sabato 25 novembre 2017

NEWS FROM BRESCIA- Motor Deficits and Cerebellar Atrophy in Elovl5 Knock Out Mice.

Abstract
Spino-Cerebellar-Ataxia type 38 (SCA38) is caused by missense mutations in the very long chain fatty acid elongase 5 gene, ELOVL5. The main clinical findings in this disease are ataxia, hyposmia and cerebellar atrophy. Mice in which Elovl5 has been knocked out represent a model of the loss of function hypothesis of SCA38. In agreement with this hypothesis, Elovl5 knock out mice reproduced the main symptoms of patients, motor deficits at the beam balance test and hyposmia. The cerebellar cortex of Elovl5 knock out mice showed a reduction of thickness of the molecular layer, already detectable at 6 months of age, confirmed at 12 and 18 months. The total perimeter length of the Purkinje cell (PC) layer was also reduced in Elovl5 knock out mice. Since Elovl5 transcripts are expressed by PCs, whose dendrites are a major component of the molecular layer, we hypothesized that an alteration of their dendrites might be responsible for the reduced thickness of this layer. Reconstruction of the dendritic tree of biocytin-filled PCs, followed by Sholl analysis, showed that the distribution of distal dendrites was significantly reduced in Elovl5 knock out mice. Dendritic spine density was conserved. These results suggest that Elovl5 knock out mice recapitulate SCA38 symptoms and that their cerebellar atrophy is due, at least in part, to a reduced extension of PC dendritic arborization.

Front Cell Neurosci 2017

NEWS FROM THE WORLD- A recessive ataxia diagnosis algorithm for the next generation sequencing era

Objective

Differential diagnosis of autosomal recessive cerebellar ataxias can be challenging. A ranking algorithm named RADIAL that predicts the molecular diagnosis based on the clinical phenotype of a patient has been developed to guide genetic testing and to align genetic findings with the clinical context.

Methods

An algorithm that follows clinical practice, including patient history, clinical, magnetic resonance imaging, electromyography, and biomarker features, was developed following a review of the literature on 67 autosomal recessive cerebellar ataxias and personal clinical experience. Frequency and specificity of each feature were defined for each autosomal recessive cerebellar ataxia, and corresponding prediction scores were assigned. Clinical and paraclinical features of patients are entered into the algorithm, and a patient's total score for each autosomal recessive cerebellar ataxia is calculated, producing a ranking of possible diagnoses. Sensitivity and specificity of the algorithm were assessed by blinded analysis of a multinational cohort of 834 patients with molecularly confirmed autosomal recessive cerebellar ataxia. The performance of the algorithm was assessed versus a blinded panel of autosomal recessive cerebellar ataxia experts.

Results

The correct diagnosis was ranked within the top 3 highest-scoring diagnoses at a sensitivity and specificity of >90% for 84% and 91% of the evaluated genes, respectively. Mean sensitivity and specificity of the top 3 highest-scoring diagnoses were 92% and 95%, respectively. The algorithm outperformed the panel of ataxia experts (p = 0.001).

Interpretation

Our algorithm is highly sensitive and specific, accurately predicting the underlying molecular diagnoses of autosomal recessive cerebellar ataxias, thereby guiding targeted sequencing or facilitating interpretation of next-generation sequencing data. 

Ann Neurol 2017

NEWS FROM THE WORLD- Idiopathic REM sleep behaviour disorder and neurodegeneration — an update

So-called idiopathic rapid eye movement (REM) sleep behaviour disorder (RBD), formerly seen as a rare parasomnia, is now recognized as the prodromal stage of an α-synucleinopathy. Given the very high risk that patients with idiopathic RBD have of developing α-synucleinopathies, such as Parkinson disease (PD), PD dementia, dementia with Lewy bodies or multiple system atrophy, and the outstandingly high specificity and very long interval between the onset of idiopathic RBD and the clinical manifestations of α-synucleinopathies, the prodromal phase of this disorder represents a unique opportunity for potentially disease-modifying intervention. This Review provides an update on classic and novel biomarkers of α-synuclein-related neurodegeneration in patients with idiopathic RBD, focusing on advances in imaging and neurophysiological, cognitive, autonomic, tissue-specific and other biomarkers. We discuss the strengths, potential weaknesses and suitability of these biomarkers for identifying RBD and neurodegeneration, with an emphasis on predicting progression to overt α-synucleinopathy. The role of video polysomnography in providing quantifiable and potentially treatment-responsive biomarkers of neurodegeneration is highlighted. In light of all these advances, and the now understood role of idiopathic RBD as an early manifestation of α-synuclein disease, we call for idiopathic RBD to be reconceptualized as isolated RBD.


