Association of Copresence of Pathogenic Variants Related to Amyotrophic Lateral Sclerosis and Prognosis.

BACKGROUND AND OBJECTIVES: Despite recent advances, it is not clear whether the various genes/genetic variants related to amyotrophic lateral sclerosis (ALS) interact in modifying patients' phenotype. The aim of this study was to determine whether the copresence of genetic variants related to ALS has interactive effects on the course of the disease. METHODS: The study population includes 1,245 patients with ALS identified through the Piemonte Register for ALS between 2007 and 2016 and not carrying superoxide dismutase type 1, TAR DNA binding protein, and fused in sarcoma pathogenic variants. Controls were 766 Italian participants age-matched, sex-matched, and geographically matched to cases. We considered Unc-13 homolog A (UNC13A) (rs12608932), calmodulin binding transcription activator 1 (CAMTA1) (rs2412208), solute carrier family 11 member 2 (SLC11A2) (rs407135), and zinc finger protein 512B (ZNF512B) (rs2275294) variants, as well as ataxin-2 (ATXN2) polyQ intermediate repeats (≥31) and chromosome 9 open reading frame 72 (C9orf72) GGGGCC intronic expansions (≥30). RESULTS: The median survival time of the whole cohort was 2.67 years (interquartile range [IQR] 1.67-5.25). In univariate analysis, only C9orf72 (2.51 years, IQR 1.74-3.82; p = 0.016), ATXN2 (1.82 years, IQR 1.08-2.33; p < 0.001), and UNC13A C/C (2.3 years, IQR 1.3-3.9; p < 0.001) significantly reduced survival. In Cox multivariable analysis, CAMTA1 also emerged to be independently related to survival (hazard ratio 1.13, 95% CI 1.001-1.30, p = 0.048). The copresence of 2 detrimental alleles/expansions was correlated with shorter survival. In particular, the median survival of patients with CAMTA1 G/G+G/T and UNC13A C/C alleles was 1.67 years (1.16-3.08) compared with 2.75 years (1.67-5.26) of the patients not carrying these variants (p < 0.001); the survival of patients with CAMTA1 G/G+G/T alleles and ATXN2 ≥31 intermediate polyQ repeats was 1.75 years (0.84-2.18) (p < 0.001); the survival of patients with ATXN2 ≥31 polyQ repeats and UNC13A C/C allele was 1.33 years (0.84-1.75) (p < 0.001); the survival of patients with C9ORF72 ≥30 and UNC13A C/C allele was 1.66 years (1.41-2.16). Each pair of detrimental alleles/expansions was associated to specific clinical phenotypes. DISCUSSION: We showed that gene variants acting as modifiers of ALS survival or phenotype can act on their own or in unison. Overall, 54% of patients carried at least 1 detrimental common variant or repeat expansion, emphasizing the clinical impact of our findings. In addition, the identification of the interactive effects of modifier genes represents a crucial clue for explaining ALS clinical heterogeneity and should be considered when designing and interpreting clinical trials results.

Pallidal functional connectivity changes are associated with disgust recognition in pure motor amyotrophic lateral sclerosis.

In the present study, we aimed to investigate the resting-state functional connectivity (RS-FC) of the globus pallidus (GP) in patients with amyotrophic lateral sclerosis (ALS) compared to healthy controls, and the relationship between RS-FC changes and disgust recognition. Twenty-six pure-motor ALS patients and 52 healthy controls underwent RS functional MRI and a neuropsychological assessment including the Comprehensive Affect Testing System. A seed-based RS-FC analysis was performed between the left and right GP and the rest of the brain and compared between groups. Correlations between RS-FC significant changes and subjects' performance in recognizing disgust were tested. Compared to controls, patients were significantly less able to recognize disgust. In ALS compared to controls, the seed-based analysis showed: reduced RS-FC between bilateral GP and bilateral middle and superior frontal and middle cingulate gyri, and increased RS-FC between bilateral GP and bilateral postcentral, supramarginal and superior temporal gyri and Rolandic operculum. Decreased RS-FC was further observed between left GP and left middle and inferior temporal gyri and bilateral caudate; and increased RS-FC was also shown between right GP and left lingual and fusiform gyri. In patients and controls, lower performance in recognizing disgust correlated with reduced RS-FC between left GP and left middle and inferior temporal gyri. In pure-motor ALS patients, we demonstrated altered RS-FC between GP and the rest of the brain. The reduced left pallidum-temporo-striatal RS-FC may have a role in the lower ability of patients in recognizing disgust.

