Objective:
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by loss of motor neurons in the brain and spinal cord, leading to muscle weakness and eventually death ...from respiratory failure. ALS is familial in about 10% of cases, with SOD1 mutations accounting for 20% of familial cases. Here we describe a consanguineous family segregating juvenile ALS in an autosomal recessive pattern and describe the genetic variant responsible for the disorder.
Methods:
We performed homozygosity mapping and direct sequencing to detect the genetic variant and tested the effect of this variant on a motor neuron‐like cell line model (NSC34) expressing the wild‐type or mutant gene.
Results:
We identified a shared homozygosity region in affected individuals that spans ∼120kbp on chromosome 9p13.3 containing 9 RefSeq genes. Sequencing the SIGMAR1 gene revealed a mutation affecting a highly conserved amino acid located in the transmembrane domain of the encoded protein, sigma‐1 receptor. The mutated protein showed an aberrant subcellular distribution in NSC34 cells. Furthermore, cells expressing the mutant protein were less resistant to apoptosis induced by endoplasmic reticulum stress.
Interpretation:
Sigma‐1 receptors are known to have neuroprotective properties, and recently Sigmar1 knockout mice have been described to have motor deficiency. Our findings emphasize the role of sigma‐1 receptors in motor neuron function and disease. ANN NEUROL 2011;
With the huge negative impact of neurological disorders on patient's life and society resources, the discovery of neuroprotective agents is critical and cost-effective. Neuroprotective agents can ...prevent and/or modify the course of neurological disorders. Despite being underestimated, riboflavin offers neuroprotective mechanisms. Significant pathogenesis-related mechanisms are shared by, but not restricted to, Parkinson's disease (PD) and migraine headache. Those pathogenesis-related mechanisms can be tackled through riboflavin proposed neuroprotective mechanisms. In fact, it has been found that riboflavin ameliorates oxidative stress, mitochondrial dysfunction, neuroinflammation, and glutamate excitotoxicity; all of which take part in the pathogenesis of PD, migraine headache, and other neurological disorders. In addition, riboflavin-dependent enzymes have essential roles in pyridoxine activation, tryptophan-kynurenine pathway, and homocysteine metabolism. Indeed, pyridoxal phosphate, the active form of pyridoxine, has been found to have independent neuroprotective potential. Also, the produced kynurenines influence glutamate receptors and its consequent excitotoxicity. In addition, methylenetetrahydrofolate reductase requires riboflavin to ensure normal folate cycle influencing the methylation cycle and consequently homocysteine levels which have its own negative neurovascular consequences if accumulated. In conclusion, riboflavin is a potential neuroprotective agent affecting a wide range of neurological disorders exemplified by PD, a disorder of neurodegeneration, and migraine headache, a disorder of pain. In this article, we will emphasize the role of riboflavin in neuroprotection elaborating on its proposed neuroprotective mechanisms in opposite to the pathogenesis-related mechanisms involved in two common neurological disorders, PD and migraine headache, as well as, we encourage the clinical evaluation of riboflavin in PD and migraine headache patients in the future.
ADCY5-related hyperkinesia encompasses a heterogeneous group of phenotypes, including paroxysmal chorea, myoclonus, and dystonia. The disease is attributed to mutations of ADCY5, which encodes an ...adenylate cyclase enzyme. The disease can occur in a sporadic or familial pattern. With exception of one study, all reports on familial ADCY5-related hyperkinesia were associated with an autosomal dominant inheritance. Herein, we describe a native Arabian Bedouin family with an autosomal recessive ADCY5-related disorder and expand the genotypic and phenotypic spectrum of this disorder.
The pedigree included 4 generations of a family with 6 affected individuals. The patients were examined clinically and radiologically. Homozygosity mapping and Whole Exome Sequencing (WES) were used to identify a variant, predicted to be pathogenic, which segregated with disease in this family.