Nature Reviews Neurology 2017

NEWS FROM THE WORLD- Association of Nonalcoholic Fatty Liver Disease With Lower Brain Volume in Healthy Middle-Aged Adults in the Framingham Study

Abstract
Importance  Nonalcoholic fatty liver disease (NAFLD) is a common condition that is most often asymptomatic. It is associated with metabolic syndrome, incident diabetes, carotid atherosclerosis, and endothelial dysfunction, conditions that in turn are strongly linked with brain damage and cognitive impairment. However, it is not known whether NAFLD is associated with structural brain measures in humans.
Objective  To assess the association between prevalent NAFLD and brain magnetic resonance imaging (MRI) measures.
Design, Setting, and Participants  The cross-sectional association between NAFLD and brain MRI measures was assessed from November 6, 2002, to March 16, 2011, in 766 individuals from the Offspring cohort of the Framingham Study. Participants were included if they did not have excessive alcohol intake and were free of stroke and dementia. Data analysis was conducted from December 30, 2015, to June 15, 2016.
Exposures  Nonalcoholic fatty liver disease was assessed by multidetector computed tomographic scans of the abdomen.
Main Outcomes and Measures  Linear or logistic regression models were used to evaluate the cross-sectional association between NAFLD and brain MRI measures, adjusting for age, sex, alcohol consumption, visceral adipose tissue, body mass index, menopausal status, systolic blood pressure, hypertension, current smoking, high-density lipoprotein and low-density lipoprotein cholesterol levels, lipid treatment, type 2 diabetes, cardiovascular disease, physical activity, insulin resistance, C-reactive protein levels, and plasma homocysteine values. Brain MRI measures included total cerebral brain volume, hippocampal and white matter hyperintensity volumes, and presence or absence of covert brain infarcts.
Results  Of the 766 individuals in the study sample (410 women and 356 men; mean [SD] age at the time of brain MRI, 67 [9] years), 137 (17.9%) had NAFLD. Nonalcoholic fatty liver disease was significantly associated with smaller total cerebral brain volume even after adjustment for all the covariates included in the study (β [SE], –0.26 [0.11]; P = .02). Differences in total cerebral brain volume between those with and without NAFLD corresponded to 4.2 years of brain aging in the general sample and to 7.3 years in individuals younger than 60 years of age. No statistically significant associations were observed between NAFLD and hippocampal or white matter hyperintensity volumes or covert brain infarcts.
Conclusions and Relevance  Nonalcoholic fatty liver disease is associated with a smaller total cerebral brain volume, independent of visceral adipose tissue and cardiometabolic risk factors, pointing to a possible link between hepatic steatosis and brain aging.

JAMA Neurology 2017

NEWS FROM THE WORLD- Management of Tiny Unruptured Intracranial Aneurysms A Comparative Effectiveness Analysis

