Advances in the understanding of dyskeratosis congenita

Dyskeratosis congenita: a rare case report

Dyskeratosis congenita (DKC) is a rare genetic disorder characterized by lacy reticular skin hyperpigmentation, bone marrow failure, nail dystrophy, and oral leukoplakia. To the best of our knowledge, only around 200 cases were reported in the medical literature, and in this report, we present another distinctive case from Syria. This case report describes a male patient with generalized reticular pigmentation and abnormal nails since childhood. The patient reported a history of recurrent urethral stenosis and corneal density. Dermoscopic examination revealed pigmented lines arranged in a netlike pattern. Histopathological findings were nonspecific. Hematological values were unremarkable. A contrast CT scan revealed changes in the bladder wall. The final diagnosis of Dyskeratosis Congenita was made based on the clinical criteria. This disorder can present with additional cutaneous manifestations and systemic complications. Treatment are generally prescribed to maintain bone marrow function, based on the fact that it is the major cause of death. Regular monitoring and screening for associated conditions are recommended.

Infection and telomere length: a systematic review protocol

INTRODUCTION

Telomeres are a measure of cellular ageing with potential links to diseases such as cardiovascular diseases and cancer. Studies have shown that some infections may be associated with telomere shortening, but whether an association exists across all types and severities of infections and in which populations is unclear. Therefore we aim to collate available evidence to enable comparison and to inform future research in this field.

METHODS AND ANALYSIS

We will search for studies involving telomere length and infection in various databases including MEDLINE (Ovid interface), EMBASE (Ovid interface), Web of Science, Scopus, Global Health and the Cochrane Library. For grey literature, the British Library of electronic theses databases (ETHOS) will be explored. We will not limit by study type, geographical location, infection type or method of outcome measurement. Two researchers will independently carry out study selection, data extraction and risk of bias assessment using the ROB2 and ROBINS-E tools. The overall quality of the studies will be determined using the Grading of Recommendations Assessment, Development and Evaluation criteria. We will also evaluate study heterogeneity with respect to study design, exposure and outcome measurement and if there is sufficient homogeneity, a meta-analysis will be conducted. Otherwise, we will provide a narrative synthesis with results grouped by exposure category and study design.

ETHICS AND DISSEMINATION

The present study does not require ethical approval. Results will be disseminated via publishing in a peer-reviewed journal and conference presentations.

PROSPERO REGISTRATION NUMBER

CRD42023444854.

A rare homozygous variant in TERT gene causing variable bone marrow failure, fragility fractures, rib anomalies and extremely short telomere lengths with high serum IgE

By whole exome sequencing, we identified a homozygous c.2086 C→T (p.R696C) TERT mutation in patients who present with a spectrum of variable bone marrow failure (BMF), raccoon eyes, dystrophic nails, rib anomalies, fragility fractures (FFs), high IgE level, extremely short telomere lengths (TLs), and skewed numbers of cytotoxic T cells with B and NK cytopenia. Haploinsufficiency in the other family members resulted in short TL and osteopenia. These patients also had the lowest bone mineral density Z-score compared to other BMF-patients. Danazol/zoledronic acid improved the outcomes of BMF and FFs. This causative TERT variant has been observed in one family afflicted with dyskeratosis congenita (DC), and thus, we also define a second report and new phenotype related to the variant which should be suspected in severe cases of DC with co-existent BMF, FFs, high IgE level and rib anomalies.

Adaptive and Maladaptive Clonal Hematopoiesis in Telomere Biology Disorders

PURPOSE OF REVIEW

Telomere biology disorders (TBDs) are germline-inherited conditions characterized by reduction in telomerase function, accelerated shortening of telomeres, predisposition to organ-failure syndromes, and increased risk of neoplasms, especially myeloid malignancies. In normal cells, critically short telomeres trigger apoptosis and/or cellular senescence. However, the evolutionary mechanism by which TBD-related telomerase-deficient cells can overcome this fitness constraint remains elusive.

RECENT FINDINGS

Preliminary data suggests the existence of adaptive somatic mosaic states characterized by variants in TBD-related genes and maladaptive somatic mosaic states that attempt to overcome hematopoietic fitness constraints by alternative methods leading to clonal hematopoiesis. TBDs are both rare and highly heterogeneous in presentation, and the association of TBD with malignant transformation is unclear. Understanding the clonal complexity and mechanisms behind TBD-associated molecular signatures that lead to somatic adaptation in the setting of defective hematopoiesis will help inform therapy and treatment for this set of diseases.

Evidence from a meta-analysis for the prognostic and clinicopathological importance of DKC1 in malignancies

Aim: We conducted a meta-analysis to evaluate the prognostic and clinicopathological relevance of DKC1 in various cancers. Methods: We searched Web of Science, Embase, PubMed, Wanfang and CNKI. Stata SE15.1 was used to calculate the hazard ratio and relative risk with 95% CIs to assess the possible correlations between DKC1 expression levels and overall and disease-free survival, as well as with clinicopathological parameters. Results: We included nine studies, with a total of 2574 patients. There was a meaningful link between elevated DKC1 and poorer disease-free (p < 0.001) and overall survival (p < 0.001). Also, it was linked to advanced tumor node metastasis stage (p = 0.005). Conclusion: High DKC1 expression was predictive of worse prognosis and poorer clinicopathological parameters.