Arterial blood gas analysis: base excess and carbonate are predictive of noninvasive ventilation adaptation and survival in amyotrophic lateral sclerosis.

Objective: To investigate the role of arterial blood gas (ABG) analysis parameters (blood carbon dioxide, pCO2; oxygen, pO2; carbonate, HCO3-; standard base excess, SBE) in monitoring respiratory function and ventilation compliance after noninvasive mechanical ventilation (NIV) adaptation, predicting survival in ALS patients. Methods: We selected the first ABG performed after NIV start in ALS patients followed from 2000 to 2015 in Turin ALS Center. Correlations between ABG parameters and survival were calculated. Risk for death/tracheostomy was computed at modifying ABG parameters by using Cox regression models, adjusted for the main prognostic factors. Kaplan-Meier curves were then performed and compared. Results: A total of 186 post-NIV ABGs were included. HCO3- and SBE showed a significant correlation with survival after NIV (respectively, R = -0.183, p = 0.018 and R = -0.200, p = 0.010). Risk for death/tracheostomy after NIV was significantly higher at increasing HCO3- and SBE blood levels, especially when HCO3- was >29 mmol/L and SBE >4 mmol/L (respectively, HR 1.466, 95% CI 1.068-2.011, p = 0.018 and HR = 1.411, 95% CI 1.030-1.32, p = 0.032). Survival in NIV was higher in patients with HCO3- < 29.0 mmol/L and SBE < 4.0 mmol/L. Conclusions: HCO3- and SBE blood levels are markers of ventilation compliance, tolerance and efficacy, being able to predict survival after NIV start in ALS.

Genome sequencing analysis identifies new loci associated with Lewy body dementia and provides insights into its genetic architecture.

The genetic basis of Lewy body dementia (LBD) is not well understood. Here, we performed whole-genome sequencing in large cohorts of LBD cases and neurologically healthy controls to study the genetic architecture of this understudied form of dementia, and to generate a resource for the scientific community. Genome-wide association analysis identified five independent risk loci, whereas genome-wide gene-aggregation tests implicated mutations in the gene GBA. Genetic risk scores demonstrate that LBD shares risk profiles and pathways with Alzheimer's disease and Parkinson's disease, providing a deeper molecular understanding of the complex genetic architecture of this age-related neurodegenerative condition.

Association between maximum tongue pressure and swallowing safety and efficacy in amyotrophic lateral sclerosis.

BACKGROUND: Oropharyngeal dysphagia (OD) is common in amyotrophic lateral sclerosis (ALS), leading to a reduction of swallowing safety and efficacy. The tongue has an important role in swallowing function for oral processing and bolus propulsion through the pharynx. The study aims to analyze the association between instrumental findings of OD and tongue pressure. METHODS: Patients with ALS referred for fiberoptic endoscopic evaluation of swallowing (FEES) were recruited. FEES was conducted to test swallowing function with liquid (5, 10, and 20 ml), semisolid (5, 10, and 20 ml), and solid. FEES recordings were assessed for swallowing safety, using the penetration-aspiration scale (PAS), and for swallowing efficacy, using the Yale Pharyngeal Residue Severity Rating Scale (YPRSRS). PAS scores >2 were suggestive of penetration, PAS scores >5 of aspiration, and YPRSRS scores >2 of residue. Maximum tongue pressure (MTP) and tongue endurance were measured using the Iowa Oral Performance Instrument. Tongue pressure measurements were compared between patients with and without penetration, aspiration, or residue. KEY RESULTS: Fifty-five patients with ALS were included. Mean MTP was 29.7 kPa, and median tongue endurance was 10 seconds. Patients with residue in the pyriform sinus had a significantly lower MTP than patients without residue in the pyriform sinus with semisolids 10 ml (P = .011) and 20 ml (P = .032). Patients with a tongue endurance <10 seconds exhibited higher frequency of penetration with liquids 5 ml (P = .046), liquids 10 ml (P = .015), and solids (P = .22). CONCLUSION AND INFERENCES: In patients with ALS, MTP is significantly associated with an impairment of swallowing efficacy and tongue endurance was significantly associated with an impairment of swallowing safety.

