Consensus paper: pathological mechanisms underlying neurodegeneration in spinocerebellar ataxias.

Intensive scientific research devoted in the recent years to understand the molecular mechanisms or neurodegeneration in spinocerebellar ataxias (SCAs) are identifying new pathways and targets providing new insights and a better understanding of the molecular pathogenesis in these diseases. In this consensus manuscript, the authors discuss their current views on the identified molecular processes causing or modulating the neurodegenerative phenotype in spinocerebellar ataxias with the common opinion of translating the new knowledge acquired into candidate targets for therapy. The following topics are discussed: transcription dysregulation, protein aggregation, autophagy, ion channels, the role of mitochondria, RNA toxicity, modulators of neurodegeneration and current therapeutic approaches. Overall point of consensus includes the common vision of neurodegeneration in SCAs as a multifactorial, progressive and reversible process, at least in early stages. Specific points of consensus include the role of the dysregulation of protein folding, transcription, bioenergetics, calcium handling and eventual cell death with apoptotic features of neurons during SCA disease progression. Unresolved questions include how the dysregulation of these pathways triggers the onset of symptoms and mediates disease progression since this understanding may allow effective treatments of SCAs within the window of reversibility to prevent early neuronal damage. Common opinions also include the need for clinical detection of early neuronal dysfunction, for more basic research to decipher the early neurodegenerative process in SCAs in order to give rise to new concepts for treatment strategies and for the translation of the results to preclinical studies and, thereafter, in clinical practice.

EFNS/ENS Consensus on the diagnosis and management of chronic ataxias in adulthood.

BACKGROUND AND OBJECTIVES: The ataxias are a challenging group of neurological diseases due the aetiological heterogeneity and the complexity of the genetic subtypes. This guideline focuses on the heredodegenerative ataxias. The aim is to provide a peer-reviewed evidence-based guideline for clinical neurologists and other specialist physicians responsible for the care of patients with ataxia. METHODS: This guideline is based on systematic evaluations of the relevant literature and on three consensus meetings of the task force. DIAGNOSIS: If acquired causes are ruled out, and if the disease course is rather slowly progressive, a (heredo)degenerative disease is likely. A positive family history gives much guidance. In the case of a dominant family history, first line genetic screening is recommended for spinocerebellar ataxia (SCA) 1, 2, 3, 6, 7 and 17 (level B), and in Asian patients also for dentatorubral-pallidoluysian atrophy (DRPLA). In the case of recessive disease, a stepwise diagnostic work-up is recommended, including both biochemical markers and targeted genetic testing, particularly aimed at Friedreich's ataxia, ataxia telangiectasia, ataxia due to vitamin E deficiency, polymerase gamma gene (POLG gene, various mutations), autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) and ataxia with oculomotor apraxia (AOA) types 1 and 2. If family history is negative, we still advise to screen for the more common dominant and recessive ataxias. In addition, if onset is below 45 years we recommend the full work-up for recessive ataxias; if onset is above 45 years we recommend to screen for fragile X mental retardation 1 FMR1 premutations (good practice points). In sporadic cases with an onset after 30 years, a diagnosis of multiple system atrophy should be considered (good practice point). In particular the genetic work-up will change over the upcoming years due to the diagnostic utility of new techniques such as gene panel diagnostics based on next generation sequencing for routine work-up, or even whole exome and genome sequencing for selected cases. TREATMENT: Some of the rare recessive ataxias are treatable, but for most of the heredodegenerative ataxias treatment is purely symptomatic. Idebenone is not effective in Friedreich's ataxia (level A). Riluzole (level B) and amantadine (level C) might provide symptomatic relief, irrespective of exact etiology. Also, varenicline for SCA3 patients (level B) can be considered. There is level Class II evidence to recommend physiotherapy, and Class III data to support occupational therapy.

Prospective analysis of falls in dominant ataxias.

