scholarly journals Mechanisms of Congenital Myasthenia Caused by Three Mutations in the COLQ Gene

2021 ◽  
Vol 9 ◽  
Author(s):  
Xiaona Luo ◽  
Chunmei Wang ◽  
Longlong Lin ◽  
Fang Yuan ◽  
Simei Wang ◽  
...  
Keyword(s):  
Missense Mutation ◽  
Neuromuscular Junctions ◽  
Three Dimensional ◽  
Missense Variant ◽  
Homozygous Deletion ◽  
Dimensional Structure ◽  
Compound Heterozygous ◽  
Splicing Mutation ◽  
Gene Encoding ◽  
Congenital Myasthenia

The gene encoding collagen like tail subunit of asymmetric acetylcholinesterase (COLQ) is responsible for the transcription of three strands of collagen of acetylcholinesterase, which is attached to the endplate of neuromuscular junctions. Mutations in the COLQ gene are inherited in an autosomal-recessive manner and can lead to type V congenital myasthenia syndrome (CMS), which manifests as decreased muscle strength at birth or shortly after birth, respiratory failure, restricted eye movements, drooping of eyelids, and difficulty swallowing. Here we reported three variants within COLQ in two unrelated children with CMS. An intronic variant (c.393+1G>A) and a novel missense variant (p.Q381P) were identified as compound heterozygous in a 13-month-old boy, with the parents being carriers of each. An intragenic deletion including exons 14 and 15 was found in a homozygous state in a 12-year-old boy. We studied the relative expression of the COLQ and AChE gene in the probands' families, performed three-dimensional protein structural analysis, and analyzed the conservation of the missense mutation c.1142A>C (p.Q381P). The splicing mutation c.393+1G>A was found to affect the normal splicing of COLQ exon 5, resulting in a 27-bp deletion. The missense mutation c.1142A>C (p.Q381P) was located in a conserved position in different species. We found that homozygous deletion of COLQ exons 14–15 resulted in a 241-bp deletion, which decreased the number of amino acids and caused a frameshift translation. COLQ expression was significantly lower in the probands than in the probands' parents and siblings, while AChE expression was significantly higher. Moreover, the mutations were found to cause significant differences in the predicted three-dimensional structure of the protein. The splicing mutation c.393+1G>A, missense mutation c.1A>C (p.Q381P), and COLQ exon 14–15 deletion could cause CMS.

scholarly journals A Novel Missense Variant in the Gene PPP2R5D Causes a Rare Neurodevelopmental Disorder with Increased Phenotype

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Lulu Yan ◽  
Ru Shen ◽  
Zongfu Cao ◽  
Chunxiao Han ◽  
Yuxin Zhang ◽  
...  
Keyword(s):  
De Novo ◽  
Genetic Disorder ◽  
Neurodevelopmental Disorder ◽  
Three Dimensional ◽  
Missense Variant ◽  
Pathogenic Variant ◽  
Dimensional Structure ◽  
Chinese Family ◽  
Speech Impairment ◽  
Pathogenic Variants

PPP2R5D-related neurodevelopmental disorder, which is mainly caused by de novo missense variants in the PPP2R5D gene, is a rare autosomal dominant genetic disorder with about 100 patients and a total of thirteen pathogenic variants known to exist globally so far. Here, we present a 24-month-old Chinese boy with developmental delay and other common clinical characteristics of PPP2R5D-related neurodevelopmental disorder including hypotonia, macrocephaly, intellectual disability, speech impairment, and behavioral abnormality. Trio-whole exome sequencing (WES) and Sanger sequencing were performed to identify the causal gene variant. The pathogenicity of the variant was evaluated using bioinformatics tools. We identified a novel pathogenic variant in the PPP2R5D gene (c.620G>T, p.Trp207Leu). The variant is located in the variant hotspot region of this gene and is predicted to cause PPP2R5D protein dysfunction due to an increase in local hydrophobicity and unstable three-dimensional structure. We report a novel pathogenic variant of PPP2R5D associated with PPP2R5D-related neurodevelopmental disorder from a Chinese family. Our findings expanded the phenotypic and mutational spectrum of PPP2R5D-related neurodevelopmental disorder.

