Alessandro Geroldi

HSPB1 and HSPB8 in inherited neuropathies: study of an Italian cohort of dHMN and CMT2 patients.

Mutations in the small heat‐shock protein 27 kDa protein 1 (HSPB1) and 22 kDa protein 8 (HSPB8) genes were associated with distal hereditary motor neuropathy (dHMN) and with the axonal form of Charcot‐Marie‐Tooth disease type 2 (CMT2). Here we report the clinical and molecular evaluation of an Italian dHMN and CMT2 cohort to establish HSPB1 and HSPB8 mutation occurrence and associated clinical features. One hundred and sixty‐seven patients with dHMN or CMT2 were studied. HSPB1 and HSPB8 exons 1 and 3 molecular analysis was carried out through DHPLC and direct sequencing of each variant chromatogram. HSPB8 exon 2 was analyzed by direct sequencing. Four mutations in five unrelated dHMN patients and four mutations in four unrelated CMT2 cases were found in HSPB1. The p.Arg136Leu mutation was found in two patients with different phenotypes. Electroneurographical follow‐up study in a dHMN patient revealed that sensory impairment occurred with disease progression. The HSPB1 mutation frequency was 8% in dHMN and 4% in CMT2 patients. The significant HSPB1 mutation frequency in both phenotypes indicates its relevance in the pathogenesis of these neuropathies. Recent literature data suggest a continuum between dHMN and CMT2. We confirm this finding in our cohort, proposing a definite relationship between these disorders.

Severe Neuropathy After Diphtheria-Tetanus-Pertussis Vaccination in a Child Carrying a Novel Frame-Shift Mutation in the Small Heat-Shock Protein 27 Gene

Mutations in small heat-shock protein 27 and small heat-shock protein 22 genes were found in association with Charcot-Marie-Tooth disease type 2 and distal hereditary motor neuropathy. We searched for mutations in small heat-shock protein 27 gene in an Italian family with peripheral neuropathy and intrafamilial phenotypic variability. A novel heterozygous frame-shift mutation c.476_477delCT was found while point mutations in most genes associated with hereditary neuropathies were ruled out. In the proband, who showed a severe early onset peripheral neuropathy, an independent pathogenetic effect on the peripheral nervous system secondary to the tetanus toxoid injection may be supposed. This is the first truncating nonsense mutation in the small heat-shock protein 27 gene identified so far and the clinical, neurophysiologic, and neuropathological findings are discussed.

Clinical features and molecular modelling of novel MPZ mutations in demyelinating and axonal neuropathies

Mutations in the myelin protein zero (MPZ) gene have been associated with different Charcot–Marie–Tooth disease (CMT) phenotypes, including classical demyelinating CMT1B and the axonal form of the disease (CMT2). The MPZ role in the pathogenesis of both demyelinating and axonal inherited neuropathies was evaluated in the Italian population by screening a cohort of 214 patients with CMT1 or CMT2. A MPZ mutation frequency of 7.9% in demyelinating cases and of 4.8% in axonal cases was observed. In the total cohort (264 patients), including those with mutations in other genes, a mutation frequency of 5.8% (7/121) in demyelinating cases and 4.2% (6/143) in axonal cases was found. Three novel MPZ mutations, two missense (p.Ser111Cys, p.Thr124Ala) and one frameshift (p.Tyr145fs) were found, and a molecular modelling approach was used to test the effects of these mutations on the protein structure. Electrostatic distribution changes within the protein, caused by the amino acid substitution, fit in with phenotypes presented by patients herein described. Our findings suggest that the clinical features associated with MPZ mutations depend partly on the nature of amino acid change and that molecular modelling may provide useful support, based on effects on secondary and tertiary protein structure, to predict the phenotype associated with MPZ mutations.

TNFα induces the expression of genes associated with endothelial dysfunction through p38MAPK-mediated down-regulation of miR-149.