In a previous retrospective study, we demonstrated that falls are common and often injurious in dominant spinocerebellar ataxias (SCAs) and that nonataxia features play an important role in these falls. Retrospective surveys are plagued by recall bias for the presence and details of prior falls. We therefore sought to corroborate and extend these retrospective findings by means of a prospective extension of this fall study. 113 patients with SCA1, SCA2, SCA3 or SCA6, recruited from the EuroSCA natural history study, were asked to keep a fall diary in between their annual visits to the participating centres. Additionally, patients completed a detailed questionnaire about the first three falls, to identify specific fall circumstances. Relevant disease characteristics were retrieved from the EuroSCA registry. 84.1% of patients reported at least one fall during a time period of 12 months. Fall-related injuries were common and their frequency increased with that of falls. The presence of nonataxia symptoms was associated with a higher fall frequency. This study confirms that falls are a frequent and serious complication of SCA, and that the presence of nonataxia symptoms is an important etiological factor in its occurrence.

Mapping of the congenital generalized hypertrichosis locus to chromosome Xq24-q27.1.

Congenital generalized hypertrichosis (CGH) is a rare, fully penetrant X-linked dominant trait previously described in a single, multigenerational Mexican family. CGH is a visually striking phenotype characterized by excessive facial and upper torso hair in males and by less severe asymmetric hairiness in females. We have found significant evidence for linkage with several markers from the long arm of the X chromosome. Recombinant chromosomes place the CGH gene within a 22 cM interval between DXS425 and DXS1227 in Xq24-Xq27.1. The localization of a gene for CGH represents the first step towards the isolation of genes involved in hair growth pattern, particularly those involved in restriction of areas in humans.

Homozygosity mapping of Hallervorden-Spatz syndrome to chromosome 20p12.3-p13.

Hallervorden-Spatz syndrome (HSS) (OMIM #234200) is a rare, autosomal recessive neurode-generative disorder with brain iron accumulation as a prominent finding. Clinical features include extrapyramidal dysfunction, onset in childhood, and a relentlessly progressive course. Histologic study reveals massive iron deposits in the basal ganglia. Systemic and cerebrospinal fluid iron levels are normal, as are plasma levels of ferritin, transferrin and ceruloplasmin. Conversely, in disorders of systemic iron overload, such as haemochromatosis, brain iron is not increased, which suggests that fundamental differences exist between brain and systemic iron metabolism and transport. In normal brain, non-haem iron accumulates regionally and is highest in basal ganglia. Pathologic brain iron accumulation is seen in common disorders, including Parkinson's disease, Alzheimer's disease and Huntington disease. In order to gain insight into normal and abnormal brain iron transport, metabolism and function, our approach was to map the gene for HSS. A primary genome scan was performed using samples from a large, consanguineous family (HS1) (see Fig. 1). While this family was immensely powerful for mapping, the region demonstrating homozygosity in all affected members spans only 4 cM, requiring very close markers in order to detect linkage. The HSS gene maps to an interval flanked by D20S906 and D20S116 on chromosome 20p12.3-p13. Linkage was confirmed in nine additional families of diverse ethnic backgrounds.

A candidate gene study of antiepileptic drug tolerability and efficacy identifies an association of CYP2C9 variants with phenytoin toxicity.

BACKGROUND AND PURPOSE: It is widely acknowledged that individual response to antiepileptic drugs (AEDs) is influenced by genetic factors. However, most of the underlying genes and genetic variants remain unidentified to date. The purpose of this study is to examine the role of common variants in a number of candidate genes in the response to commonly prescribed AEDs. METHODS: We recruited 495 patients with epilepsy. Patients were classified according to their response to several AEDs. We genotyped 104 polymorphisms in 17 candidate genes for AED response. We looked for statistically significant associations between these polymorphisms and well-defined AED response phenotypes. RESULTS: We identified significant associations of CYP2C9 variant alleles with presence of phenytoin (PHT) adverse drug reactions (ADRs) and of GSTM1 copy number variation with the presence of carbamazepine ADRs. The latter association could not be confirmed in a replication study. CONCLUSIONS: Our study is the first comprehensive candidate gene association study in epilepsy pharmacogenetics. Our results confirm the role of CYP2C9 variants in PHT toxicity. No other definite associations were identified. Large-scale efforts are needed to unravel the genetic determinants of AED response.

Metabarcoding analysis of gut microbiota of healthy individuals reveals impact of probiotic and maltodextrin consumption.

