Use of the combination of spirometry, arterial blood gas analysis and overnight oximetry to predict the outcomes of patients affected by motor neuron disease: The Milan-Torin respiratory score (Mi-To-RS).

BACKGROUND AND PURPOSE: The use of multiple tests, including spirometry, arterial blood gas (ABG) analysis and overnight oximetry (OvOx), is highly recommended to monitor the respiratory function of patients with motor neuron disease (MND). In this study, we propose a composite score to simplify the respiratory management of MND patients and better stratify their prognosis. MATERIALS AND METHODS: We screened the clinical charts of 471 non-ventilated MND patients referred to the Neuro-rehabilitation Unit of the San Raffaele Scientific Institute of Milan (January 2001-December 2019), collecting spirometric, ABG and OvOx parameters. To evaluate the prognostic role of each measurement, univariate Cox regression for death/tracheostomy was performed, and the variables associated with survival were selected to design a scoring system. Univariate and multivariate Cox regression analyses were then carried out to evaluate the prognostic role of the score. Finally, results were replicated in an independent cohort from the Turin ALS Center. RESULTS: The study population included 450 patients. Six measurements were found to be significantly associated with survival and were selected to design a scoring system (maximum score = 8 points). Kaplan-Meier analysis showed significant stratification of survival and time to non-invasive mechanical ventilation adaptation according to score values, and multivariate analysis confirmed the independent effect of the respiratory score on survival of each cohort. CONCLUSION: Forced vital capacity, ABG and OvOx parameters provide complementary information for the respiratory management and prognosis of MND patients and the combination of these parameters into a single score might help neurologists predict prognosis and guide decisions on the timing of the implementation of different diagnostic or therapeutic approaches.

Predictors for progression in amyotrophic lateral sclerosis associated to SOD1 mutation: insight from two population-based registries.

BACKGROUND: Uncovering distinct features and trajectories of amyotrophic lateral sclerosis (ALS) associated with SOD1 mutations (SOD1-ALS) can provide valuable insights for patient' counseling and stratification for trials, and interventions timing. Our study aims to pinpoint distinct clinical characteristics of SOD1-ALS by delving into genotype-phenotype correlations and factors that potentially impact disease progression. METHODS: This is a retrospective observational study of a SOD1-ALS cohort from two Italian registers situated in the regions of Emilia-Romagna, Piedmont and Valle d'Aosta. RESULTS: Out of 2204 genotyped ALS patients, 2.5% carried SOD1 mutations, with a M:F ratio of 0.83. SOD1-ALS patients were younger, and more frequently reported a family history of ALS and/or FTD. SOD1-ALS had a longer survival compared to patients without ALS-associated gene mutations. However, here was considerable variability in survival across distinct SOD1 mutations, with an average survival of less than a year for the L39V, G42S, G73S, D91N mutations. Among SOD1-ALS, multivariate analysis showed that, alongside established clinical prognostic factors such as advanced age at onset and high progression rate at diagnosis, mutations located in exon 2 or within highly conserved gene positions predicted worse survival. Conversely, among comorbidities, cancer history was independently associated with longer survival. INTERPRETATION: Within the context of an overall slower disease, SOD1-ALS exhibits some degree of heterogeneity linked to the considerable genetic diversity arising from the multitude of potential mutations sites and specific clinical prognostic factors, including cancer history. Revealing the factors that modulate the phenotypic heterogeneity of SOD1-ALS could prove advantageous in improving the efficacy of upcoming therapeutic approaches.