All patients presented with early-onset dystonia and myoclonus. The patients had delayed motor and language milestones, axial hypotonia, severe anxiety, social phobia, and isolation. One patient had dilated cardiomyopathy. WES of one affected individual revealed a novel homozygous missense mutation (c.1762G > A, p.D588N) of ADCY5, that segregated with disease in an autosomal recessive manner, and was absent in more than 1000 ethnically-matched chromosomes. The mutation replaces a highly conserved nucleotide and is predicted to be deleterious.
This study reports the second family with autosomal recessive childhood-onset ADCY5-related disorder and expands our understanding of phenotype/genotype correlations of this disorder.
•ADCY5-related hyperkinesis encompasses a heterogeneous group of phenotypes.•It can occur in a sporadic or familial pattern.•We report a novel homozygous missense mutation in the ADCY5 gene, c.1762G > A, p.D588N, in 6 individuals.•This is the second family with autosomal recessive childhood-onset ADCY5-related disorder.
Amyotrophic lateral sclerosis (ALS) is characterized by the selective degeneration of motor neurons (MNs) and their target muscles. Misfolded proteins which often form intracellular aggregates are a ...pathological hallmark of ALS. Disruption of the functional interplay between protein degradation (ubiquitin proteasome system and autophagy) and RNA-binding protein homeostasis has recently been suggested as an integrated model that merges several ALS-associated proteins into a common pathophysiological pathway. The E102Q mutation in one such candidate gene, the endoplasmic reticulum (ER) chaperone Sigma receptor-1 (SigR1), has been reported to cause juvenile ALS. Although loss of SigR1 protein contributes to neurodegeneration in several ways, the molecular mechanisms underlying E102Q-SigR1-mediated neurodegeneration are still unclear. In the present study, we showed that the E102Q-SigR1 protein rapidly aggregates and accumulates in the ER and associated compartments in transfected cells, leading to structural alterations of the ER, nuclear envelope and mitochondria and to subsequent defects in proteasomal degradation and calcium homeostasis. ER defects and proteotoxic stress generated by E102Q-SigR1 aggregates further induce autophagy impairment, accumulation of stress granules and cytoplasmic aggregation of the ALS-linked RNA-binding proteins (RBPs) matrin-3, FUS, and TDP-43. Similar ultrastructural abnormalities as well as altered protein degradation and misregulated RBP homeostasis were observed in primary lymphoblastoid cells (PLCs) derived from E102Q-SigR1 fALS patients. Consistent with these findings, lumbar α-MNs of both sALS as well as fALS patients showed cytoplasmic matrin-3 aggregates which were not co-localized with pTDP-43 aggregates. Taken together, our results support the notion that E102Q-SigR1-mediated ALS pathogenesis comprises a synergistic mechanism of both toxic gain and loss of function involving a vicious circle of altered ER function, impaired protein homeostasis and defective RBPs.
Parkinson's disease (PD) is one of the major causes of parkinsonism syndrome. Its characteristic motor symptoms are attributable to dopaminergic neurons loss in the midbrain. Genetic advances have ...highlighted underlying molecular mechanisms and provided clues to potential therapies. However, most of the studies focusing on the genetic component of PD have been performed on American, European and Asian populations, whereas Arab populations (excluding North African Arabs), particularly Saudis remain to be explored. Here we investigated the genetic causes of PD in Saudis by recruiting 98 PD-cases (sporadic and familial) and screening them for potential pathogenic mutations in PD-established genes; SNCA, PARKIN, PINK1, PARK7/DJ1, LRRK2 and other PD-associated genes using direct sequencing. To our surprise, the screening revealed only three pathogenic point mutations; two in PINK1 and one in PARKIN. In addition to mutational analysis, CNV and cDNA analysis was performed on a subset of patients. Exon/intron dosage alterations in PARKIN were detected and confirmed in 2 cases. Our study suggests that mutations in the ORF of the screened genes are not a common cause of PD in Saudi population; however, these findings by no means exclude the possibility that other genetic events such as gene expression/dosage alteration may be more common nor does it eliminate the possibility of the involvement of novel genes.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Objective:
Primary lateral sclerosis (PLS) is a motor neuron disorder that exclusively affects upper motor neurons leading to their degeneration. Mutations in the ALS2 gene encoding the protein Alsin ...have been described previously in the juvenile form of the disease. In this study, we identify mutation of the ERLIN2 gene in juvenile PLS patients and describe an in vitro model for loss of ERLIN2 function.
