scholarly journals Broadening the Mutation Spectrum in GJA8 and CHMP4B: Novel Missense Variants and the Associated Phenotypes in Six Chinese Han Congenital Cataracts Families

2021 ◽  
Vol 8 ◽  
Author(s):  
Xun Wang ◽  
Dongni Wang ◽  
Qiwei Wang ◽  
Weiming Huang ◽  
Meimei Dongye ◽  
...  
Keyword(s):  
Transmembrane Domain ◽  
Computational Prediction ◽  
Bioinformatic Analysis ◽  
Mutation Spectrum ◽  
Chinese Patients ◽  
Missense Mutations ◽  
Chinese Han ◽  
Congenital Cataracts ◽  
Missense Variants ◽  
And Function

Purpose: To broaden the mutation and phenotype spectrum of the GJA8 and CHMP4B genes and to reveal genotype-phenotype correlations in a cohort of Chinese patients with congenital cataracts (CCs).Methods: Six Chinese Han families with CCs inherited in an autosomal dominant (AD) pattern were recruited for this study. All patients underwent full ocular examinations. Genomic DNA was extracted from the leukocytes of peripheral blood collected from all available patients and their unaffected family members. Whole-exome sequencing (WES) was performed on all probands and at least one of their parents. Candidate variants were further confirmed by Sanger sequencing. Bioinformatic analysis with several computational predictive programs was performed to assess the impacts of the candidate variants on the structure and function of the proteins.Results: Four heterozygous candidate variants in three different genes (CRYBB2, GJA8, and CHMP4B) were identified in affected individuals from the six families, including two novel missense variants (GJA8: c.64G > C/p. G22R, and CHMP4B: c.587C > G/p. S196C), one missense mutation (CRYBB2: c.562C > T/p. R188C), and one small deletion (GJA8: c.426_440delGCTGGAGGGGACCCT/p.143_147delLEGTL). The three missense mutations were predicted as deleterious in all four computational prediction programs. In the homologous model, the GJA8: p.143_147delLEGTL mutation showed a sequence deletion of five amino acids at the cytoplasmic loop of the Cx50 protein, close to the third transmembrane domain. Patients carrying mutations in the same gene showed similar cataract phenotypes at a young age, including total cataracts, Y-sutural with fetal nuclear cataracts, and subcapsular cataracts.Conclusion: This study further expands the mutation spectrum and genotype-phenotype correlation of CRYBB2, GJA8, and CHMP4B underlying CCs. This study sheds light on the importance of comparing congenital cataract phenotypes in patients at the same age stage. It offers clues for the pathogenesis of CCs and allows for an early prenatal diagnosis for families carrying these genetic variants.

Genetic mutation analysis of 22 patients with congenital absence of vas deferens: A single-center study

2021 ◽  
Author(s):  
Mao-Qing Tan ◽  
Wu-Jian Huang ◽  
Feng-Hua Lan ◽  
Yong-Jun Xu ◽  
Mei-Yu Zheng ◽  
...  
Keyword(s):  
Vas Deferens ◽  
Bioinformatic Analysis ◽  
Genetic Mutation ◽  
Congenital Absence ◽  
Chinese Patients ◽  
Obstructive Azoospermia ◽  
Missense Mutations ◽  
Transmembrane Conductance Regulator ◽  
Transmembrane Conductance ◽  
Single Center Study

