Marco Luigetti

Contribution of major amyotrophic lateral sclerosis genes to the etiology of sporadic disease

Objectives: To quantify the overall contribution of mutations in the currently known amyotrophic lateral sclerosis (ALS) genes in a large cohort of sporadic patients and to make genotype–phenotype correlations. Methods: Screening for SOD1, TARDBP, FUS, ANG, ATXN2, OPTN, and C9ORF72 was carried out in 480 consecutive patients with sporadic ALS (SALS) and in 48 familial ALS (FALS) index patients admitted to a single Italian referral center. Results: Mutations were detected in 53 patients, with a cumulative frequency of 11. Seven of them were novel. The highest frequencies of positive cases were obtained in TARDBP (2.7%), C9ORF72 (2.5%), and SOD1 (2.1%). The overall group of mutated patients was indistinguishable from that without mutations as no significant differences were observed with regard to age and site of onset, frequency of clinical phenotypes, and survival. However, by separately evaluating genotype–phenotype correlation in single genes, clinical differences were observed among different genes. Duration of disease was significantly shorter in patients harboring the C9ORF72 expansion and longer in the SOD1 group. A high frequency of predominant upper motor neuron phenotype was observed among patients with TARDBP mutations. Two patients, 1 with C9ORF72 and 1 with SOD1 mutation, had concurrent ANG mutations. Mutations were detected in 43.7% of patients with FALS. Conclusions: A considerable proportion of patients with SALS harbored mutations in major ALS genes. This result has relevant implications in clinical practice, namely in genetic counseling. The detection of double mutations in 2 patients raises the hypothesis that multiple mutations model may explain genetic architecture of SALS. Neurology® 2012;79:66–72

Rituximab in patients with chronic inflammatory demyelinating polyradiculoneuropathy: a report of 13 cases and review of the literature

Background A few case reports have shown controversial results of rituximab efficacy in patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). Objective To analyse the efficacy of rituximab in a large CIDP cohort. Methods A retrospective, observational and multicentre study on the use of rituximab in CIDP. 13 Italian CIDP patients were treated with rituximab after the partial or complete lack of efficacy of conventional therapies. Eight patients had co-occurring haematological diseases. Patients who improved by at least two points in standard clinical scales, or who reduced or discontinued the pre-rituximab therapies, were considered as responders. Results Nine patients (seven with haematological diseases) responded to rituximab: six of them, who were non-responders to conventional therapies, improved clinically, and the other three maintained the improvement that they usually achieved with intravenous immunoglobulin or plasma exchange. Significantly associated with shorter disease duration, rituximab responses started after a median period of 2.0 months (range, 1–6) and lasted for a median period of 1 year (range, 1–5). Conclusions Rituximab seems to be a promising therapeutic choice when it targets both CIDP and co-occurring haematological diseases. Timely post-onset administration of rituximab seems to be associated with better responses.

Natural history of young-adult amyotrophic lateral sclerosis

Background: Amyotrophic lateral sclerosis (ALS) affects people of all ages, but whether the wide range of age at onset is due to distinct diseases or merely reflects phenotypic variability of the same disorder is still unknown. The purpose of this study is to describe clinical and prognostic features of young-adult ALS, with onset before age 40 years, and to compare them with features of the common adult-onset type. Methods: We analyzed clinical features and long-term follow-up of 57 young-adult ALS patients, with disease onset between 20 and 40 years, and compared them with 450 patients affected by adult-onset ALS. Results: We found that the majority of young-adult patients showed a predominant upper motor neuron (p-UMN) ALS, characterized by marked spastic paraparesis, with lower motor neuron signs confined to the upper limbs. The proportion of patients with p-UMN ALS phenotype was 59.6% in the young-adult patients and 17.4% in the adult-onset form (p < 0.0001). Young-adult ALS with p-UMN phenotype had longer survival than did the classic phenotype: median survival was 74 months (range 10–226, 95% CI 60.61–87.38) in the former and 56 months (range 6–106, 95% CI 48.65–63.34) in the latter (p = 0.03). In the young-adult patients, a marked male excess was observed in the p-UMN ALS group (5.8:1), whereas the ratio of men to women was 1.1:1 in the classic phenotype (p = 0.01). Conclusions: Our findings show that young-adult amyotrophic lateral sclerosis with the predominant upper motor neuron phenotype represents a distinctive clinical variant characterized by a unique clinical pattern, longer survival, and male prevalence.

P525L FUS mutation is consistently associated with a severe form of juvenile Amyotrophic Lateral Sclerosis

Some FUS mutations have been observed in patients with the juvenile form of Amyotrophic Lateral Sclerosis starting before 25 years. We report an 11-year-old girl affected by sporadic juvenile ALS with a rapid course resulting in tracheostomy after 14 months from the onset. Sequencing FUS gene revealed a de novo P525L mutation. Our findings, together with literature data, indicate that this mutation is consistently associated with a specific phenotype characterized by juvenile onset, severe course and high proportion of de novo mutations in sporadic cases.

