scholarly journals De novo stop-loss variants in CLDN11 cause hypomyelinating leukodystrophy

Brain ◽  
2020 ◽  
Author(s):  
Korbinian M Riedhammer ◽  
Sylvia Stockler ◽  
Rafal Ploski ◽  
Maren Wenzel ◽  
Burkhard Adis-Dutschmann ◽  
...  
Keyword(s):  
Cytoplasmic Membrane ◽  
De Novo ◽  
Brain Mri ◽  
Alpha Helix ◽  
Radial Component ◽  
Gene Encoding ◽  
Nonsense Mediated Decay ◽  
Junction Protein ◽  
Intracellular Proteins ◽  
Stop Loss

Abstract Claudin-11, a tight junction protein, is indispensable in the formation of the radial component of myelin. Here, we report de novo stop-loss variants in the gene encoding claudin-11, CLDN11, in three unrelated individuals presenting with an early-onset spastic movement disorder, expressive speech disorder and eye abnormalities including hypermetropia. Brain MRI showed a myelin deficit with a discrepancy between T1-weighted and T2-weighted images and some progress in myelination especially involving the central and peripheral white matter. Exome sequencing identified heterozygous stop-loss variants c.622T>C, p.(*208Glnext*39) in two individuals and c.622T>G, p.(*208Gluext*39) in one individual, all occurring de novo. At the RNA level, the variant c.622T>C did not lead to a loss of expression in fibroblasts, indicating this transcript is not subject to nonsense-mediated decay and most likely translated into an extended protein. Extended claudin-11 is predicted to form an alpha helix not incorporated into the cytoplasmic membrane, possibly perturbing its interaction with intracellular proteins. Our observations suggest that stop-loss variants in CLDN11 expand the genetically heterogeneous spectrum of hypomyelinating leukodystrophies.

scholarly journals Gain-of-function GABRB3 variants identified in vigabatrin-hypersensitive epileptic encephalopathies

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
Nathan L Absalom ◽  
Vivian W Y Liao ◽  
Kavitha Kothur ◽  
Dinesh C Indurthi ◽  
Bruce Bennetts ◽  
...  
Keyword(s):  
De Novo ◽  
Drug Effects ◽  
Receptor Expression ◽  
Aminobutyric Acid ◽  
Loss Of Function ◽  
Molecular Phenotype ◽  
Gain Of Function ◽  
Gene Encoding ◽  
Epileptic Encephalopathies ◽  
Receptor Phenotype

Abstract Variants in the GABRB3 gene encoding the β3-subunit of the γ-aminobutyric acid type A ( receptor are associated with various developmental and epileptic encephalopathies. Typically, these variants cause a loss-of-function molecular phenotype whereby γ-aminobutyric acid has reduced inhibitory effectiveness leading to seizures. Drugs that potentiate inhibitory GABAergic activity, such as nitrazepam, phenobarbital or vigabatrin, are expected to compensate for this and thereby reduce seizure frequency. However, vigabatrin, a drug that inhibits γ-aminobutyric acid transaminase to increase tonic γ-aminobutyric acid currents, has mixed success in treating seizures in patients with GABRB3 variants: some patients experience seizure cessation, but there is hypersensitivity in some patients associated with hypotonia, sedation and respiratory suppression. A GABRB3 variant that responds well to vigabatrin involves a truncation variant (p.Arg194*) resulting in a clear loss-of-function. We hypothesized that patients with a hypersensitive response to vigabatrin may exhibit a different γ-aminobutyric acid A receptor phenotype. To test this hypothesis, we evaluated the phenotype of de novo variants in GABRB3 (p.Glu77Lys and p.Thr287Ile) associated with patients who are clinically hypersensitive to vigabatrin. We introduced the GABRB3 p.Glu77Lys and p.Thr287Ile variants into a concatenated synaptic and extrasynaptic γ-aminobutyric acid A receptor construct, to resemble the γ-aminobutyric acid A receptor expression by a patient heterozygous for the GABRB3 variant. The mRNA of these constructs was injected into Xenopus oocytes and activation properties of each receptor measured by two-electrode voltage clamp electrophysiology. Results showed an atypical gain-of-function molecular phenotype in the GABRB3 p.Glu77Lys and p.Thr287Ile variants characterized by increased potency of γ-aminobutyric acid A without change to the estimated maximum open channel probability, deactivation kinetics or absolute currents. Modelling of the activation properties of the receptors indicated that either variant caused increased chloride flux in response to low concentrations of γ-aminobutyric acid that mediate tonic currents. We therefore propose that the hypersensitivity reaction to vigabatrin is a result of GABRB3 variants that exacerbate GABAergic tonic currents and caution is required when prescribing vigabatrin. In contrast, drug strategies increasing tonic currents in loss-of-function variants are likely to be a safe and effective therapy. This study demonstrates that functional genomics can explain beneficial and adverse anti-epileptic drug effects, and propose that vigabatrin should be considered in patients with clear loss-of-function GABRB3 variants.

