Extreme phenotypic heterogeneity in non-expansion spinocerebellar ataxias.

Although the best-known spinocerebellar ataxias (SCAs) are triplet repeat diseases, many SCAs are not caused by repeat expansions. The rarity of individual non-expansion SCAs, however, has made it difficult to discern genotype-phenotype correlations. We therefore screened individuals who had been found to bear variants in a non-expansion SCA-associated gene through genetic testing, and after we eliminated genetic groups that had fewer than 30 subjects, there were 756 subjects bearing single-nucleotide variants or deletions in one of seven genes: CACNA1A (239 subjects), PRKCG (175), AFG3L2 (101), ITPR1 (91), STUB1 (77), SPTBN2 (39), or KCNC3 (34). We compared age at onset, disease features, and progression by gene and variant. There were no features that reliably distinguished one of these SCAs from another, and several genes-CACNA1A, ITPR1, SPTBN2, and KCNC3-were associated with both adult-onset and infantile-onset forms of disease, which also differed in presentation. Nevertheless, progression was overall very slow, and STUB1-associated disease was the fastest. Several variants in CACNA1A showed particularly wide ranges in age at onset: one variant produced anything from infantile developmental delay to ataxia onset at 64 years of age within the same family. For CACNA1A, ITPR1, and SPTBN2, the type of variant and charge change on the protein greatly affected the phenotype, defying pathogenicity prediction algorithms. Even with next-generation sequencing, accurate diagnosis requires dialogue between the clinician and the geneticist.

Long-Term Follow-Up before and during Riluzole Treatment in Six Patients from Two Families with Spinocerebellar Ataxia Type 7.

BACKGROUND: Currently no curative treatment exists for spinocerebellar ataxias (SCAs). Riluzole repurposing was proposed as a symptomatic treatment in different types of cerebellar ataxia. We report a long-term-follow up under riluzole treatment in SCA type 7. METHODS: Six patients received Riluzole 50 mg twice daily on a compassionate use program for a mean of 4.8 years (range 3.5-9). We measured ataxia onset and progression through the Scale for the Assessment and Rating of Ataxia (SARA), and collected extensive ophthalmological data before and after Riluzole treatment. Electrocardiogram and laboratory profile for drug safety were performed every six months. RESULTS: Riluzole treatment showed no effect on visual function in two patients with an advanced retinal damage. Improvements of visual function occurred in four patients followed by ophthalmologic stability up to 5 years after starting treatment. Two patients had a less steep deterioration of ataxia after treatment compared to pre-treatment, during the first 2,5 years of therapy. One showed soon after therapy an improvement of the SARA score, and then overall stability lasting 3,5 years, followed by ataxia worsening. One visually impaired patient without neurological impairment did not worse until the last visit after 3,5 years of follow-up. The remaining 2 patients showed an improvement of SARA scores soon after therapy, and an overall stability lasting respectively 5 and 3 years. No adverse event was registered during the observation period. DISCUSSION: This study suggests a possible beneficial action of Riluzole in SCA7 and provides a detailed description of the ophthalmologic profile of these patients.

Content Validity of the Modified Functional Scale for the Assessment and Rating of Ataxia (f-SARA) Instrument in Spinocerebellar Ataxia.

The functional Scale for the Assessment and Rating of Ataxia (f-SARA) assesses Gait, Stance, Sitting, and Speech. It was developed as a potentially clinically meaningful measure of spinocerebellar ataxia (SCA) progression for clinical trial use. Here, we evaluated content validity of the f-SARA. Qualitative interviews were conducted among individuals with SCA1 (n = 1) and SCA3 (n = 6) and healthcare professionals (HCPs) with SCA expertise (USA, n = 5; Europe, n = 3). Interviews evaluated symptoms and signs of SCA and relevance of f-SARA concepts for SCA. HCP cognitive debriefing was conducted. Interviews were recorded, transcribed, coded, and analyzed by ATLAS.TI software. Individuals with SCA1 and 3 reported 85 symptoms, signs, and impacts of SCA. All indicated difficulties with walking, stance, balance, speech, fatigue, emotions, and work. All individuals with SCA1 and 3 considered Gait, Stance, and Speech relevant f-SARA concepts; 3 considered Sitting relevant (42.9%). All HCPs considered Gait and Speech relevant; 5 (62.5%) indicated Stance was relevant. Sitting was considered a late-stage disease indicator. Most HCPs suggested inclusion of appendicular items would enhance clinical relevance. Cognitive debriefing supported clarity and comprehension of f-SARA. Maintaining current abilities on f-SARA items for 1 year was considered meaningful for most individuals with SCA1 and 3. All HCPs considered meaningful changes as stability in f-SARA score over 1-2 years, 1-2-point change in total f-SARA score, and deviation from natural history. These results support content validity of f-SARA for assessing SCA disease progression in clinical trials.

