL5), and DNA repair deficiency (LIG4). Many patients had an atypical presentation, and the mutated gene was often not clinically suspected. We also found mutations in genes seldom reported in inherited BMF (IBMF), such as SAMD9 and SAMD9L (N = 16 of the 86 patients, 18.6%), MECOM/EVI1 (N = 6, 7.0%), and ERCC6L2 (N = 7, 8.1%), each of which was associated with a distinct natural history; SAMD9 and SAMD9L patients often experienced transient aplasia and monosomy 7, whereas MECOM patients presented early-onset severe aplastic anemia, and ERCC6L2 patients, mild pancytopenia with myelodysplasia. This study broadens the molecular and clinical portrait of IBMF syndromes and sheds light on newly recognized disease entities. Using a high-throughput sequencing screen to implement precision medicine at diagnosis can improve patient management and family counseling.

Clinical heterogeneity in a family with DKC1 mutation, dyskeratosis congenita and Hoyeraal-Hreidarsson syndrome in first cousins

Dyskeratosis congenita (DC) is an inherited bone marrow failure disorder characterized by mucocutaneous features (skin pigmentation, nail dystrophy and oral leukoplakia), pulmonary fibrosis, hematologic and solid malignancies. Its severe form, recognized as Hoyeraal-Hreidarsson syndrome (HHS), also includes cerebellar hypoplasia, microcephaly, developmental delay and prenatal growth retardation. In literature phenotypic variability among DC patients sharing the same mutation is wellknown. To our knowledge this report describes for the first time a family of DC patients, characterized by a member with features of classic DC and another one with some features of HHS, both with the same mutation in DKC1. Our family confirms again that one mutation can be associated with different phenotypes and different hematological manifestations. It's possible to speculate that there are likely to be patients who do not clinically fit neatly into either classical DC or HHS, but whose clinical features are due to mutations in DKC1 or in genes responsible for autosomal DC/HHS.

Periodontal and other oral manifestations of immunodeficiency diseases

The list of immunodeficiency diseases grows each year as novel disorders are discovered, classified, and sometimes reclassified due to our ever-increasing knowledge of immune system function. Although the number of patients with secondary immunodeficiencies (SIDs) greatly exceeds those with primary immunodeficiencies (PIDs), the prevalence of both appears to be on the rise probably because of scientific breakthroughs that facilitate earlier and more accurate diagnosis. Primary immunodeficiencies in adults are not as rare as once thought. Globally, the main causes of secondary immunodeficiency are HIV infection and nutritional insufficiencies. Persons with acquired immune disorders such as AIDS caused by the human immunodeficiency virus (HIV) are now living long and fulfilling lives as a result of highly active antiretroviral therapy (HAART). Irrespective of whether the patient's immune-deficient state is a consequence of a genetic defect or is secondary in nature, dental and medical practitioners must be aware of the constant potential for infections and/or expressions of autoimmunity in these individuals. The purpose of this review was to study the most common conditions resulting from primary and secondary immunodeficiency states, how they are classified, and the detrimental manifestations of these disorders on the periodontal and oral tissues.

Telomere length and hTERT in mania and subsequent remission

OBJECTIVE

The findings of telomere length (TL) studies in bipolar disorder (BD) are controversial. The aim of the present study was to detect TL, human telomerase reverse transcriptase (hTERT), and brain derived neurotrophic factor (BDNF) in severe mania and subsequent remission.

METHODS

Twenty-one medication-free male patients and 20 age and gender matched controls were recruited. The patients were followed in the inpatient clinic, and comparisons were made between the same patients in their remission state and controls. Patients received lithium plus antipsychotics during the follow-up period. Quantitative real-time polymerase chain reaction was performed to verify leukocyte TL and whole blood hTERT gene expression levels. Serum BDNF levels were verified by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Compared to controls, manic patients presented shorter telomeres (p < 0.001) whose length increased with treatment (p = 0.001). Patients in the late stages showed shorter TL than those in the early stages and controls (p < 0.001). hTERT gene expression levels were up-regulated in mania and remission compared to controls (p = 0.03 and p = 0.01, respectively). BDNF changes did not reach statistically significant levels.

CONCLUSIONS

TL and hTERT gene expression might reflect a novel aspect of BD pathophysiology and TL might represent a novel biomarker for BD staging.

