Jessica Mandrioli

Clinical characteristics of patients with familial amyotrophic lateral sclerosis carrying the pathogenic GGGGCC hexanucleotide repeat expansion of C9ORF72

A large hexanucleotide (GGGGCC) repeat expansion in the first intron of C9ORF72, a gene located on chromosome 9p21, has been recently reported to be responsible for ~40% of familial amyotrophic lateral sclerosis cases of European ancestry. The aim of the current article was to describe the phenotype of amyotrophic lateral sclerosis cases carrying the expansion by providing a detailed clinical description of affected cases from representative multi-generational kindreds, and by analysing the age of onset, gender ratio and survival in a large cohort of patients with familial amyotrophic lateral sclerosis. We collected DNA and analysed phenotype data for 141 index Italian familial amyotrophic lateral sclerosis cases (21 of Sardinian ancestry) and 41 German index familial amyotrophic lateral sclerosis cases. Pathogenic repeat expansions were detected in 45 (37.5%) patients from mainland Italy, 12 (57.1%) patients of Sardinian ancestry and nine (22.0%) of the 41 German index familial amyotrophic lateral sclerosis cases. The disease was maternally transmitted in 27 (49.1%) pedigrees and paternally transmitted in 28 (50.9%) pedigrees (P = non-significant). On average, children developed disease 7.0 years earlier than their parents [children: 55.8 years (standard deviation 7.9), parents: 62.8 (standard deviation 10.9); P = 0.003]. Parental phenotype influenced the type of clinical symptoms manifested by the child: of the 13 cases where the affected parent had an amyotrophic lateral sclerosis-frontotemporal dementia or frontotemporal dementia, the affected child also developed amyotrophic lateral sclerosis-frontotemporal dementia in nine cases. When compared with patients carrying mutations of other amyotrophic lateral sclerosis-related genes, those with C9ORF72 expansion had commonly a bulbar onset (42.2% compared with 25.0% among non-C9ORF72 expansion cases, P = 0.03) and cognitive impairment (46.7% compared with 9.1% among non-C9ORF72 expansion cases, P = 0.0001). Median survival from symptom onset among cases carrying C9ORF72 repeat expansion was 3.2 years lower than that of patients carrying TARDBP mutations (5.0 years; 95% confidence interval: 3.6-7.2) and longer than those with FUS mutations (1.9 years; 95% confidence interval: 1.7-2.1). We conclude that C9ORF72 hexanucleotide repeat expansions were the most frequent mutation in our large cohort of patients with familial amyotrophic lateral sclerosis of Italian, Sardinian and German ancestry. Together with mutation of SOD1, TARDBP and FUS, mutations of C9ORF72 account for ~60% of familial amyotrophic lateral sclerosis in Italy. Patients with C9ORF72 hexanucleotide repeat expansions present some phenotypic differences compared with patients with mutations of other genes or with unknown mutations, namely a high incidence of bulbar-onset disease and comorbidity with frontotemporal dementia. Their pedigrees typically display a high frequency of cases with pure frontotemporal dementia, widening the concept of familial amyotrophic lateral sclerosis.

A two-stage genome-wide association study of sporadic amyotrophic lateral sclerosis

The cause of sporadic amyotrophic lateral sclerosis (ALS) is largely unknown, but genetic factors are thought to play a significant role in determining susceptibility to motor neuron degeneration. To identify genetic variants altering risk of ALS, we undertook a two-stage genome-wide association study (GWAS): we followed our initial GWAS of 545 066 SNPs in 553 individuals with ALS and 2338 controls by testing the 7600 most associated SNPs from the first stage in three independent cohorts consisting of 2160 cases and 3008 controls. None of the SNPs selected for replication exceeded the Bonferroni threshold for significance. The two most significantly associated SNPs, rs2708909 and rs2708851 [odds ratio (OR) = 1.17 and 1.18, and P-values = 6.98 x 10(-7) and 1.16 x 10(-6)], were located on chromosome 7p13.3 within a 175 kb linkage disequilibrium block containing the SUNC1, HUS1 and C7orf57 genes. These associations did not achieve genome-wide significance in the original cohort and failed to replicate in an additional independent cohort of 989 US cases and 327 controls (OR = 1.18 and 1.19, P-values = 0.08 and 0.06, respectively). Thus, we chose to cautiously interpret our data as hypothesis-generating requiring additional confirmation, especially as all previously reported loci for ALS have failed to replicate successfully. Indeed, the three loci (FGGY, ITPR2 and DPP6) identified in previous GWAS of sporadic ALS were not significantly associated with disease in our study. Our findings suggest that ALS is more genetically and clinically heterogeneous than previously recognized. Genotype data from our study have been made available online to facilitate such future endeavors.