Disentangling multiple sclerosis phenotypes through Mendelian disorders: A network approach.

BACKGROUND: The increasing knowledge about multiple sclerosis (MS) pathophysiology has reinforced the need for an improved description of disease phenotypes, connected to disease biology. Growing evidence indicates that complex diseases constitute phenotypical and genetic continuums with "simple," monogenic disorders, suggesting shared pathomechanisms. OBJECTIVES: The objective of this study was to depict a novel MS phenotypical framework leveraging shared physiopathology with Mendelian diseases and to identify phenotype-specific candidate drugs. METHODS: We performed an enrichment testing of MS-associated variants with Mendelian disorders genes. We defined a "MS-Mendelian network," further analyzed to define enriched phenotypic subnetworks and biological processes. Finally, a network-based drug screening was implemented. RESULTS: Starting from 617 MS-associated loci, we showed a significant enrichment of monogenic diseases (p < 0.001). We defined an MS-Mendelian molecular network based on 331 genes and 486 related disorders, enriched in four phenotypic classes: neurologic, immunologic, metabolic, and visual. We prioritized a total of 503 drugs, of which 27 molecules active in 3/4 phenotypical subnetworks and 140 in subnetwork pairs. CONCLUSION: The genetic architecture of MS contains the seeds of pathobiological multiplicities shared with immune, neurologic, metabolic and visual monogenic disorders. This result may inform future classifications of MS endophenotypes and support the development of new therapies in both MS and rare diseases.

Peripheral Biomarkers in Manifest and Premanifest Huntington's Disease.

Huntington's disease (HD) is characterized by clinical motor impairment (e.g., involuntary movements, poor coordination, parkinsonism), cognitive deficits, and psychiatric symptoms. An inhered expansion of the CAG triplet in the huntingtin gene causing a pathogenic gain-of-function of the mutant huntingtin (mHTT) protein has been identified. In this review, we focus on known biomarkers (e.g., mHTT, neurofilament light chains) and on new biofluid biomarkers that can be quantified in plasma or peripheral blood mononuclear cells from mHTT carriers. Circulating biomarkers may fill current unmet needs in HD management: better stratification of patients amenable to etiologic treatment; the initiation of preventive treatment in premanifest HD; and the identification of peripheral pathogenic central nervous system cascades.

A Clinical and Epidemiological Prevalence Study on Friedreich's Ataxia in Latium, Italy.

OBJECTIVE: The aim of this study was to estimate the Friedreich's ataxia (FRDA) prevalence in a highly populated region of Italy (previous studies in small geographic areas gave a largely variable prevalence) and to define the patients' molecular and clinical characteristics. METHODS: For the point-prevalence study, we considered patients belonging to families with a molecular diagnosis of FRDA and resident in Latium on 1 January 2019. The crude prevalence of FRDA, specific for age and sex, was calculated and standardized for age using the Italian population. Moreover, we investigated possible correlations among patients' genetic profile, symptoms, and age of onset. RESULTS: We identified 63 FRDA patients; the crude prevalence for total, males, and females were 1.07 (95% CI: 0.81-1.37), 0.81 (95% CI: 0.54-1.22), and 1.32 (95% CI: 0.97-1.79), per 100,000 inhabitants. We divided FRDA patients by three age-at-onset groups (early-EOFA 73%; late-LOFA 11.1%; very late-VLOFA 15.9%) and found significant differences in the scale for the assessment and rating of ataxia (SARA; p = 0.001), a biased distribution of the shorter allele (p = 0.001), an excess of scoliosis and cardiomyopathy (p = 0.001) in EOFA. To determine the contribution of patients' molecular and clinical characteristics to the annual rate of progression, we performed a multivariate regression analysis that gave an R2 value of 45.3%. CONCLUSIONS: We estimated the crude and standardized prevalence of FRDA in Latium. A clinical classification (EOFA, LOFA, VLOFA) gave significant correlations. This epidemiological estimate allows monitoring disease prevalence over time in cohort studies and/or for developing disease registry.