Congenital Disorders of Red Blood Cells

See Bonus NeoBriefs videos and downloadable teaching slides Understanding the physiologic process of red blood cell development in utero and subsequent erythropoiesis in the neonate is crucial as this determines red blood cell structure and therefore function, which is vital to neonatal health. Infants frequently experience anemia, and special consideration must be given to the evaluation of these infants to determine the correct etiology. Traditionally, anemia is conceptualized in terms of inadequate red blood cell production, increased red blood cell destruction, or whole blood loss. This framework translates well to inherited red blood cell defects, which include genetic abnormalities in bone marrow productivity or structure of the red blood cell membrane, enzymes, or hemoglobin. This article highlights fetal and neonatal erythropoiesis and the underlying etiologies of the inherited red blood cell disorders, as well as reviews the appropriate diagnostic evaluation and next steps in management. It is imperative that neonatal clinicians remain informed about these disorders to enable early recognition and treatment, and ultimately to improve outcomes in affected infants.

de novo TINF2 C.845G>A: Pathogenic Variant in Patient with Dyskeratosis Congenita

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 (TERT, DKC1, TERC, NOP10, and NHP2), T-loop assembly protein (RTEL1), telomere capping (CTC1), telomere shelterin complex (TINF2), and telomerase trafficking protein (TCAB1). Mutations in TINF2 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 de novo heterozygous pathogenic variant c.845G>A, p.(Arg282His) was located in exon 6 of TINF2 gene and was identified via clinical exome sequencing. The findings confirmed the diagnosis of DC. This is the first case with DC due to TINF2 pathogenic variant reported in North Macedonia.

Assessment of Telomerase Reverse Transcriptase Single Nucleotide Polymorphism in Sleep Bruxism

Introduction: Sleep bruxism (SB) is a widespread masticatory muscle activity during sleep and affects approximately 13.2% of the general population. Telomerase reverse transcriptase (TERT) plays a role in preventing the shortening of the telomere. This prospective, observational study aimed to investigate the relationship between single nucleotide polymorphism (SNP) of TERT and the severity of SB and to identify the independent risk factors for SB. Methods: A total of 112 patients were diagnosed by performing one-night polysomnography based on the guidelines of the American Academy of Sleep Medicine. TERT SNP was detected by real-time quantitative polymerase chain reaction (qPCR). Results: Statistical analysis showed the lack of relationship between the rs2853669 polymorphism of TERT and severity of SB (p > 0.05). However, the study showed that patients with allele T in the 2736100 polymorphism of TERT had a lower score on the phasic bruxism episode index (BEI). Based on the receiver operating characteristic (ROC) curve, the value of phasic BEI was 0.8 for the differential prediction for the presence of allele T in the locus. The sensitivity and specificity were 0.328 and 0.893, respectively. The regression analysis showed that lack of TERT rs2736100 T allele, male gender, and arterial hypertension are the risk factors for the higher value of phasic BEI. Conclusion: The SNP of the TERT gene affects phasic SB intensity. The absence of TERT rs2736100 T allele, male sex, and arterial hypertension are independent risk factors for phasic SB.

Dyskerin: an essential pseudouridine synthase with multifaceted roles in ribosome biogenesis, splicing, and telomere maintenance

Dyskerin and its homologs are ancient and conserved enzymes that catalyze the most common post-transcriptional modification found in cells, pseudouridylation. The resulting pseudouridines provide stability to RNA molecules and regulate ribosome biogenesis and splicing events. Dyskerin does not act independently-it is the core component of a protein heterotetramer, which associates with RNAs that contain the H/ACA motif. The variety of H/ACA RNAs that guide the function of this ribonucleoprotein (RNP) complex highlights the diversity of cellular processes in which dyskerin participates. When associated with small nucleolar (sno) RNAs, it regulates ribosomal (r) RNAs and ribosome biogenesis. By interacting with small Cajal body (sca) RNAs, it targets small nuclear (sn) RNAs to regulate pre-mRNA splicing. As a component of the telomerase holoenzyme, dyskerin binds to the telomerase RNA to modulate telomere maintenance. In a disease context, dyskerin malfunction can result in multiple detrimental phenotypes. Mutations in DKC1, the gene that encodes dyskerin, cause the premature aging syndrome X-linked dyskeratosis congenita (X-DC), a still incurable disorder that typically leads to bone marrow failure. In this review, we present the classical and most recent findings on this essential protein, discussing the evolutionary, structural, and functional aspects of dyskerin and the H/ACA RNP. The latest research underscores the role that dyskerin plays in the regulation of gene expression, translation efficiency, and telomere maintenance, along with the impacts that defective dyskerin has on aging, cell proliferation, haematopoietic potential, and cancer.

Characterization of In Vitro G-Quadruplex Formation of Imetelstat Telomerase Inhibitor

Imetelstat (GRN163L) is a potent and specific telomerase inhibitor currently in clinical development for the treatment of hematological malignancies such as myelofibrosis and myelodysplastic syndrome. It is a 13-mer N3'-P5' thio-phosphoramidate oligonucleotide covalently functionalized at the 5'-end with a palmitoyl lipid moiety through an aminoglycerol linker. As a competitive inhibitor of human telomerase, imetelstat directly binds to the telomerase RNA component sequence (hTR) in the catalytic site of the enzyme and acts as a direct competitor of human telomere binding. Administration of imetelstat causes progressive shortening of the telomeres, thereby inhibiting malignant cells' proliferation. We report here the ability of imetelstat to form stable, parallel, intermolecular G-quadruplex structures in vitro. The impact of the ionic environment on the formation and stability of imetelstat higher-order structure was investigated through circular dichroism spectroscopy, thermal denaturation analysis, and size-exclusion chromatography. We demonstrated that different structural elements, such as the 5'-palmitoyl linker and the thio-phosphoramidate backbone, critically contribute to G-quadruplex stability. Experiments further showed that G-quadruplex formation does not hamper binding to the hTR oligonucleotide sequence in vitro.

