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Hematology. American Society of... Dec 2022Numerous genetic discoveries and the advent of clinical telomere length testing have led to the recognition of a spectrum of telomere biology disorders (TBDs) beyond the... (Review)
Review
Numerous genetic discoveries and the advent of clinical telomere length testing have led to the recognition of a spectrum of telomere biology disorders (TBDs) beyond the classic dyskeratosis congenita (DC) triad of nail dysplasia, abnormal skin pigmentation, and oral leukoplakia occurring with pediatric bone marrow failure. Patients with DC/TBDs have very short telomeres for their age and are at high risk of bone marrow failure, cancer, pulmonary fibrosis (PF), pulmonary arteriovenous malformations, liver disease, stenosis of the urethra, esophagus, and/or lacrimal ducts, avascular necrosis of the hips and/or shoulders, and other medical problems. However, many patients with TBDs do not develop classic DC features; they may present in middle age and/or with just 1 feature, such as PF or aplastic anemia. TBD-associated clinical manifestations are progressive and attributed to aberrant telomere biology caused by the X-linked recessive, autosomal dominant, autosomal recessive, or de novo occurrence of pathogenic germline variants in at least 18 different genes. This review describes the genetics and clinical manifestations of TBDs and highlights areas in need of additional clinical and basic science research.
Topics: Humans; Child; Dyskeratosis Congenita; Telomere; Germ-Line Mutation; Bone Marrow Failure Disorders; Anemia, Aplastic
PubMed: 36485133
DOI: 10.1182/hematology.2022000394 -
World Journal of Clinical Cases Nov 2022Dyskeratosis congenita is a rare disease characterized by bone marrow failure and a clinical triad of oral leukoplakia, nail dystrophy, and abnormal skin pigmentation....
BACKGROUND
Dyskeratosis congenita is a rare disease characterized by bone marrow failure and a clinical triad of oral leukoplakia, nail dystrophy, and abnormal skin pigmentation. The genetics of dyskeratosis congenita include mutations in genes involved in telomere maintenance, including .
CASE SUMMARY
Here, we report a female patient who presented thrombocytopenia, anemia, reticulate hyperpigmentation, dystrophy in fingernails and toenails, and leukoplakia on the tongue. A histopathological study of the skin showed dyskeratocytes; however, a bone marrow biopsy revealed normal cell morphology. The patient was diagnosed with dyskeratosis congenita, but her family history did not reveal significant antecedents. Whole-exome sequencing showed a novel heterozygous punctual mutation in exon 6 from the gene, namely, NM_001099274.1:c.854delp.(Val285Alafs*32). An analysis of telomere length showed short telomeres relative to the patient's age.
CONCLUSION
The disease in this patient was caused by a germline novel mutation of in one of her parents.
PubMed: 36483815
DOI: 10.12998/wjcc.v10.i33.12440 -
Indian Dermatology Online Journal 2022
PubMed: 36386733
DOI: 10.4103/idoj.idoj_23_22 -
Faculty Reviews 2022Germline genetic defects impairing telomere length maintenance may result in severe medical conditions in humans, from aplastic anemia and myeloid neoplasms to... (Review)
Review
Germline genetic defects impairing telomere length maintenance may result in severe medical conditions in humans, from aplastic anemia and myeloid neoplasms to interstitial lung disease and liver cirrhosis, from childhood (dyskeratosis congenita) to old age (pulmonary fibrosis). The molecular mechanisms underlying these clinically distinct disorders are pathologically excessive telomere erosion, limiting cell proliferation and differentiation, tissue regeneration, and increasing genomic instability. Recent findings also indicate that telomere shortening imbalances stem cell fate and is associated with an abnormal inflammatory response and the senescent-associated secretory phenotype. Bone marrow failure is the most common phenotype in patients with telomere diseases. Pulmonary fibrosis is a typical phenotype in older patients, and disease progression appears faster than in pulmonary fibrosis not associated with telomeropathies. Liver cirrhosis may present in isolation or in combination with other phenotypes. Diagnosis is based on clinical suspicion and may be confirmed by telomere length measurement and genetic testing. Next-generation sequencing (NGS) techniques have improved genetic testing; today, at least 16 genes have been implicated in telomeropathies. NGS also allows tracking of clonal hematopoiesis and malignant transformation. Patients with telomere diseases are at high risk of developing cancers, including myeloid neoplasms and head and neck cancer. However, treatment options are still limited. Transplant modalities (bone marrow, lung, and liver) may be definitive to the respective organ involvement but limited by donor availability, comorbidities, and impact on other affected organs. In clinical trials, androgens elongate telomeres of peripheral blood leukocytes and improve hematopoiesis. Further understanding of how telomere erosion impairs organ function and how somatic mutations evolve in the hematopoietic tissue may help develop new strategies to treat and prevent telomere diseases.
