Francesco Saccà

Ataxia with oculomotor apraxia type 2: A clinical, pathologic, and genetic study

Background: Ataxia with oculomotor apraxia type 2 (AOA2) is characterized by onset between age 10 and 22 years, cerebellar atrophy, peripheral neuropathy, oculomotor apraxia (OMA), and elevated serum alpha-fetoprotein (AFP) levels. Recessive mutations in SETX have been described in AOA2 patients. Objective: To describe the clinical features of AOA2 and to identify the SETX mutations in 10 patients from four Italian families. Methods: The patients underwent clinical examination, routine laboratory tests, nerve conduction studies, sural nerve biopsy, and brain MRI. All were screened for SETX mutations. Results: All the patients had cerebellar features, including limb and truncal ataxia, and slurred speech. OMA was observed in two patients, extrapyramidal symptoms in two, and mental impairment in three. High serum AFP levels, motor and sensory axonal neuropathy, and marked cerebellar atrophy on MRI were detected in all the patients who underwent these examinations. Sural nerve biopsy revealed a severe depletion of large myelinated fibers in one patient, and both large and small myelinated fibers in another. Postmortem findings are also reported in one of the patients. Four different homozygous SETX mutations were found (a large-scale deletion, a missense change, a single-base deletion, and a splice-site mutation). Conclusions: The clinical phenotype of oculomotor apraxia type 2 is fairly homogeneous, showing only subtle intrafamilial variability. OMA is an inconstant finding. The identification of new mutations expands the array of SETX variants, and the finding of a missense change outside the helicase domain suggests the existence of at least one more functional region in the N-terminus of senataxin.

SCA Functional Index A useful compound performance measure for spinocerebellar ataxia

Objective: To evaluate the usefulness of functional measures in patients with spinocerebellar ataxia (SCA). Methods: We assessed three functional measures—8 m walking time (8MW), 9-hole peg test (9HPT), and PATA repetition rate—in 412 patients with autosomal dominant SCA (genotypes 1, 2, 3, and 6) in a multicenter trial. Results: While PATA rate was normally distributed (mean/median 21.7/20.5 per 10 s), the performance times for 8MW (mean/median 10.8/7.5 s) or 9HPT (mean/median 47.2/35.0 s in dominant, 52.2/37.9 s in nondominant hand) were markedly skewed. Possible learning effects were small and likely clinically irrelevant. A composite functional index (SCAFI) was formed after appropriate transformation of subtest results. The Z-scores of each subtest correlated well with the Scale for the Assessment and Rating of Ataxia (SARA), the Unified Huntingtons disease Rating Scale functional assessment, and disease duration. Correlations for SCAFI with each of these parameters were stronger (Pearson r = −0.441 to −0.869) than for each subtest alone. Furthermore, SCAFI showed a linear decline over the whole range of disease severity, while 9HPT and 8MW had floor effects with respect to SARA. Analysis of possible confounders showed no effect of genotype or study site and only minor effects of age for 8MW. Conclusion: The proposed functional measures and their composite SCAFI have favorable properties to assess patients with spinocerebellar ataxia.

A genome-wide association meta-analysis identifies a novel locus at 17q11.2 associated with sporadic amyotrophic lateral sclerosis

Identification of mutations at familial loci for amyotrophic lateral sclerosis (ALS) has provided novel insights into the aetiology of this rapidly progressing fatal neurodegenerative disease. However, genome-wide association studies (GWAS) of the more common (∼90%) sporadic form have been less successful with the exception of the replicated locus at 9p21.2. To identify new loci associated with disease susceptibility, we have established the largest association study in ALS to date and undertaken a GWAS meta-analytical study combining 3959 newly genotyped Italian individuals (1982 cases and 1977 controls) collected by SLAGEN (Italian Consortium for the Genetics of ALS) together with samples from Netherlands, USA, UK, Sweden, Belgium, France, Ireland and Italy collected by ALSGEN (the International Consortium on Amyotrophic Lateral Sclerosis Genetics). We analysed a total of 13 225 individuals, 6100 cases and 7125 controls for almost 7 million single-nucleotide polymorphisms (SNPs). We identified a novel locus with genome-wide significance at 17q11.2 (rs34517613 with P = 1.11 × 10(-8); OR 0.82) that was validated when combined with genotype data from a replication cohort (P = 8.62 × 10(-9); OR 0.833) of 4656 individuals. Furthermore, we confirmed the previously reported association at 9p21.2 (rs3849943 with P = 7.69 × 10(-9); OR 1.16). Finally, we estimated the contribution of common variation to heritability of sporadic ALS as ∼12% using a linear mixed model accounting for all SNPs. Our results provide an insight into the genetic structure of sporadic ALS, confirming that common variation contributes to risk and that sufficiently powered studies can identify novel susceptibility loci.