Heterozygous KIF1A variants underlie a wide spectrum of neurodevelopmental and neurodegenerative disorders.

BACKGROUND: Dominant and recessive variants in the KIF1A gene on chromosome 2q37.3 are associated with several phenotypes, although only three syndromes are currently listed in the OMIM classification: hereditary sensory and autonomic neuropathy type 2 and spastic paraplegia type 30, both recessively inherited, and mental retardation type 9 with dominant inheritance. METHODS: In this retrospective multicentre study, we describe the clinical, neuroradiological and genetic features of 19 Caucasian patients (aged 3-65 years) harbouring heterozygous KIF1A variants, and extensively review the available literature to improve current classification of KIF1A-related disorders. RESULTS: Patients were divided into two groups. Group 1 comprised patients with a complex phenotype with prominent pyramidal signs, variably associated in all but one case with additional features (ie, epilepsy, ataxia, peripheral neuropathy, optic nerve atrophy); conversely, patients in group 2 presented an early onset or congenital ataxic phenotype. Fourteen different heterozygous missense variants were detected by next-generation sequencing screening, including three novel variants, most falling within the kinesin motor domain. CONCLUSION: The present study further enlarges the clinical and mutational spectrum of KIF1A-related disorders by describing a large series of patients with dominantly inherited KIF1A pathogenic variants ranging from pure to complex forms of hereditary spastic paraparesis/paraplegias (HSP) and ataxic phenotypes in a lower proportion of cases. A comprehensive review of the literature indicates that KIF1A screening should be implemented in HSP regardless of its mode of inheritance or presentations as well as in other complex neurodegenerative or neurodevelopmental disorders showing congenital or early onset ataxia.

Circulating U13 Small Nucleolar RNA as a Potential Biomarker in Huntington's Disease: A Pilot Study.

Plasma small RNAs have been recently explored as biomarkers in Huntington's disease (HD). We performed an exploratory study on nine HD patients, eight healthy subjects (HS), and five psychiatric patients (PP; to control for iatrogenic confounder effects) through an Affymetrix-Gene-Chip-miRNA-Array. We validated the results in an independent population of 23 HD, 15 pre-HD, 24 PP, 28 Alzheimer's disease (AD) patients (to control the disease-specificity) and 22 HS through real-time PCR. The microarray results showed higher levels of U13 small nucleolar RNA (SNORD13) in HD patients than controls (fold change 1.54, p = 0.003 HD vs. HS, and 1.44, p = 0.0026 HD vs. PP). In the validation population, a significant increase emerged with respect to both pre-HD and the control groups (p < 0.0001). SNORD13 correlated with the status of the mutant huntingtin carrier (r = 0.73; p < 0.001) and the disease duration (r = 0.59; p = 0.003). The receiver operating characteristic (ROC) curve analysis showed the high accuracy of SNORD13 in discriminating HD patients from other groups (AUC = 0.963). An interactome and pathway analysis on SNORD13 revealed enrichments for factors relevant to HD pathogenesis. We report the unprecedented finding of a potential disease-specific role of SNORD13 in HD. It seems to peripherally report a 'tipping point' in the pathogenic cascade at the neuronal level.

A Case of Double Standard: Sex Differences in Multiple Sclerosis Risk Factors.

Multiple sclerosis is a complex, multifactorial, dysimmune disease prevalent in women. Its etiopathogenesis is extremely intricate, since each risk factor behaves as a variable that is interconnected with others. In order to understand these interactions, sex must be considered as a determining element, either in a protective or pathological sense, and not as one of many variables. In particular, sex seems to highly influence immune response at chromosomal, epigenetic, and hormonal levels. Environmental and genetic risk factors cannot be considered without sex, since sex-based immunological differences deeply affect disease onset, course, and prognosis. Understanding the mechanisms underlying sex-based differences is necessary in order to develop a more effective and personalized therapeutic approach.