scholarly journals Identification of Novel CDH23 Variants Causing Moderate to Profound Progressive Nonsyndromic Hearing Loss

Genes ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1474
Author(s):  
Khushnooda Ramzan ◽  
Nouf S. Al-Numair ◽  
Sarah Al-Ageel ◽  
Lina Elbaik ◽  
Nadia Sakati ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Phenotypic Variability ◽  
Usher Syndrome ◽  
Three Dimensional ◽  
Homozygosity Mapping ◽  
Dimensional Structure ◽  
Molecular Testing ◽  
Compound Heterozygous ◽  
Nonsyndromic Hearing Loss ◽  
Missense Variants

Mutant alleles of CDH23, a gene that encodes a putative calcium-dependent cell-adhesion glycoprotein with multiple cadherin-like domains, are responsible for both recessive DFNB12 nonsyndromic hearing loss (NSHL) and Usher syndrome 1D (USH1D). The encoded protein cadherin 23 (CDH23) plays a vital role in maintaining normal cochlear and retinal function. The present study’s objective was to elucidate the role of DFNB12 allelic variants of CDH23 in Saudi Arabian patients. Four affected offspring of a consanguineous family with autosomal recessive moderate to profound NSHL without any vestibular or retinal dysfunction were investigated for molecular exploration of genes implicated in hearing impairment. Parallel to this study, we illustrate some possible pitfalls that resulted from unexpected allelic heterogeneity during homozygosity mapping due to identifying a shared homozygous region unrelated to the disease locus. Compound heterozygous missense variants (p.(Asp918Asn); p.(Val1670Asp)) in CDH23 were identified in affected patients by exome sequencing. Both the identified missense variants resulted in a substitution of the conserved residues and evaluation by multiple in silico tools predicted their pathogenicity and variable disruption of CDH23 domains. Three-dimensional structure analysis of human CDH23 confirmed that the residue Asp918 is located at a highly conserved DXD peptide motif and is directly involved in “Ca2+” ion contact. In conclusion, our study identifies pathogenic CDH23 variants responsible for isolated moderate to profound NSHL in Saudi patients and further highlights the associated phenotypic variability with a genotypic hierarchy of CDH23 mutations. The current investigation also supports the application of molecular testing in the clinical diagnosis and genetic counseling of hearing loss.

scholarly journals Ribokinase fromLeishmania donovani: purification, characterization and X-ray crystallographic analysis

2018 ◽  
Vol 74 (2) ◽  
pp. 99-104 ◽  
Author(s):  
Santhosh Gatreddi ◽  
Sayanna Are ◽  
Insaf Ahmed Qureshi
Keyword(s):  
Functional Characterization ◽  
Three Dimensional ◽  
Protozoan Parasite ◽  
Crystallographic Analysis ◽  
Size Exclusion ◽  
Dimensional Structure ◽  
Diffusion Method ◽  
Gene Encoding ◽  
Cell Parameters ◽  
Α Helix

Leishmaniais an auxotrophic protozoan parasite which acquires D-ribose by transporting it from the host cell and also by the hydrolysis of nucleosides. The enzyme ribokinase (RK) catalyzes the first step of ribose metabolism by phosphorylating D-ribose using ATP to produce D-ribose-5-phosphate. To understand its structure and function, the gene encoding RK fromL. donovaniwas cloned, expressed and purified using affinity and size-exclusion chromatography. Circular-dichroism spectroscopy of the purified protein showed comparatively more α-helix in the secondary-structure content, and thermal unfolding revealed theTmto be 317.2 K. Kinetic parameters were obtained by functional characterization ofL. donovaniRK, and theKmvalues for ribose and ATP were found to be 296 ± 36 and 116 ± 9.0 µM, respectively. Crystals obtained by the hanging-drop vapour-diffusion method diffracted to 1.95 Å resolution and belonged to the hexagonal space groupP61, with unit-cell parametersa=b= 100.25,c= 126.77 Å. Analysis of the crystal content indicated the presence of two protomers in the asymmetric unit, with a Matthews coefficient (VM) of 2.45 Å3 Da−1and 49.8% solvent content. Further study revealed that human counterpart of this protein could be used as a template to determine the first three-dimensional structure of the RK from trypanosomatid parasites.

