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Human Molecular Genetics Apr 2024Telomeres are nucleoprotein structures at the end of chromosomes that maintain their integrity. Mutations in genes coding for proteins involved in telomere protection...
Clinical mutations in the TERT and TERC genes coding for telomerase components induced oxidative stress, DNA damage at telomeres and cell apoptosis besides decreased telomerase activity.
Telomeres are nucleoprotein structures at the end of chromosomes that maintain their integrity. Mutations in genes coding for proteins involved in telomere protection and elongation produce diseases such as dyskeratosis congenita or idiopathic pulmonary fibrosis known as telomeropathies. These diseases are characterized by premature telomere shortening, increased DNA damage and oxidative stress. Genetic diagnosis of telomeropathy patients has identified mutations in the genes TERT and TERC coding for telomerase components but the functional consequences of many of these mutations still have to be experimentally demonstrated. The activity of twelve TERT and five TERC mutants, five of them identified in Spanish patients, has been analyzed. TERT and TERC mutants were expressed in VA-13 human cells that express low telomerase levels and the activity induced was analyzed. The production of reactive oxygen species, DNA oxidation and TRF2 association at telomeres, DNA damage response and cell apoptosis were determined. Most mutations presented decreased telomerase activity, as compared to wild-type TERT and TERC. In addition, the expression of several TERT and TERC mutants induced oxidative stress, DNA oxidation, DNA damage, decreased recruitment of the shelterin component TRF2 to telomeres and increased apoptosis. These observations might indicate that the increase in DNA damage and oxidative stress observed in cells from telomeropathy patients is dependent on their TERT or TERC mutations. Therefore, analysis of the effect of TERT and TERC mutations of unknown function on DNA damage and oxidative stress could be of great utility to determine the possible pathogenicity of these variants.
Topics: Humans; Apoptosis; DNA; DNA Damage; Dyskeratosis Congenita; Mutation; Oxidative Stress; RNA; Telomerase; Telomere
PubMed: 38641551
DOI: 10.1093/hmg/ddae015 -
International Journal of Molecular... Apr 2024We explore the possibility that defects in genes associated with the response and repair of DNA double strand breaks predispose oral potentially malignant disorders... (Review)
Review
We explore the possibility that defects in genes associated with the response and repair of DNA double strand breaks predispose oral potentially malignant disorders (OPMD) to undergo malignant transformation to oral squamous cell carcinoma (OSCC). Defects in the homologous recombination/Fanconi anemia (HR/FA), but not in the non-homologous end joining, causes the DNA repair pathway to appear to be consistent with features of familial conditions that are predisposed to OSCC (FA, Bloom's syndrome, Ataxia Telangiectasia); this is true for OSCC that occurs in young patients, sometimes with little/no exposure to classical risk factors. Even in Dyskeratosis Congenita, a disorder of the telomerase complex that is also predisposed to OSCC, attempts at maintaining telomere length involve a pathway with shared HR genes. Defects in the HR/FA pathway therefore appear to be pivotal in conditions that are predisposed to OSCC. There is also some evidence that abnormalities in the HR/FA pathway are associated with malignant transformation of sporadic cases OPMD and OSCC. We provide data showing overexpression of HR/FA genes in a cell-cycle-dependent manner in a series of OPMD-derived immortal keratinocyte cell lines compared to their mortal counterparts. The observations in this study argue strongly for an important role of the HA/FA DNA repair pathway in the development of OSCC.
Topics: Humans; Mouth Neoplasms; Carcinoma, Squamous Cell; Squamous Cell Carcinoma of Head and Neck; Fanconi Anemia; Head and Neck Neoplasms; DNA
PubMed: 38612901
DOI: 10.3390/ijms25074092 -
Skin Appendage Disorders Apr 2024Bowen's disease is a squamous cell carcinoma in situ, the most common malignancy of the nail unit. Presenting more frequently in the fingernails, common risk factors...
INTRODUCTION
Bowen's disease is a squamous cell carcinoma in situ, the most common malignancy of the nail unit. Presenting more frequently in the fingernails, common risk factors include ionizing radiation, oral exposure to arsenic or pesticides, dyskeratosis congenita, and quite commonly diverse subtypes of HPV. We report the first case of multiple periungual pigmented Bowen's disease in a pediatric patient.