Methods:
Single nucleotide polymorphism arrays were used for homozygosity mapping. DNA sequencing of candidate genes was used to detect the underlying mutation. Level of ERLIN2 mRNA was measured by quantitative real time polymerase chain reaction. Knocking down ERLIN2 in NSC34 cells was accomplished by short‐hairpin RNA interference.
Results:
We identified a splice junction mutation in the ERLIN2 gene—a component of the endoplasmic reticulum (ER) lipid rafts—that resulted in abnormal splicing of ERLIN2 transcript and nonsense‐mediated decay of ERLIN2 mRNA. Knocking down ERLIN2 in NSC34 cells suppressed their growth in culture.
Interpretation:
Recently, we found that mutation of SIGMAR1, a component of ER lipid rafts, leads to juvenile amyotrophic lateral sclerosis. The identification of mutation in another component of the ER lipid rafts in juvenile PLS patients emphasizes their role in motor neuron function. Furthermore, the discovered effect of ERLIN2 loss on cell growth may advance understanding of the mechanism behind motor neuron degeneration in PLS. ANN NEUROL 2012;72:510–516
Botulinum toxin (BT) therapy is a complex and highly individualised therapy defined by treatment algorithms and injection schemes describing its target muscles and their dosing. Various consensus ...guidelines have tried to standardise and to improve BT therapy. We wanted to update and improve consensus guidelines by: (1) Acknowledging recent advances of treatment algorithms. (2) Basing dosing tables on statistical analyses of real-life treatment data of 1831 BT injections in 36 different target muscles in 420 dystonia patients and 1593 BT injections in 31 different target muscles in 240 spasticity patients. (3) Providing more detailed dosing data including typical doses, dose variabilities, and dosing limits. (4) Including total doses and target muscle selections for typical clinical entities thus adapting dosing to different aetiologies and pathophysiologies. (5) In addition, providing a brief and concise review of the clinical entity treated together with general principles of its BT therapy. For this, we collaborated with IAB—Interdisciplinary Working Group for Movement Disorders which invited an international panel of experts for the support.
Gordon Holmes syndrome (GHS) is a distinct phenotype of autosomal recessive cerebellar ataxia, characterized by ataxia, dementia, reproductive defects and hypogonadism; it has been recently found to ...be associated with RNF216 mutation. We performed whole-exome sequencing and filtered the resulting novel variants by the coordinates of the shared autozygome. We identified a novel splicing variant in RNF216 that is likely to abolish the canonical splice site at the junction of exon/intron 13 (NM_207111.3:c.2061G>A). We herein report two patients with GHS caused by a novel RNF216 mutation as the first follow up report on RNF216-related GHS, and show interfamilial variability of phenotype supporting the previously reported RNF216-related cases.
Genetic studies of the familial forms of Parkinson's disease (PD) have identified a number of causative genes with an established role in its pathogenesis. These genes only explain a fraction of the ...diagnosed cases. The emergence of Next Generation Sequencing (NGS) expanded the scope of rare variants identification in novel PD related genes. In this study we describe whole exome sequencing (WES) genetic findings of 60 PD patients with 125 variants validated in 51 of these cases. We used strict criteria for variant categorization that generated a list of variants in 20 genes. These variants included loss of function and missense changes in 18 genes that were never previously linked to PD (NOTCH4, BCOR, ITM2B, HRH4, CELSR1, SNAP91, FAM174A, BSN, SPG7, MAGI2, HEPHL1, EPRS, PUM1, CLSTN1, PLCB3, CLSTN3, DNAJB9 and NEFH) and 2 genes that were previously associated with PD (EIF4G1 and ATP13A2). These genes either play a critical role in neuronal function and/or have mouse models with disease related phenotypes. We highlight NOTCH4 as an interesting candidate in which we identified a deleterious truncating and a splice variant in 2 patients. Our combined molecular approach provides a comprehensive strategy applicable for complex genetic disorders.
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