Chemical inhibition of PAPD5/7 rescues telomerase function and hematopoiesis in dyskeratosis congenita

Dyskeratosis congenita (DC) is a pediatric bone marrow failure syndrome caused by germline mutations in telomere biology genes. Mutations in DKC1 (the most commonly mutated gene in DC), the 3' region of TERC, and poly(A)-specific ribonuclease (PARN) cause reduced levels of the telomerase RNA component (TERC) by reducing its stability and accelerating TERC degradation. We have previously shown that depleting wild-type DKC1 levels by RNA interference or expression of the disease-associated A353V mutation in the DKC1 gene leads to decay of TERC, modulated by 3'-end oligoadenylation by noncanonical poly(A) polymerase 5 (PAPD5) followed by 3' to 5' degradation by EXOSC10. Furthermore, the constitutive genetic silencing of PAPD5 is sufficient to rescue TERC levels, restore telomerase function, and elongate telomeres in DKC1_A353V mutant human embryonic stem cells (hESCs). Here, we tested a novel PAPD5/7 inhibitor (RG7834), which was originally discovered in screens against hepatitis B viral loads in hepatic cells. We found that treatment with RG7834 rescues TERC levels, restores correct telomerase localization in DKC1 and PARN-depleted cells, and is sufficient to elongate telomeres in DKC1_A353V hESCs. Finally, treatment with RG7834 significantly improved definitive hematopoietic potential from DKC1_A353V hESCs, indicating that the chemical inhibition of PAPD5 is a potential therapy for patients with DC and reduced TERC levels.

A Case of Presumed Dyskeratosis Congenita Causing Severe Retinal Vascular Occlusion

Dyskeratosis congenita (DKC) is a rare, multisystem, bone marrow failure disease characterized by abnormalities such as in the skin, mucosa, nervous system, and lungs. Here we report a rare case of presumed DKC causing total retinal detachment in the right eye and severe peripheral retinal vascular occlusion in the left eye. A 3-year-old boy was presented with vitreous hemorrhage and total retinal detachment in the right eye and was scheduled to undergo vitreous surgery in the right eye and detailed ophthalmologic examination of the left eye under general anesthesia. Since a systemic examination revealed anemia and marked thrombocytopenia, he underwent a detailed pediatric examination. Although genetic testing revealed no significant pathologic mutations, the presence of shortened telomere length and other clinical findings suggested the possibility of DKC. His right eye had severe proliferative vitreoretinopathy, and retinal reattachment was not achieved with vitreous surgery, thus resulting in phthisis bulbi. The left eye showed a wide retinal avascular area in the temporal retina, retinal neovascularization, and hard exudates on fluorescein fundus angiography and was treated with laser photocoagulation using a binocular indirect ophthalmoscopic photocoagulator. Following laser surgery, the new blood vessels regressed, and the visual acuity was maintained at 1.0. The findings in this rare case indicate that DKC can cause severe retinal vascular occlusion, thus leading to vitreous hemorrhage and retinal detachment. Therefore, early detection with fundus examination and early treatment with photocoagulation are important.

Pediatric Nail Disorders

Many pediatric nail findings are normal variants and are no cause for alarm. Others represent congenital abnormalities or genetic syndromes for which there is no cure. Still others are inflammatory or infectious entities that require treatment. Pediatric nail disorders are reviewed, along with management.

Telomere Dysfunction Activates p53 and Represses HNF4α Expression Leading to Impaired Human Hepatocyte Development and Function

BACKGROUND AND AIMS

Telomere attrition is a major risk factor for end-stage liver disease. Due to a lack of adequate models and intrinsic difficulties in studying telomerase in physiologically relevant cells, the molecular mechanisms responsible for liver disease in patients with telomere syndromes remain elusive. To circumvent that, we used genome editing to generate isogenic human embryonic stem cells (hESCs) harboring clinically relevant mutations in telomerase and subjected them to an in vitro, stage-specific hepatocyte differentiation protocol that resembles hepatocyte development in vivo.

APPROACH AND RESULTS

Using this platform, we observed that while telomerase is highly expressed in hESCs, it is quickly silenced, specifically due to telomerase reverse transcriptase component (TERT) down-regulation, immediately after endoderm differentiation and completely absent in in vitro-derived hepatocytes, similar to what is observed in human primary hepatocytes. While endoderm derivation is not impacted by telomere shortening, progressive telomere dysfunction impaired hepatic endoderm formation. Consequently, hepatocyte derivation, as measured by expression of specific hepatic markers as well by albumin expression and secretion, is severely compromised in telomerase mutant cells with short telomeres. Interestingly, this phenotype was not caused by cell death induction or senescence. Rather, telomere shortening prevents the up-regulation and activation of human hepatocyte nuclear factor 4 alpha (HNF4α) in a p53-dependent manner. Both reactivation of telomerase and silencing of p53 rescued hepatocyte formation in telomerase mutants. Likewise, the conditional expression (doxycycline-controlled) of HNF4α, even in cells that retained short telomeres, accrued DNA damage, and exhibited p53 stabilization, successfully restored hepatocyte formation from hESCS.