scholarly journals Transketolase from Leishmania mexicana has a dual subcellular localization

2004 ◽  
Vol 382 (2) ◽  
pp. 759-767 ◽  
Author(s):  
Nicola J. VEITCH ◽  
Dante A. MAUGERI ◽  
Juan Jose CAZZULO ◽  
Ylva LINDQVIST ◽  
Michael P. BARRETT
Keyword(s):  
Subcellular Localization ◽  
Three Dimensional ◽  
Total Activity ◽  
Pentose Phosphate ◽  
Dimensional Structure ◽  
Leishmania Mexicana ◽  
Gene Encoding ◽  
X Ray Crystallography ◽  
C Terminus ◽  
Targeting Signal

Transketolase has been characterized in Leishmania mexicana. A gene encoding this enzyme was identified and cloned. The gene was expressed in Escherichia coli and the protein was purified and characterized. An apparent Km of 2.75 mM for ribose 5-phosphate was determined. X-ray crystallography was used to determine the three-dimensional structure of the enzyme to a resolution of 2.2 Å (1 Å≡0.1 nm). The C-terminus of the protein contains a type-1 peroxisome-targeting signal, suggestive of a possible glycosomal subcellular localization. Subcellular localization experiments performed with promastigote forms of the parasite revealed that the protein was predominantly cytosolic, although a significant component of the total activity was associated with the glycosomes. Transketolase is thus the first enzyme of the nonoxidative branch of the pentose phosphate pathway whose presence has been demonstrated in a peroxisome-like organelle.

scholarly journals Association of a novel missense mutation in MYO15A with nonsyndromic hearing loss: a case report

2020 ◽  
Author(s):  
Siji Wang ◽  
Ziqi Chen ◽  
Jiaqiu Dai ◽  
Xi Ouyang ◽  
Lin Zhu ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Missense Mutation ◽  
Sanger Sequencing ◽  
Three Dimensional ◽  
Sensorineural Deafness ◽  
Chinese Family ◽  
Common Disease ◽  
Compound Heterozygous ◽  
Nonsyndromic Hearing Loss ◽  
Genetic Sequencing

Abstract Background Hearing loss is a common disease globally, and more than 50% of the cases are genetic. Autosomal recessive nonsyndromic hearing loss (ARNSHL) is one of the most common types of hereditary hearing loss. Here, a novel MYO15A missense mutation was identified in a Chinese family with ARNSHL, using targeted genetic sequencing and Sanger sequencing. Case presentation: A 6-year-old girl with congenital nonsyndromic sensorineural deafness was presented from the First Affiliated hospital of Chongqing Medical University, China. We used targeted region sequencing, Sanger sequencing, functional prediction, and three-dimensional protein structure modeling to identify and verify the genes responsible for deafness in the family. Conclusions We found pathogenic compound heterozygous mutations in MYO15A, including a novel missense mutation, c.6353T > C (p.Leu2118Pro). It could provide help not only for genetic counseling but also for further understanding of the functional role of MYO15A mutations.

