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Arzuffi P.,The Foundation Carlo Besta Institute of Neurology IRCCS | Lamperti C.,The Foundation Carlo Besta Institute of Neurology IRCCS | Fernandez-Vizarra E.,University Institute of Health Sciences | Tonin P.,University of Verona | And 2 more authors.
Neuromuscular Disorders | Year: 2012

An 80-year-old woman (PI) has been suffering of late onset progressive weakness and wasting of lower-limb muscles, accompanied by high creatine kinase levels in blood. A muscle biopsy, performed at 63years, showed myopathic features with partial deficiency of cytochrome c oxidase. A second biopsy taken 7years later confirmed the presence of a mitochondrial myopathy but also of vacuolar degeneration and other morphological features resembling inclusion body myopathy. Her 46-year-old daughter (PII) and 50-year-old son (PIII) are clinically normal, but the creatine kinase levels were moderately elevated and the EMG was consistently myopathic in both. Analysis of mitochondrial DNA sequence revealed in all three patients a novel, homoplasmic 15bp tandem duplication adjacent to the 5' end of mitochondrial tRNA Phe gene, encompassing the first 11 nucleotides of this gene and the four terminal nucleotides of the adjacent D-loop region. Both mutant fibroblasts and cybrids showed low oxygen consumption rate, reduced mitochondrial protein synthesis, and decreased mitochondrial tRNA Phe amount. These findings are consistent with an unconventional pathogenic mechanism causing the tandem duplication to interfere with the maturation of the mitochondrial tRNA Phe transcript. © 2011 Elsevier B.V. Source

Di Meo I.,The Foundation Carlo Besta Institute of Neurology IRCCS | Auricchio A.,Telethon Institute of Genetics and Medicine | Lamperti C.,The Foundation Carlo Besta Institute of Neurology IRCCS | Burlina A.,University of Padua | And 2 more authors.
EMBO Molecular Medicine | Year: 2012

Ethylmalonic encephalopathy (EE) is an invariably fatal disease, characterized by the accumulation of hydrogen sulfide (H2S), a highly toxic compound. ETHE1, encoding sulfur dioxygenase (SDO), which takes part in the mitochondrial pathway that converts sulfide into harmless sulfate, is mutated in EE. The main source of H2S is the anaerobic bacterial flora of the colon, although in trace amount it is also produced by tissues, where it acts as a 'gasotransmitter'. Here, we show that AAV2/8-mediated, ETHE1-gene transfer to the liver of a genetically, metabolically and clinically faithful EE mouse model resulted in full restoration of SDO activity, correction of plasma thiosulfate, a biomarker reflecting the accumulation of H2S, and spectacular clinical improvement. Most of treated animals were alive and well >6-8 months after birth, whereas untreated individuals live 26±7 days. Our results provide proof of concept on the efficacy and safety of AAV2/8-mediated livergene therapy for EE, and alike conditions caused by the accumulation of harmful compounds in body fluids and tissues, which can directly be transferred to the clinic. © 2012 EMBO Molecular Medicine. Source

Mancuso M.,University of Pisa | Orsucci D.,University of Pisa | Angelini C.,University of Padua | Bertini E.,Laboratory of Molecular Medicine | And 28 more authors.
Journal of Neurology | Year: 2015

Progressive external ophthalmoplegia (PEO), Kearns–Sayre syndrome (KSS) and Pearson syndrome are the three sporadic clinical syndromes classically associated with single large-scale deletions of mitochondrial DNA (mtDNA). PEO plus is a term frequently utilized in the clinical setting to identify patients with PEO and some degree of multisystem involvement, but a precise definition is not available. The purpose of the present study is to better define the clinical phenotypes associated with a single mtDNA deletion, by a retrospective study on a large cohort of 228 patients from the database of the “Nation-wide Italian Collaborative Network of Mitochondrial Diseases”. In our database, single deletions account for about a third of all patients with mtDNA-related disease, more than previously recognized. We elaborated new criteria for the definition of PEO and “KSS spectrum” (a category of which classic KSS represents the most severe extreme). The criteria for “KSS spectrum” include the resulting multisystem clinical features associated with the KSS features, and which therefore can predict their presence or subsequent development. With the new criteria, we were able to classify nearly all our single-deletion patients: 64.5 % PEO, 31.6 % KSS spectrum (including classic KSS 6.6 %) and 2.6 % Pearson syndrome. The deletion length was greater in KSS spectrum than in PEO, whereas heteroplasmy was inversely related with age at onset. We believe that the new phenotype definitions implemented here may contribute to a more homogeneous patient categorization, which will be useful in future cohort studies of natural history and clinical trials. © 2015, Springer-Verlag Berlin Heidelberg. Source

Viscomi C.,The Foundation Carlo Besta Institute of Neurology IRCCS | Viscomi C.,MRC Mitochondrial Biology Unit | Bottani E.,MRC Mitochondrial Biology Unit | Zeviani M.,The Foundation Carlo Besta Institute of Neurology IRCCS | Zeviani M.,MRC Mitochondrial Biology Unit
Biochimica et Biophysica Acta - Bioenergetics | Year: 2015

Abstract Mitochondrial disorders are an important group of genetic conditions characterized by impaired oxidative phosphorylation. Mitochondrial disorders come with an impressive variability of symptoms, organ involvement, and clinical course, which considerably impact the quality of life and quite often shorten the lifespan expectancy. Although the last 20 years have witnessed an exponential increase in understanding the genetic and biochemical mechanisms leading to disease, this has not resulted in the development of effective therapeutic approaches, amenable of improving clinical course and outcome of these conditions to any significant extent. Therapeutic options for mitochondrial diseases still remain focused on supportive interventions aimed at relieving complications. However, new therapeutic strategies have recently been emerging, some of which have shown potential efficacy at the pre-clinical level. This review will present the state of the art on experimental therapy for mitochondrial disorders. Crown Copyright © 2015. Source

Perli E.,University of Rome La Sapienza | Perli E.,Pasteur Institute Cenci Bolognetti Foundation | Giordano C.,University of Rome La Sapienza | Pisano A.,University of Rome La Sapienza | And 20 more authors.
EMBO Molecular Medicine | Year: 2014

Mitochondrial (mt) diseases are multisystem disorders due to mutations in nuclear or mtDNA genes. Among the latter, more than 50% are located in transfer RNA (tRNA) genes and are responsible for a wide range of syndromes, for which no effective treatment is available at present. We show that three human mt aminoacyl-tRNA syntethases, namely leucyl-, valyl-, and isoleucyl-tRNA synthetase are able to improve both viability and bioenergetic proficiency of human transmitochondrial cybrid cells carrying pathogenic mutations in the mt-tRNAIle gene. Importantly, we further demonstrate that the carboxy-terminal domain of human mt leucyl-tRNA synthetase is both necessary and sufficient to improve the pathologic phenotype associated either with these "mild" mutations or with the "severe" m.3243A>G mutation in the mt-tRNALeu(UUR) gene. Furthermore, we provide evidence that this small, non-catalytic domain is able to directly and specifically interact in vitro with human mt-tRNALeu(UUR) with high affinity and stability and, with lower affinity, with mt-tRNAIle. Taken together, our results sustain the hypothesis that the carboxy-terminal domain of human mt leucyl-tRNA synthetase can be used to correct mt dysfunctions caused by mt-tRNA mutations. © 2014 The Authors. Source

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