scholarly journals Targeting Poison Exons to Treat Developmental and Epileptic Encephalopathy

2021 ◽  
pp. 1-6
Author(s):  
Miriam C. Aziz ◽  
Patricia N. Schneider ◽  
Gemma L. Carvill
Keyword(s):  
Alternative Splicing ◽  
Rna Binding ◽  
De Novo ◽  
Rna Binding Proteins ◽  
Autism Spectrum ◽  
Epileptic Encephalopathy ◽  
Nonsense Mediated Decay ◽  
Subsequent Degradation ◽  
Alternative Splicing Events ◽  
Genetic Epilepsies

Developmental and epileptic encephalopathies (DEEs) describe a subset of neurodevelopmental disorders categorized by refractory epilepsy that is often associated with intellectual disability and autism spectrum disorder. The majority of DEEs are now known to have a genetic basis with de novo coding variants accounting for the majority of cases. More recently, a small number of individuals have been identified with intronic <i>SCN1A</i> variants that result in alternative splicing events that lead to ectopic inclusion of poison exons (PEs). PEs are short highly conserved exons that contain a premature truncation codon, and when spliced into the transcript, lead to premature truncation and subsequent degradation by nonsense-mediated decay. The reason for the inclusion/exclusion of these PEs is not entirely clear, but research suggests an autoregulatory role in gene expression and protein abundance. This is seen in proteins such as RNA-binding proteins and serine/arginine-rich proteins. Recent studies have focused on targeting these PEs as a method for therapeutic intervention. Targeting PEs using antisense oligonucleotides (ASOs) has shown to be effective in modulating alternative splicing events by decreasing the amount of transcripts harboring PEs, thus increasing the abundance of full-length transcripts and thereby the amount of protein in haploinsufficient genes implicated in DEE. In the age of personalized medicine, cellular and animal models of the genetic epilepsies have become essential in developing and testing novel precision therapeutics, including PE-targeting ASOs in a subset of DEEs.

Cortical Thinning Associated with Age and CSF Biomarkers in Early Parkinson’s Disease Is Modified by the SNCA rs356181 Polymorphism

2018 ◽  
Vol 18 (5-6) ◽  
pp. 233-238
Author(s):  
Frederic Sampedro ◽  
Juan Marín-Lahoz ◽  
Saul Martínez-Horta ◽  
Javier Pagonabarraga ◽  
Jaime Kulisevsky
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Cognitive Decline ◽  
De Novo ◽  
Brain Regions ◽  
Cortical Atrophy ◽  
Csf Biomarkers ◽  
Gene Encoding ◽  
Cortical Thinning ◽  
Age Related

The role of cerebrospinal fluid (CSF) biomarkers such as CSF α-synuclein and CSF tau in predicting cognitive decline in Parkinson’s disease (PD) continues to be inconsistent. Here, using a cohort of de novo PD patients with preserved cognition from the Parkinson’s Progression Markers Initiative (PPMI), we show that the SNCA rs356181 single nucleotide polymorphism (SNP) modulates the effect of these CSF biomarkers on cortical thinning. Depending on this SNP’s genotype, cortical atrophy was associated with either higher or lower CSF biomarker levels. Additionally, this SNP modified age-related atrophy. Importantly, the integrity of the brain regions where this phenomenon was observed correlated with cognitive measures. These results suggest that this genetic variation of the gene encoding the α-synuclein protein, known to be involved in the development of PD, also interferes in its subsequent neurodegeneration. Overall, our findings could shed light on the so far incongruent association of common CSF biomarkers with cognitive decline in PD.

scholarly journals Long-term follow-up until early adulthood in autosomal dominant, complex SPG30 with a novel KIF1A variant: a case report