CASE PRESENTATION
A healthy 13-year-old boy presented with a 9-month history of a pigmented erythematous patch on the proximal nail fold of his 3rd right finger without associated symptoms. A punch biopsy was taken, and the diagnosis of Bowen's disease was made. The patient received photodynamic therapy and three cycles of imiquimod without response, and two new lesions appeared on the first and second right fingers. Surgical removal was performed on all lesions. A polymerase chain reaction detected an HPV type 16.
DISCUSSION/CONCLUSION
Multiple periungual Bowen's disease is rare, with the most frequent risk factors being HPV infection and chronic immunosuppression. Less than 10% of the cases present as longitudinal melanonychia. To date, there are no previous reports of multiple pigmented periungual Bowen's disease. HPV-induced Bowen's disease is usually present in adults aged between 22 and 89 years as persistent verrucae. In this case, koilocytosis and the fact that all lesions appeared on the right hand are suggestive of HPV infection.
PubMed: 38572196
DOI: 10.1159/000534734 -
Indian Journal of Dermatology 2024Dyskeratosis congenita (DC) is a rare inherited bone marrow failure syndrome and telomere biology disorder, usullay consisting of a triad of oral leucoplakia, dystrophic...
Dyskeratosis congenita (DC) is a rare inherited bone marrow failure syndrome and telomere biology disorder, usullay consisting of a triad of oral leucoplakia, dystrophic nails, reticular skin pigmentation. The diagnosis in the majority of cases can be made following all the clinical findings of this triad are established. Here we report 7 years-old boy who had oral leukoplakia and nail abnormality without skin involvement, associated with bone marrow failure diagnosed with X-linked DC due to dyskerin (DKC1) mutation. Our report emphasizes the fact that clinical suspicion can prevent fatal consequences since all manifestations may not always be seen collectively.
PubMed: 38572035
DOI: 10.4103/ijd.ijd_556_23 -
Indian Journal of Gastroenterology :... Mar 2024
PubMed: 38504006
DOI: 10.1007/s12664-023-01505-x -
Italian Journal of Dermatology and... Jun 2024Telomeres, the safeguarding caps at the tips of chromosomes, are pivotal in the aging process of cells and have been linked to skin ailments and inflammatory conditions.... (Review)
Review
Telomeres, the safeguarding caps at the tips of chromosomes, are pivotal in the aging process of cells and have been linked to skin ailments and inflammatory conditions. Telomeres undergo a gradual reduction in length and factors such as oxidative stress hasten this diminishing process. Skin diseases including inflammatory conditions can be correlated with the shortening of telomeres and the persistent activation of DNA damage response in skin tissues. Telomere dysfunction could disrupt the balance of the skin, impairs wound healing, and may contribute to abnormal cytokine production. Skin aging and processes related to telomeres may function as one of the triggers for skin diseases. The presence of proinflammatory cytokines and dysfunctional telomeres in conditions such as Dyskeratosis Congenita implies a possible connection between the shortening of telomeres and the onset of chronic inflammatory skin disorders. In autoinflammatory skin diseases, chronic inflammation hinders wound healing thus aggravating the progression of the disease. The NF-ĸB pathway might contribute to the initiation or progression of chronic disorders by influencing mechanisms associated with telomere biology. The intricate connections between telomeres, telomerase, telomere-associated proteins, and skin diseases are still a complex puzzle to be solved. Here, we provide an overview of the impact of telomeres on both health and disease with a specific emphasis on their role in skin, inflammation and autoinflammatory skin disorders.
Topics: Humans; Telomere; Skin Diseases; Inflammation; Telomere Shortening; Telomerase; Dyskeratosis Congenita; Skin Aging
PubMed: 38502535
DOI: 10.23736/S2784-8671.23.07689-2 -
ERJ Open Research Jan 2024Pulmonary fibrosis is a severe disease which can be familial. A genetic cause can only be found in ∼40% of families. Searching for shared novel genetic variants may...
INTRODUCTION
Pulmonary fibrosis is a severe disease which can be familial. A genetic cause can only be found in ∼40% of families. Searching for shared novel genetic variants may aid the discovery of new genetic causes of disease.