In a previously published double-blind, placebo-controlled study, we showed that probiotics intake exerted a positive effect on sleep quality and a general improvement across time in different aspects of the profile of mood state, like sadness, anger, and fatigue in 33 healthy individuals. The present work investigates the impact of the probiotic product, constituted of Limosilactobacillus fermentum LF16, Lacticaseibacillus rhamnosus LR06, Lactiplantibacillus plantarum LP01 (all former members of Lactobacillus genus), and Bifidobacterium longum 04, on the gut microbiota composition of the same cohort through a metabarcoding analysis. Both the placebo and probiotic treatments had a significant impact on the microbiota composition. Statistical analysis showed that the microbiota of the individuals could be clustered into three groups, or bacteriotypes, at the baseline, and, inherently, bacterial compositions were linked to different responses to probiotic and placebo intakes. Interestingly, L. rhamnosus and L. fermentum were retrieved in the probiotic-treated cohort, while a bifidogenic effect of maltodextrin, used as placebo, was observed. The present study shed light on the importance of defining bacteriotypes to assess the impact of interventions on the gut microbiota and allowed to reveal microbial components which could be related to positive effects (i.e. sleep quality improvement) to be verified in further studies.

Metabolic or bariatric surgery? Long-term effects of malabsorptive vs restrictive bariatric techniques on body composition and cardiometabolic risk factors.

BACKGROUND: Obesity is an increasing health problem and surgery seems to be the only treatment effective in achieving weight loss without relapse. Among bariatric techniques, many differences exist in terms of weight loss and resolution of comorbidities. Up to now, there are no prospective studies comparing long-term effects of malabsorptive vs restrictive techniques. OBJECTIVE: In this study, cardiometabolic risk factors and body composition changes after malabsorptive biliointestinal bypass (BIBP) and restrictive laparoscopic adjustable gastric banding (LAGB) were compared during a 4-year follow-up. DESIGN: Prospective, case-control and cohort study. PATIENTS: In all, 80 obese subjects, matched for weight and age. Altogether, 40 patients underwent BIBP and 40 underwent LAGB. MEASUREMENTS: Weight, body composition, fasting and post-loading plasma glucose and insulin, homeostatic model assessment index (HOMA-I), lipid profile, blood pressure (BP), erythrocyte sedimentation rate and fibrinogen were monitored at baseline, 12 and 48 months. RESULTS: At 12 months after surgery, a significant reduction in body mass index, total fat mass (FM), trunk FM (trFM), trFM/legs FM (lFM) ratio (trFM/lFM), triglycerides, BP and inflammation markers was observed in both groups. BIBP patients showed a significant reduction in total cholesterol (Tot-C), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C), whereas the LAGB group showed a significant increase of HDL-C. A further improvement of all the parameters evaluated was seen in the BIBP group at 48 months after surgery. CONCLUSIONS: Both bariatric procedures exerted positive effects on cardiometabolic risk factors and on weight loss in the population studied, but on the long-term period, HOMA-I, Tot-C/HDL-C ratio and body composition improvements were more evident after BIBP. We conclude that malabsorptive BIBP seems to be more effective than LAGB in treating visceral obesity and its metabolic complications.

Regulation of mitochondrial iron accumulation by Yfh1p, a putative homolog of frataxin.

The gene responsible for Friedreich's ataxia, a disease characterized by neurodegeneration and cardiomyopathy, has recently been cloned and its product designated frataxin. A gene in Saccharomyces cerevisiae was characterized whose predicted protein product has high sequence similarity to the human frataxin protein. The yeast gene (yeast frataxin homolog, YFH1) encodes a mitochondrial protein involved in iron homeostasis and respiratory function. Human frataxin also was shown to be a mitochondrial protein. Characterizing the mechanism by which YFH1 regulates iron homeostasis in yeast may help to define the pathologic process leading to cell damage in Friedreich's ataxia.

Friedreich's ataxia: autosomal recessive disease caused by an intronic GAA triplet repeat expansion.

Friedreich's ataxia (FRDA) is an autosomal recessive, degenerative disease that involves the central and peripheral nervous systems and the heart. A gene, X25, was identified in the critical region for the FRDA locus on chromosome 9q13. This gene encodes a 210-amino acid protein, frataxin, that has homologs in distant species such as Caenorhabditis elegans and yeast. A few FRDA patients were found to have point mutations in X25, but the majority were homozygous for an unstable GAA trinucleotide expansion in the first X25 intron.

TARDBP (TDP-43) sequence analysis in patients with familial and sporadic ALS: identification of two novel mutations.