Abstract Congenital absence of the vas deferens (CAVD), a congenital malformation of the male reproductive system, causes obstructive azoospermia and male infertility. Currently, the cystic fibrosis transmembrane conductance regulator (CFTR) has been recognized as the main pathogenic gene in CAVD, with some other genes, such as adhesion G-protein coupled receptor G2 (ADGRG2), solute carrier family 9 isoform 3 (SLC9A3), sodium channel epithelial 1 subunit beta (SCNN1B), and carbonic anhydrase 12 (CA12) being candidate genes in the pathogenesis of CAVD. However, the frequency and spectrum of these mutations, as well as the pathogenic mechanisms of CAVD, have not been fully investigated. Here, we sequenced all genes with potentially pathogenic mutations using next-generation sequencing and verified all identified variants by Sanger sequencing. Further bioinformatic analysis was performed to predict the pathogenicity of mutations. We described the distribution of the p.V470M, poly-T, and TG-repeat CFTR polymorphisms, and identified novel missense mutations in the CFTR and SLC9A3 genes, respectively. Taken together, we identified mutations in the CFTR, ADGRG2, SLC9A3, SCNN1B, and CA12 genes in 22 patients with CAVD, thus broadening the genetic spectrum of Chinese patients with CAVD.

scholarly journals Probing biophysical sequence constraints within the transmembrane domains of rhodopsin by deep mutational scanning

2020 ◽  
Vol 6 (10) ◽  
pp. eaay7505 ◽  
Author(s):  
Wesley D. Penn ◽  
Andrew G. McKee ◽  
Charles P. Kuntz ◽  
Hope Woods ◽  
Veronica Nash ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Transmembrane Domain ◽  
Evolutionary Analysis ◽  
Missense Mutations ◽  
Evolutionary Sequence ◽  
Membrane Expression ◽  
Plasma Membrane Expression ◽  
Tm Domain ◽  
And Function ◽  
Sequence Constraints

Membrane proteins must balance the sequence constraints associated with folding and function against the hydrophobicity required for solvation within the bilayer. We recently found the expression and maturation of rhodopsin are limited by the hydrophobicity of its seventh transmembrane domain (TM7), which contains polar residues that are essential for function. On the basis of these observations, we hypothesized that rhodopsin’s expression should be less tolerant of mutations in TM7 relative to those within hydrophobic TM domains. To test this hypothesis, we used deep mutational scanning to compare the effects of 808 missense mutations on the plasma membrane expression of rhodopsin in HEK293T cells. Our results confirm that a higher proportion of mutations within TM7 (37%) decrease rhodopsin’s plasma membrane expression relative to those within a hydrophobic TM domain (TM2, 25%). These results in conjunction with an evolutionary analysis suggest solvation energetics likely restricts the evolutionary sequence space of polar TM domains.

scholarly journals Mutational Characteristics of Causative Genes in Chinese Hereditary Spherocytosis Patients: a Report on Fourteen Cases and a Review of the Literature

2021 ◽  
Vol 12 ◽  
Author(s):  
Dong Wang ◽  
Li Song ◽  
Li Shen ◽  
Kaihui Zhang ◽  
Yuqiang Lv ◽  
...  
Keyword(s):  
Hereditary Spherocytosis ◽  
Clinical Information ◽  
Mutation Spectrum ◽  
Chinese Patients ◽  
Missense Mutations ◽  
Review Of The Literature ◽  
Entire Region ◽  
Causative Gene ◽  
Chinese Families ◽  
Whole Exome

Background: Hereditary spherocytosis (HS), characterized by the presence of spherocytic red cells in peripheral blood, hemolysis, splenomegaly, jaundice, and gallstones, is a common form of inherited hemolytic anemia (HA). To date, five causative genes associated with HS have been identified, including ANK1, SPTB, SPTA1, SLC4A1, and EPB42.Methods: Clinically suspected patients with HS or undiagnosed HA from 14 Chinese families were enrolled in this study. We presented the patients’ clinical features and identified the causative gene variants in these patients using whole exome sequencing (WES), with 10 novel and four reported mutations in the ANK1 and SPTB genes (seven mutations in ANK1 and seven in SPTB), individually. Then, we reviewed all available literature on Chinese HS patients from 2000 to 2020 in PubMed and Chinese Journals with genetic results and clinical information, to delineate gene mutation spectrum and potential correlation with phenotypes.Results: A total of 158 variants (including 144 in previous reports and 14 in this study) indicated that ANK1 (46%) and SPTB (42%) were the most frequently mutated genes in Chinese HS patients, followed by SLC4A1 (11%) and SPTA1 (1%), while no mutations in EPB42 was reported. Most of the mutations in ANK1 and SPTB were nonsense (26/73 in ANK1 and 32/66 in SPTB) and frameshift (20/73 in ANK1 and 15/66 in SPTB), while missense mutations (14/18) accounted for the majority in SLC4A1. The higher mutation frequency of ANK1 was found in its exon 8, 9, 26, and 28. The majority of mutations in SPTB were located in its exon 13, 15, and 18–30, whereas mutations in SLC4A1 were scattered throughout the entire region of the gene.Conclusion: Our study expanded the mutation spectrum of ANK1 and SPTB. Furthermore, we clarified the mutational characteristics of causative genes by reviewing all available literature on Chinese patients with HS.