CONCLUSIONS

Our data show that telomere dysfunction acts as a major regulator of HNF4α during hepatocyte development, pointing to a target in the treatment of liver disease in telomere-syndrome patients.

Dyskeratosis congenita: a literature review

Dyskeratosis congenita is a rare hereditary disease that occurs predominantly in males and manifests clinically as the classic triad of reticulate hyperpigmentation, nail dystrophy and leukoplakia. It increases the risk of malignancy and other potentially lethal complications such as bone marrow failure, lung and liver diseases. Mutations in 19 genes are associated with dyskeratosis congenita, and a fifth of the pathogenic mutations are found in DKC1, the gene coding for dyskerin. This review aims to address the clinical and genetic aspects of the disease.

Chromosomal Breakage in Fanconi Anemia and Consanguineous Marriages: A Social Dilemma for Developing Countries

Introduction A clear picture of the prevalence of Fanconi anemia is not known due to limited studies and research of the subject. This study will detect the frequency of positive chromosomal breakage in pediatric aplastic patients and provide the evidence-based guidelines which help in consideration of appropriate treatment and awareness to the society. Methods A total of 104 aplastic anemia patients were recruited of age <18 years whose samples were tested for chromosomal breakage with mitomycin C (MMC). History of consanguinity between parents were documented for all the patients referred to us. Result Out of 104 diagnosed aplastic anemia patients, 35 (33.7%) patients were found to be Fanconi positive. Mean age of all hypoplastic patients for aplastic anemia and Fanconi anemia was 10.7 ± 4.5 and 10.6 ± 3.5, respectively. Male preponderance was found to be higher (64, 61.5%) as compared to females (40, 38.5%) in aplastic patients. The male to female ratio was observed as 2.5:1 in Fanconi patients while 1.3:1 in non-Fanconi aplastic patients. Parental consanguinity was observed in 33 (94.2%) with Fanconi anemia. Conclusion Fanconi anemia accounts for significant number of patients with hypoplastic bone marrow, therefore consanguineous marriages should be avoided through mass education in Pakistan.

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.

PRDM8 reveals aberrant DNA methylation in aging syndromes and is relevant for hematopoietic and neuronal differentiation

BACKGROUND

Dyskeratosis congenita (DKC) and idiopathic aplastic anemia (AA) are bone marrow failure syndromes that share characteristics of premature aging with severe telomere attrition. Aging is also reflected by DNA methylation changes, which can be utilized to predict donor age. There is evidence that such epigenetic age predictions are accelerated in premature aging syndromes, but it is yet unclear how this is related to telomere length. DNA methylation analysis may support diagnosis of DKC and AA, which still remains a challenge for these rare diseases.

RESULTS

In this study, we analyzed blood samples of 70 AA and 18 DKC patients to demonstrate that their epigenetic age predictions are overall increased, albeit not directly correlated with telomere length. Aberrant DNA methylation was observed in the gene PRDM8 in DKC and AA as well as in other diseases with premature aging phenotype, such as Down syndrome and Hutchinson-Gilford-Progeria syndrome. Aberrant DNA methylation patterns were particularly found within subsets of cell populations in DKC and AA samples as measured with barcoded bisulfite amplicon sequencing (BBA-seq). To gain insight into the functional relevance of PRDM8, we used CRISPR/Cas9 technology to generate induced pluripotent stem cells (iPSCs) with heterozygous and homozygous knockout. Loss of PRDM8 impaired hematopoietic and neuronal differentiation of iPSCs, even in the heterozygous knockout clone, but it did not impact on epigenetic age.

CONCLUSION

Taken together, our results demonstrate that epigenetic aging is accelerated in DKC and AA, independent from telomere attrition. Furthermore, aberrant DNA methylation in PRDM8 provides another biomarker for bone marrow failure syndromes and modulation of this gene in cellular subsets may be related to the hematopoietic and neuronal phenotypes observed in premature aging syndromes.

Inverse changes in telomere length between the blood and brain in depressive-like mice

BACKGROUND

Telomeres are nucleoprotein complexes located at the end of chromosomes. Previous studies have confirmed that telomere length is reduced in the peripheral blood of depression patients. However, studies regarding whether telomere length is altered in brain regions associated with depression are limited. It remains unclear whether the peripheral blood telomere length indicates telomere variation in the brain.

METHODS

Using quantitative PCR, we measured telomere length in five brain regions (prefrontal cortex, amygdala, nucleus accumbens, paraventricular nucleus, and hippocampus) from depressive-like mice and in peripheral blood from depressive-like mice and major depressive disorder (MDD) patients. We also examined the expression of telomerase- and alternative lengthening of telomere (ALT)-related genes in the prefrontal cortex and amygdala of depressive-like mice.

RESULTS

Telomeres were shortened in the peripheral blood of depressive-like mice and MDD patients, but were elongated in the prefrontal cortex and amygdala compared with healthy controls. We also observed that the expression of ALT-related genes increased in the prefrontal cortex and amygdala.

LIMITATIONS

The amount of human sample was limited. The mechanism of telomere lengthening in the brain of depressive-like mice was not well explained. Mice and humans have inherently different telomere and telomere maintenance systems.