MicroRNAs have been proposed as novel regulators of vascular inflammation and dysfunction. This study aimed to evaluate the role of miR-149 in regulating the expression of key molecules associated with TNFα-induced endothelial activation. miR-149 was selected by in silico analysis and microRNA target prediction. Endothelial dysfunction was induced by TNFα treatment in Eahy926 endothelial cells and HUVEC. miR-149 level was evaluated by quantitative real time-polymerase chain reaction (RT-qPCR). Metalloproteinase-9 (MMP-9) was measured by zymography, Inducible Nitric Oxide Synthase (iNOS) by immunoblotting, Interleukin-6 (IL-6) and Interleukin-8 (IL-8) by ELISA. miR-149 regulatory effect was evaluated by gain-of-function technique upon miR-149 mimics transfection. TNFα down-modulated miR-149 level in Eahy926 and HUVEC. This effect was significantly abolished in Eahy926 by treatment with p38MAPK inhibitor. miR-149 mimic transfection counteracted the TNFα-induced expression of MMP-9, iNOS and IL-6. No effect was detected on IL-8 expression. Our results suggest that miR-149 represents an important new regulator of endothelial function through negative regulation of molecules associated with TNFα-induced endothelial dysfunction.

Gap junction beta 1 (GJB1) gene mutations in Italian patients with X-linked Charcot-Marie-Tooth disease

AbstractX-linked Charcot-Marie-Tooth disease (CMT1X) is a peripheral neuropathy transmitted in a dominant manner and caused by mutations in the Connexin 32 (Cx32) gene (GJB1, gap junction beta 1). Here we report the mutation analysis of the GJB1 gene in 76 subjects with possible CMT1 and absence of 17p11.2 duplication, and in 38 CMT2 patients without mutations in CMT2-associated-genes, selected from a cohort of 684 patients with peripheral sensory-motor neuropathy. The analysis was performed by direct sequencing of the coding sequence and exon/intron boundaries of the GJB1 gene. The mutation screening identified 22 mutations in GJB1, eight of which have not been previously published: six point mutations (c.50C > G, c.107T > A, c.545C > T, c.545C > G, c.548G > C, c.791G > T) and two deletions (c.84delC, c.573_581delCGTCTTCAT). The GJB1 mutation frequency (19.3%) and the clinical heterogeneity of our patients suggest searching for GJB1 mutations in all CMT cases without the 17p11.2 duplication, regardless of the gender of the proband, as well as in CMT2 patients with possible X-linked inheritance.

Fast course ALS presenting with vocal cord paralysis: Clinical features, bioinformatic and modelling analysis of the novel SOD1 Gly147Ser mutation

Abstract In this report we describe a novel SOD1 mutation (Gly147Ser) in an Italian sporadic ALS patient. The patient presented with hoarseness due to bilateral vocal cord paralysis and a rapid clinical course. Mutational analysis of the SOD1 gene was carried out by direct sequencing. In silico bioinformatics analysis and molecular modelling was used to analyse the SOD1 function modifications produced by the mutated residue. A heterozygous c.442 G > A transition, which leads to a change at codon 147 resulting in a serine rather than glycine, was found in the patient. Bioinformatics analysis and molecular modelling strongly suggest a dramatic effect of Gly147Ser mutation on SOD1 function. In conclusion, Gly147Ser represent a new missense mutation whose effect may correlate with the peculiar clinical bulbar phenotype onset with bilateral vocal cord paresis and rapid clinical course of the disease. Ethical and psychological dilemmas about genetic testing in apparently sporadic subjects are still matter of debate.