Computational Approaches to Predict the Non-canonical DNAs

2019 ◽  
Vol 14 (6) ◽  
pp. 470-479 ◽  
Author(s):  
Nazia Parveen ◽  
Amen Shamim ◽  
Seunghee Cho ◽  
Kyeong Kyu Kim
Keyword(s):  
Computational Methods ◽  
Genetic Instability ◽  
Computational Prediction ◽  
Structure And Function ◽  
Sequence Motifs ◽  
Computational Approaches ◽  
Functional Roles ◽  
And Function ◽  
Genetic Events ◽  
Insight Into

Background: Although most nucleotides in the genome form canonical double-stranded B-DNA, many repeated sequences transiently present as non-canonical conformations (non-B DNA) such as triplexes, quadruplexes, Z-DNA, cruciforms, and slipped/hairpins. Those noncanonical DNAs (ncDNAs) are not only associated with many genetic events such as replication, transcription, and recombination, but are also related to the genetic instability that results in the predisposition to disease. Due to the crucial roles of ncDNAs in cellular and genetic functions, various computational methods have been implemented to predict sequence motifs that generate ncDNA. Objective: Here, we review strategies for the identification of ncDNA motifs across the whole genome, which is necessary for further understanding and investigation of the structure and function of ncDNAs. Conclusion: There is a great demand for computational prediction of non-canonical DNAs that play key functional roles in gene expression and genome biology. In this study, we review the currently available computational methods for predicting the non-canonical DNAs in the genome. Current studies not only provide an insight into the computational methods for predicting the secondary structures of DNA but also increase our understanding of the roles of non-canonical DNA in the genome.

scholarly journals Alterations in ZnT1 expression and function lead to impaired intracellular zinc homeostasis in cancer

2019 ◽  
Vol 5 (1) ◽  
Author(s):  
Adrian Israel Lehvy ◽  
Guy Horev ◽  
Yarden Golan ◽  
Fabian Glaser ◽  
Yael Shammai ◽  
...  
Keyword(s):  
Malignant Tumors ◽  
Zinc Homeostasis ◽  
Healthy Population ◽  
Missense Mutations ◽  
Protein Alignment ◽  
Loss Of Function ◽  
Intracellular Zinc ◽  
Dismal Prognosis ◽  
Zinc Levels ◽  
And Function