ULTRASOUND VISUALIZATION OF NERVE MORPHOLOGICAL ALTERATION AT THE SITE OF CONDUCTION BLOCK

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is an acquired autoimmune peripheral neuropathy. Neurophysiological investigations are the most important tool for establishing the diagnosis, as electrophysiological findings reveal a prominent demyelinating process, frequently resulting in conduction block. Previous studies performed with ultrasound (US) or magnetic resonance in CIDP and in other

Rare Missense Variants of Neuronal Nicotinic Acetylcholine Receptor Altering Receptor Function Are Associated with Sporadic Amyotrophic Lateral Sclerosis

Sporadic amyotrophic lateral sclerosis (SALS) is a motor neuron degenerative disease of unknown etiology. Current thinking on SALS is that multiple genetic and environmental factors contribute to disease liability. Since neuronal acetylcholine receptors (nAChRs) are part of the glutamatergic pathway, we searched for sequence variants in CHRNA3, CHRNA4 and CHRNB4 genes, encoding neuronal nicotinic AChR subunits, in 245 SALS patients and in 450 controls. We characterized missense variants by in vitro mutagenesis, cell transfection and electrophysiology. Sequencing the regions encoding the intracellular loop of AChRs subunits disclosed 15 missense variants (6.1%) in 14 patients compared with only six variants (1.3%) in controls (P = 0.001; OR 4.48, 95% CI 1.7-11.8). The frequency of variants in exons encoding extracellular and transmembrane domains and in intronic regions did not differ. NAChRs formed by mutant alpha3 and alpha4 and wild-type (WT) beta4 subunits exhibited altered affinity for nicotine (Nic), reduced use-dependent rundown of Nic-activated currents (I(Nic)) and reduced desensitization leading to sustained intracellular Ca(2+) concentration, in comparison with WT-nAChR. The cellular loop has a crucial importance for receptor trafficking and regulating ion channel properties. Missense variants in this domain are significantly over-represented in SALS patients and alter functional properties of nAChR in vitro, resulting in increased Ca(2+) entry into the cells. We suggest that these gain-of-function variants might contribute to disease liability in a subset of SALS because Ca(2+) signals mediate nAChRs neuromodulatory effects, including regulation of glutamate release and control of cell survival.

A novel HSPB1 mutation in an Italian patient with CMT2/dHMN phenotype.

Mutations in the gene encoding 27-kDa small heat-shock protein B1 (HSPB1) have been reported in association with Charcot-Marie-Tooth disease type 2F or dHMN type II. We describe an Italian patient with wasting and weakness of distal muscles, involving primarily and mostly the lower limbs and later the upper limbs, in which a novel mutation of HSPB1, T180I, was detected. Electrophysiological evaluation disclosed a pure motor axonal neuropathy. Sural nerve biopsy showed a mild reduction of myelinated fibre density. All these findings suggested a CMT2/dHMN phenotype.

pSTAT1, pSTAT3, and T-bet as markers of disease activity in chronic inflammatory demyelinating polyradiculoneuropathy.

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is considered an auto‐immune disorder. We evaluated expression of pSTAT1, T‐bet, and pSTAT3 in circulating T‐cells, B‐cells, and monocytes and spontaneous production of interleukin‐17 (IL17), interferon‐gamma (IFNγ), and interleukin‐10 (IL10) by peripheral blood mononuclear cells (PBMCs) from 14 active CIDP patients compared with 6 patients with long‐lasting remission and 20 controls. Active disease patients showed higher pSTAT1, T‐bet, and pSTAT3 in CD4+ T‐cells than controls (p < 0.001, p = 0.0002, p = 0.0097, respectively) and remission patients (p < 0.001, p = 0.0036, p = 0.0008, respectively). pSTAT1, T‐bet, and pSTAT3 were also higher in monocytes from active CIDP patients than controls (p = 0.0011, p = 0.0041, p = 0.0413, respectively) and remission patients (p = 0.0073, p = 0.0274, p = 0.0251, respectively). Moreover in CD8+ T‐cells, pSTAT3 expression was higher in active CIDP patients than in remission patients (p = 0.0345) and in controls (p = 0.0023). IL17 and IFNγ production were significantly higher in active CIDP patients than in controls (p < 0.0395, p = 0.0010, respectively); IFNγ levels were higher also in remission CIDP patients (p = 0.0073). IL10 levels were higher in active phase patients than in controls (p = 0.0334). Our data suggest that pSTAT1, T‐bet, and pSTAT3 can be considered putative markers of disease activity and potential targets for specific therapies.

SOD1 G93D sporadic amyotrophic lateral sclerosis (SALS) patient with rapid progression and concomitant novel ANG variant

SOD1 G93D mutation has been described in amyotrophic lateral sclerosis (ALS) patients with slowly progressive disease. We describe an Italian patient affected by sporadic ALS with the SOD1 G93D mutation that disclosed an unusual rapid progression with death occurring after 30 months from the symptom onset. Considering the atypical clinical course further genes associated with ALS or known to be causative were studied including ANG, PGRN, TARDBP, FUS, VCP, CHRNA3, CHRNA4, and CHRNB4. A novel heterozygous ANG missense variant (c.433 C>T, p.R145C) was identified which is neither reported in controls nor in 1000 genomes and single nucleotide polymorphism (SNP) databases. This report confirms that clinical course of SOD1-related ALS may be modulated by other causative or associated genes, including ANG and suggests that extensive screening of ALS-associated genes in patients with an already identified mutation may be helpful for better knowledge of genetic architecture of ALS.

Nerve ultrasound findings in neuropathy associated with anti-myelin-associated glycoprotein antibodies

No systematic nerve ultrasound (US) studies on patients with neuropathy and anti‐myelin‐associated glycoprotein (anti‐MAG) antibodies are available.