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Role of SCN5A coding and non-coding sequences in Brugada syndrome onset: What's behind the scenes?
Daimi, H, Khelil, AH, Neji, A, Ben Hamda, K, Maaoui, S, Aranega, A, Be Chibani, J, Franco, D
Biomedical journal. 2019;(4):252-260
Abstract
BACKGROUND Brugada syndrome (BrS) is a rare inherited cardiac arrhythmia associated with a high risk of sudden cardiac death (SCD) due to ventricular fibrillation (VF). BrS is characterized by coved-type ST-segment elevation in the right precordial leads (V1-V3). Mutations in SCN5A gene coding for the α-subunit of the NaV1.5 cardiac sodium channel are identified in 15-30% of BrS cases. Genetic testing of BrS patients generally involves sequencing of the protein-coding portions and flanking intronic regions of SCN5A. This excludes the 5'UTR and 3'UTR from the routine genetic testing. METHODS We here screened the coding sequence, the flanking intronic regions as well as the 5' and 3'UTR regions of SCN5A gene and further five candidate genes (GPD1L, SCN1B, KCNE3, SCN4B, and MOG1) in a Tunisian family diagnosed with BrS. RESULTS A new SCN5A-Q1000K mutation was identified along with two common polymorphisms (H558R and D1819). Multiple genetic variants were identified on the SCN5A 3'UTR, one of which is predicted to create additional microRNA binding site for miR-1270. Additionally, we identified the hsa-miR-219a-rs107822. No relevant coding sequence variant was identified in the remaining studied candidate genes. CONCLUSIONS The absence of genotype-phenotype concordance within all the identified genetic variants in this family gives extra evidences about the complexity of the disease and suggests that the occurrence and prognosis of BrS is most likely controlled by a combination of multiple genetic factors, rather than a single variant. Most SCN5A variants were localized in non-coding regions hypothesizing an impact on the miRNA-target complementarities.
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2.
Novel mutations in c2orf71 causing an early onset form of cone-rod dystrophy: A molecular diagnosis after 20 years of clinical follow-up.
Serra, R, Floris, M, Pinna, A, Boscia, F, Cucca, F, Angius, A
Molecular vision. 2019;:814-820
Abstract
PURPOSE Cone rod-dystrophies (CRDs) are pigmentary retinopathies mainly involving cones. CRDs typically present with decreased visual acuity and loss of sensitivity in the central visual field, reflecting the primary dysfunction of cones associated with night blindness and concentric visual field loss due to rod dysfunction. We describe the phenotype, natural history, and molecular analysis results of an early onset form of CRD. METHODS An otherwise healthy 25-year-old man from Sardinia, Italy, initially presented with subacute visual loss and central scotoma in both eyes. He underwent a complete ophthalmic examination, electrophysiologic testing, and genetic counseling. We first applied a candidate gene approach on ABCA4 to detect mutations; then, we performed exome sequencing (WES) on all family members to identify causative mutations. RESULTS The ophthalmic examination was unremarkable except the fundus examination, which revealed a well-circumscribed ring-shaped area of choroidal and RPE atrophy surrounding the fovea in the left eye and small white patches of atrophy around the fovea in the right eye. The ocular features and medical history were consistent with a diagnosis of CRD. Twenty years later, he showed a marked impairment in visual function, secondary to severe atrophic maculopathy associated with sparse pigmentary deposits. Molecular analysis identified two novel frameshift mutations in C2orf71: c.3039dupC: p.Ser1014Leufs*93 and c.1804_1805delAG:p. His603Argfs*77. CONCLUSIONS The mutations in C2orf71 reported in this study comprise protein truncation mutations, which are likely to be involved in the pathogenesis of this severe form of early onset CRD.
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3.
When tumor doesn't read textbook. Third case of TTF1 and p40 co-expression in the same tumour cells in a non-small cell carcinoma. A potential new entity to consider?
Spinelli, M, Khorshad, J, Viola, P
Pathologica. 2019;(2):58-61
Abstract
INTRODUCTION The 2011 WHO Classification for lung adenocarcinoma enlightened the need for a wise use of immunohistochemistry to preserve tissue for both diagnosis and molecular studies. The current recommendation is to use a panel comprising TTF1 and p40 to classify tumors with no clear squamous or glandular differentiation as many studies have showed the higher specificity of p40 over p63 as marker of squamous differentiation. However, the co-expression of both markers opens a new scenario with subsequent classification and potentially treatment issues. MATERIALS AND METHODS We report a case of a non-small lung cell carcinoma (NSCLC) with coexistent expression of TTF1 and p40 in the same tumour cells. To our knowledge, this peculiar immunohistochemical profile is very rare, and thus a review of the clinical and molecular features including molecular variances of the tumour was performed. Review of the pertinent literature was also carried out. RESULTS Two additional articles describing unusual cases of NSCLC with coexistent expression of TTF1 and p40 were found and compared to our case. Interestingly, they all carried out aberrant mutation in TP53 oncogene and were of advance stage. CONCLUSION The positivity for both "squamous" and "adenocarcinomatous" markers and mutations of TP53 could be the expression of a not fully recognized variant of NSCLC with possible implications for classification, diagnosis and therapy.