Abstract Zinc is vital for the structure and function of ~3000 human proteins and hence plays key physiological roles. Consequently, impaired zinc homeostasis is associated with various human diseases including cancer. Intracellular zinc levels are tightly regulated by two families of zinc transporters: ZIPs and ZnTs; ZIPs import zinc into the cytosol from the extracellular milieu, or from the lumen of organelles into the cytoplasm. In contrast, the vast majority of ZnTs compartmentalize zinc within organelles, whereas the ubiquitously expressed ZnT1 is the sole zinc exporter. Herein, we explored the hypothesis that qualitative and quantitative alterations in ZnT1 activity impair cellular zinc homeostasis in cancer. Towards this end, we first used bioinformatics to analyze inactivating mutations in ZIPs and ZNTs, catalogued in the COSMIC and gnomAD databases, representing tumor specimens and healthy population controls, respectively. ZnT1, ZnT10, ZIP8, and ZIP10 showed extremely high rates of loss of function mutations in cancer as compared to healthy controls. Analysis of the putative functional impact of missense mutations in ZnT1-ZnT10 and ZIP1-ZIP14, using homologous protein alignment and structural predictions, revealed that ZnT1 displays a markedly increased frequency of predicted functionally deleterious mutations in malignant tumors, as compared to a healthy population. Furthermore, examination of ZnT1 expression in 30 cancer types in the TCGA database revealed five tumor types with significant ZnT1 overexpression, which predicted dismal prognosis for cancer patient survival. Novel functional zinc transport assays, which allowed for the indirect measurement of cytosolic zinc levels, established that wild type ZnT1 overexpression results in low intracellular zinc levels. In contrast, overexpression of predicted deleterious ZnT1 missense mutations did not reduce intracellular zinc levels, validating eight missense mutations as loss of function (LoF) mutations. Thus, alterations in ZnT1 expression and LoF mutations in ZnT1 provide a molecular mechanism for impaired zinc homeostasis in cancer formation and/or progression.

scholarly journals Mice with cleavage-resistant N-cadherin exhibit synapse anomaly in the hippocampus and outperformance in spatial learning tasks

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
M. Asada-Utsugi ◽  
K. Uemura ◽  
M. Kubota ◽  
Y. Noda ◽  
Y. Tashiro ◽  
...  
Keyword(s):  
Memory Function ◽  
Three Dimensional ◽  
Excitatory Synapses ◽  
Missense Mutations ◽  
Glutamatergic Synapses ◽  
Learning Tasks ◽  
Transmission Electron ◽  
Nmdar Activation ◽  
And Function

AbstractN-cadherin is a homophilic cell adhesion molecule that stabilizes excitatory synapses, by connecting pre- and post-synaptic termini. Upon NMDA receptor (NMDAR) activation by glutamate, membrane-proximal domains of N-cadherin are cleaved serially by a-disintegrin-and-metalloprotease 10 (ADAM10) and then presenilin 1(PS1, catalytic subunit of the γ-secretase complex). To assess the physiological significance of the initial N-cadherin cleavage, we engineer the mouse genome to create a knock-in allele with tandem missense mutations in the mouse N-cadherin/Cadherin-2 gene (Cdh2R714G, I715D, or GD) that confers resistance on proteolysis by ADAM10 (GD mice). GD mice showed a better performance in the radial maze test, with significantly less revisiting errors after intervals of 30 and 300 s than WT, and a tendency for enhanced freezing in fear conditioning. Interestingly, GD mice reveal higher complexity in the tufts of thorny excrescence in the CA3 region of the hippocampus. Fine morphometry with serial section transmission electron microscopy (ssTEM) and three-dimensional (3D) reconstruction reveals significantly higher synaptic density, significantly smaller PSD area, and normal dendritic spine volume in GD mice. This knock-in mouse has provided in vivo evidence that ADAM10-mediated cleavage is a critical step in N-cadherin shedding and degradation and involved in the structure and function of glutamatergic synapses, which affect the memory function.

scholarly journals Fibrillin-1 gene mutations in a Chinese cohort with congenital ectopia lentis: spectrum and genotype–phenotype analysis

2021 ◽  
pp. bjophthalmol-2021-319084
Author(s):  
Zexu Chen ◽  
Tianhui Chen ◽  
Min Zhang ◽  
Jiahui Chen ◽  
Michael Deng ◽  
...  
Keyword(s):  
Calcium Binding ◽  
Gene Mutations ◽  
Mutation Spectrum ◽  
Missense Mutations ◽  
Ectopia Lentis ◽  
Phenotype Analysis ◽  
Chinese Cohort ◽  
Fibrillin 1 ◽  
Epidermal Growth ◽  
Dependent Probe