Recombinant human erythropoietin increases frataxin protein expression without increasing mRNA expression.

Friedreich’s ataxia is an autosomal recessive neurodegenerative disease that is due to the loss of function of the frataxin protein. The molecular basis of this disease is still a matter of debate and treatments have so far focused on managing symptoms. Drugs that can increase the amount of frataxin protein offer a possible therapy for the disease. One such drug is recombinant human erythropoietin (rhu-EPO). Here, we report the effects of rhu-EPO on frataxin mRNA and protein in primary fibroblast cell cultures derived from Friedreich’s ataxia patients. We observed a slight but significant increase in the amount of frataxin protein. Interestingly, we did not observe any increase in the messenger RNA expression at any of the times and doses tested, suggesting that the regulatory effects of rhu-EPO on the frataxin protein was at the post-translational level. These findings could help the evaluation of the treatment with erythropoietin as a potential therapeutic agent for Friedreich’s ataxia.

VASCULAR SMOOTH MUSCLE CELL DYSFUNCTION IN PATIENTS WITH MIGRAINE

Background: Migraine is associated with increased risk of cardiovascular disease, but the mechanisms are unclear. Objective: To investigate the activity of endothelial and vascular smooth muscle cells (VSMCs) in patients with migraine. Methods: Case-control study of 12 patients with migraine without aura and 12 matched healthy control subjects. Endothelial and VSMC components of vascular reactivity were explored by plethysmography measurement of forearm blood flow (FBF) during infusions of vasoactive agents into the brachial artery. Forearm production of nitric oxide (NO) and cyclic guanosine monophosphate (cGMP) was also quantified. Results: In patients with migraine, the vasodilating effect of acetylcholine (ACh), an endothelium-dependent vasodilator, was markedly reduced (p < 0.001 by analysis of variance). In response to the highest dose of ACh, FBF rose to 8.6 ± 2.2 in patients with migraine and to 22.7 ± 3.0 mL × dL−1 × min−1 in controls (p = 0.001). The dose-response curve to nitroprusside, a vasodilator directly acting on VSMCs, was depressed in patients with migraine (p < 0.001 by analysis of variance). The maximal response of FBF to nitroprusside was 12.1 ± 2.0 in patients with migraine and 24.1 ± 1.8 mL × dl−1 × min−1 in controls (p < 0.001). During ACh infusion, NO release from the endothelium was similar in patients and controls. In contrast, there was a marked release of cGMP from VSMCs in controls, but not in patients with migraine (−1.9 ± 2.2 in patients with migraine and −19.1 ± 5.4 nmol × dL−1 × min−1 in controls; p = 0.03). Conclusions: Patients with migraine are characterized by a distinct vascular smooth muscle cell dysfunction, revealed by impaired cyclic guanosine monophosphate and hemodynamic response to nitric oxide.

Novel mutation of SACS gene in a Spanish family with autosomal recessive spastic ataxia.

Autosomal recessive spastic ataxia of Charlevoix–Saguenay (ARSACS) is an inherited neurodegenerative disorder characterized by early‐onset, spastic ataxia and peripheral neuropathy. It was originally described in an inbred population of Quebec and later in some other countries. We report a new missense SACS mutation (7848C>T) in a Spanish family whose phenotype is similar to that of the previously described ARSACS patients. 7848C>T is the first SACS mutation reported in Spain confirming worldwide distribution of the disease.

A gene expression phenotype in lymphocytes from Friedreich ataxia patients.

Gene expression studies in peripheral tissues from patients with neurodegenerative disorders can provide insights into disease pathogenesis, and identify potential biomarkers, an important goal of translational research in neurodegeneration. Friedreich Ataxia (FRDA) is a chronic neurodegenerative disease caused by reduced transcription of frataxin, a ubiquitously expressed protein. We studied in vitro lymphocytes from FRDA patients and carriers to identify a peripheral gene expression phenotype. Peripheral biomarkers related to disease status would be extremely valuable for assessing drug efficacy and could provide new pathophysiological insights.