CONCLUSION

These findings illustrate that the telomere length in the peripheral blood may not indicate the dynamics of telomere length in the brain. They offer a new perspective on variable telomere length in different brain regions affected in depression and provide a new basis for understanding the relationship between variable telomere length and MDD.

Successful liver transplantation in short telomere syndromes without bone marrow failure due to DKC1 mutation

Short telomere syndromes are a heterogenous spectrum of disorders leading to premature cellular aging. These may involve bone marrow failure, adult-onset idiopathic pulmonary fibrosis, and liver disease, and classical entities such as dyskeratosis congenita. We report a patient who presented with common variable immunodeficiency at 3 years of age and autoimmune cytopenias at 8 years of age. He was found to have short telomeres, and genetic testing confirmed a hemizygous mutation NM_001363.4: c.-142C > G in DKC1 gene. He subsequently developed cirrhosis with severe portal hypertension and hepatopulmonary syndrome, prompting liver transplantation at 11 years of age. He remains well 10 years after transplant with no progression of bone marrow failure or progressive lung disease. In conclusion, short telomere syndromes should be considered as a potential cause of pediatric liver disease of unknown etiology, and in severe cases, isolated liver transplantation may be both appropriate and successful.

Fatal Acute Exacerbation of Familial Interstitial Pneumonia Complicated with Dyskeratosis Congenita after Influenza Virus B Infection

Dyskeratosis congenita (DC) is occasionally complicated in patients with familial interstitial pneumonia (FIP). However, there have been no reports of FIP patients with DC that develop acute exacerbation (AE). We herein report a FIP patient with DC that showed AE of FIP after influenza virus B infection. Although DC is a rare disease in clinical practice, physicians should keep in mind that FIP combined with DC has the potential to cause AE.

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.

Dyskeratosis congenita: presentation of cutaneous triad in a sporadic case

Dyskeratosis congenita (DKC) also known as Zinsser-Cole-Engman syndrome is a progressive genetic disease with a classical presentation characterised by a triad of reticulate pigmentation of skin, nail dystrophy and leukoplakia. It may be a multisystem disease with the involvement of haematological, gastrointestinal, genitourinary, neurological, ophthalmic, pulmonary and skeletal system. We report a sporadic case of DKC presenting with poikiloderma, nail dystrophy and oral leukoplakia.

Long-Term Follow-Up of a Case with Dyskeratosis Congenita Caused by NHP2-V126M/X154R Mutation: Genotype-Phenotype Association

Dyskeratosis congenita (DC) is a rare inherited syndrome characterized by classical mucocutaneous features and the presence of other clinical features including bone marrow failure, pulmonary fibrosis, liver cirrhosis, and a predisposition to cancer. The symptoms develop at various ages and may manifest over time. Gene mutations associated with DC, such as DC1, TERC, TERT, TINF2, NHP2, NOP10, ACD, CTC1, NAF1, PARN, POT1, RTEL1, STN1, and WRAP53, have been identified in about 70% of patients. Since the number of patients with DC is small and the effect of genetic pathogenic variant may affect the phenotype, we wanted to present the clinical features and course of illness in a patient with NHP2 gene mutation (compound heterozygote for the NHP2 mutations c.376G>A/c.460T>A; amino acid substitutions: p.Val126Met and p.X154Arg) that occurred as a compound heterozygous state.

Germ line predisposition to myeloid malignancies appearing in adulthood

INTRODUCTION

Germ line predisposition to myeloid neoplasms has been incorporated in the WHO 2016 classification of myeloid neoplasms and acute leukemia. The new category of disease is named hereditary myeloid disorder (HMD). Although most myeloid neoplasms are sporadic, germ line mutations and familial predisposition can contribute to development of chronic myeloid diseases and acute myeloid leukemia. This finding and upcoming frequent use of genome wide detection of molecular aberrations will lead to a higher detection rate of a genetic predisposition and influence treatment decisions. Hereditary predisposition is responsible for 5-10% of myeloid malignancies. Management of affected patients begins by the awareness of treating physicians of the problem and a precise work up of the patient and family members. Areas covered: This review focuses on current knowledge about germ line predisposition for myeloid neoplasms including diagnostic, prognostic, and therapeutic aspects in adult patients. Essential information for clinical routine is provided. Expert commentary: Compared to a patient without predisposition, adaptation of treatment strategy for patients with an HMD is often necessary, especially to avoid higher risk of relapse or higher toxicity during chemotherapy or transplantation. Mistakes in choice of a related donor can be omitted. Relatives at risk of developing a HMD need specific surveillance.

Epitranscriptomics of cancer

The functional impact of modifications of cellular RNAs, including mRNAs, miRNAs and lncRNAs, is a field of intense study. The role of such modifications in cancer has started to be elucidated. Diverse and sometimes opposite effects of RNA modifications have been reported. Some RNA modifications promote, while others decrease the growth and invasiveness of cancer. The present manuscript reviews the current knowledge on the potential impacts of N6-Methyladenosine, Pseudouridine, Inosine, 2’O-methylation or methylcytidine in cancer’s RNA. It also highlights the remaining questions and provides hints on research avenues and potential therapeutic applications, whereby modulating dynamic RNA modifications may be a new method to treat cancer.

A unique homozygous WRAP53 Arg298Trp mutation underlies dyskeratosis congenita in a Chinese Han family

BACKGROUND

Dyskeratosis congenita (DC) is an inherited telomeropathy characterized by mucocutaneous dysplasia, bone marrow failure, cancer predisposition, and other somatic abnormalities. Cells from patients with DC exhibit short telomere. The genetic basis of the majority of DC cases remains unknown.