AimsTo identify the mutation spectrum and genotype–phenotype correlations of fibrillin-1 (FBN1) mutations in a Chinese cohort with congenital ectopia lentis (EL).MethodsPatients clinically suspected of congenital zonulopathy were screened using panel-based next-generation sequencing followed by multiplex ligation-dependent probe amplification. All the probands were subjected to thorough ocular examinations. Molecular and clinical data were integrated in pursuit of genotype–phenotype correlation.ResultsA total of 131 probands of FBN1 mutations from unrelated families were recruited. Around 65% of the probands were children younger than 9 years old. Overall, 110 distinct FBN1 mutations were identified, including 39 novel ones. The most at-risk regions were exons 13, 2, 6, 15, 24 and 33 in descending order of mutation frequency. The most prevalent mutation was c.184C>T (seven, 5.34%) in the coding sequence and c.5788+5G>A (three, 2.29%) in introns. Missense mutations were the most frequent type (103, 78.63%); half of which were distributed in the N-terminal regions (53, 51.46%). The majority of missense mutations were detected in one of the calcium-binding epidermal growth factor-like domains (62, 60.19%), and 39 (62.90%) of them were substitutions of conserved cysteine residues. Microspherophakia (MSP) was found in 15 patients (11.45%). Mutations in the middle region (exons 22–42), especially exon 26, had higher risks of combined MSP (OR, 5.51 (95% CI 1.364 to 22.274), p=0.017).ConclusionsThis study extended the knowledge of the FBN1 mutation spectrum and provided novel insights into its clinical correlation regarding EL and MSP in the Chinese population.

scholarly journals Bioinformatic Analysis of Structure and Function of LIM Domains of Human Zyxin Family Proteins

2021 ◽  
Vol 22 (5) ◽  
pp. 2647
Author(s):  
M. Quadir Siddiqui ◽  
Maulik D. Badmalia ◽  
Trushar R. Patel
Keyword(s):  
Nucleic Acid ◽  
Nuclear Export ◽  
Consensus Sequence ◽  
Nuclear Export Signal ◽  
Bioinformatic Analysis ◽  
Nucleic Acid Binding ◽  
Protein Protein Interaction ◽  
Lim Domains ◽  
Protein Nucleic Acid ◽  
And Function

Members of the human Zyxin family are LIM domain-containing proteins that perform critical cellular functions and are indispensable for cellular integrity. Despite their importance, not much is known about their structure, functions, interactions and dynamics. To provide insights into these, we used a set of in-silico tools and databases and analyzed their amino acid sequence, phylogeny, post-translational modifications, structure-dynamics, molecular interactions, and functions. Our analysis revealed that zyxin members are ohnologs. Presence of a conserved nuclear export signal composed of LxxLxL/LxxxLxL consensus sequence, as well as a possible nuclear localization signal, suggesting that Zyxin family members may have nuclear and cytoplasmic roles. The molecular modeling and structural analysis indicated that Zyxin family LIM domains share similarities with transcriptional regulators and have positively charged electrostatic patches, which may indicate that they have previously unanticipated nucleic acid binding properties. Intrinsic dynamics analysis of Lim domains suggest that only Lim1 has similar internal dynamics properties, unlike Lim2/3. Furthermore, we analyzed protein expression and mutational frequency in various malignancies, as well as mapped protein-protein interaction networks they are involved in. Overall, our comprehensive bioinformatic analysis suggests that these proteins may play important roles in mediating protein-protein and protein-nucleic acid interactions.

scholarly journals AB0008 APPLYING WHOLE EXOME SEQUENCING TO FAMILIAL ANTIPHOSPHOLIPID SYNDROME: NEW PLAYERS IN A RARE DISEASE?