Abstract
Importance  Unruptured intracranial aneurysms (UIAs) are relatively common in the general population and are being increasingly diagnosed; a significant proportion are tiny (≤3 mm) aneurysms. There is significant heterogeneity in practice and lack of clear guidelines on the management of incidental, tiny UIAs. It is important to quantify the implications of different management strategies in terms of health benefits to patients.
Objective  To evaluate the effectiveness of routine treatment (aneurysm coiling) vs 3 strategies for imaging surveillance compared with no preventive treatment or routine follow-up of tiny UIAs.
Design, Setting, and Participants  A decision-analytic model-based comparative effectiveness analysis was conducted from May 1 to June 30, 2017, using inputs from the medical literature. PubMed searches were performed to identify relevant literature for all key model inputs, each of which was derived from the clinical study with the most robust data and greatest applicability. Analysis included 10 000 iterations simulating adult patients with incidental detections of UIAs 3 mm or smaller and no history of subarachnoid hemorrhage.
Interventions  The following 5 management strategies for tiny UIAs were evaluated: annual magnetic resonance angiography (MRA) screening, biennial MRA screening, MRA screening every 5 years, aneurysm coiling and follow-up, and no treatment or preventive follow-up.
Main Outcomes and Measures  A Markov decision model for lifetime rupture was constructed from a societal perspective per 10 000 patients with incidental, tiny UIAs. Outcomes were assessed in terms of quality-adjusted life-years. Probabilistic, 1-way, and 2-way sensitivity analyses were performed.
Results  In this analysis of 10 000 iterations simulating adult patients with a mean age of 50 years, the base-case calculation shows that the management strategy of no treatment or preventive follow-up has the highest health benefit (mean [SD] quality-adjusted life-years, 19.40 [0.31]). Among the management strategies that incorporate follow-up imaging, MRA every 5 years is the best strategy with the next highest effectiveness (mean [SD] quality-adjusted life-years, 18.05 [0.62]). The conclusion remains robust in probabilistic and 1-way sensitivity analyses. No routine follow-up remains the optimal strategy when the annual growth rate and risk of rupture of growing aneurysms are varied. When the annual risk of rupture of nongrowing UIAs is less than 1.7% (0.23% in base case scenario), no follow-up is the optimal strategy. If annual risk of rupture is more than 1.7%, coiling should be performed directly.
Conclusions and Relevance  Given the current literature, no preventive treatment or imaging follow-up is the most effective strategy in patients with aneurysms that are 3 mm or smaller, resulting in better health outcomes. More aggressive imaging surveillance for aneurysm growth or preventive treatment should be reserved for patients with a high risk of rupture. Given these findings, it is important to critically evaluate the appropriateness of current clinical practices, and potentially determine specific guidelines to reflect the most effective management strategy for patients with incidental, tiny UIAs.

JAMA Neurology 2017

NEWS FROM THE WORLD- Altered caudate connectivity is associated with executive dysfunction after traumatic brain injury

Abstract

Traumatic brain injury often produces executive dysfunction. This characteristic cognitive impairment often causes long-term problems with behaviour and personality. Frontal lobe injuries are associated with executive dysfunction, but it is unclear how these injuries relate to corticostriatal interactions that are known to play an important role in behavioural control. We hypothesized that executive dysfunction after traumatic brain injury would be associated with abnormal corticostriatal interactions, a question that has not previously been investigated. We used structural and functional MRI measures of connectivity to investigate this. Corticostriatal functional connectivity in healthy individuals was initially defined using a data-driven approach. A constrained independent component analysis approach was applied in 100 healthy adult dataset from the Human Connectome Project. Diffusion tractography was also performed to generate white matter tracts. The output of this analysis was used to compare corticostriatal functional connectivity and structural integrity between groups of 42 patients with traumatic brain injury and 21 age-matched controls. Subdivisions of the caudate and putamen had distinct patterns of functional connectivity. Traumatic brain injury patients showed disruption to functional connectivity between the caudate and a distributed set of cortical regions, including the anterior cingulate cortex. Cognitive impairments in the patients were mainly seen in processing speed and executive function, as well as increased levels of apathy and fatigue. Abnormalities of caudate functional connectivity correlated with these cognitive impairments, with reductions in right caudate connectivity associated with increased executive dysfunction, information processing speed and memory impairment. Structural connectivity, measured using diffusion tensor imaging between the caudate and anterior cingulate cortex was impaired and this also correlated with measures of executive dysfunction. We show for the first time that altered subcortical connectivity is associated with large-scale network disruption in traumatic brain injury and that this disruption is related to the cognitive impairments seen in these patients.

Brain 2017

NEWS FROM THE WORLD-Macrophage enzyme and reduced inflammation drive brain correction of mucopolysaccharidosis IIIB by stem cell gene therapy