METHODS
Whole-exome sequencing was performed in 152 unrelated patients with a suspected genetic cause of pulmonary fibrosis from the St Antonius interstitial lung disease biobank. Variants of interest were selected by filtering for novel, potentially deleterious variants that were present in at least three unrelated pulmonary fibrosis patients.
RESULTS
The novel c.586G>A p.(E196K) variant in the gene was observed in three unrelated patients: two familial patients and one sporadic patient, who was later genealogically linked to one of the families. The variant was identified in nine additional relatives with pulmonary fibrosis and other telomere-related phenotypes, such as pulmonary arterial venous malformations, emphysema, myelodysplastic syndrome, acute myeloid leukaemia and dyskeratosis congenita. One family showed incomplete segregation, with absence of the variant in one pulmonary fibrosis patient who carried a variant. The majority of variant carriers showed short telomeres in blood. ZCCHC8 protein was located in different lung cell types, including alveolar type 2 (AT2) pneumocytes, the culprit cells in pulmonary fibrosis. AT2 cells showed telomere shortening and increased DNA damage, which was comparable to patients with sporadic pulmonary fibrosis and those with pulmonary fibrosis carrying a telomere-related gene variant, respectively.
DISCUSSION
The c.586G>A variant confirms the involvement of ZCCHC8 in pulmonary fibrosis and short-telomere syndromes and underlines the importance of including the gene in diagnostic gene panels for these diseases.
PubMed: 38375433
DOI: 10.1183/23120541.00487-2023 -
International Journal of Molecular... Jan 2024Dyskeratosis Congenita (DC) is a multisystem disorder intrinsically associated with telomere dysfunction, leading to bone marrow failure (BMF). Although the pathology of...
Dyskeratosis Congenita (DC) is a multisystem disorder intrinsically associated with telomere dysfunction, leading to bone marrow failure (BMF). Although the pathology of DC is largely driven by mutations in telomere-associated genes, the implications of gene fusions, which emerge due to telomere-induced genomic instability, remain unexplored. We meticulously analyzed gene fusions in RNA-Seq data from DC patients to provide deeper insights into DC's progression. The most significant DC-specific gene fusions were subsequently put through in silico assessments to ascertain biophysical and structural attributes, including charge patterning, inherent disorder, and propensity for self-association. Selected candidates were then analyzed using deep learning-powered structural predictions and molecular dynamics simulations to gauge their potential for forming higher-order oligomers. Our exploration revealed that genes participating in fusion events play crucial roles in upholding genomic stability, facilitating hematopoiesis, and suppressing tumors. Notably, our analysis spotlighted a particularly disordered polyampholyte fusion protein that exhibits robust higher-order oligomerization dynamics. To conclude, this research underscores the potential significance of several high-confidence gene fusions in the progression of BMF in DC, particularly through the dysregulation of genomic stability, hematopoiesis, and tumor suppression. Additionally, we propose that these fusion proteins might hold a detrimental role, specifically in inducing proteotoxicity-driven hematopoietic disruptions.
Topics: Humans; Dyskeratosis Congenita; Telomerase; Pancytopenia; Bone Marrow Failure Disorders; Mutation; Telomere; Genomic Instability
PubMed: 38338888
DOI: 10.3390/ijms25031606 -
Frontiers in Genetics 2023The inherited bone marrow failure syndromes (IBMFSs) are a group of rare disorders characterized by bone marrow failure (BMF), physical abnormalities, and an increased...