2021 ◽  
Vol 80 (Suppl 1) ◽  
pp. 1039.1-1039
Author(s):  
A. Barinotti ◽  
M. Radin ◽  
I. Cecchi ◽  
S. G. Foddai ◽  
E. Rubini ◽  
...  
Keyword(s):  
Immune Response ◽  
Ischemic Stroke ◽  
Exome Sequencing ◽  
Whole Exome Sequencing ◽  
Antiphospholipid Syndrome ◽  
Missense Mutations ◽  
Literature Research ◽  
Missense Variants ◽  
Vein Thrombosis ◽  
Whole Exome

Background:Antiphospholipid Syndrome (APS) is an autoimmune disease whose precise aetiology is still unknown, but the high heterogeneity of its manifestations and clinical course is presumably due to the occurrence of different mechanisms and alterations at different levels and pathways [1]. The first genetic studies in APS focused primarily on the human leukocytes antigen system region, but more recent data highlighted a role of other genes in APS susceptibility, primarily those involved in the immune response and in the haemostatic process.Objectives:We aimed to deepen the investigation of APS genetic background starting from a case of familial APS, analysing two siblings with thrombotic APS (Table 1), both triple positive for antiphospholipid antibodies (aPL).Table 1.Main clinical and laboratory characteristics of the patients included in the study.PatientAgeaPL ProfileRelevant Clinical History1 (F)51Triple positive (LA, aCL IgG, aβ2GPI IgG)Two episodes of ischemic stroke, one episode of CAPS (renal thrombotic microangiopathy, visual impairment, ischemic stroke)2 (M)47Triple positive (LA, aCL IgG, aβ2GPI IgG)Three episodes of deep vein thrombosis, regardless ongoing well conducted therapy vitamin k antagonist and additional retinal vein thrombosisLA: lupus anticoagulant; aCL: anti-cardiolipin antibodies; aβ2GPI: anti- β2 glycoprotein I antibodies; CAPS: catastrophic APS.Methods:Genomic DNA was extracted from peripheral blood and the samples underwent Whole Exome Sequencing (WES). Sequencing was done on a 100X coverage, and reads have been aligned to the human reference genome (GRCh37/hg19 assembly) using the Burrows–Wheeler Alignment tool (BWA). The mean sequencing depth on target regions was 170X for patient 1, 205X for patient 2, moreover, 99.50% of the targeted bases had at least 10X coverage for all the three donors. The resulting single nucleotide polymorphisms (SNPs) have been analysed through a step-by-step process based on their frequency population (using Genome Aggregation Database), their predicted effects on the protein (using VarSome) and a literature research about the genes carrying them. Moreover, genes previously associated with a pro-thrombotic tendency and with APS have been analysed in the two patients.Results:Starting from more than 120000 SNPs for each patients, the analysis led to reduce the list of SNPs of interest to 27 missense mutations. The complete literature research regarding the genes carrying these mutations allowed to further reduce the number of selected genes, focusing on those that exert a role potentially involved in APS pathogenesis and development. In particular, these genes (PLA2G6, HSPG2, BCL3, ZFAT, ATP2B2, CRTC3 and ADCY3) take part in the immune response and the vascular homeostasis. The list of the DNA missense variants of interest found in our cases of familial APS is resumed in Figure 2.Figure 2.List of DNA missense variants of interest found in patient 1 and 2. Genes potentially involved in APS pathogenesis and development are highlighted in bold.No mutations on genes known to be associated with a pro-thrombotic state (F5, F2, MTHFR, F13A1, PROC, PROS1, FGB and SERPINE1), or on genes previously associated with APS (B2GPI, PF4V1, SELP, TLR2, TLR4, GP Ia, GP1BA, F2R, F2RL1, TFPI, F3, VEGFA, FLT1, and TNF) have been found in the WES analysis.Conclusion:To some extent, this can be seen as a proof of concept of the complexity of APS. Efforts to interpret the genetic risk factors involved in the heterogeneous clinical features of the syndrome, for instance, the integration of WES and network-based approaches might help to identify and stratify patients at risk of developing APS.References:[1]Iuliano A, Galeazzi M, Sebastiani GD. Antiphospholipid syndrome’s genetic and epigenetic aspects. Autoimmun Rev. 2019;18(9).Disclosure of Interests:None declared

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