PubMed: 36311538
DOI: 10.12703/r/11-31 -
NPJ Genomic Medicine Oct 2022Hoyeraal-Hreidarsson syndrome (HHS) is the most severe form of dyskeratosis congenita (DC) and is caused by mutations in genes involved in telomere maintenance. Here, we...
Hoyeraal-Hreidarsson syndrome (HHS) is the most severe form of dyskeratosis congenita (DC) and is caused by mutations in genes involved in telomere maintenance. Here, we identified male siblings from a family with HHS carrying a hemizygous mutation (c.1345C > G, p.R449G), located in the C-terminal nuclear localization signal (NLS) of the DKC1 gene. These patients exhibit progressive cerebellar hypoplasia, recurrent infections, pancytopenia due to bone marrow failure, and short leukocyte telomere lengths. Single-cell RNA sequencing analysis suggested defects in the NLRP3 inflammasome in monocytes and the activation and maturation of NK cells and B cells. In experiments using induced pluripotent stem cells (iPSCs) from patients, DKC1_R449G iPSCs had short telomere lengths due to reduced levels of human telomerase RNA (hTR) and increased cytosolic proportions of DKC1. Treatment with dihydroquinolizinone RG7834 and 3'deoxyanosine cordycepin rescued telomere length in patient-derived iPSCs. Together, our findings not only provide new insights into immunodeficiency in DC patients but also provide treatment options for telomerase insufficiency disorders.
PubMed: 36309505
DOI: 10.1038/s41525-022-00335-8 -
Hematology Reports Oct 2022Classic dyskeratosis congenita is a hereditary disease where the majority of patients present with bone marrow failure and mucocutaneous changes: mainly skin...
Classic dyskeratosis congenita is a hereditary disease where the majority of patients present with bone marrow failure and mucocutaneous changes: mainly skin pigmentation, nail dystrophy, oral premalignant leukoplakia, in addition to increased risk for malignancies. A 63-year-old man with a long history of untreated chronic pulmonary disease, a smoker in the past, presented initially with pancytopenia and a clinical diagnosis of myelodysplastic syndrome with excess blasts returned a month later with leukocytosis (WBC 215.9 × 10/μL) and diagnosed with acute myeloid leukemia (AML) with deletion of chromosome 7 and -TKD mutation. The patient's mother and sister died in their 6th decade from rapidly progressing fulminant pulmonary fibrosis. He had abnormal skin pigmentation and oral leukoplakia on presentation. He was induced with 7 + 3 chemotherapy and started on midostaurin but experienced prolonged cytopenias, complicated by hypoxic acute on chronic respiratory failure requiring intubation and mechanical ventilation. D + 28 and D + 36 bone marrow examination showed trilineage hypoplasia but no blasts, though the D + 28 bone marrow biopsy revealed one metaphase with del (7) that was cleared on D + 35. The constellation of clinical features and strong family history along with del 7 and -TKD AML with preceding MDS highly suggests a germline predisposition state dyskeratosis congenita. Germline predispositions are often underrecognized as delayed onset conditions leading to AML and may have treatment and preventative implications especially genetic counseling for blood-related family members.
PubMed: 36278519
DOI: 10.3390/hematolrep14040042 -
JAAD Case Reports Nov 2022
PubMed: 36275875
DOI: 10.1016/j.jdcr.2022.09.011 -
Cancer Reports (Hoboken, N.J.) Jan 2023With the progression of next-generation sequencing technologies, researchers have identified numerous variants of the regulator of telomere elongation helicase 1 (RTEL1)... (Review)
Review
BACKGROUND
With the progression of next-generation sequencing technologies, researchers have identified numerous variants of the regulator of telomere elongation helicase 1 (RTEL1) gene that are associated with a broad spectrum of phenotypic manifestations, including malignancies. At the molecular level, RTEL1 is involved in the regulation of the repair, replication, and transcription of deoxyribonucleic acid (DNA) and the maintenance of telomere length. RTEL1 can act both as a promotor and inhibitor of tumorigenesis. Here, we review the potential mechanisms implicated in the malignant transformation of tissues under conditions of RTEL1 deficiency or its aberrant overexpression.