Sensory neuropathy in amyotrophic lateral sclerosis: a systematic review.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by the degeneration of both upper and lower motoneurons, leading to motor and non-motor symptoms. Recent evidence suggests that ALS is indeed a multisystem disorder, associated with cognitive impairment, dysautonomia, pain and fatigue, excess of secretions, and sensory symptoms. To evaluate whether sensory neuropathy could broaden its spectrum, we systematically reviewed its presence and characteristics in ALS, extracting data on epidemiological, clinical, neurophysiological, neuropathological, and genetic features. Sensory neuropathy can be found in up to 20% of ALS patients, affecting both large and small fibers, although there is a great heterogeneity related to different techniques used for its detection (electromyography vs skin biopsy vs nerve biopsy). Moreover, the association between CIDP-like neuropathy and ALS needs to be better explored, although it could be interpreted as part of the neuroinflammatory process in the latter disease. Sensory neuropathy in ALS may be associated with a spinal onset and might be more frequent in SOD1 patients. Moreover, it seems mutually exclusive with cognitive impairment. No associations with sex and other genetic mutation were observed. All these data in the literature reveal the importance of actively looking for sensory neuropathy in ALS patients, and suggest including sensory neuropathy among ALS non-motor features, as it may explain sensory symptoms frequently reported throughout the course of the disease. Its early identification could help avoid diagnostic delays and improve patients' treatment and quality of life.

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.

Exposure to electromagnetic fields does not modify neither the age of onset nor the disease progression in ALS patients.

Being exposed to electromagnetic fields has been suggested to increase the risk of developing Amyotrophic Lateral Sclerosis (ALS). Here, we investigated the effect of exposure to electromagnetic fields on ALS onset age and progression rate (ΔALSFRS-r). A large cohort of ALS patients (n = 1098) was geolocalized at the time of their diagnosis. Concomitantly, data on the distribution of power lines and repeater antennas (extremely low frequency electromagnetic fields) during the same period were retrieved. Exposure to each repeater antenna was calculated as the sum of 1/(distance from each antenna)^2. Exposure to power lines was calculated assuming each patient's address as the center of several circles of variable radius (100, 250, 500, 1000, and 2000 m). For each radius, the exposure was calculated as the length of the power lines included in the circle. Finally, patients were divided into low- and high-exposed based on the median of the exposure and compared using the Mann-Whitney test. A regression model (one for each radius) was also performed. Neither the onset age nor the ΔALSFRS-r differed among patients' low- and high-exposed to electromagnetic fields. Similarly, we could not find any significant relationship using the regression models. Our findings suggest that electromagnetic fields do not modify the ALS phenotype or progression.

Phenotype Analysis of Fused in Sarcoma Mutations in Amyotrophic Lateral Sclerosis.

Background and Objectives: Pathogenic variations in fused in sarcoma (FUS) are among the most common genetic causes of amyotrophic lateral sclerosis (ALS) worldwide. They are supposedly characterized by a homogeneous pure motor phenotype with early-onset and short disease duration. However, a few FUS-mutated cases with a very late disease onset and slow progression have been reported. To analyze genotype-phenotype correlations and identify the prognostic factors in FUS-ALS cases. Methods: We identified and cross-sectionally analyzed 22 FUS-ALS patient histories from a single-center cohort of 2,615 genetically tested patients and reviewed 289 previously published FUS-ALS cases. Survival analysis was performed by Kaplan-Meier survival curves, followed by the log-rank test and multivariate Cox analysis. Results: Survival of FUS-ALS is age-dependent: In our cohort, early-onset cases had a rapid disease progression and short survival (p = 0.000003) while the outcome of FUS-mutated patients with mid-to-late onset did not differ from non-FUS-ALS patients (p = 0.437). Meta-analysis of literature data confirmed this trend (p = 0.00003). This survival pattern is not observed in other ALS-related genes in our series. We clustered FUS-ALS patients in 3 phenotypes: (1) axial ALS, with upper cervical and dropped-head onset in mid-to-late adulthood; (2) benign ALS, usually with a late-onset and slow disease progression; and (3) juvenile ALS, often with bulbar onset and preceded by learning disability or mild mental retardation. Those phenotypes arise from different mutations. Discussion: We observed specific genotype-phenotype correlations of FUS-ALS and identified age at onset as the most critical prognostic factor. Our results demonstrated that FUS mutations underlie a specific subtype of ALS and enable a careful stratification of newly diagnosed FUS-ALS cases for clinical course and potential therapeutic windows. This will be crucial in the light of incoming gene-specific therapy.