Disease-modifying therapies in amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder of adult life, causing weakness and wasting of voluntary muscles, associated in about 50% of cases with a cognitive impairment. Pathologically, the disease is characterized by a degeneration of upper and lower motor neurons. A hallmark of the pathological process is the aggregation of the protein TDP43 in the cytoplasm of affected neurons detected in almost 97% of cases. About 15% of cases has a family history. Currently, only two drugs have been demonstrated to be effective in ALS, riluzole and edaravone, which show only modest effects on disease progression. The quest for disease-modifying therapies in ALS has several obstacles, the most important being the sub-optimal quality of the design of clinical trials, and the clinical and pathological heterogeneity of the disease. In this paper the pathological mechanisms relevant to ALS and current and future pharmacological and non-pharmacological trials, including gene and stem cells therapies, will be presented. This article is part of the special issue entitled 'The Quest for Disease-Modifying Therapies for Neurodegenerative Disorders'.

Shared polygenic risk and causal inferences in amyotrophic lateral sclerosis.

OBJECTIVE: To identify shared polygenic risk and causal associations in amyotrophic lateral sclerosis (ALS). METHODS: Linkage disequilibrium score regression and Mendelian randomization were applied in a large-scale, data-driven manner to explore genetic correlations and causal relationships between >700 phenotypic traits and ALS. Exposures consisted of publicly available genome-wide association studies (GWASes) summary statistics from MR Base and LD-hub. The outcome data came from the recently published ALS GWAS involving 20,806 cases and 59,804 controls. Multivariate analyses, genetic risk profiling, and Bayesian colocalization analyses were also performed. RESULTS: We have shown, by linkage disequilibrium score regression, that ALS shares polygenic risk genetic factors with a number of traits and conditions, including positive correlations with smoking status and moderate levels of physical activity, and negative correlations with higher cognitive performance, higher educational attainment, and light levels of physical activity. Using Mendelian randomization, we found evidence that hyperlipidemia is a causal risk factor for ALS and localized putative functional signals within loci of interest. INTERPRETATION: Here, we have developed a public resource (https://lng-nia.shinyapps.io/mrshiny) which we hope will become a valuable tool for the ALS community, and that will be expanded and updated as new data become available. Shared polygenic risk exists between ALS and educational attainment, physical activity, smoking, and tenseness/restlessness. We also found evidence that elevated low-desnity lipoprotein cholesterol is a causal risk factor for ALS. Future randomized controlled trials should be considered as a proof of causality. Ann Neurol 2019;85:470-481.

Physicians' attitudes toward end-of-life decisions in amyotrophic lateral sclerosis.

OBJECTIVE: This study aims (1) to assess physicians' attitudes toward different palliative end-of-life (EOL) practices in amyotrophic lateral sclerosis (ALS) care, including forgoing artificial nutrition and hydration (FANH), continuous sedation until death (CSD), and withdrawing invasive ventilation (WIV), and toward physician-assisted dying (PAD) including physician-assisted suicide and euthanasia and (2) to explore variables influencing these attitudes. METHODS: We used two clinical vignettes depicting ALS patients in different stages of their disease progression to assess the influence of suffering (physical/psycho-existential) on attitudes toward WIV and the influence of suffering and prognosis (short-term/long-term) on attitudes toward FANH, CSD, and PAD. RESULTS: 50 physicians from European ALS centers and neurological departments completed our survey. Short-term prognosis had a positive impact on attitudes toward offering FANH (p = 0.014) and CSD (p = 0.048) as well as on attitudes toward performing CSD (p = 0.036) and euthanasia (p = 0.023). Predominantly psycho-existential suffering was associated with a more favorable attitude toward WIV but influenced attitudes toward performing CSD negatively. Regression analysis showed that religiosity was associated with more reluctant attitudes toward palliative EOL practices and PAD, whereas training in palliative care was associated with more favorable attitudes toward palliative EOL practices only. CONCLUSION: ALS physicians seem to acknowledge psycho-existential suffering as a highly acceptable motive for WIV but not CSD. Physicians appear to be comfortable with responding to the patient's requests, but more reluctant to assume a proactive role in the decision-making process. Palliative care training may support ALS physicians in these challenging situations.

The multistep hypothesis of ALS revisited: The role of genetic mutations.