RECENT FINDINGS
A major hemostatic challenge during RTEL1 dysfunction could arise from its unbalanced activity for unwinding guanine-rich quadruplex DNA (G4-DNA) structures. In contrast, RTEL1 deficiency leads to alterations in telomeric and genome-wide DNA maintenance mechanisms, ribonucleoprotein metabolism, and the creation of an inflammatory and immune-deficient microenvironment, all promoting malignancy. Additionally, we hypothesize that functionally similar molecules could act to compensate for the deteriorated functions of RTEL1, thereby facilitating the survival of malignant cells. On the contrary, RTEL1 over-expression was directed toward G4-unwinding, by promoting replication fork progression and maintaining intact telomeres, may facilitate malignant transformation and proliferation of various pre-malignant cellular compartments.
CONCLUSIONS
Therefore, restoring the equilibrium of RTEL1 functions could serve as a therapeutic approach for preventing and treating malignancies.
Topics: Humans; DNA; Neoplasms; Telomere; Tumor Microenvironment; DNA Helicases
PubMed: 36253342
DOI: 10.1002/cnr2.1735 -
Balkan Journal of Medical Genetics :... Nov 2021Dyskeratosis congenita (DC) is a clinically and genetically heterogeneous, multisystem inherited syndrome with a very high risk for bone marrow failure (BMF) and cancer...
Dyskeratosis congenita (DC) is a clinically and genetically heterogeneous, multisystem inherited syndrome with a very high risk for bone marrow failure (BMF) and cancer predisposition. The classical clinical form of DC is characterized by abnormal skin pigmentation, nail dystrophy, and oral leukoplakia. Bone marrow failure is considered to be an important and major complication of DC and the leading cause of death which develops in around 85% of cases. A number of genes involved in telomere maintenance are associated with DC, such as genes that encode the components of the telomerase complex (, , , 10, and 2), T-loop assembly protein (), telomere capping (), telomere shelterin complex (), and telomerase trafficking protein (). Mutations in have been reported in 11-20% of all patients with DC and have been associated with bone marrow failure. Here we report on a 19-month old boy with very early presentation of bone marrow failure as a first clinical manifestation of DC. Upon first admission, the patient presented with thrombocytopenia and macrocytic anemia. Soon after, his blood counts deteriorated with the development of pancytopenia and aplastic anemia. Four months later, he developed nail dystrophy and skin hyperpigmentation. A heterozygous pathogenic variant c.845G>A, p.(Arg282His) was located in exon 6 of gene and was identified via clinical exome sequencing. The findings confirmed the diagnosis of DC. This is the first case with DC due to pathogenic variant reported in North Macedonia.
PubMed: 36249522
DOI: 10.2478/bjmg-2021-0027 -
American Journal of Ophthalmology Case... Dec 2022To describe a case of Coats Plus Syndrome (CPS), a vision and life threatening disease belonging to a family of diseases known as the Telomere Biology Disorders.
PURPOSE
To describe a case of Coats Plus Syndrome (CPS), a vision and life threatening disease belonging to a family of diseases known as the Telomere Biology Disorders.
OBSERVATIONS
A 15-year-old girl with a history of small for gestational age, short stature, microcephaly, thinning/greying of scalp hair, skin hyperpigmentation, nail ridging, and multiple pathological fractures presented with bilateral Coats-like retinopathy. We discovered a new observation of multiple peripheral pinpoint retinal pigment epithelial detachments (PEDs). Further genetic testing revealed CTC1 gene mutation and she was diagnosed with Coats plus syndrome with features of dyskeratosis congenita, a telomere biology disorder.
CONCLUSION AND IMPORTANCE
Patients with bilateral Coats-like retinopathy and associated systemic features suggestive of CPS should be evaluated through genetic testing to diagnose this disease and treat vision and life threatening manifestations as early as possible. In this report, we also document, for the first time, multiple pinpoint PEDs that could be related to an accelerated aging process with telomere dysfunction.
PubMed: 36177296
DOI: 10.1016/j.ajoc.2022.101713