Two Italian kindreds with familial amyotrophic lateral sclerosis due to FUS mutation

Recently, fused in sarcoma/translated in liposarcoma (FUS/TLS) gene, located on chromosome 16p11.2, has been identified as a disease gene in familial amyotrophic lateral sclerosis (FALS). We have analyzed FUS/TLS in a cohort of 52 index cases from seven Italian regions with non-SOD1 and non-TARDBP FALS. We identified a heterozygous c.G1542C missense mutation in a family of northern Italian origin, and a heterozygous c.C1574T missense mutation in a family of Sicilian origin. Both variants are located in exon 15 encoding the RNA-recognition motif, and result in a substitution of an arginine with a serine in position 514 (p.R514S) and substitution of a proline with a leucine at position 525 (p.P525L), respectively. Overall, the two mutations accounted for 3.8% of 52 non-SOD1 and non-TDP43 index cases of FALS. The clinical phenotype was similar within each of the families, with a predominantly upper limb onset in the family carrying the p.R514S mutation and bulbar onset, with very young age and a rapid course in the family carrying the p.P525L mutation.

Pathogenic VCP Mutations Induce Mitochondrial Uncoupling and Reduced ATP Levels

Summary Valosin-containing protein (VCP) is a highly expressed member of the type II AAA+ ATPase family. VCP mutations are the cause of inclusion body myopathy, Paget’s disease of the bone, and frontotemporal dementia (IBMPFD) and they account for 1%–2% of familial amyotrophic lateral sclerosis (ALS). Using fibroblasts from patients carrying three independent pathogenic mutations in the VCP gene, we show that VCP deficiency causes profound mitochondrial uncoupling leading to decreased mitochondrial membrane potential and increased mitochondrial oxygen consumption. This mitochondrial uncoupling results in a significant reduction of cellular ATP production. Decreased ATP levels in VCP-deficient cells lower their energy capacity, making them more vulnerable to high energy-demanding processes such as ischemia. Our findings propose a mechanism by which pathogenic VCP mutations lead to cell death.

C9ORF72 hexanucleotide repeat expansions in the Italian sporadic ALS population.

It has been recently reported that a large proportion of patients with familial amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are associated with a hexanucleotide (GGGGCC) repeat expansion in the first intron of C9ORF72. We have assessed 1757 Italian sporadic ALS cases, 133 from Sardinia, 101 from Sicily, and 1523 from mainland Italy. Sixty (3.7%) of 1624 mainland Italians and Sicilians and 9 (6.8%) of the 133 Sardinian sporadic ALS cases carried the pathogenic repeat expansion. None of the 619 regionally matched control samples (1238 chromosomes) carried the expansion. Twenty-five cases (36.2%) had behavioral FTD in addition to ALS. FTD or unspecified dementia was also detected in 19 pedigrees (27.5%) in first-degree relatives of ALS patients. Cases carrying the C9ORF72 hexanucleotide expansion survived 1 year less than cases who did not carry this mutation. In conclusion, we found that C9ORF72 hexanucleotide repeat expansions represents a sizeable proportion of apparent sporadic ALS in the Italian and Sardinian population, representing by far the most common mutation in Italy and the second most common in Sardinia.

Lithium carbonate in amyotrophic lateral sclerosis: lack of efficacy in a dose-finding trial