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4.
Diseases caused by mutations in luteinizing hormone/chorionic gonadotropin receptor.
Qiao, J, Han, B
Progress in molecular biology and translational science. 2019;:69-89
Abstract
Accumulating evidence showed that the luteinizing hormone/chorionic gonadotropin receptor (LHCGR) is an essential regulator of sexual development and reproduction from zebrafish to human. Activating and inactivating mutations of LHCGR gene have been identified from patients of different phenotypes. Familial male-limited precocious puberty, Leydig cell hypoplasia, and empty follicle syndrome are caused by LHCGR mutations. More than 50 mutations have been reported from subjects of different ethnic backgrounds. Functional analyses of the mutant LHCGR revealed multiple defects, including cell surface expression, ligand binding, and signaling. The difference of the two native ligands and signaling pathway activated by LHCGR are illustrated. Potential therapeutic implications from the analyses of the naturally occurring LHCGR mutations, such as pharmacological chaperones, are highlighted.
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5.
Irregularities in genetic variation and mutation rates with environmental stresses.
Ferenci, T
Environmental microbiology. 2019;(11):3979-3988
Abstract
The appearance of new mutations is determined by the equilibrium between DNA error formation and repair. In bacteria like Escherichia coli, stresses are thought shift this balance towards increased mutagenesis. Recent findings, however, suggest a very uneven relationship between stress and mutations. Only a subset of stressful environments increase the net rate of mutation and different forms of nutritional stress (such as oxygen, carbon or phosphorus limitations) result in markedly different mutation rates after similar reductions in growth rate. Moreover, different stresses result in altered mutational spectra, with some increasing transposition and others increasing indel formation. Single-base substitution rates are lower with some stresses than in unstressed bacteria. Indeed, changes to the mix of mutations with stress are more widespread than a marked increase in net mutation rate. Much remains to be learned on how environments have unique mutational signatures and why some stresses are more mutagenic than others. Even beyond stress-induced genetic variation, the fundamental unresolved question in the stress-mutation relationship is the adaptive value of different types of mutations and mutation rates; is transposition, for example, more advantageous under anaerobic conditions? It remains to be investigated whether stress-specific genetic variation impacts on evolvability differentially in distinct environments.
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6.
Novel FBN1 Heterozygous Mutations Identified in Chinese Families with Marfan Syndrome.
Yao, X, Wu, J, Chen, J
Annals of clinical and laboratory science. 2019;(4):539-545
Abstract
OBJECTIVE To detect the mutations in the fibronectin-1 gene (FBN1) of four Chinese families with autosomal dominant Marfan syndrome (MFS), and to discuss the associated phenotypes. METHODS We examined ten patients, and five non-carriers, in four Chinese families with autosomal dominant Marfan syndrome (MFS) for FBN1 mutations. Comprehensive physical, ophthalmic, and cardiovascular examinations were performed on the family members. The FBN1 gene was amplified with PCR from the DNA of the patients and their relatives. The amplified products were sequenced and compared with a reference sequence from the GenBank database. The changes in the structure and function of the protein caused by the amino acid substitution were investigated with a bioinformatics analysis. RESULTS In our study, sequencing FBN1 revealed three novel mutations, and one mutation which was found earlier in 2012. One of the novel mutations is c.649T>C in exon 7, which results in the substitution tryptophan by arginine at codon 217 (p.Trp217Arg), the other is a splice defect in intron 39 (c.4816+1G>A), and the third one is c.407G>T in exon 5, which altered an amino acid at residue 136 from Cysteine to Phenylalanine (p.Cys136Phe). The recurrent mutation was c.4151T>C in exon 34, resulting in methionine being replaced by threonine (p.Met1384Thr). The occurrence of the mutations correlated strongly with the phenotypes of the patients, and no mutation was detected in the normal relatives of the affected patients. CONCLUSIONS In this study, three novel and a recurrent FBN1 mutations were detected. The results expand the mutation spectrum of FBN1, helping in the study of molecular pathogenesis of MFS and Marfan-related disorders.