DNA damage signatures in peripheral blood cells as biomarkers in prodromal huntington disease.

Easily accessible biomarkers in Huntington disease (HD) are actively searched. We investigated telomere length and DNA double-strand breaks (histone variant pγ-H2AX) as predictive disease biomarkers in peripheral blood mononuclear cells (PBMC) from 25 premanifest subjects, 58 HD patients with similar CAG expansion in the huntingtin gene (HTT), and 44 healthy controls (HC). PBMC from the pre-HD and HD groups showed shorter telomeres (p < 0.0001) and a significant increase of pγ-H2AX compared to the controls (p < 0.0001). The levels of pγ-H2AX correlated robustly with the presence of the mutated gene in pre-HD and HD. The availability of a potentially reversible biomarker (pγ-H2AX) in the premanifest stage of HD, negligible in HC, provides a novel tool to monitor premanifest subjects and find patient-specific drugs. Ann Neurol 2018;00:1-6 ANN NEUROL 2019;85:296-301.

Altered intestinal permeability in patients with relapsing-remitting multiple sclerosis: A pilot study.

BACKGROUND: Alterations of intestinal permeability (IP) may contribute to the pathophysiology of immune-mediated diseases. OBJECTIVE: We investigated the possible association between IP changes and multiple sclerosis (MS). METHODS: We studied 22 patients with relapsing-remitting multiple sclerosis (RRMS) and 18 age- and sex-matched healthy donors (HDs), including five twin pairs (one concordant, and four discordant for disease). Measurement of lactulose (L) and mannitol (M; two non-metabolized sugars) levels in urine samples, after an oral load, allowed to quantify gut dysfunction. RESULTS: The proportion of participants with increased IP was significantly higher in patients than in HDs (16/22 (73%) versus 5/18 (28%); p = 0.001). Accordingly, the L/M urinary ratio showed significantly higher values in patients than in controls ( p = 0.0284). Urinary mannitol concentration was significantly lower in patients than in controls ( p = 0.022), suggesting a deficit of absorption from intestinal lumen. Such changes did not appear related to patients' clinical-radiological features. CONCLUSION: The relatively high proportion of IP changes in RR-MS patients seems to confirm our work hypothesis and warrants more work to confirm the result on a larger sample, and to understand the implications for related immunological disturbances and intestinal microbiota alterations. Our finding may also have relevance for oral treatments, recently introduced in clinical practice.

Twin studies in multiple sclerosis: A meta-estimation of heritability and environmentality.

BACKGROUND: Most twin studies of multiple sclerosis (MS) are inconclusive regarding the impact of genes and environment on disease susceptibility. In particular, high uncertainty exists about whether shared environmental factors are aetiologically relevant. OBJECTIVE: To disentangle, with a reasonable degree of confidence, the relative contributions of heritability and of shared and unique environmental components of MS susceptibility. METHODS: We performed a meta-analysis of previous twin studies. After a MEDLINE search, we selected eight twin studies in France, UK, Canada, Denmark, North America, Italy, Finland and Sweden. We conducted a biometric multi-group analysis under the liability-threshold model, by taking account of the study-specific ascertainment strategies and the population-specific prevalence rates of MS. RESULTS: The meta-analytic estimates of tetrachoric correlations were 0.71 (95% confidence interval (CI): 0.67-0.74) in monozygotic pairs and 0.46 (95% CI: 0.41-0.50) in dizygotic pairs. The biometric multi-group model provided meta-analytic estimates of 0.50 (95% CI: 0.39-0.61) for heritability, 0.21 (95% CI: 0.11-0.30) for shared environmental component and 0.29 (95% CI: 0.26-0.33) for unique environmental component. CONCLUSION: Our results support the continuing efforts to identify unknown genetic factors that fill the gap of 'missing heritability'; moreover, a 'missing environmentality' deserves future investigations into the role of non-heritable components that act as both shared and individual-specific exposures.

Subacute multicranial neuropathy revealing an early case of meningeal syphilis.