2019 ◽  
Vol 45 (1) ◽  
Author(s):  
Carlotta Spagnoli ◽  
Susanna Rizzi ◽  
Grazia Gabriella Salerno ◽  
Daniele Frattini ◽  
Carlo Fusco
Keyword(s):  
Autosomal Dominant ◽  
De Novo ◽  
Current Knowledge ◽  
Brain Mri ◽  
Early Adulthood ◽  
Cerebellar Atrophy ◽  
Mild Intellectual Disability ◽  
Long Term Follow Up

Abstract Background Pathogenic variants in KIF1A (kinesin family member 1A) gene have been associated with hereditary spastic paraplegia (HSP) type 30 (SPG30), encopassing autosomal dominant and recessive, pure and complicated forms. Case presentation We report the long-term follow-up of a 19 years-old boy first evaluated at 18 months of age because of toe walking and unstable gait with frequent falls. He developed speech delay, mild intellectual disability, a slowly progressive pyramidal syndrome, microcephaly, bilateral optic subatrophy and a sensory axonal polyneuropathy. Brain MRI showed cerebellar atrophy, stable along serial evaluations (last performed at 18 years of age). Targeted NGS sequencing disclosed the de novo c.914C > T missense, likely pathogenic variant on KIF1A gene. Conclusions We report on a previously unpublished de novo heterozygous likely pathogenic KIF1A variant associated with slowly progressive complicated SPG30 and stable cerebellar atrophy on long-term follow-up, adding to current knowledge on this HSP subtype.

scholarly journals Regulation of the Bacillus subtilis bcrC Bacitracin Resistance Gene by Two Extracytoplasmic Function σ Factors

2002 ◽  
Vol 184 (22) ◽  
pp. 6123-6129 ◽  
Author(s):  
Min Cao ◽  
John D. Helmann
Keyword(s):  
Bacillus Subtilis ◽  
Resistance Gene ◽  
Mutant Strain ◽  
Stress Responses ◽  
Double Mutant ◽  
De Novo ◽  
De Novo Synthesis ◽  
Gene Encoding ◽  
Single Promoter ◽  
Higher Sensitivity

ABSTRACT Bacitracin resistance is normally conferred by either of two major mechanisms, the BcrABC transporter, which pumps out bacitracin, or BacA, an undecaprenol kinase that provides C55-isoprenyl phosphate by de novo synthesis. We demonstrate that the Bacillus subtilis bcrC (ywoA) gene, encoding a putative bacitracin transport permease, is an important bacitracin resistance determinant. A bcrC mutant strain had an eightfold-higher sensitivity to bacitracin. Expression of bcrC initiated from a single promoter site that could be recognized by either of two extracytoplasmic function (ECF) σ factors, σX or σM. Bacitracin induced expression of bcrC, and this induction was dependent on σM but not on σX. Under inducing conditions, expression was primarily dependent on σM. As a consequence, a sigM mutant was fourfold more sensitive to bacitracin, while the sigX mutant was only slightly sensitive. A sigX sigM double mutant was similar to a bcrC mutant in sensitivity. These results support the suggestion that one function of B. subtilis ECF σ factors is to coordinate antibiotic stress responses.

scholarly journals Prevalence of congenital non syndromic hearing loss among offspring of consanguineous marriage: a pilot study

2020 ◽  
Vol 6 (5) ◽  
pp. 874
Author(s):  
Gangadhar K. S. ◽  
Geetha Bhaktha ◽  
Manjula B. ◽  
Nageshwari P.
Keyword(s):  
Hearing Loss ◽  
Consanguineous Marriage ◽  
Gene Encoding ◽  
Single Nucleotide ◽  
Junction Protein ◽  
Study Population ◽  
Syndromic Hearing Loss ◽  
Gap Junction Protein ◽  
Polymerase Chain ◽  
Recessive Defect

<p class="abstract"><strong>Background:</strong> Mutations in the gene encoding the gap-junction protein connexin-26, is understood to be the most important cause of non-syndromic hearing loss (NSHL). An attempt to identify the single nucleotide polymorphism (SNP) for W24X mutation was done.  Consanguineous marriage was seen among the NSHL subjects.</p><p class="abstract"><strong>Methods:</strong> SNP was identified using restriction fragment length polymorphism-polymerase chain reaction (RFLP-PCR).  Forty-five subjects were screened for congenital hearing loss. Twenty subjects matched the inclusion criteria and were included in the study.</p><p class="abstract"><strong>Results:</strong> 5 out of 20 subjects were found to have mutation i.e., 25%. Though consanguinity is known to cause autosomal recessive defect, the same could not be depicted in this study.</p><p class="abstract"><strong>Conclusions:</strong> 25% of the study population had a mutation in their gene and the rest though had consanguineous marriage had not been affected genotypically.</p>

scholarly journals Gain of channel function and modified gating properties in TRPM3 mutants causing intellectual disability and epilepsy