METHODS

A 2 generational Chinese Han family with DC was studied using targeted capture and next-generation sequencing to identify the underlying DC-related mutations.

RESULTS

In this study, we identified a unique homozygous WD repeat containing antisense to TP53 (WRAP53) Arg298Trp mutation in the proband with DC and heterozygous WRAP53 Arg298Trp mutations in his asymptomatic, consanguineous parents and his sister, indicating an autosomal recessive inheritance mode. The proband with the homozygous WRAP53 Arg298Trp mutation had short telomere, classic clinical symptoms, and no response to danazol, glucocorticoid or cyclosporin A.

CONCLUSIONS

Thus, we reported for the first time that a unique homozygous WRAP53 mutation site underlies the development of DC.

The Biology of Aging and Cancer: A Brief Overview of Shared and Divergent Molecular Hallmarks

Aging is the inevitable time-dependent decline in physiological organ function and is a major risk factor for cancer development. Due to advances in health care, hygiene control and food availability, life expectancy is increasing and the population in most developed countries is shifting to an increasing proportion of people at a cancer susceptible age. Mechanisms of aging are also found to occur in carcinogenesis, albeit with shared or divergent end-results. It is now clear that aging and cancer development either share or diverge in several disease mechanisms. Such mechanisms include the role of genomic instability, telomere attrition, epigenetic changes, loss of proteostasis, decreased nutrient sensing and altered metabolism, but also cellular senescence and stem cell function. Cancer cells and aged cells are also fundamentally opposite, as cancer cells can be thought of as hyperactive cells with advantageous mutations, rapid cell division and increased energy consumption, while aged cells are hypoactive with accumulated disadvantageous mutations, cell division inability and a decreased ability for energy production and consumption. Nonetheless, aging and cancer are tightly interconnected and many of the same strategies and drugs may be used to target both, while in other cases antagonistic pleiotrophy come into effect and inhibition of one can be the activation of the other. Cancer can be considered an aging disease, though the shared mechanisms underpinning the two processes remain unclear. Better understanding of the shared and divergent pathways of aging and cancer is needed.

Fungal Ribotoxins: A Review of Potential Biotechnological Applications

Fungi establish a complex network of biological interactions with other organisms in nature. In many cases, these involve the production of toxins for survival or colonization purposes. Among these toxins, ribotoxins stand out as promising candidates for their use in biotechnological applications. They constitute a group of highly specific extracellular ribonucleases that target a universally conserved sequence of RNA in the ribosome, the sarcin-ricin loop. The detailed molecular study of this family of toxic proteins over the past decades has highlighted their potential in applied research. Remarkable examples would be the recent studies in the field of cancer research with promising results involving ribotoxin-based immunotoxins. On the other hand, some ribotoxin-producer fungi have already been studied in the control of insect pests. The recent role of ribotoxins as insecticides could allow their employment in formulas and even as baculovirus-based biopesticides. Moreover, considering the important role of their target in the ribosome, they can be used as tools to study how ribosome biogenesis is regulated and, eventually, may contribute to a better understanding of some ribosomopathies.

Changes of telomere status with aging: An update

Accumulated data have shown that most human somatic cells or tissues show irreversible telomere shortening with age, and that there are strong associations between telomere attrition and aging-related diseases, including cancers, diabetes and cognitive disorders. Although it has been largely accepted that telomere attrition is one of the major causes of aging-related disorders, critical aspects of telomere biology remain unresolved, especially the lack of standardized methodology for quantification of telomere length. Another frustrating issue is that no potentially promising methods for safe prevention of telomere erosion, or for telomere elongation, have been devised. Here, we review several methods for quantification of telomere length currently utilized worldwide, considering their advantages and drawbacks. We also summarize the results of our recent studies of human cells and tissues, mainly using quantitative fluorescence in situ hybridization and Southern blotting, including those derived from patients with progeria-prone Werner syndrome and trisomy 21, and several strains of induced pluripotent stem cells. We discuss the possible merits of using telomere shortness as an indicator, or a new marker, for diagnosis of precancerous states and aging-related disorders. In addition, we describe newly found factors that are thought to impact telomere dynamics, providing a new avenue for examining the unsolved issues related to telomere restoration and maintenance.

Zinsser-Cole-Engman Syndrome: A Rare Case Report

Zinsser-Cole-Engmann syndrome also called Dyskeratosis Congenita (DKC) is a rare genodermatosis first described by Zinsser in 1906. Mutations in DKC1 gene is responsible for DKC. It is usually inherited as an X-linked recessive trait, resulting in a striking male predilection. It is characterized by a triad of reticular skin pigmentation, nail dystrophy and mucosal leukoplakia. Complications include predisposition to malignancy and bone marrow failure. Here, we report a case of DKC in a 9-year-old boy with classic triad of signs. Special investigations like endoscopy, barium swallow and bone-marrow aspiration study confirmed the diagnosis. There is no effective treatment for DKC. Some preventive measures can be adopted and the only long term cure for the haematological abnormalities is allogenic haemopoietic stem cell transplantation.