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7.
Pediatric Erythromelalgia and SCN9A Mutations: Systematic Review and Single-Center Case Series.
Arthur, L, Keen, K, Verriotis, M, Peters, J, Kelly, A, Howard, RF, Dib-Hajj, SD, Waxman, SG, Walker, SM
The Journal of pediatrics. 2019;:217-224.e9
Abstract
OBJECTIVES To evaluate the clinical features of erythromelalgia in childhood associated with gain-of-function SCN9A mutations that increase activity of the Nav1.7 voltage-gated sodium channel, we conducted a systematic review of pediatric presentations of erythromelalgia related to SCN9A mutations, and compared pediatric clinical presentations of symptomatic erythromelalgia, with or without SCN9A mutations. STUDY DESIGN PubMed, Embase, and PsycINFO Databases were searched for reports of inherited erythromelalgia in childhood. Clinical features, management, and genotype were extracted. Case notes of pediatric patients with erythromelalgia from the Great Ormond Street Hospital Pain Service were reviewed for clinical features, patient-reported outcomes, and treatments. Children aged over 10 years were recruited for quantitative sensory testing. RESULTS Twenty-eight publications described erythromelalgia associated with 15 different SCN9A gene variants in 25 children. Pain was severe and often refractory to multiple treatments, including nonspecific sodium channel blockers. Skin damage or other complications of cold immersion for symptomatic relief were common (60%). SCN9A mutations resulting in greater hyperpolarizing shifts in Nav1.7 sodium channels correlated with symptom onset at younger ages (P = .016). Variability in reporting, and potential publication bias toward severe cases, limit any estimations of overall prevalence. In our case series, symptoms were similar but comorbidities were more common in children with SCN9A mutations. Quantitative sensory testing revealed marked dynamic warm allodynia. CONCLUSIONS Inherited erythromelalgia in children is associated with difficult-to-manage pain and significant morbidity. Standardized reporting of outcome and management in larger series will strengthen identification of genotype-phenotype relationships. More effective long-term therapies are a significant unmet clinical need.
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8.
[Sitosterolemia (phytosterolemia)].
Lütjohann, D
Der Internist. 2019;(8):871-877
Abstract
Sitosterolemia or phytosterolemia is a rare autosomal recessive hereditary lipid storage disorder. It is caused by homozygous or compound heterozygous mutations in one of the two ABCG5 and ABCG8 genes encoding the intestinal and hepatic heterodimer ABCG5 (sterolin 1)/ABCG8 (sterolin 2) efflux transporters. These mutations lead to intestinal hyperabsorption and reduced hepatic secretion of cholesterol and plant sterols with subsequent accumulation of phytosterols and cholesterol in plasma and deposition in tissue (xanthoma). Phytosterols are found mainly in vegetable oils, margarine, nuts, grains, soybeans and avocados. Patients with sitosterolemia show extreme phenotypic heterogeneity from almost asymptomatic individuals to those with combined severe hypercholesterolemia at a young age, leading to increased atherosclerosis and premature cardiac death. Early abnormalities include hemolytic anemia with stomatocytosis, macrothrombocytopenia and splenomegaly. In addition to strict avoidance of phytosterol-containing foods, the use of the sterol absorption inhibitor ezetimibe, possibly in combination with the bile acid-binding resin cholestyramine, is the most effective treatment option.
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9.
Diseases associated with mutations in CNGA3: Genotype-phenotype correlation and diagnostic guideline.
Sun, W, Zhang, Q
Progress in molecular biology and translational science. 2019;:1-27
Abstract
Along with the molecular and functional characterization of CNGA3, knowledge about diseases associated with CNGA3 mutations has made great progress. So far, CNGA3 mutations are not only one of the most common causes of achromatopsia and cone dystrophy or cone-rod dystrophy but also one of the most commonly mutated genes among various forms of retinopathy. Understanding the clinical characteristics of CNGA3-associated retinal diseases may help clinical practice of infants or children with related diseases. Recognizing the importance of CNGA3 in inherited retinal diseases may enhance related research in searching for functional restoration or repair of CNGA3 defects.
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10.
A CIB1 Splice-Site Founder Mutation in Families with Typical Epidermodysplasia Verruciformis.
Vahidnezhad, H, Youssefian, L, Saeidian, AH, Mansoori, B, Jazayeri, A, Azizpour, A, Hesari, KK, Yousefi, M, Zeinali, S, Jouanguy, E, et al
The Journal of investigative dermatology. 2019;(5):1195-1198