Causal associations of genetic factors with clinical progression in amyotrophic lateral sclerosis.

BACKGROUND AND OBJECTIVE: Recent advances in the genetic causes of ALS reveals that about 10% of ALS patients have a genetic origin and that more than 30 genes are likely to contribute to this disease. However, four genes are more frequently associated with ALS: C9ORF72, TARDBP, SOD1, and FUS. The relationship between genetic factors and ALS progression rate is not clear. In this study, we carried out a causal analysis of ALS disease with a genetics perspective in order to assess the contribution of the four mentioned genes to the progression rate of ALS. METHODS: In this work, we applied a novel causal learning model to the CRESLA dataset which is a longitudinal clinical dataset of ALS patients including genetic information of such patients. This study aims to discover the relationship between four mentioned genes and ALS progression rate from a causation perspective using machine learning and probabilistic methods. RESULTS: The results indicate a meaningful association between genetic factors and ALS progression rate with causality viewpoint. Our findings revealed that causal relationships between ALSFRS-R items associated with bulbar regions have the strongest association with genetic factors, especially C9ORF72; and other three genes have the greatest contribution to the respiratory ALSFRS-R items with a causation point of view. CONCLUSIONS: The findings revealed that genetic factors have a significant causal effect on the rate of ALS progression. Since C9ORF72 patients have higher proportion compared to those carrying other three gene mutations in the CRESLA cohort, we need a large multi-centric study to better analyze SOD1, TARDBP and FUS contribution to the ALS clinical progression. We conclude that causal associations between ALSFRS-R clinical factors is a suitable predictor for designing a prognostic model of ALS.

Effects of intracellular calcium accumulation on proteins encoded by the major genes underlying amyotrophic lateral sclerosis.

The aetiology of Amyotrophic Lateral Sclerosis (ALS) is still poorly understood. The discovery of genetic forms of ALS pointed out the mechanisms underlying this pathology, but also showed how complex these mechanisms are. Excitotoxicity is strongly suspected to play a role in ALS pathogenesis. Excitotoxicity is defined as neuron damage due to excessive intake of calcium ions (Ca2+) by the cell. This study aims to find a relationship between the proteins coded by the most relevant genes associated with ALS and intracellular Ca2+ accumulation. In detail, the profile of eight proteins (TDP-43, C9orf72, p62/sequestosome-1, matrin-3, VCP, FUS, SOD1 and profilin-1), was analysed in three different cell types induced to raise their cytoplasmic amount of Ca2+. Intracellular Ca2+ accumulation causes a decrease in the levels of TDP-43, C9orf72, matrin3, VCP, FUS, SOD1 and profilin-1 and an increase in those of p62/sequestosome-1. These events are associated with the proteolytic action of two proteases, calpains and caspases, as well as with the activation of autophagy. Interestingly, Ca2+ appears to both favour and hinder autophagy. Understanding how and why calpain-mediated proteolysis and autophagy, which are physiological processes, become pathological may elucidate the mechanisms responsible for ALS and help discover new therapeutic targets.

A novel splice site FUS mutation in a familial ALS case: effects on protein expression.

Objective: To investigate the impact of a novel heterozygous FUS mutation in the acceptor splice site of intron 14 (c.1542 - 1 g > t) on protein expression in Peripheral Blood Mononuclear Cells (PBMC) from a familial ALS patient. Methods: PBMC were isolated for mRNA analysis (cDNA synthesis, sequencing and one-step RT-PCR), Western Immunoblot (WI), and Immunofluorescence (IF). Results: cDNA analysis revealed the skipping of exon 15 and a premature stop codon at c.228. RT-PCR showed reduced FUS mRNA by more than half compared to a healthy control (HC) and an ALS patient without genetic mutations (wtALS). In WI FUS band intensity in the proband was 30-50% compared to HC and wtALS. An antibody expected to detect only the wild-type protein did not reveal any reduction of FUS band intensity compared to the other antibodies. IF showed no difference among HC, wtALS, and the proband. Discussion: The reduction of FUS mRNA and protein in PBMC suggests the absence of the truncated protein, probably due to nonsense-mediated decay, leading to loss of function.