Abstract

Mucopolysaccharidosis IIIB is a paediatric lysosomal storage disease caused by deficiency of the enzyme α-N-acetylglucosaminidase (NAGLU), involved in the degradation of the glycosaminoglycan heparan sulphate. Absence of NAGLU leads to accumulation of partially degraded heparan sulphate within lysosomes and the extracellular matrix, giving rise to severe CNS degeneration with progressive cognitive impairment and behavioural problems. There are no therapies. Haematopoietic stem cell transplant shows great efficacy in the related disease mucopolysaccharidosis I, where donor-derived monocytes can transmigrate into the brain following bone marrow engraftment, secrete the missing enzyme and cross-correct neighbouring cells. However, little neurological correction is achieved in patients with mucopolysaccharidosis IIIB. We have therefore developed an ex vivo haematopoietic stem cell gene therapy approach in a mouse model of mucopolysaccharidosis IIIB, using a high-titre lentiviral vector and the myeloid-specific CD11b promoter, driving the expression of NAGLU (LV.NAGLU). To understand the mechanism of correction we also compared this with a poorly secreted version of NAGLU containing a C-terminal fusion to IGFII (LV.NAGLU-IGFII). Mucopolysaccharidosis IIIB haematopoietic stem cells were transduced with vector, transplanted into myeloablated mucopolysaccharidosis IIIB mice and compared at 8 months of age with mice receiving a wild-type transplant. As the disease is characterized by increased inflammation, we also tested the anti-inflammatory steroidal agent prednisolone alone, or in combination with LV.NAGLU, to understand the importance of inflammation on behaviour. NAGLU enzyme was substantially increased in the brain of LV.NAGLU and LV.NAGLU-IGFII-treated mice, with little expression in wild-type bone marrow transplanted mice. LV.NAGLU treatment led to behavioural correction, normalization of heparan sulphate and sulphation patterning, reduced inflammatory cytokine expression and correction of astrocytosis, microgliosis and lysosomal compartment size throughout the brain. The addition of prednisolone improved inflammatory aspects further. Substantial correction of lysosomal storage in neurons and astrocytes was also achieved in LV.NAGLU-IGFII-treated mice, despite limited enzyme secretion from engrafted macrophages in the brain. Interestingly both wild-type bone marrow transplant and prednisolone treatment alone corrected behaviour, despite having little effect on brain neuropathology. This was attributed to a decrease in peripheral inflammatory cytokines. Here we show significant neurological disease correction is achieved using haematopoietic stem cell gene therapy, suggesting this therapy alone or in combination with anti-inflammatories may improve neurological function in patients.

Brain 2017

NEWS FROM THE WORLD- Diagnosis, pathophysiology, and management of cluster headache

Summary

Cluster headache is a trigeminal autonomic cephalalgia characterised by extremely painful, strictly unilateral, short-lasting headache attacks accompanied by ipsilateral autonomic symptoms or the sense of restlessness and agitation, or both. The severity of the disorder has major effects on the patient's quality of life and, in some cases, might lead to suicidal ideation. Cluster headache is now thought to involve a synchronised abnormal activity in the hypothalamus, the trigeminovascular system, and the autonomic nervous system. The hypothalamus appears to play a fundamental role in the generation of a permissive state that allows the initiation of an episode, whereas the attacks are likely to require the involvement of the peripheral nervous system. Triptans are the most effective drugs to treat an acute cluster headache attack. Monoclonal antibodies against calcitonin gene-related peptide, a crucial neurotransmitter of the trigeminal system, are under investigation for the preventive treatment of cluster headache. These studies will increase our understanding of the disorder and perhaps reveal other therapeutic targets.

Lancet Neurology 2017

sabato 18 novembre 2017

NEWS FROM BRESCIA -Progranulin plasma levels predict the presence of GRN mutations in asymptomatic subjects and do not correlate with brain atrophy: results from the GENFI study.

Abstract
We investigated whether progranulin plasma levels are predictors of the presence of progranulin gene (GRN) null mutations or of the development of symptoms in asymptomatic at risk members participating in the Genetic Frontotemporal Dementia Initiative, including 19 patients, 64 asymptomatic carriers, and 77 noncarriers. In addition, we evaluated a possible role of TMEM106B rs1990622 as a genetic modifier and correlated progranulin plasma levels and gray-matter atrophy. Plasma progranulin mean ± SD plasma levels in patients and asymptomatic carriers were significantly decreased compared with noncarriers (30.5 ± 13.0 and 27.7 ± 7.5 versus 99.6 ± 24.8 ng/mL, p < 0.00001). Considering the threshold of >61.55 ng/mL, the test had a sensitivity of 98.8% and a specificity of 97.5% in predicting the presence of a mutation, independent of symptoms. No correlations were found between progranulin plasma levels and age, years from average age at onset in each family, or TMEM106B rs1990622 genotype (p > 0.05). Plasma progranulin levels did not correlate with brain atrophy. Plasma progranulin levels predict the presence of GRN null mutations independent of proximity to symptoms and brain atrophy.

Neurobiol.Aging 2017

NEWS FROM BRESCIA- The Italian Version of the Five-Word Test: A Simple Diagnostic Test for Dementia due to Alzheimer's Disease in Routine Clinical Practice.