OBJECTIVE: Amyotrophic lateral sclerosis (ALS) incidence rates are consistent with the hypothesis that ALS is a multistep process. We tested the hypothesis that carrying a large effect mutation might account for ≥1 steps through the effect of the mutation, thus leaving fewer remaining steps before ALS begins. METHODS: We generated incidence data from an ALS population register in Italy (2007-2015) for which genetic analysis for C9orf72, SOD1, TARDBP, and FUS genes was performed in 82% of incident cases. As confirmation, we used data from ALS cases diagnosed in the Republic of Ireland (2006-2014). We regressed the log of age-specific incidence against the log of age with least-squares regression for the subpopulation carrying disease-associated variation in each separate gene. RESULTS: Of the 1,077 genetically tested cases, 74 (6.9%) carried C9orf72 mutations, 20 (1.9%) had SOD1 mutations, 15 (1.4%) had TARDBP mutations, and 3 (0.3%) carried FUS mutations. In the whole population, there was a linear relationship between log incidence and log age (r2 = 0.98) with a slope estimate of 4.65 (4.37-4.95), consistent with a 6-step process. The analysis for C9orf72-mutated patients confirmed a linear relationship (r2 = 0.94) with a slope estimate of 2.22 (1.74-2.29), suggesting a 3-step process. This estimate was confirmed by data from the Irish ALS register. The slope estimate was consistent with a 2-step process for SOD1 and with a 4-step process for TARDBP. CONCLUSION: The identification of a reduced number of steps in patients with ALS with genetic mutations compared to those without mutations supports the idea of ALS as a multistep process and is an important advance for dissecting the pathogenic process in ALS.

Influence of cigarette smoking on ALS outcome: a population-based study.

OBJECTIVE: To assess the prognostic influence of premorbid smoking habits and vascular risk profile on amyotrophic lateral sclerosis (ALS) phenotype and outcome in a population-based cohort of Italian patients. METHODS: A total of 650 patients with ALS from the Piemonte/Valle d'Aosta Register for ALS, incident in the 2007-2011 period, were recruited. Information about premorbid cigarette smoking habits and chronic obstructive pulmonary disease (COPD) were collected at the time of diagnosis. RESULTS: Current smokers had a significantly shorter median survival (1.9 years, IQR 1.2-3.4) compared with former (2.3 years, IQR 1.5-4.2) and never smokers (2.7 years, IQR 1.8-4.6) (p=0.001). Also COPD adversely influenced patients' prognosis. Both smoking habits and CODP were retained in Cox multivariable model. CONCLUSIONS: This study has demonstrated in a large population-based cohort of patients with ALS that cigarette smoking is an independent negative prognostic factor for survival, with a dose-response gradient. Its effect is not related to the presence of COPD or to respiratory status at time of diagnosis. The understanding of the mechanisms, either genetic or epigenetic, through which exogenous factors influence disease phenotype is of major importance towards a more focused approach to cure ALS.

Mutational analysis of COQ2 in patients with MSA in Italy.

COQ2 mutations have been implicated in the etiology of multiple system atrophy (MSA) in Japan. However, several genetic screenings have not confirmed the role of its variants in the disease. We performed COQ2 sequence analysis in 87 probable MSA. A homozygous change p.A43G was found in an MSA-C patient. Cosegregation analysis and the evaluation of CoQ10 content in muscle and fibroblasts did not support the pathogenic role of this variant.

Peptidylprolyl isomerase A governs TARDBP function and assembly in heterogeneous nuclear ribonucleoprotein complexes.

Peptidylprolyl isomerase A (PPIA), also known as cyclophilin A, is a multifunctional protein with peptidyl-prolyl cis-trans isomerase activity. PPIA is also a translational biomarker for amyotrophic lateral sclerosis, and is enriched in aggregates isolated from amyotrophic lateral sclerosis and frontotemporal lobar degeneration patients. Its normal function in the central nervous system is unknown. Here we show that PPIA is a functional interacting partner of TARDBP (also known as TDP-43). PPIA regulates expression of known TARDBP RNA targets and is necessary for the assembly of TARDBP in heterogeneous nuclear ribonucleoprotein complexes. Our data suggest that perturbation of PPIA/TARDBP interaction causes 'TDP-43' pathology. Consistent with this model, we show that the PPIA/TARDBP interaction is impaired in several pathological conditions. Moreover, PPIA depletion induces TARDBP aggregation, downregulates HDAC6, ATG7 and VCP, and accelerates disease progression in the SOD1(G93A) mouse model of amyotrophic lateral sclerosis. Targeting the PPIA/TARDBP interaction may represent a novel therapeutic avenue for conditions involving TARDBP/TDP-43 pathology, such as amyotrophic lateral sclerosis and frontotemporal lobar degeneration.

ATXN2 polyQ intermediate repeats are a modifier of ALS survival.