Fingolimod versus interferon beta/glatiramer acetate after natalizumab suspension in multiple sclerosis

The comparative effectiveness of fingolimod versus interferon beta/glatiramer acetate was assessed in a multicentre, observational, prospectively acquired cohort study including 613 patients with relapsing multiple sclerosis discontinuing natalizumab in the Italian iMedWeb registry. First, after natalizumab suspension, the relapse risk during the untreated wash-out period and during the course of switch therapies was estimated through Poisson regression analyses in separated models. During the wash-out period an increased risk of relapses was found in patients with a higher number of relapses before natalizumab treatment (incidence rate ratio = 1.31, P = 0.0014) and in patients discontinuing natalizumab due to lack of efficacy (incidence rate ratio = 2.33, P = 0.0288), patients choice (incidence rate ratio = 2.18, P = 0.0064) and adverse events (incidence rate ratio = 2.09, P = 0.0084). The strongest independent factors influencing the relapse risk after the start of switch therapies were a wash-out duration longer than 3 months (incidence rate ratio = 1.78, P < 0.0001), the number of relapses experienced during and before natalizumab treatment (incidence rate ratio = 1.61, P < 0.0001; incidence rate ratio = 1.13, P = 0.0118, respectively) and the presence of comorbidities (incidence rate ratio = 1.4, P = 0.0097). Switching to fingolimod was associated with a 64% reduction of the adjusted-risk for relapse in comparison with switching to interferon beta/glatiramer acetate (incidence rate ratio = 0.36, P < 0.0001). Secondly, patients who switched to fingolimod or to interferon beta/glatiramer acetate were propensity score-matched on a 1-to-1 basis at the switching date. In the propensity score-matched sample a Poisson model showed a significant lower incidence of relapses in patients treated with fingolimod in comparison with those treated with interferon beta/glatiramer acetate (incidence rate ratio = 0.52, P = 0.0003) during a 12-month follow-up. The cumulative probability of a first relapse after the treatment switch was significantly lower in patients receiving fingolimod than in those receiving interferon beta/glatiramer acetate (P = 0.028). The robustness of this result was also confirmed by sensitivity analyses in subgroups with different wash-out durations (less or more than 3 months). Time to 3-month confirmed disability progression was not significantly different between the two groups (Hazard ratio = 0.58; P = 0.1931). Our results indicate a superiority of fingolimod in comparison to interferon beta/glatiramer acetate in controlling disease reactivation after natalizumab discontinuation in the real life setting.

A Combined Nucleic Acid and Protein Analysis in Friedreich Ataxia: Implications for Diagnosis, Pathogenesis and Clinical Trial Design

Background Friedreichs ataxia (FRDA) is the most common hereditary ataxia among caucasians. The molecular defect in FRDA is the trinucleotide GAA expansion in the first intron of the FXN gene, which encodes frataxin. No studies have yet reported frataxin protein and mRNA levels in a large cohort of FRDA patients, carriers and controls. Methodology/Principal Findings We enrolled 24 patients with classic FRDA phenotype (cFA), 6 late onset FRDA (LOFA), all homozygous for GAA expansion, 5 pFA cases who harbored the GAA expansion in compound heterozygosis with FXN point mutations (namely, p.I154F, c.482+3delA, p.R165P), 33 healthy expansion carriers, and 29 healthy controls. DNA was genotyped for GAA expansion, mRNA/FXN was quantified in real-time, and frataxin protein was measured using lateral-flow immunoassay in peripheral blood mononuclear cells (PBMCs). Mean residual levels of frataxin, compared to controls, were 35.8%, 65.6%, 33%, and 68.7% in cFA, LOFA, pFA and healthy carriers, respectively. Comparison of both cFA and pFA with controls resulted in 100% sensitivity and specificity, but there was overlap between LOFA, carriers and controls. Frataxin levels correlated inversely with GAA1 and GAA2 expansions, and directly with age at onset. Messenger RNA expression was reduced to 19.4% in cFA, 50.4% in LOFA, 52.7% in pFA, 53.0% in carriers, as compared to controls (p<0.0001). mRNA levels proved to be diagnostic when comparing cFA with controls resulting in 100% sensitivity and specificity. In cFA and LOFA patients mRNA levels correlated directly with protein levels and age at onset, and inversely with GAA1 and GAA2. Conclusion/Significance We report the first explorative study on combined frataxin and mRNA levels in PBMCs from a cohort of FRDA patients, carriers and healthy individuals. Lateral-flow immunoassay differentiated cFA and pFA patients from controls, whereas determination of mRNA in q-PCR was sensitive and specific only in cFA.

Ataxia with oculomotor apraxia type 1 in Southern Italy: late onset and variable phenotype.

Ataxia with oculomotor apraxia type 1 (AOA1) is an autosomal recessive disorder characterized by early-onset cerebellar ataxia, oculomotor apraxia, and peripheral neuropathy. The causative gene (APTX) has been recently identified in Portuguese and Japanese kindreds. Three patients with AOA1 were identified in an APTX mutation screening on 28 Southern Italian patients with progressive ataxia and peripheral neuropathy. A novel homozygous missense mutation (H201Q) was found in one patient and a Japanese missense mutation (P206L) in two. AOA1 clinical heterogeneity and onset later than previously described are shown.