Molecular Genetics of Hereditary Prothrombin Deficiency in Indian Patients: Identification of a Novel Ala362→Thr (Prothrombin Vellore 1) Mutation by Conformation Sensitive Gel Electrophoresis.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 1037-1037
Author(s):  
G Jayandharan ◽  
R.V. Shaji ◽  
Auro Viswabandhya ◽  
Sukesh C. Nair ◽  
Joy Mammen ◽  
...  
Keyword(s):  
Missense Mutation ◽  
Gel Electrophoresis ◽  
Molecular Basis ◽  
Dimensional Structure ◽  
Compound Heterozygous ◽  
Cycle Sequencing ◽  
Missense Change ◽  
Indian Patients ◽  
Prothrombin Gene ◽  
A Chain

Abstract Prothrombin deficiency is a rare (1:200000) autosomal recessive disorder caused by diverse mutations in prothrombin gene. We have studied the molecular basis of this disorder in 4 unrelated Indian patients. The clinical features of these patients included easy bruisability, post-traumatic bleeds, hemarthroses (50% each) and epistaxis, gum bleedings, menorrhagia, hematemesis and post-surgical bleeding (25% each). The diagnosis was based on prolonged prothrombin and activated partial thromboplastin times and low factor II coagulant activity (FII: C) measured using a prothrombin time based assay. FII: C levels ranged between 4.7–17.5%. Genomic DNA was screened for prothrombin gene mutations by a novel PCR and conformation sensitive gel electrophoresis (CSGE) strategy. Fourteen exonic and their flanking intronic regions and 3′ untranslated region of prothrombin gene were amplified by 12 pairs of primers designed by Primer3 software. CSGE was performed in a mildly denaturing gel containing 10% acrylamide. Samples displaying abnormal CSGE profiles were sequenced by the Big Dye Terminator cycle sequencing kit to confirm the nature of nucleotide change. A novel missense mutation was studied based on the coordinates (identifier 1ppb) for the human ∞-thrombin (1.92Å resolution) three-dimensional structure. The evolutionary conservation of this aminoacid, mutated by missense change, was studied in the prothrombin sequence in 17 different species and 7 related proteases obtained from SwissProt and Trembl databases using PSI-BLAST. Mutations were identified in all the four patients. Five different causative mutations including 4 (80%) missense and an in-frame deletion (20%) were identified. One of them was a novel, Ala362→Thr aminoacid change affecting ‘B’ chain of ∞-thrombin. This mutation was identified in a compound heterozygous state with a previously reported Arg-1→Gln missense change affecting pro-peptide cleavage site. Ala362→Thr occurred at a codon, evolutionarily conserved in all the 24 different prothrombins or its related serine proteases studied. This indicates its importance to the structure of α-thrombin. Molecular modeling of this Ala362→Thr mutation was found to cause a conformational change around the region involving a catalytic triad residue His363 and a cysteine residue at codon 364 due to the accommodation of a larger and polar side chain of threonine. The FII: C level in this patient was 17.5%. Three other previously reported mutations were also detected in the homozygous state: Arg271→Cys missense mutation in Kringle-2 region, a Glu309→Lys missense mutation in ‘A’ chain of ∞-thrombin and an in-frame deletion of 3bp (AAG) leading to Del Lys301/302 in ‘A’ chain of ∞-thrombin. This is the first report of the molecular basis of prothrombin deficiency in Indian patients and we suggest the eponym ‘Prothrombin Vellore 1′ for Ala362→Thr mutation.

scholarly journals Characterization of a Missense Mutation in the Catalytic Domain and a Splicing Mutation of Coagulation Factor X Compound Heterozygous in a Chinese Pedigree

Genes ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1521
Author(s):  
Yuanzheng Feng ◽  
Jiewen Ma ◽  
Liang V Tang ◽  
Wenyi Lin ◽  
Yanyi Tao ◽  
...  
Keyword(s):  
Genetic Analysis ◽  
Missense Mutation ◽  
Coagulation Factor ◽  
Functional Study ◽  
Compound Heterozygous ◽  
Splicing Mutation ◽  
Factor X ◽  
In Vitro Expression ◽  
Minigene Assay