Abstract

BACKGROUND:

The five-word test (FWT) is a neuropsychological tool (derived from the Grober and Buschke paradigm), measuring hippocampal memory trace consolidation. The study aimed to validate the test for the Italian language and to verify its ability to discriminate patients affected by mild cognitive impairment and dementia due to Alzheimer's disease from healthy matches.

METHODS:

217 subjects (127 controls, 47 MCI due to AD, and 43 AD) underwent neuropsychological evaluation. The Spearman rank coefficient (ρ) was used to assess the correlation between immediate (IRS), delayed (DRS), and total score (TRS) of the FWT and correspondent matches of a specific short story test, while receiving operator characteristic (ROC) curves were built to investigate the diagnostic accuracy of both.

RESULTS:

Correlation between almost all the scores was significant in all the diagnostic subgroups; the ROC curves of the two tests were not statistically different. A TRS of the FWT with a cut-off of ≤9/10 could accurately discriminate AD patients (sensitivity: 97%, specificity: 94%) and MCI due to AD (sensitivity: 76%, specificity: 68%) from control matches.

CONCLUSION:

FWT is a simple and valid test of hippocampal memory which appears recommendable in routine clinical practice.

Behav Neurol 2017

NEWS FROM THE WORLD- Mutations affecting glycinergic neurotransmission in hyperekplexia increase pain sensitivity

Abstract

Inhibitory interneurons in the spinal cord use glycine and GABA for fast inhibitory neurotransmission. While there is abundant research on these inhibitory pain pathways in animal models, their relevance in humans remains unclear, largely due to the limited possibility to manipulate selectively these pathways in humans. Hyperekplexia is a rare human disease that is caused by loss-of-function mutations in genes encoding for glycine receptors and glycine transporters. In the present study, we tested whether hyperekplexia patients display altered pain perception or central pain modulation compared with healthy subjects. Seven patients with genetically and clinically confirmed hyperekplexia were compared to 14 healthy age- and sex-matched controls. The following quantitative sensory tests were performed: pressure pain detection threshold (primary outcome), ice water tolerance, single and repeated electrical pain detection thresholds, nociceptive withdrawal reflex threshold, and conditioned pain modulation. Statistical analysis was performed using linear mixed models. Hyperekplexia patients displayed lower pain thresholds than healthy controls for all of the quantitative sensory tests [mean (standard deviation)]: pressure pain detection threshold [273 (170) versus 475 (115) kPa, P = 0.003], ice water tolerance [49.2 (36.5) versus 85.7 (35.0) s, P = 0.015], electrical single pain detection threshold [5.42 (2.64) versus 7.47 (2.62) mA, P = 0.012], electrical repeated pain detection threshold [3.76 (1.41) versus 5.8 (1.73) mA, P= 0.003], and nociceptive withdrawal reflex [7.42 (3.63) versus 14.1 (6.9) mA, P = 0.015]. Conditioned pain modulation was significantly reduced in hyperekplexia [increase to baseline: 53.2 (63.7) versus 105 (57) kPa, P = 0.030]. Our data demonstrate increased pain sensitivity and impaired central pain modulation in hyperekplexia patients, supporting the importance of glycinergic neurotransmission for central pain modulation in humans.

Brain 2017

NEWS FROM THE WORLD- A clinical predictive score for postoperative myasthenic crisis

Abstract

Objective

Myasthenia gravis (MG) is an autoimmune disease mostly caused by autoantibodies against acetylcholine receptor associated with thymus abnormalities. Thymectomy has been proven to be an efficacious treatment for patients with MG, but postoperative myasthenic crisis often occurs and is a major complication. We aimed to develop and validate a simple scoring system based on clinical characteristics in the preoperative status to predict the risk of postoperative myasthenic crisis.

Methods

We studied 393 patients with MG who underwent thymectomy at 6 tertiary centers in Japan (275 patients for derivation and 118 for validation). Clinical characteristics, such as gender, age at onset and operation, body mass index, disease duration, MG subtype, severity, symptoms, preoperative therapy, operative data, and laboratory data, were reviewed retrospectively. A multivariate logistic regression with LASSO penalties was used to determine the factors associated with postoperative myasthenic crisis, and a score was assigned. Finally, the predictive score was evaluated using bootstrapping technique in the derivation and validation groups.