Genome-wide association study identifies multiple risk loci for renal cell carcinoma

Previous genome-wide association studies (GWAS) have identified six risk loci for renal cell carcinoma (RCC). We conducted a meta-analysis of two new scans of 5,198 cases and 7,331 controls together with four existing scans, totalling 10,784 cases and 20,406 controls of European ancestry. Twenty-four loci were tested in an additional 3,182 cases and 6,301 controls. We confirm the six known RCC risk loci and identify seven new loci at 1p32.3 (rs4381241, P=3.1 × 10-10), 3p22.1 (rs67311347, P=2.5 × 10-8), 3q26.2 (rs10936602, P=8.8 × 10-9), 8p21.3 (rs2241261, P=5.8 × 10-9), 10q24.33-q25.1 (rs11813268, P=3.9 × 10-8), 11q22.3 (rs74911261, P=2.1 × 10-10) and 14q24.2 (rs4903064, P=2.2 × 10-24). Expression quantitative trait analyses suggest plausible candidate genes at these regions that may contribute to RCC susceptibility.

Genetic predisposition to hematologic malignancies: management and surveillance

As individuals with germ line predisposition to hematologic malignancies are diagnosed with increasing frequency, the need for clinical surveillance has become apparent. Unfortunately, few prospective data are available, so recommendations are based on collective experience and expert consensus. There is general agreement to advocate for expert consultation or referral of patients to centers with expertise in these syndromes, since presentations and disease progression can be subtle, and treatment strategies must be tailored. Here, we summarize and integrate expert consensus recommendations and medical management considerations for the patient newly diagnosed with a leukemia predisposition disorder. Indications to consider additional studies and referral for allogeneic stem cell transplantation are also discussed.

Progress in Human and Tetrahymena Telomerase Structure Determination

Telomerase is an RNA-protein complex that extends the 3' ends of linear chromosomes, using a unique telomerase reverse transcriptase (TERT) and template in the telomerase RNA (TR), thereby helping to maintain genome integrity. TR assembles with TERT and species-specific proteins, and telomerase function in vivo requires interaction with telomere-associated proteins. Over the past two decades, structures of domains of TR and TERT as well as other telomerase- and telomere-interacting proteins have provided insights into telomerase function. A recently reported 9-Å cryo-electron microscopy map of the Tetrahymena telomerase holoenzyme has provided a framework for understanding how TR, TERT, and other proteins from ciliate as well as vertebrate telomerase fit and function together as well as unexpected insight into telomerase interaction at telomeres. Here we review progress in understanding the structural basis of human and Tetrahymena telomerase activity, assembly, and interactions.

Shorter leukocyte telomere length is associated with higher risk of infections: a prospective study of 75,309 individuals from the general population

In the general population, older age is associated with short leukocyte telomere length and with high risk of infections. In a recent study of allogeneic hematopoietic cell transplantation for severe aplastic anemia, long donor leukocyte telomere length was associated with improved survival in the recipients. These findings suggest that leukocyte telomere length could possibly be a marker of immune competence. Therefore, we tested the hypothesis that shorter leukocyte telomere length is associated with higher risk of infectious disease hospitalization and infection-related death. Relative peripheral blood leukocyte telomere length was measured using quantitative polymerase chain reaction in 75,309 individuals from the general population and the individuals were followed for up to 23 years. During follow up, 9228 individuals were hospitalized with infections and infection-related death occurred in 1508 individuals. Shorter telomere length was associated with higher risk of any infection (hazard ratio 1.05 per standard deviation shorter leukocyte telomere length; 95% confidence interval 1.03–1.07) and pneumonia (1.07; 1.03–1.10) after adjustment for conventional infectious disease risk factors. Corresponding hazard ratios for infection-related death were 1.10 (1.04–1.16) for any infection and 1.11 (1.04–1.19) for pneumonia. Telomere length was not associated with risk of skin infection, urinary tract infection, sepsis, diarrheal disease, endocarditis, meningitis or other infections. In conclusion, our findings indicate that leukocyte telomere length may be a marker of immune competence. Further studies are needed to determine whether risk of infections in allogeneic hematopoietic cell transplantation recipients can be reduced by considering donor leukocyte telomere length when selecting donors.

Telomere maintenance in soft tissue sarcomas

Soft tissue sarcomas (STS) are a diverse group of heterogeneous malignant tumours derived from mesenchymal tissues. Over 50 different STS subtypes are recognised by WHO, which show a wide range of different biological behaviours and prognoses. At present, clinicians managing this complex group of tumours face several challenges. This is reflected by the relatively poor outcome of patients with STSs compared with many other solid malignant tumours. These include difficulties securing accurate diagnoses, a lack of effective systemic treatments and absence of any sensitive circulating biomarkers to monitor patients throughout their treatment and follow-up. In order to progress STS's cells must evade the usual cellular proliferative checkpoints, and then activate a telomere maintenance mechanism in order to achieve replicative immortality. The purpose of this review is to provide an overview of STS genetics focusing particularly on these mechanisms. We will also highlight some of the key barriers to improving outcome for patients with STS, and hypothesise how a better understanding of these genetic characteristics may impact on future STS management.