OBJECTIVE: To analyze the frequency and clinical characteristics of patients with amyotrophic lateral sclerosis (ALS) with intermediate-length (CAG) expansion (encoding 27-33 glutamines, polyQ) in the ATXN2 gene, in a population-based cohort of Italian patients with ALS (discovery cohort), and to replicate the findings in an independent cohort of consecutive patients from an ALS tertiary center (validation cohort). METHODS: PolyQ repeats were assessed in 672 patients with incident ALS in Piemonte and Valle d'Aosta regions, Italy, in the 2007-2012 period (discovery cohort); controls were 509 neurologically healthy age- and sex-matched subjects resident in the study area. The validation cohort included 661 patients with ALS consecutively seen between 2001 and 2013 in the ALS Clinic Center of the Catholic University in Rome, Italy. RESULTS: In the discovery cohort, the frequency of ≥31 polyQ ATNX2 repeats was significantly more common in ALS cases (19 patients vs 1 control, p = 0.0001; odds ratio 14.8, 95% confidence interval 1.9-110.8). Patients with an increased number of polyQ repeats had a shorter survival than those with <31 repeats (median survival, polyQ ≥31, 1.8 years, interquartile range [IQR] 1.3-2.2; polyQ <31, 2.7 years, IQR 1.6-5.1; p = 0.001). An increased number of polyQ repeats remained independently significant at multivariable analysis. In the validation cohort, patients with ≥31 polyQ repeats had a shorter survival than those with <31 repeats (median survival, polyQ ≥31, 2.0 years, IQR 1.5-3.4; polyQ <31, 3.2 years, IQR 2.0-6.4; p = 0.007). CONCLUSIONS: ATXN2 polyQ intermediate-length repeat is a modifier of ALS survival. Disease-modifying therapies targeted to ATXN2 represent a promising therapeutic approach for ALS.

Analysis of amyotrophic lateral sclerosis as a multistep process: a population-based modelling study.

BACKGROUND: Amyotrophic lateral sclerosis shares characteristics with some cancers, such as onset being more common in later life, progression usually being rapid, the disease affecting a particular cell type, and showing complex inheritance. We used a model originally applied to cancer epidemiology to investigate the hypothesis that amyotrophic lateral sclerosis is a multistep process. METHODS: We generated incidence data by age and sex from amyotrophic lateral sclerosis population registers in Ireland (registration dates 1995-2012), the Netherlands (2006-12), Italy (1995-2004), Scotland (1989-98), and England (2002-09), and calculated age and sex-adjusted incidences for each register. We regressed the log of age-specific incidence against the log of age with least squares regression. We did the analyses within each register, and also did a combined analysis, adjusting for register. FINDINGS: We identified 6274 cases of amyotrophic lateral sclerosis from a catchment population of about 34 million people. We noted a linear relationship between log incidence and log age in all five registers: England r(2)=0·95, Ireland r(2)=0·99, Italy r(2)=0·95, the Netherlands r(2)=0·99, and Scotland r(2)=0·97; overall r(2)=0·99. All five registers gave similar estimates of the linear slope ranging from 4·5 to 5·1, with overlapping confidence intervals. The combination of all five registers gave an overall slope of 4·8 (95% CI 4·5-5·0), with similar estimates for men (4·6, 4·3-4·9) and women (5·0, 4·5-5·5). INTERPRETATION: A linear relationship between the log incidence and log age of onset of amyotrophic lateral sclerosis is consistent with a multistage model of disease. The slope estimate suggests that amyotrophic lateral sclerosis is a six-step process. Identification of these steps could lead to preventive and therapeutic avenues. FUNDING: UK Medical Research Council; UK Economic and Social Research Council; Ireland Health Research Board; The Netherlands Organisation for Health Research and Development (ZonMw); the Ministry of Health and Ministry of Education, University, and Research in Italy; the Motor Neurone Disease Association of England, Wales, and Northern Ireland; and the European Commission (Seventh Framework Programme).

Extensive genetics of ALS: a population-based study in Italy.