Results

Multivariate logistic regression identified 3 clinical factors for predicting postoperative myasthenic crisis risk: (1) vital capacity < 80%, (2) disease duration < 3 months, and (3) bulbar symptoms immediately before thymectomy. The postoperative myasthenic crisis predictive score, ranging from 0 to 6 points, had areas under the curve of 0.84 (0.66–0.96) in the derivation group and 0.80 (0.62–0.95) in the validation group.

Interpretation

A simple scoring system based on 3 preoperative clinical characteristics can predict the possibility of postoperative myasthenic crisis. 


Ann Neurol 2017

NEWS FROM THE WORLD- Efficacy and Safety of Extracranial Vein Angioplasty in Multiple Sclerosis A Randomized Clinical Trial

Abstract
Importance  Chronic cerebrospinal venous insufficiency (CCSVI) is characterized by restricted venous outflow from the brain and spinal cord. Whether this condition is associated with multiple sclerosis (MS) and whether venous percutaneous transluminal angioplasty (PTA) is beneficial in persons with MS and CCSVI is controversial.
Objective  To determine the efficacy and safety of venous PTA in patients with MS and CCSVI.
Design, Setting, and Participants  We analyzed 177 patients with relapsing-remitting MS; 62 were ineligible, including 47 (26.6%) who did not have CCSVI on color Doppler ultrasonography screening. A total of 115 patients were recruited in the study timeframe. All patients underwent a randomized, double-blind, sham-controlled, parallel-group trial in 6 MS centers in Italy. The trial began in August 2012 and concluded in March 2016; data were analyzed from April 2016 to September 2016. The analysis was intention to treat.
Interventions  Patients were randomly allocated (2:1) to either venous PTA or catheter venography without venous angioplasty (sham).
Main Outcomes and Measures  Two primary end points were assessed at 12 months: (1) a composite functional measure (ie, walking control, balance, manual dexterity, postvoid residual urine volume, and visual acuity) and (2) a measure of new combined brain lesions on magnetic resonance imaging, including the proportion of lesion-free patients. Combined lesions included T1 gadolinium-enhancing lesions plus new or enlarged T2 lesions.
Results  Of the included 115 patients with relapsing-remitting MS, 76 were allocated to the PTA group (45 female [59%]; mean [SD] age, 40.0 [10.3] years) and 39 to the sham group (29 female [74%]; mean [SD] age, 37.5 [10.6] years); 112 (97.4%) completed follow-up. No serious adverse events occurred. Flow restoration was achieved in 38 of 71 patients (54%) in the PTA group. The functional composite measure did not differ between the PTA and sham groups (41.7% vs 48.7%; odds ratio, 0.75; 95% CI, 0.34-1.68; P = .49). The mean (SD) number of combined lesions on magnetic resonance imaging at 6 to 12 months were 0.47 (1.19) in the PTA group vs 1.27 (2.65) in the sham group (mean ratio, 0.37; 95% CI, 0.15-0.91; P = .03: adjusted P = .09) and were 1.40 (4.21) in the PTA group vs 1.95 (3.73) in the sham group at 0 to 12 months (mean ratio, 0.72; 95% CI, 0.32-1.63; P = .45; adjusted P = .45). At follow-up after 6 to 12 months, 58 of 70 patients (83%) in the PTA group and 22 of 33 (67%) in the sham group were free of new lesions on magnetic resonance imaging (odds ratio, 2.64; 95% CI, 1.11-6.28; P = .03; adjusted P = .09). At 0 to 12 months, 46 of 73 patients (63.0%) in the PTA group and 18 of 37 (49%) in the sham group were free of new lesions on magnetic resonance imaging (odds ratio, 1.80; 95% CI, 0.81-4.01; P = .15; adjusted P = .30).
Conclusion and Relevance  Venous PTA has proven to be a safe but largely ineffective technique; the treatment cannot be recommended in patients with MS.
JAMA Neurology 2017

NEWS FROM THE WORLD- Excessive burden of lysosomal storage disorder gene variants in Parkinson’s disease