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.

The heterozygous deletion c.1509_1510delAG in exon 14 of FUS causes an aggressive childhood-onset ALS with cognitive impairment.

We report a case of childhood-onset ALS with a FUS gene mutation presenting cognitive impairment and a rapid clinical progression. The patient, an 11-year-old girl, presented with right distal upper limb weakness and mild intellectual disability at the Griffith Mental Development Scales. The disease rapidly worsened and the patient became tetraplegic and bed-ridden 2 years after symptom onset. A c.1509_1510delAG mutation in exon 14 of the FUS gene was detected, resulting in a predicted truncated protein, p.G504Wfs*12, lacking the nuclear localization signal. The levels of FUS mRNA in the proband were not significantly different compared to controls. Western immunoblot analysis showed that one antibody (500-526) detected in the proband ~50% of the amount of FUS protein compared to controls, while 3 other antibodies (2-27, 400-450 and FUS C-terminal), which recognize both wild type and the mutated FUS, detected 60% to 75% of the amount of the protein. These findings indicate that p.G504Wfs*12 FUS is more prone to undergo post-translational modification respect to wild type FUS.

Comorbidity of Cervical Spondylogenic Myelopathy and Amyotrophic Lateral Sclerosis: When Electromyography Makes the Difference in Diagnosis.

Cervical spondylogenic myelopathy (CSM) represents a common differential diagnosis for spinal onset Amyotrophic Lateral Sclerosis (ALS). Identifying occurrence of ALS in patients with CSM may be challenging. We evaluated the accuracy of Awaji criteria in the diagnosis of ALS in a cohort of patients with CSM. We screened all patients attending Turin ALS Center during the 2006-2018 period. We selected only patients for whom cervical cord MRI showed radiological signs of CSM. All patients underwent electromyography (EMG), and Awaji criteria were used for diagnosis of clinically probable ALS. All patients were followed up clinically for at least 6 months, and ALS diagnosis was eventually confirmed according to El-Escorial revised criteria, based on disease progression. Of 2,059 patients screened, in 42 cases, MRI showed signs of CSM; CSM incidence and prevalence risks were 0.16 and 2.04%, respectively. Based on clinical progression, 72.7% of patients were diagnosed as CSM and 27.3% as CSM + ALS. At EMG 6 (18.2%) patients fulfilled the criteria for ALS, 5 of them (83.3%) during clinical follow-up were diagnosed as clinical definite ALS + CSM. Accuracy of Awaji criteria in diagnosing ALS was good (AUC = 0.757, p = 0.03). Sensitivity and specificity of Awaji criteria were, respectively, 55.6 and 95.8%. Positive predictive value was 83.3%, while negative predictive value was 85.2%. CSM-ALS comorbidity is a relatively common problem in clinical practice. To better choose patients who could benefit from surgery, EMG should be performed in CSM patients, due to its good accuracy in recognizing ALS.

Association between alcohol exposure and the risk of amyotrophic lateral sclerosis in the Euro-MOTOR study.

OBJECTIVES: Several studies focused on the association between alcohol consumption and amyotrophic lateral sclerosis (ALS), although with inconsistent findings. Antioxidants may play a role since lyophilised red wine was found to prolong SOD1 mice lifespan. The aim of this international population-based case-control study performed in Ireland, The Netherlands and Italy was to assess the role of alcohol, and red wine in particular, in developing ALS. METHODS: Euro-MOTOR is a case-control study where patients with incident ALS and controls matched for gender, age and area of residency were recruited in a population-based design. Logistic regression models adjusted for sex, age, cohort, education, leisure time physical activity, smoking, heart problems, hypertension, stroke, cholesterol and diabetes were performed. RESULTS: 1557 patients with ALS and 2922 controls were enrolled in the study. Exposure to alcohol drinking was not significantly associated with ALS risk. A stratified analysis of exposure to alcohol by cohort revealed significant ORs in The Netherlands and in Apulia, with opposite directions (respectively 0.68 and 2.38). With regard to red wine consumption, only in Apulia the double-fold increased risk (OR 2.53) remained significant. A decreased risk was found for current alcohol drinkers (OR 0.83), while a significantly increased risk was detected among former drinkers (OR 1.63). Analysis of cumulative exposure to alcohol revealed no significant associations with ALS risk. CONCLUSION: With few exceptions, no significant association was found between alcohol consumption and ALS. The study of the association between alcohol and ALS requires a thorough exploration, especially considering the role of different type of alcoholic beverages.