Background: Congenital coagulation factor X (FX) deficiency is a rare bleeding disorder with an incidence of one in one million caused by mutations in the FX-coding gene(F10), leading to abnormal coagulation activity and a tendency for severe hemorrhage. Therefore, identifying mutations in FX is important for diagnosing congenital FX deficiency. Results: Genetic analysis of the proband identified two single-base substitutions: c.794T > C: p.Ile265Thr and c.865 + 5G > A: IVS7 + 5G > A. His FX activity and antigen levels were < 1% and 49.7%, respectively; aPTT and PT were prolonged to 65.3 and 80.5 s, respectively. Bioinformatics analysis predicted the two novel variants to be pathogenic. In-vitro expression study of the missense mutation c.794T > C: p.Ile265Thr showed normal synthesis and secretion. Activation of FXs by RVV, FVII/TF, and FVIII/FIX all showed no obvious difference between the variant and the reference. However, clotting activity by PT and aPTT assays and activity of thrombin generation in a TGA assay all indicated reduced activity of the mutant FX-Ile265Thr compared to FX-WT. Minigene assay showed a normal splicing mode c.865 + 5G > A: IVS7 + 5G > A, which is inconsistent with clinical phenotype. Conclusions: The heterozygous variants c.794T > C: p.Ile265Thr or c.865 + 5G > A: IVS7 + 5G > A indicate mild FX deficiency, but the compound heterozygous mutation of the two causes severe congenital FX deficiency. Genetic analysis of these two mutations may help characterize the bleeding tendency and confirm congenital FX deficiency. In-vitro expression and functional study showed that the low activity of the mutant FX-Ile265Thr is caused by decrease in its enzyme activity rather than self-activation. The minigene assay help us explore possible mechanisms of the splicing mutation. However, more in-depth mechanism research is needed in the future.

scholarly journals Mutational spectrum of SMPD1 gene in Pakistani Niemann-Pick disease patients

2020 ◽  
Vol 36 (3) ◽  
Author(s):  
Huma Arshad Cheema ◽  
Iqra Ghulam Rasool ◽  
Muhammad Nadeem Anjum ◽  
Muhammad Yasir Zahoor
Keyword(s):  
Missense Mutation ◽  
In Silico Analysis ◽  
Missense Variant ◽  
Compound Heterozygous Mutation ◽  
Heterozygous Mutation ◽  
Compound Heterozygous ◽  
Mutational Spectrum ◽  
Niemann Pick Disease ◽  
Niemann Pick ◽  
Pick Disease

Objective: Genetic variation analysis of rare autosomal recessive Niemann-Pick disease (NPD) Pakistani patients. Methods: We sequenced the SMPD1 gene including its all coding and flanking regions in seven unrelated sporadic patients suffering from Niemann-Pick disease through targeted exome sequencing. Genetic variants mapping and their protein predictions were evaluated using different bioinformatics tools and clinical phenotypes were correlated. The study was conducted from January 2018 to March 2019 at The Children’s Hospital Lahore. Results: We have mapped five different mutations in SMPD1 gene of enrolled patients with a novel homozygous missense variant (c.1718G>C) (p.Trp573Ser) in one patient. A missense mutation (c.1267C>T) (p.His423Tyr) has been identified in three unrelated patients. A nonsense mutation (c.1327C>T) (p.Arg443Term) and one missense mutation (c.1493G>A) (p.Arg498His) mapped in one patient each. A compound heterozygous mutation has been mapped in one patient (c.740G>A) (p.Gly247Asp); (c.1493G>A) (p.Arg498His). Pathogenic effect of novel variant has been predicted through in-silico analysis and has not been reported in general overall population in the globe. Conclusion: This is the first report of genetic demographic assessment of Niemann-Pick disease in Pakistan. The mapped mutations would be helpful to build a disease variants algorithm of Pakistani population. This will be used for determining disease clinical magnitude along with provision of genetic screening services in affected families. doi: https://doi.org/10.12669/pjms.36.3.467 How to cite this:Cheema HA, Rasool IG, Anjum MN, Zahoor MY. Mutational spectrum of SMPD1 gene in Pakistani Niemann-Pick disease patients. Pak J Med Sci. 2020;36(3):---------. doi: https://doi.org/10.12669/pjms.36.3.467 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

AGRN Gene Mutation Leads to Congenital Myasthenia Syndromes: A Pediatric Case Report and Literature Review