Abstract

Mutations in the glucocerebrosidase gene (GBA), which cause Gaucher disease, are also potent risk factors for Parkinson’s disease. We examined whether a genetic burden of variants in other lysosomal storage disorder genes is more broadly associated with Parkinson’s disease susceptibility. The sequence kernel association test was used to interrogate variant burden among 54 lysosomal storage disorder genes, leveraging whole exome sequencing data from 1156 Parkinson’s disease cases and 1679 control subjects. We discovered a significant burden of rare, likely damaging lysosomal storage disorder gene variants in association with Parkinson’s disease risk. The association signal was robust to the exclusion of GBA, and consistent results were obtained in two independent replication cohorts, including 436 cases and 169 controls with whole exome sequencing and an additional 6713 cases and 5964 controls with exome-wide genotyping. In secondary analyses designed to highlight the specific genes driving the aggregate signal, we confirmed associations at the GBA and SMPD1 loci and newly implicate CTSDSLC17A5, and ASAH1 as candidate Parkinson’s disease susceptibility genes. In our discovery cohort, the majority of Parkinson’s disease cases (56%) have at least one putative damaging variant in a lysosomal storage disorder gene, and 21% carry multiple alleles. Our results highlight several promising new susceptibility loci and reinforce the importance of lysosomal mechanisms in Parkinson’s disease pathogenesis. We suggest that multiple genetic hits may act in combination to degrade lysosomal function, enhancing Parkinson’s disease susceptibility.

NEWS FROM THE WORLD- Novel genes associated with amyotrophic lateral sclerosis: diagnostic and clinical implications

Summary

Background

The disease course of amyotrophic lateral sclerosis (ALS) is rapid and, because its pathophysiology is unclear, few effective treatments are available. Genetic research aims to understand the underlying mechanisms of ALS and identify potential therapeutic targets. The first gene associated with ALS was SOD1, identified in 1993 and, by early 2014, more than 20 genes had been identified as causative of, or highly associated with, ALS. These genetic discoveries have identified key disease pathways that are therapeutically testable and could potentially lead to the development of better treatments for people with ALS.

Recent developments

Since 2014, seven additional genes have been associated with ALS (MATR3, CHCHD10, TBK1, TUBA4A, NEK1, C21orf2, and CCNF), all of which were identified by genome-wide association studies, whole genome studies, or exome sequencing technologies. Each of the seven novel genes code for proteins associated with one or more molecular pathways known to be involved in ALS. These pathways include dysfunction in global protein homoeostasis resulting from abnormal protein aggregation or a defect in the protein clearance pathway, mitochondrial dysfunction, altered RNA metabolism, impaired cytoskeletal integrity, altered axonal transport dynamics, and DNA damage accumulation due to defective DNA repair. Because these novel genes share common disease pathways with other genes implicated in ALS, therapeutics targeting these pathways could be useful for a broad group of patients stratified by genotype. However, the effects of these novel genes have not yet been investigated in animal models, which will be a key step to translating these findings into clinical practice.

Where next?

The identification of these seven novel genes has been important in unravelling the molecular mechanisms underlying ALS. However, our understanding of what causes ALS is not complete, and further genetic research will provide additional detail about its causes. Increased genetic knowledge will also identify potential therapeutic targets and could lead to the development of individualised medicine for patients with ALS. These developments will have a direct effect on clinical practice when genome sequencing becomes a routine and integral part of disease diagnosis and management.
Lancet Neurology 2017

NEWS FROM THE WORLD- Nonalcoholic fatty liver disease in spinal and bulbar muscular atrophy

ABSTRACT

Objective: To determine the prevalence and features of fatty liver disease in spinal and bulbar muscular atrophy (SBMA).
Methods: Two groups of participants with SBMA were evaluated. In the first group, 22 participants with SBMA underwent laboratory analysis and liver imaging. In the second group, 14 participants with SBMA were compared to 13 female carriers and 23 controls. Liver biopsies were done in 4 participants with SBMA.
Results: Evidence of fatty liver disease was detected by magnetic resonance spectroscopy in all participants with SBMA in the first group, with an average dome intrahepatic triacylglycerol of 27% (range 6%–66%, ref ≤5.5%). Liver dome magnetic resonance spectroscopy measurements were significantly increased in participants with SBMA in the second group relative to age- and sex-matched controls, with average disease and male control measurements of 17% and 3%, respectively. Liver biopsies were consistent with simple steatosis in 2 participants and nonalcoholic steatohepatitis in 2 others.
Conclusions: We observed evidence of nonalcoholic liver disease in nearly all of the participants with SBMA evaluated. These observations expand the phenotypic spectrum of the disease and provide a potential biomarker that can be monitored in future studies.