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.

Assessing and treating pain in movement disorders, amyotrophic lateral sclerosis, severe acquired brain injury, disorders of consciousness, dementia, oncology and neuroinfectivology. Evidence and recommendations from the Italian Consensus Conference on Pain in Neurorehabilitation.

Pain is an important non-motor symptom in several neurological diseases, such as Parkinson's disease, cervical dystonia, amyotrophic lateral sclerosis, severe acquired brain injury, disorders of consciousness and dementia, as well as in oncology and neuroinfectivology. To overcome the lack of evidence-based data on pain management in these diseases, the Italian Consensus Conference on Pain in Neurorehabilitation (ICCPN) has defined criteria for good clinical practice among Italian neurorehabilitation professionals. Here a review of the literature (PubMed, EMBASE and gray literature) on pain characteristics, treatment and impact of pain in a neurorehabilitation setting is provided. Despite the heterogeneity of data, a consensus was reached on pain management for patients with these diseases: it is an approach originating from an analysis of the available data on pain characteristics in each disease, the evolution of pain in relation to the natural course of the disease and the impact of pain on the overall process of rehabilitation. There was unanimous consensus regarding the utility of a multidisciplinary approach to pain therapy, combining the benefits of pharmacological therapy with the techniques of physiotherapy and neurorehabilitation for all the conditions considered. While some treatments could be different depending on pathology, a progressive approach to the pharmacological treatment of pain is advisable, starting with non-opioid analgesics (paracetamol) and nonsteroidal anti-inflammatory drugs as a first-line treatment, and opioid analgesics as a second-line treatment. In cases of pain secondary to spasticity, botulinum neurotoxin, and, in some cases, intrathecal baclofen infusion should be considered. Randomized controlled trials and prospective multicenter studies aimed at documenting the efficacy of pain treatment and their risk-benefit profile are recommended for these conditions.

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.

Genetic architecture of ALS in Sardinia.

Conserved populations, such as Sardinians, displaying elevated rates of familial or sporadic amyotrophic lateral sclerosis (ALS) provide unique information on the genetics of the disease. Our aim was to describe the genetic profile of a consecutive series of ALS patients of Sardinian ancestry. All ALS patients of Sardinian ancestry, identified between 2008 and 2013 through the Italian ALS Genetic Consortium, were eligible to be included in the study. Patients and controls underwent the analysis of TARDBP, C9ORF72, SOD1, and FUS genes. Genetic mutations were identified in 155 out of 375 Sardinian ALS cases (41.3%), more commonly the p.A382T and p.G295S mutations of TARDBP and the GGGGCC hexanucleotide repeat expansion of C9ORF72. One patient had both p.G295S and p.A382T mutations of TARDBP and 8 carried both the heterozygous p.A382T mutation of TARDBP and a repeat expansion of C9ORF72. Patients carrying the p.A382T and the p.G295S mutations of TARDBP and the C9ORF72 repeat expansion shared distinct haplotypes across these loci. Patients with cooccurrence of C9ORF72 and TARDBP p.A382T missense mutation had a significantly lower age at onset and shorter survival. More than 40% of all cases on the island of Sardinia carry a mutation of an ALS-related gene, representing the highest percentage of ALS cases genetically explained outside of Scandinavia. Clinical phenotypes associated with different genetic mutations show some distinctive characteristics, but the heterogeneity between and among families carrying the same mutations implies that ALS manifestation is influenced by other genetic and nongenetic factors.