BACKGROUND AND PURPOSE: Increasing evidence suggests a direct role of the TAR DNA-binding protein 43 (TDP-43) in neurodegeneration. Mutations in the TARDBP gene, which codes for TDP-43, have been recently reported in familial and sporadic amyotrophic lateral sclerosis (ALS) cases. METHODS: To further define the spectrum and frequency of TARDBP mutations, we present genetic analysis data on TARDBP in 314 ALS mainly Italian patients, including 16 subjects with non-SOD1 familial ALS. RESULTS: We identified four heterozygous missense mutations in five unrelated ALS patients (1.6%). Two of these mutations (p.G348C and p.A382T) were detected in carriers coming from families with an autosomal dominant transmission of different geographic origin (Belgian and Italian, respectively). The Belgian pedigree showed several affected members within five generations and with variable clinical features. Two novel mutations (p.G294V and p.G295S) were identified in two sporadic cases. CONCLUSION: The identification of five ALS patients carrying TARDBP alterations extends the spectrum of TARDBP mutations and supports the pathological role of TDP-43 in motor neurone disease. Our findings provide evidence that TARDBP mutations are not frequent in Italian sporadic ALS patients (1%); however, combined with the literature, our data further support TARDBP mutations as a relevant cause of familial ALS.

Pharmacoscintigraphic and pharmacokinetic evaluation on healthy human volunteers of sustained-release floating minitablets containing levodopa and carbidopa.

In this study, scintigraphic and pharmacokinetic studies were conducted on 10 healthy, fed volunteers. Two concepts of sustained-release floating minitablets--Levo-Form 1 (matrix) and 2 (coated)--were evaluated and compared to the marketed product Prolopa HBS 125. All the floating forms were radiolabelled with (111)In in order to evaluate their gastric residence time using gamma-scintigraphy. It was shown that the three formulations offered almost the same mean gastric residence time, which was about 240 min. Prolopa HBS 125 and Levo-Form 2 presented intragastric disintegration, which can lead to a more pronounced "peak & valley" effect on the plasma concentration-time profile of levodopa. In contrast, the plasma concentration-time profile of levodopa following the administration of Levo-Form 1 was more evenly distributed. Moreover, Levo-Form 1 provided the lowest variations between men and women in terms of AUC and C(max) values. Finally, when the same amount of inhibitors of extracerebral dopa decarboxylase--carbidopa and benserazide--had been administrated, the mean AUC, C(max) and T(max) values obtained for benserazide were lower than those obtained for carbidopa.

Urinary excretion of low molecular weight proteins in patients with pure monoclonal light chain proteinuria.

BACKGROUND: Because urinary low molecular weight protein (LMWP) measurement shows changes in renal integrity at an early stage, beta2-microglobulin (B2m), retinol-binding protein (RBP) and alpha1-microglobulin (A1m) were evaluated in 24-hour urine collection of 65 patients with pure monoclonal light chain (MLC) proteinuria and in 47 patients with different kidney diseases (DKDs) for comparison. METHODS AND RESULTS: Albumin, kappa, lambda, A1m and B2m were measured by immunonephelometry. RBP was determined by ELISA. The mean values of LMWP quantitation were significant for origin of the disease (MLC and DKD) (p<0.05) and renal failure (RF) (p<0.001) (MANOVA). Tukey HSD test only showed significant differences for LMWP between MLC patients with RF and DKD patients without RF. The mean value of A1m was different between patients with and without RF in each group (p<0.05 for MLC, and p<0.01 for DKD). In the group without RF, the frequency of A1m excretion above 12 mg/L differed between MLC patients and DKD patients (p<0.01). CONCLUSION: A tubular dysfunction occurred in a great number of patients excreting pure MLC even in those with well-preserved renal function, as it did in patients with DKDs. In patients with MLC without RF, A1m might be measured for the early recognition of tubular involvement.

Chronic inflammatory demyelinating polyneuropathy in a diabetic patient: deterioration after intravenous immunoglobulins treatment and favorable response to steroid treatment.

The authors report the case of a 54-year old type-2 diabetic female patient with a Chronic Inflammatory Demyelinating Polyneuropathy (CIDP). She progressively developed distal hypoesthesia and tetraparesis. She deteriorated after two courses of intravenous immunoglobulins (IVIG) administration and became rapidly wheelchair bound. After one month of steroid treatment, the patient was walking alone. This case raises the question whether IVIG is to be considered as first line treatment for diabetes associated CIDP.