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Evelien Van Hoeymissen ◽  
Katharina Held ◽  
Ana Cristina Nogueira Freitas ◽  
Annelies Janssens ◽  
Thomas Voets ◽  
...  
Keyword(s):  
Intellectual Disability ◽  
De Novo ◽  
Epileptic Activity ◽  
Gene Encoding ◽  
Epileptic Encephalopathies ◽  
Channel Function ◽  
Functional Consequences ◽  
Altered Response ◽  
Voltage Sensor Domain ◽  
Higher Sensitivity

Developmental and epileptic encephalopathies (DEE) are a heterogeneous group of disorders characterized by epilepsy with comorbid intellectual disability. Recently, two de novo heterozygous mutations in the gene encoding TRPM3, a calcium permeable ion channel, were identified as the cause of DEE in eight probands, but the functional consequences of the mutations remained elusive. Here we demonstrate that both mutations (V990M and P1090Q) have distinct effects on TRPM3 gating, including increased basal activity, higher sensitivity to stimulation by the endogenous neurosteroid pregnenolone sulfate (PS) and heat, and altered response to ligand modulation. Most strikingly, the V990M mutation affected the gating of the non-canonical pore of TRPM3, resulting in large inward cation currents via the voltage sensor domain in response to PS stimulation. Taken together, these data indicate that the two DEE mutations in TRPM3 result in a profound gain of channel function, which may lie at the basis of epileptic activity and neurodevelopmental symptoms in the patients.

A de novo missense mutation in the gene encoding the SOX10 transcription factor in a Spanish sporadic case of Waardenburg syndrome type IV

2008 ◽  
Vol 146A (8) ◽  
pp. 1032-1037 ◽  
Author(s):  
Matías Morín ◽  
Antonio Viñuela ◽  
Teresa Rivera ◽  
Manuela Villamar ◽  
Miguel A. Moreno-Pelayo ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Missense Mutation ◽  
De Novo ◽  
Sporadic Case ◽  
Syndrome Type ◽  
Waardenburg Syndrome ◽  
Gene Encoding ◽  
Type Iv

Infection of the germ line by retroviral particles produced in the follicle cells: a possible mechanism for the mobilization of the gypsy retroelement of Drosophila

Development ◽  
1997 ◽  
Vol 124 (14) ◽  
pp. 2789-2798 ◽  
Author(s):  
S.U. Song ◽  
M. Kurkulos ◽  
J.D. Boeke ◽  
V.G. Corces
Keyword(s):  
High Frequency ◽  
Cytoplasmic Membrane ◽  
De Novo ◽  
Germ Line ◽  
High Rate ◽  
Follicle Cells ◽  
Nurse Cells ◽  
Perivitelline Space ◽  
Viral Particles ◽  
Secretory Apparatus

The gypsy retroelement of Drosophila moves at high frequency in the germ line of the progeny of females carrying a mutation in the flamenco (flam) gene. This high rate of de novo insertion correlates with elevated accumulation of full-length gypsy RNA in the ovaries of these females, as well as the presence of an env-specific RNA. We have prepared monoclonal antibodies against the gypsy Pol and Env products and found that these proteins are expressed in the ovaries of flam females and processed in the manner characteristic of vertebrate retroviruses. The Pol proteins are expressed in both follicle and nurse cells, but they do not accumulate at detectable levels in the oocyte. The Env proteins are expressed exclusively in the follicle cells starting at stage 9 of oogenesis, where they accumulate in the secretory apparatus of the endoplasmic reticulum. They then migrate to the inner side of the cytoplasmic membrane where they assemble into viral particles. These particles can be observed in the perivitelline space starting at stage 10 by immunoelectron microscopy using anti-Env antibodies. We propose a model to explain flamenco-mediated induction of gypsy mobilization that involves the synthesis of gypsy viral particles in the follicle cells, from where they leave and infect the oocyte, thus explaining gypsy insertion into the germ line of the subsequent generation.

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