We report a case of neurosyphilis presenting with meningitis and subacute multicranial neuropathy in a young immune-competent man. Signs of primary and secondary stages of syphilitic infection occurred almost contemporarily in our patient. MRI revealed the involvement of several cranial nerves. CSF examination proved to be diagnostic. Syphilitic meningitis should be considered among the differential diagnoses of subacute, multicranial neuropathy, or skull base meningitis. The clinical course of this patient shows that early diagnosis and treatment warrant a good neurological outcome.

IFN-ß therapy modulates B-cell and monocyte crosstalk via TLR7 in multiple sclerosis patients.

The implication of B lymphocytes in the immunopathology of multiple sclerosis (MS) is increasingly recognized. Here we investigated the response of B cells to IFN-ß, a first-line therapy for relapsing-remitting MS patients, upon stimulation with TLR. IFN-ß restored the frequency of TLR7-induced IgM and IgG-secreting cells in MS patients to the levels found in healthy donors, showing a specific deficiency in the TLR7 pathway. However, no difference was observed in the TLR9 response. Furthermore, in MS-derived PBMCs, TLR7-mediated production of IL-6 and the ex vivo expression of B-cell-activating factor of the TNF family, two crucial cytokines for B-cell differentiation and survival, were induced by IFN-ß. Depletion of monocytes, which are key producers of both IL-6 and B-cell-activating factor of the TNF family, showed that TLR7-mediated B-cell differentiation into Ig-secreting cells is strongly dependent on the cross-talk between B cells and monocytes. Accordingly, impaired expression of TLR7 mRNA was observed in PBMCs and monocytes isolated from MS-affected individuals as compared with those from healthy donors, which was rescued by IFN-ß therapy. Collectively, our data unveil a novel TLR7-regulated mechanism in in vivo IFN-ß-stimulated whole leukocytes that could be exploited to define new TLR7-based strategies for the treatment of MS.

Gut Microbiota Composition Is Causally Linked to Multiple Sclerosis: A Mendelian Randomization Analysis.

Accumulating evidence links the microbial communities inhabiting the gut to the pathophysiological processes underlying multiple sclerosis (MS). However, most studies on the microbiome in MS are correlative in nature, thus being at risk of confounding and reverse causality. Mendelian randomization (MR) analyses allow the estimation of the causal relationship between a risk factor and an outcome of interest using genetic variants as proxies for environmental exposures. Here, we performed a two-sample MR to assess the causality between the gut microbiome and MS. We extracted genetic instruments from summary statistics from three large genome-wide association studies (GWASs) on the gut microbiome (18,340, 8959, and 7738 subjects). The exposure data were derived from the latest GWAS on MS susceptibility (47,429 patients and 68,374 controls). We pinpointed several microbial strains whose abundance is linked with enhanced MS risk (Actinobacteria class, Bifidobacteriaceae family, Lactobacillus genus) or protection (Prevotella spp., Lachnospiranaceae genus, Negativibacillus genus). The largest risk effect was seen for Ruminococcus Torques (OR, 2.89, 95% C.I. 1.67-5, p = 1.51 × 10-4), while Akkermansia municiphila emerged as strongly protective (OR, 0.43, 95% C.I. 0.32-0.57, p = 1.37 × 10-8). Our findings support a causal relationship between the gut microbiome and MS susceptibility, reinforcing the relevance of the microbiome-gut-brain axis in disease etiology, opening wider perspectives on host-environmental interactions for MS prevention.

Case report: A novel mutation of glial fibrillary acidic protein gene causing juvenile-onset Alexander disease.