The inherited bone marrow failure syndromes (IBMFSs) are a group of rare disorders characterized by bone marrow failure (BMF), physical abnormalities, and an increased risk of neoplasia. The National Institute of Pediatrics (INP) is a major medical institution in Mexico, where patients with BMF receive a complete approach that includes paraclinical tests. Readily recognizable features, such as the hematological and distinctive physical phenotypes, identified by clinical dysmorphologists, remain crucial for the diagnosis and management of these patients, particularly in circumstances where next-generation sequencing (NGS) is not easily available. Here, we describe a group of Mexican patients with a high clinical suspicion of an IBMFS. We performed a systematic retrospective analysis of the medical records of patients who had a high IBMFS suspicion at our institution from January 2018 to July 2021. An initial assessment included first ruling out acquired causes of BMF by the Hematology Department and referral of the patient to the Department of Human Genetics for physical examination to search for specific phenotypes suggesting an IBMFS. Patients with high suspicion of having an IBMFS were classified into two main groups: 1) , including dyskeratosis congenita (DC), Diamond-Blackfan anemia (DBA), Shwachman-Diamond syndrome (SDS), thrombocytopenia with absent radii (TAR), and severe congenital neutropenia (SCN); 2) We established a high suspicion of having an IBMFS in 48 patients. At initial evaluation, the most common hematologic features were bicytopenia (20%) and aplastic anemia (16%); three patients received hematopoietic stem cell transplantation. Among patients with a suspicion of an IBMFS, the most common physical abnormality was minor craniofacial features in 83% of patients and neurodevelopmental disorders in 52%. The specific suspicions that we built were DBA (31%), SDS (18%), DC (14%), TAR (4%), and SCN (4%), whereas 27% of cases remained as undefined IBMFS. SDS, TAR, and SCN were more commonly suspected at an earlier age (<1 year), followed by DBA (2 years) and DC (5 years). Thorough examination of reported clinical data allowed us to highly suspect a specific IBMFS in approximately 70% of patients; however, an important number of patients remained with suspicion of an undefined IBMFS. Implementation of NGS and telomere length measurement are forthcoming measures to improve IBMFS diagnosis in Mexico.
PubMed: 38327701
DOI: 10.3389/fgene.2023.1293929 -
JMIR Infodemiology Jan 2024Social media has the potential to provide social support for rare disease communities; however, little is known about the use of social media for the expression of...
BACKGROUND
Social media has the potential to provide social support for rare disease communities; however, little is known about the use of social media for the expression of medical uncertainty, a common feature of rare diseases.
OBJECTIVE
This study aims to evaluate the expression of medical uncertainty on social media in the context of dyskeratosis congenita, a rare cancer-prone inherited bone marrow failure and telomere biology disorder (TBD).
METHODS
We performed a content analysis of uncertainty-related posts on Facebook and Twitter managed by Team Telomere, a patient advocacy group for this rare disease. We assessed the frequency of uncertainty-related posts, uncertainty sources, issues, and management and associations between uncertainty and social support.
RESULTS
Across all TBD social media platforms, 45.98% (1269/2760) of posts were uncertainty related. Uncertainty-related posts authored by Team Telomere on Twitter focused on scientific (306/434, 70.5%) or personal (230/434, 53%) issues and reflected uncertainty arising from probability, ambiguity, or complexity. Uncertainty-related posts in conversations among patients and caregivers in the Facebook community group focused on scientific (429/511, 84%), personal (157/511, 30.7%), and practical (114/511, 22.3%) issues, many of which were related to prognostic unknowns. Both platforms suggested uncertainty management strategies that focused on information sharing and community building. Posts reflecting response-focused uncertainty management strategies (eg, emotional regulation) were more frequent on Twitter compared with the Facebook community group (χ=3.9; P=.05), whereas posts reflecting uncertainty-focused management strategies (eg, ordering information) were more frequent in the Facebook community group compared with Twitter (χ=55.1; P<.001). In the Facebook community group, only 36% (184/511) of members created posts during the study period, and those who created posts did so with a low frequency (median 3, IQR 1-7 posts). Analysis of post creator characteristics suggested that most users of TBD social media are White, female, and parents of patients with dyskeratosis congenita.
CONCLUSIONS
Although uncertainty is a pervasive and multifactorial issue in TBDs, our findings suggest that the discussion of medical uncertainty on TBD social media is largely limited to brief exchanges about scientific, personal, or practical issues rather than ongoing supportive conversation. The nature of uncertainty-related conversations also varied by user group: patients and caregivers used social media primarily to discuss scientific uncertainties (eg, regarding prognosis), form social connections, or exchange advice on accessing and organizing medical care, whereas Team Telomere used social media to express scientific and personal issues of uncertainty and to address the emotional impact of uncertainty. The higher involvement of female parents on TBD social media suggests a potentially greater burden of uncertainty management among mothers compared with other groups. Further research is needed to understand the dynamics of social media engagement to manage medical uncertainty in the TBD community.
Topics: Humans; Female; Uncertainty; Social Media; Dyskeratosis Congenita; Rare Diseases; Probability
PubMed: 38224480
DOI: 10.2196/46693