Dyskerin and TERC expression may condition survival in lung cancer patients

Dyskerin mediates both the modification of uridine on ribosomal and small nuclear RNAs and the stabilization of the telomerase RNA component (TERC). In human tumors dyskerin expression was found to be associated with both rRNA modification and TERC levels. Moreover, dyskerin overexpression has been linked to unfavorable prognosis in a variety of tumor types, however an explanation for the latter association is not available. To clarify this point, we analyzed the connection between dyskerin expression, TERC levels and clinical outcome in two series of primary lung cancers, differing for the presence of TERC gene amplification, a genetic alteration inducing strong TERC overexpression. TERC levels were significantly higher in tumors bearing TERC gene amplification (P = 0.017). In addition, the well-established association between dyskerin expression and TERC levels was observed only in the series without TERC gene amplification (P = 0.003), while it was not present in TERC amplified tumors (P = 0.929). Similarly, the association between dyskerin expression and survival was found in cases not bearing TERC gene amplification (P = 0.009) and was not observed in TERC amplified tumors (P = 0.584). These results indicate that the influence of dyskerin expression on tumor clinical outcome is linked to its role on the maintenance of high levels of TERC.

Fatal transfusion-transmitted infection due to Citrobacter koseri

BACKGROUND

Transfusion-transmitted bacterial infection (TTBI) is still one of the most feared complications of blood transfusion.

CASE REPORT

We report a fatal case involving an 8-year-old child with congenital dyskeratosis complicated by severe aplastic anemia who was regularly transfused with platelet (PLT) concentrates for 5 years. The patient received an apheresis PLT concentrate (APC) on Day 0 due to thrombocytopenia complicated by mucocutaneous hemorrhage. Thirty minutes after the start of the transfusion, bradycardia and dyspnea appeared, quickly followed by chills, nausea, vomiting, headache, and hyperthermia. TTBI was suspected and the patient was immediately treated with intravascular antibiotherapy. On Day 3, the patient developed severe acute respiratory distress syndrome leading to death on Day 7. Patient blood cultures and APC cultures were both positive for Citrobacter koseri.

RESULTS

The donor was a 19-year-old woman. She had previously given blood. No infectious symptom was reported during the medical interviews before and after the donation and no postdonation information was received. On the day of the donation (Day -2), her white blood cell count was 5.83 × 10⁹ /L. She came back on Day 8 to undergo additional tests. The cultures from blood, stool, urine, the skin of the inside of the elbow at the point of needle insertion, and ear samples were all negative for C. koseri. However, a nasal sample was positive for C. koseri.

CONCLUSION

The isolates from the donor's blood cultures, the APC bag, the attached tube, and the donor's nasal sample all gave identical profiles; they were thus identified as the same strain and the TTBI was confirmed.

Juvenile Idiopathic Inflammatory Myopathy in a Patient With Dyskeratosis Congenita Due to C16orf57 Mutation

Dyskeratosis congenita (DC) is a rare inherited disorder characterized by reticular skin pigmentation, oral cavity leukoplakia, and nail dystrophy. A variety of noncutaneous (dental, pulmonary, gastrointestinal, neurological, genitourinary, ophthalmic, and skeletal) abnormalities also have been reported. An 8-year-old boy with DC developed juvenile idiopathic inflammatory myopathy. C16orf57 mutation was identified as a genetic cause of DC. Treatment with methylprednisolone was initiated, followed with methotrexate, prednisolone, and high-dose intravenous immunoglobulin treatment. This is the first report on a patient with juvenile idiopathic inflammatory myopathy and DC.

Human telomere biology: A contributory and interactive factor in aging, disease risks, and protection

Telomeres are the protective end-complexes at the termini of eukaryotic chromosomes. Telomere attrition can lead to potentially maladaptive cellular changes, block cell division, and interfere with tissue replenishment. Recent advances in the understanding of human disease processes have clarified the roles of telomere biology, especially in diseases of human aging and in some aging-related processes. Greater overall telomere attrition predicts mortality and aging-related diseases in inherited telomere syndrome patients, and also in general human cohorts. However, genetically caused variations in telomere maintenance either raise or lower risks and progression of cancers, in a highly cancer type-specific fashion. Telomere maintenance is determined by genetic factors and is also cumulatively shaped by nongenetic influences throughout human life; both can interact. These and other recent findings highlight both causal and potentiating roles for telomere attrition in human diseases.

Clinical and genetic features of dyskeratosis congenita, cryptic dyskeratosis congenita, and Hoyeraal-Hreidarsson syndrome in Japan

Dyskeratosis congenita (DKC) is an inherited bone marrow failure (BMF) syndrome typified by reticulated skin pigmentation, nail dystrophy, and mucosal leukoplakia. Hoyeraal-Hreidarsson syndrome (HHS) is considered to be a severe form of DKC. Unconventional forms of DKC, which develop slowly in adulthood but without the physical anomalies characteristic of DKC (cryptic DKC), have been reported. Clinical and genetic features of DKC have been investigated in Caucasian, Black, and Hispanic populations, but not in Asian populations. The present study aimed to determine the clinical and genetic features of DKC, HHS, and cryptic DKC among Japanese patients. We analyzed 16 patients diagnosed with DKC, three patients with HHS, and 15 patients with cryptic DKC. We found that platelet count was significantly more depressed than neutrophil count or hemoglobin value in DKC patients, and identified DKC patients with large deletions in the telomerase reverse transcriptase and cryptic DKC patients with RTEL1 mutations on both alleles. This led to some patients previously considered to have unclassifiable BMF being diagnosed with cDKC through identification of new gene mutations. It thus seems important from a clinical viewpoint to re-examine the clinical characteristics, frequency of genetic mutations, and treatment efficacy in DKC, HHS, and cDKC.