Alexander disease (AxD) is a rare inherited autosomal dominant (AD) disease with different clinical phenotypes according to the age of onset. It is caused by mutations in the glial fibrillary acid protein (GFAP) gene, which causes GFAP accumulation in astrocytes. A wide spectrum of mutations has been described. For some variants, genotype-phenotype correlations have been described, although variable expressivity has also been reported in late-onset cases among members of the same family. We present the case of a 19-year-old girl who developed gait ataxia and subtle involuntary movements, preceded by a history of enuresis and severe scoliosis. Her mother has been affected by ataxia since her childhood, which was then complicated by pyramidal signs and heavily worsened through the years. Beyond her mother, no other known relatives suffered from neurologic syndromes. The scenario was further complicated by a complex brain and spinal cord magnetic resonance imaging (MRI) pattern in both mother and daughter. However, the similar clinical phenotype made an inherited cause highly probable. Both AD and autosomal recessive (AR) ataxic syndromes were considered, lacking a part of the proband's pedigree, but no causative genetic alterations were found. Considering the strong suspicion for an inherited condition, we performed clinical exome sequencing (CES), which analyzes more than 4,500 genes associated with diseases. CES evidenced the new heterozygous missense variant c.260 T > A in exon 1 of the glial fibrillary acidic protein (GFAP) gene (NM_002055.4), which causes the valine to aspartate amino acid substitution at codon 87 (p. Val87Asp) in the GFAP. The same heterozygous variant was detected in her mother. This mutation has never been described before in the literature. This case should raise awareness for this rare and under-recognized disease in juvenile-adult cases.

Cytomegalovirus, Epstein-Barr Virus, Herpes Simplex Virus, and Varicella Zoster Virus Infection Dynamics in People with Multiple Sclerosis from Northern Italy.

Previous exposure to Epstein-Barr virus (EBV) is strongly associated with the development of multiple sclerosis (MS). By contrast, past cytomegalovirus (CMV) infection may have no association, or be negatively associated with MS. This study aimed to investigate the associations of herpesvirus infections with MS in an Italian population. Serum samples (n = 200) from Italian people with multiple sclerosis (PwMS) classified as the relapsing-and-remitting clinical phenotype and (n = 137) healthy controls (HCs) were obtained from the CRESM Biobank, Orbassano, Italy. Both PwMS and HCs samples were selected according to age group (20-39 years, and 40 or more years) and sex. EBV virus capsid antigen (VCA) IgG, EBV nucleic acid-1 antigen (EBNA-1) IgG, CMV IgG, herpes simplex virus (HSV) IgG, and varicella zoster virus (VZV) IgG testing was undertaken using commercial ELISAs. EBV VCA IgG and EBNA-1 IgG seroprevalences were 100% in PwMS and 93.4% and 92.4%, respectively, in HCs. EBV VCA IgG and EBNA-1 IgG levels were higher (p < 0.001) in PwMS compared with HCs. For PwMS, the EBNA-1 IgG levels decreased with age, particularly in females. The CMV IgG seroprevalence was 58.7% in PwMS and 62.9% in HCs. CMV IgG seroprevalence increased with age. The HSV IgG seroprevalence was 71.2% in PwMS and 70.8% in HCs. HSV IgG levels were lower (p = 0.0005) in PwMS compared with HCs. VZV IgG seroprevalence was 97.5% in PwMS and 98.5% in HCs. In the population studied, several herpesvirus infections markers may have been influenced by the age and sex of the groups studied. The lack of a negative association of MS with CMV infection, and the observation of lower levels of HSV IgG in PwMS compared with HCs are findings worthy of further investigation.

The value of Interferon ß in multiple sclerosis and novel opportunities for its anti-viral activity: a narrative literature review.

Interferon-beta (IFN-ß) for Multiple Sclerosis (MS) is turning 30. The COVID-19 pandemic rejuvenated the interest in interferon biology in health and disease, opening translational opportunities beyond neuroinflammation. The antiviral properties of this molecule are in accord with the hypothesis of a viral etiology of MS, for which a credible culprit has been identified in the Epstein-Barr Virus. Likely, IFNs are crucial in the acute phase of SARS-CoV-2 infection, as demonstrated by inherited and acquired impairments of the interferon response that predispose to a severe COVID-19 course. Accordingly, IFN-ß exerted protection against SARS-CoV-2 in people with MS (pwMS). In this viewpoint, we summarize the evidence on IFN-ß mechanisms of action in MS with a focus on its antiviral properties, especially against EBV. We synopsize the role of IFNs in COVID-19 and the opportunities and challenges of IFN-ß usage for this condition. Finally, we leverage the lessons learned in the pandemic to suggest a role of IFN-ß in long-COVID-19 and in special MS subpopulations.