Iron and Friedreich ataxia.

Friedreich ataxia is due to insufficient levels of frataxin, a mitochondrial iron chaperone that shields this metal from reactive oxygen species (ROS) and renders it bioavailable as Fe II. Frataxin participates in the synthesis of iron-sulfur clusters (ISCs), cofactors of several enzymes, including mitochondrial and cytosolic aconitase, complexes I, II and III of the respiratory chain, and ferrochelatase. It also plays a role in the maintenance of ISCs, in particular for mitochondrial aconitase. A role of frataxin in heme synthesis has been postulated, but is controversial. Insufficient frataxin leads to deficit of ISC enzymes and energy deficit. Iron levels increase in mitochondria. Oxidative stress may result from respiratory chain dysfunction and from direct reaction between iron and ROS. Stress pathways are activated that may lead to apoptosis or other forms of cell death. The basis for the selective vulnerability of specific neurons, like sensory neurons, is still unknown.

Identification of a novel mutation in the spastin gene (SPG4) in an Italian family with hereditary spastic paresis.

Hereditary spastic paraparesis (HSP) includes a heterogeneous group of neurodegenerative diseases characterised by progressive spasticity and hyper-reflexia of the lower limbs. Autosomal dominant HSP type 4 is the most common clinical form, accounting for about 40-50% of autosomal dominant HSP families. This form is due to mutation of the gene encoding spastin (SPG4), an ATP-ase associated with a variety of cellular function (AAA). Here we describe a novel missense mutation (1297T>C; 391L>P) in exon 8 of SPG4 gene, identified in 2 members (mother and son) of an Italian family with autosomal dominant HSP, clinically pure in the mother and complicated in the son. The mutation lies in a highly conserved AAA box domain between amino acids 342 and 599 in spastin sequence. In both patients, this novel mutation was associated with the absence of relatively common clinical characteristics, such as vibratory sensory deficit and loss of sphincter control, and partial temporal epilepsy, particularly in the son, with infantile onset, secondarily generalised and moderately severe neuropsychiatric symptoms.

Novel mutations in the arylsulfatase A gene in eight Italian families with metachromatic leukodystrophy.

Metachromatic leukodystrophy (MLD) is an autosomal recessive lysosomal storage disease caused by arylsulfatase A (ARSA) deficiency. We analysed the ARSA gene in eight unrelated Italian families with different clinical variants of MLD and identified three novel mutations: two Ser406Gly, (Glu329Ter) associated with late infantile MLD and one (Leu52Pro) with juvenile MLD. Only one family carried a pseudodeficiency allele (Asn350Ser). The IVS2+1G>A mutation occurred in four families. We also identified three polymorphisms, all in heterozygosis: Thr391Ser was present in five families, Trp193Cys in four families, and Ala210Ala in one family. We could identify 100% of the alleles causing MLD in the families, involving 12 different mutations, resulting in improved prognosis and genetic counselling.

Mapping of Friedreich's ataxia locus by identification of recombination events in patients homozygous by descent.

The Friedreich's ataxia locus (FRDA) maps on chromosome 9q13. Genetic data, obtained from a small number of recombination events, indicated that the FRDA locus might be located centromeric to the D9S15/D9S5 linkage group, the most probable order being cen-FRDA-D9S5-D9S111-D9S15-D9S110-qter. Recently, new centromeric markers have been reported. Analysis of these markers allowed us to localize the recombination breakpoint in some of the recombinant families. However, only one proximal recombination has been found with these markers. To increase the genetic information from FRDA families, we have analyzed the centromeric markers FR1, FR2, FR7, FR8, and FR5 in patients homozygous by descent. These were ascertained because parents were consanguineous or because they were homozygous for the entire haplotype D9S15 or D9S111-D9S5-D9S411E-D9S202. Haplotype divergence for, at least, two contiguous markers was observed in two patients homozygous for the core D9S111-FR2 haplotype and in one third-degree consanguineous family homozygous for haplotype D9S411E-FR5. Interpretation of divergence as the result of ancient meiotic crossovers allowed the definition of three new recombination events which place the FRDA locus within the interval defined by markers D9S411E and FR8. A consanguineous family with first-cousin parents showed homozygosity only at D9S202 and FR2. Further investigations are needed to discern whether two different mutations are segregating in the family or whether two recombinations, one distal and one proximal, have taken place.