OBJECTIVE: To assess the frequency and clinical characteristics of patients with mutations of major amyotrophic lateral sclerosis (ALS) genes in a prospectively ascertained, population-based epidemiologic series of cases. METHODS: The study population includes all ALS cases diagnosed in Piemonte, Italy, from January 2007 to June 2011. Mutations of SOD1, TARDBP, ANG, FUS, OPTN, and C9ORF72 have been assessed. RESULTS: Out of the 475 patients included in the study, 51 (10.7%) carried a mutation of an ALS-related gene (C9ORF72, 32; SOD1, 10; TARDBP, 7; FUS, 1; OPTN, 1; ANG, none). A positive family history for ALS or frontotemporal dementia (FTD) was found in 46 (9.7%) patients. Thirty-one (67.4%) of the 46 familial cases and 20 (4.7%) of the 429 sporadic cases had a genetic mutation. According to logistic regression modeling, besides a positive family history for ALS or FTD, the chance to carry a genetic mutation was related to the presence of comorbid FTD (odds ratio 3.5; p = 0.001), and age at onset ≤54 years (odds ratio 1.79; p = 0.012). CONCLUSIONS: We have found that ∼11% of patients with ALS carry a genetic mutation, with C9ORF72 being the commonest genetic alteration. Comorbid FTD or a young age at onset are strong indicators of a possible genetic origin of the disease.

Valosin-containing protein (VCP) mutations in sporadic amyotrophic lateral sclerosis.

We recently reported that mutations in the valosin-containing protein (VCP) gene are a cause of 1%-2% of familial amyotrophic lateral sclerosis (ALS) cases, but their role in the pathogenesis of sporadic ALS is unclear. We undertook mutational screening of VCP in 701 sporadic ALS cases. Three pathogenic variants (p.Arg159Cys, p.Asn387Thr, and p.R662C) were found in three U.S. cases, each of whom presented with progressive upper and lower motor neuron signs consistent with definite ALS by El Escorial diagnostic criteria. Our data indicate that VCP mutations may underlie apparently sporadic ALS but account for <1% of this form of disease.

Repeated courses of granulocyte colony-stimulating factor in amyotrophic lateral sclerosis: clinical and biological results from a prospective multicenter study.

Granulocyte colony-stimulating factor (G-CSF) induces a transient mobilization of hematopoietic progenitor cells from bone marrow to peripheral blood. Our aim was to evaluate safety of repeated courses of G-CSF in patients with amyotrophic lateral sclerosis (ALS), assessing disease progression and changes in chemokine and cytokine levels in serum and cerebrospinal fluid (CSF). Twenty-four ALS patients entered an open-label, multicenter trial in which four courses of G-CSF and mannitol were administered at 3-month intervals. Levels of G-CSF were increased after treatment in the serum and CSF. Few and transitory adverse events were observed. No significant reduction of the mean monthly decrease in ALSFRS-R score and forced vital capacity was observed. A significant reduction in CSF levels of monocyte chemoattractant protein-1 (MCP-1) and interleukin-17 (IL-17) was observed. G-CSF treatment was safe and feasible in a multicenter series of ALS patients. A decrease in the CSF levels of proinflammatory cytokines MCP-1 and IL-17 was found, indicating a G-CSF-induced central anti-inflammatory response.

FUS mutations in sporadic amyotrophic lateral sclerosis.

Mutations in the FUS gene have recently been described as a cause of familial amyotrophic lateral sclerosis (ALS), but their role in the pathogenesis of sporadic ALS is unclear. We undertook mutational screening of all coding exons of FUS in 228 sporadic ALS cases, and, as previous reports suggest that exon 15 represents a mutational hotspot, we sequenced this exon in an additional 1295 sporadic cases. Six variants in six different cases were found, indicating that FUS mutations can underlie apparently sporadic ALS, but account for less than 1% of this form of disease.

Exome sequencing reveals VCP mutations as a cause of familial ALS.

Using exome sequencing, we identified a p.R191Q amino acid change in the valosin-containing protein (VCP) gene in an Italian family with autosomal dominantly inherited amyotrophic lateral sclerosis (ALS). Mutations in VCP have previously been identified in families with Inclusion Body Myopathy, Paget disease, and Frontotemporal Dementia (IBMPFD). Screening of VCP in a cohort of 210 familial ALS cases and 78 autopsy-proven ALS cases identified four additional mutations including a p.R155H mutation in a pathologically proven case of ALS. VCP protein is essential for maturation of ubiquitin-containing autophagosomes, and mutant VCP toxicity is partially mediated through its effect on TDP-43 protein, a major constituent of ubiquitin inclusions that neuropathologically characterize ALS. Our data broaden the phenotype of IBMPFD to include motor neuron degeneration, suggest that VCP mutations may account for ∼1%-2% of familial ALS, and provide evidence directly implicating defects in the ubiquitination/protein degradation pathway in motor neuron degeneration.