A novel autosomal dominant GDAP1 mutation in an Italian CMT2 family

We report the clinical, electrophysiological, and skin biopsy findings of an Italian Charcot‐Marie‐Tooth disease type 2 (CMT2) family with a novel heterozygous GDAP1 mutation. We observed a marked intra‐familial phenotypic variability, in age at onset and disease severity which ranged from a typical CMT phenotype to an asymptomatic status. Electrophysiological study, consistent with an axonal sensory‐motor neuropathy, confirmed a different degree of severity and disclosed minimal electrophysiological abnormalities also in the asymptomatic subjects. Skin biopsy findings showed a variable loss of large and small somatic nerve fibers. Molecular analysis identified a novel heterozygous missense mutation (Arg120Gly) in the GDAP1 gene which co‐segregated with the disease within the pedigree. In conclusion, our findings confirm that the GDAP1 autosomal dominant mutations underlie a pronounced phenotypic variability, mimicking the effects of reduced penetrance. Notably, electrophysiological study in this family allowed to reveal hidden positive family history and assess a dominant inheritance pattern, revealing subclinical neuropathy in asymptomatic mutation carriers.

Molecular chaperones in the pathogenesis of amyotrophic lateral sclerosis : the role of HSPB1

Genetic discoveries in amyotrophic lateral sclerosis (ALS) have a significant impact on deciphering molecular mechanisms of motor neuron degeneration but, despite recent advances, the etiology of most sporadic cases remains elusive. Several cellular mechanisms contribute to the motor neuron degeneration in ALS, including RNA metabolism, cellular interactions between neurons and nonneuronal cells, and seeding of misfolded protein with prion‐like propagation. In this scenario, the importance of protein turnover and degradation in motor neuron homeostasis gained increased recognition. In this study, we evaluated the role of the candidate gene HSPB1, a molecular chaperone involved in several proteome‐maintenance functions. In a cohort of 247 unrelated Italian ALS patients, we identified two variants (c.570G>C, p.Gln190His and c.610dupG, p.Ala204Glyfs*6). Functional characterization of the p.Ala204Glyfs*6 demonstrated that the mutant protein alters HSPB1 dynamic equilibrium, sequestering the wild‐type protein in a stable dimer and resulting in a loss of chaperone‐like activity. Our results underline the relevance of identifying rare but pathogenic variations in sporadic neurodegenerative diseases, suggesting a possible correlation between specific pathomechanisms linked to HSPB1 mutations and the associated neurological phenotype. Our study provides additional lines of evidence to support the involvement of HSPB1 in the pathogenesis of sporadic ALS.

A novel LITAF/SIMPLE mutation within a family with a demyelinating form of Charcot–Marie–Tooth disease

Charcot-Marie-Tooth disease type 1 (CMT1) is a common disorder of the peripheral nervous system. The underlying genetic cause is highly heterogeneous, and mutations in SIMPLE (small integral membrane protein of lysosome/late endosome) represent a rare cause of CMT type 1, named CMT1C. Herein, we report the clinical, electrophysiological, and neuropathological findings of an Italian CMT1 family with a novel SIMPLE missense mutation. The family exhibited electrophysiological signs of demyelination, predominantly affecting the lower limbs, with conduction blocks, and a wide variability of age of onset among the members. Molecular analysis identified the novel heterozygous missense mutation p.Pro135Arg in SIMPLE which co-segregated with the disease within the pedigree. In conclusion, our findings confirm that the genetic analysis of LITAF/SIMPLE should be considered for the diagnostic flow-chart of CMT1 patient, especially when nerve conduction studies show the presence of conduction blocks.

The FIG4 gene does not play a major role in causing ALS in Italian patients

Eighty ALS Italian patients were enrolled at the Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics and Maternal Child Health of the University of Genoa. All patients fulfi lled the El Escorial criteria for defi nite or probable ALS. In this cohort ataxia, cognitive decline or any other atypical feature were not observed. After receiving adequate information, patients signed written consent for genetic molecular analysis and clinical investigation. Genomic DNA was extracted from peripheral blood samples according to standard procedures. All the 23 exons and splice junctions of FIG4 located at position 6q21, were amplifi ed with PCR using specifi c primers (1), purifi ed and analysed by direct sequencing.