Novel Mutation of the TINF2 Gene in a Patient with Dyskeratosis Congenita

Dyskeratosis congenita (DKC) is a rare inherited disease that is characterized by abnormal skin pigmentation, nail dystrophy and mucosal leukoplakia. DKC is caused by an abnormality in a component of the telomerase and shelterin complexes. TINF2 encodes a protein in the shelterin complex and TERC encodes a component of the telomerase complex. Mutations of both genes have been associated with DKC. This study examined mutations in TINF2.

A case report on a rare disease: dyskeratosis congenita

Dyskeratosis congenita (DC) is a rare hereditary disorder characterized by bone marrow failure, cancer predisposition (11-fold increase compared to general population), ectodermal dysplasia (nail dystrophy, oral leukoplakia, and abnormal skin pigmentation) and other additional somatic abnormalities. A 22-year-old man presented with fever, chills, and a painful throat. Leukoplakia was noted on his tongue and some of his fingers and toe nails were markedly dystrophic. His skin seemed spotted with pigmentation on the anterior chest and neck. Patient reported family history of “blood disease” and leukemia. He was admitted for the management of neutropenic fever (102.9 °F, WBC: 940, ANC: 404, platelets: 21,000 and Hb: 9.2), and was put on broad spectrum antibiotics. A bone marrow biopsy revealed normocellular marrow with erythroid predominance and mild dyserythropoiesis. Chromosomal analysis indicated no numerical or structural chromosomal abnormalities. The fluorescence in situ hybridization report did not reveal any assay specific abnormalities. Viral marker for hepatitis and studies of autoimmune antibodies showed negative results. CT scan had shown splenomegaly. Patient was discharged after he has been fever and symptoms free, with a follow-up at hematology clinic. Individuals with DC most commonly present with skin pigmentation, dystrophic nails and leukoplakia, as presented in this case. Genetic abnormality was not confirmed in our patient, but it is suggested that X-linked recessive pattern would be significant because of greater prevalence in men than in women (10:1). The distribution of blood counts and bone marrow biopsy categorizes our patient in the moderate aplastic anemia class which is the most prevalent pattern. When fever in young patients with a failing bone marrow is diagnosed, it is important that physicians rule out the possible underlying causes. DC is a rare disease, but can be diagnosed by simple inspection of the mucocutaneous abnormalities. DC is a severe multisystem disorder associated with premature morbidity and mortality. We believe that reporting this case would add more information to the existing fund of knowledge.

Structure and interactions of the CS domain of human H/ACA RNP assembly protein Shq1

Shq1 is an essential protein involved in the early steps of biogenesis and assembly of H/ACA ribonucleoprotein particles (RNPs). Shq1 binds to dyskerin (Cbf5 in yeast) at an early step of H/ACA RNP assembly and is subsequently displaced by the H/ACA RNA. Shq1 contains an N-terminal CS and a C-terminal Shq1-specific domain (SSD). Dyskerin harbors many mutations associated with dyskeratosis congenita. Structures of yeast Shq1 SSD bound to Cbf5 revealed that only a subset of these mutations is in the SSD binding site, implicating another subset in the putative CS binding site. Here, we present the crystal structure of human Shq1 CS (hCS) and the nuclear magnetic resonance (NMR) and crystal structures of hCS containing a serine substitution for proline 22 that is associated with some prostate cancers. The structure of hCS is similar to yeast Shq1 CS domain (yCS) and consists of two β-sheets that form an immunoglobulin-like β-sandwich fold. The N-terminal affinity tag sequence AHHHHHH associates with a neighboring protein in the crystal lattice to form an extra β-strand. Deletion of this tag was required to get spectra suitable for NMR structure determination, while the tag was required for crystallization. NMR chemical shift perturbation (CSP) experiments with peptides derived from putative CS binding sites on dyskerin and Cbf5 revealed a conserved surface on CS important for Cbf5/dyskerin binding. A HADDOCK (high-ambiguity-driven protein-protein docking) model of a Shq1-Cbf5 complex that defines the position of CS domain in the pre-H/ACA RNP was calculated using the CSP data.

Novel insights into the evolution and structural characterization of dyskerin using comprehensive bioinformatics analysis

Dyskerin is a conserved nucleolar protein. Several related genetic diseases are caused by defects in dyskerin. We hypothesized that having a comprehensive bioinformatic analysis of dyskerin will help to develop new drugs for this diseases. We predicted protein domains and compared sequences and structures to detect the universe of dyskerin-like proteins. We identified conserved features of shared domains in the three superkingdoms. We analyzed the phylogenetic diversity, confirming that there is a strong structural conservation. Also, we studied the relationship of dyskerin-like proteins with other proteins through an integrative protein-protein interaction approach. Most of them are conserved among homologous eukaryotic and archaeal proteins. Our results highlighted the preservation of proteins interacting with dyskerin. We identified conserved dyskerin interactor proteins between the different eukaryotes organisms. Furthermore, we studied the existence of dyskerin-like proteins in different species. Also, we compared and analyzed the secondary structure with the hydrophobic profile, confirming that all have hydrophilic properties highly conserved among proteins. The greatest difference was observed in the NTE and CTE regions. Another aspect studied was the comparison and analysis of tertiary structures. In our knowledge, this is the first time that these analyses were performed in such a comprehensive manner.