Neurology 2017

NEWS FROM THE WORLD- Virtual Reality Training for Upper Extremity in Subacute Stroke (VIRTUES) A multicenter RCT

ABSTRACT

Objective: To compare the effectiveness of upper extremity virtual reality rehabilitation training (VR) to time-matched conventional training (CT) in the subacute phase after stroke.
Methods: In this randomized, controlled, single-blind phase III multicenter trial, 120 participants with upper extremity motor impairment within 12 weeks after stroke were consecutively included at 5 rehabilitation institutions. Participants were randomized to either VR or CT as an adjunct to standard rehabilitation and stratified according to mild to moderate or severe hand paresis, defined as ≥20 degrees wrist and 10 degrees finger extension or less, respectively. The training comprised a minimum of sixteen 60-minute sessions over 4 weeks. The primary outcome measure was the Action Research Arm Test (ARAT); secondary outcome measures were the Box and Blocks Test and Functional Independence Measure. Patients were assessed at baseline, after intervention, and at the 3-month follow-up.
Results: Mean time from stroke onset for the VR group was 35 (SD 21) days and for the CT group was 34 (SD 19) days. There were no between-group differences for any of the outcome measures. Improvement of upper extremity motor function assessed with ARAT was similar at the postintervention (p = 0.714) and follow-up (p = 0.777) assessments. Patients in VR improved 12 (SD 11) points from baseline to the postintervention assessment and 17 (SD 13) points from baseline to follow-up, while patients in CT improved 13 (SD 10) and 17 (SD 13) points, respectively. Improvement was also similar for our subgroup analysis with mild to moderate and severe upper extremity paresis.
Conclusions: Additional upper extremity VR training was not superior but equally as effective as additional CT in the subacute phase after stroke. VR may constitute a motivating training alternative as a supplement to standard rehabilitation.
ClinicalTrials.gov identifier: NCT02079103.
Classification of evidence: This study provides Class I evidence that for patients with upper extremity motor impairment after stroke, compared to conventional training, VR training did not lead to significant differences in upper extremity function improvement.

Neurology 2017

NEWS FROM THE WORLD- Motor, cognitive, and functional declines contribute to a single progressive factor in early HD

ABSTRACT

Objective: To identify an improved measure of clinical progression in early Huntington disease (HD) using data from prospective observational cohort studies and placebo group data from randomized double-blind clinical trials.
Methods: We studied Unified Huntington Disease Rating Scale (UHDRS) and non-UHDRS clinical measures and brain measures of progressive atrophy in 1,668 individuals with early HD followed up prospectively for up to 30 to 36 months of longitudinal clinical follow-up.
Results: The results demonstrated that a composite measure of motor, cognitive, and global functional decline best characterized clinical progression and was most strongly associated with brain measures of progressive corticostriatal atrophy.
Conclusions: Use of a composite motor, cognitive, and global functional clinical outcome measure in HD provides an improved measure of clinical progression more related to measures of progressive brain atrophy and provides an opportunity for enhanced clinical trial efficiency relative to currently used individual motor, cognitive, and functional outcome measures.

Neurology 2017

NEWS FROM THE WORLD- Increased florbetapir binding in the temporal neocortex from age 20 to 60 years

ABSTRACT

Objective: To improve our understanding of early β-amyloid (Aβ) accumulation processes using florbetapir-PET scan in 20- to 60-year-old individuals.
Methods: Seventy-six cognitively normal individuals aged 20 to 60 years, 57 cognitively normal older individuals (61–84 years old), and 70 patients with mild cognitive impairment or probable Alzheimer disease (AD) underwent a florbetapir-PET scan. Images were spatially normalized and scaled using the whole cerebellum. The relationship with age was assessed on the mean neocortical standardized uptake value ratio (SUVR) and voxelwise in the younger group to assess early Aβ accumulation processes. To compare the topography of early-age-related vs AD-related changes, Aβ increase in patients vs cognitively normal older adults was also assessed.
Results: A linear increase of Aβ deposition from 20 to 60 years old was found on the mean neocortical SUVR, and more specifically on the temporal neocortex. By contrast, increase in patients predominated in frontal and medial parietal areas. The temporal increase in healthy participants was still significant when including only the 20- to 50-year-old individuals and controlling for several possible methodologic confounds.
Conclusions: Florbetapir binding increases linearly from 20 to 60 years old in the temporal lobe. Pending replication, including with other PET tracers, this study suggests that the well-described medial frontal and parietal accumulation in late adulthood and AD might superimpose to a physiologic accumulation of Aβ, starting from young adulthood, in temporal lobes.

Neurology 2017