Background: A neuroprotective effect of lithium in amyotrophic lateral sclerosis (ALS) has been recently reported. We performed a multicenter trial with lithium carbonate to assess its tolerability, safety, and efficacy in patients with ALS, comparing 2 different target blood levels (0.4–0.8 mEq/L, therapeutic group [TG], vs 0.2–0.4 mEq/L, subtherapeutic group [STG]). Methods: The study was a multicenter, single-blind, randomized, dose-finding trial, conducted from May 2008 to November 2009 in 21 Italian ALS centers. The trial was registered with the public database of the Italian Agency for Drugs (http://oss-sper-clin.agenziafarmaco.it/) (EudraCT number 2008–001094-15). Results: As of October 2009, a total of 171 patients had been enrolled, 87 randomized to the TG and 84 to the STG. The interim data analysis, performed per protocol, showed that 117 patients (68.4%) discontinued the study because of death/tracheotomy/severe disability, adverse events (AEs)/serious AEs (SAEs), or lack of efficacy. The Data Monitoring Committee recommended stopping the trial on November 2, 2009. Conclusions: Lithium was not well-tolerated in this cohort of patients with ALS, even at subtherapeutic doses. The 2 doses were equivalent in terms of survival/severe disability and functional data. The relatively high frequency of AEs/SAEs and the reduced tolerability of lithium raised serious doubts about its safety in ALS. Classification of evidence: The study provides Class II evidence that therapeutic (0.4–0.8 mEq/L) vs subtherapeutic (0.2–0.4 mEq/L) lithium carbonate did not differ in the primary outcome of efficacy (survival/loss of autonomy) in ALS. Both target levels led to dropouts in more than 30% of participants due to patient-perceived lack of efficacy and AEs.

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.

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.

Selenium neurotoxicity in humans: Bridging laboratory and epidemiologic studies

Selenium is a metalloid of considerable interest in the human from both a toxicological and a nutritional perspective, with a very narrow safe range of intake. Acute selenium intoxication is followed by adverse effects on the nervous system with special clinical relevance, while the neurotoxicity of long-term overexposure is less characterized and recognized. We aimed to address this issue from a public health perspective, focusing on both laboratory studies and the few epidemiologic human studies available, with emphasis on their methodological strengths and limitations. The frequently overlooked differences in toxicity and biological activity of selenium compounds are also outlined. In addition to lethargy, dizziness, motor weakness and paresthesias, an excess risk of amyotrophic lateral sclerosis is the effect on the nervous system which has been more consistently associated with chronic low-level selenium overexposure, particularly to its inorganic compounds. Additional research efforts are needed to better elucidate the neurotoxic effects exerted by selenium overexposure.

A multifactorial prognostic index in multiple sclerosis. Cerebrospinal fluid IgM oligoclonal bands and clinical features to predict the evolution of the disease.

BackgroundThe ability to predict the future progression of MS represents a key issue for the neurologist. The aim of the study was to create a multifactorial prognostic index (MPI) providing the probability of a severe MS course at diagnosis based on clinical and immunological CSF parameters.Methods64 clinically definite relapsing-remitting (RR)MS patients (38 benign, 26 severe MS) followed up for at least 10 years were included. Clinical and demographic details, EDSS after 5 and 10 years, progression index, relapse number and rate, time to a second relapse were assessed. CSF and serum samples collected at diagnosis were examined for CSF IgM and IgG oligoclonal bands (OB) and quantitative IgM and IgG determination.ResultsKaplan-Meier analysis showed that the probability of reaching an EDSS score of 3 or 4 was significantly influenced by the presence of IgMOB (p < 0.01 and p < 0.01, log-rank test) and by the symptoms at onset (p = 0.04 and p = 0.03, log-rank test). These results were confirmed at multivariate analysis (Cox model). Univariate logistic analysis showed that IgMOB presence predicted a severe MS course (OR = 9.33, CI = 2.92– 29.88), whereas sensory symptoms at onset predicted a benign MS course (OR = 0.12, CI = 0.02–0.56). Using multivariate logistic regression the factors found to be significant were: presence/absence of IgMOB (p < 0.01), onset with sensory (p < 0.01) and pyramidal symptoms (p = 0.01), and first inter-attack interval (p = 0.03). The individual probability of a severe evolution was thus estimated by a simple formula comprising clinical and biological markers of prognosis available at diagnosis (pyramidal and sensory symptoms, months to the 2nd episode, and IgMOB presence/absence), giving the probability of developing a severe MS course. Applied to the same patient cohort this formula showed a global error of 6/64 (9.37 %). We then used another independent series of 65 RRMS patients to validate this model. In this second patient cohort, 4/45 BMS and 4/20 SMS patients were found to have been incorrectly classified (based on the formula), with a global error of 8/65 (12.31 %).ConclusionFor the first time we created a MPI, using clinical and biological markers to predict the clinical course of MS at diagnosis. This index can support the clinician in patient counselling, therapeutic choices, as well as in patient selection criteria for clinical trials.