2020 ◽  
Vol 51 (05) ◽  
pp. 364-367
Author(s):  
Siyi Gan ◽  
Haiyan Yang ◽  
Ting Xiao ◽  
Zou Pan ◽  
Liwen Wu
Keyword(s):  
Gene Mutation ◽  
Muscle Weakness ◽  
Motor Development ◽  
Neuromuscular Junctions ◽  
Age Of Onset ◽  
Lower Limbs ◽  
Compound Heterozygous Mutation ◽  
Heterozygous Mutation ◽  
Compound Heterozygous ◽  
Congenital Myasthenia

AbstractThe congenital myasthenia syndromes (CMS) are a group of autosomal recessive or autosomal dominant diseases that affect neuromuscular junctions. CMS caused by AGRN mutations is very uncommon typically characterized by ptosis, mild weakness, and proximal limb weakness. We report the case of an 8-year-old female who exhibited the onset of motor development retardation from infancy and slow progression to proximal muscle weakness. Repeated nerve stimulation at 3 Hz showed a clear decrement with 17%. Whole exon sequencing showed an AGRN gene compound heterozygous mutation (c.5009C >T and c.5078T > C). She was treated with salbutamol but without improvement. Then pseudoephedrine was adapted as a treatment choice and obtained remarkable curative effect. We have summarized and analyzed 12 patients who have been reported in the literature. An early age of onset and muscle weakness in the lower limbs are the main feature of an early AGRN gene mutation. Both types of AGRN-related CMS respond favorably to ephedrine. This is the first report showing that pseudoephedrine is effective as a choice for the treatment of AGRN-related CMS.

scholarly journals Germline DLST Variants Promote Epigenetic Modifications in Pheochromocytoma-Paraganglioma

2020 ◽  
Author(s):  
Alexandre Buffet ◽  
Juan Zhang ◽  
Heggert Rebel ◽  
Eleonora P M Corssmit ◽  
Jeroen C Jansen ◽  
...  
Keyword(s):  
Familial Cancer ◽  
Missense Variant ◽  
Tca Cycle ◽  
Compound Heterozygous ◽  
University Hospitals ◽  
Dna Hypermethylation ◽  
Clinical Genetic ◽  
Gene Encoding ◽  
Novel Variant ◽  
Compound Heterozygous Variants

Abstract Context Pheochromocytomas and paragangliomas (PPGLs) are neuroendocrine tumors in which altered central metabolism appears to be a major driver of tumorigenesis, and many PPGL genes encode proteins involved in the tricarboxylic acid (TCA) cycle. Objective/design While about 40% of PPGL cases carry a variant in a known gene, many cases remain unexplained. In patients with unexplained PPGL showing clear evidence of a familial burden or multiple tumors, we aimed to identify causative factors using genetic analysis of patient DNA and functional analyses of identified DNA variants in patient tumor material and engineered cell lines. Patients and Setting Patients with a likely familial cancer burden of pheochromocytomas and/or paragangliomas and under investigation in a clinical genetic and clinical research setting in university hospitals. Results While investigating unexplained PPGL cases, we identified a novel variant, c.1151C&gt;T, p.(Pro384Leu), in exon 14 of the gene encoding dihydrolipoamide S-succinyltransferase (DLST), a component of the multi-enzyme complex 2-oxoglutarate dehydrogenase. Targeted sequence analysis of further unexplained cases identified a patient carrying a tumor with compound heterozygous variants in DLST, consisting of a germline variant, c.1121G&gt;A, p.(Gly374Glu), together with a somatic missense variant identified in tumor DNA, c.1147A&gt;G, p.(Thr383Ala), both located in exon 14. Using a range of in silico and functional assays we show that these variants are predicted to be pathogenic, profoundly impact enzyme activity, and result in DNA hypermethylation. Conclusions The identification and functional analysis of these DLST variants further validates DLST as an additional PPGL gene involved in the TCA cycle.

Sign in / Sign up

Export Citation Format

Share Document