Percorrer por autor "Carrozzo, Rosalba"
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- Autosomal Recessive Cerebellar Ataxia and Low Mitocondrial Complex III in a Portuguese FamilyPublication . Nogueira, Célia; Nesti, Claudia; Meschini, Maria Chiara; Carrozzo, Rosalba; Barros, Jose; Sá, Maria José; Azevedo, Luisa; Vilarinho, Laura; Santorelli, FilippoIntroduction: Defects of mitochondrial complex III (CIII) are a relatively rare cause of mitochondrial dysfunction. The complex catalyzes the electron transfer from reduced coenzyme Q to cytochrome c and is composed of 11 subunits, one of which (MT-CYB) is mtDNA encoded. Mutations in MT-CYB and in assembly factor BCS1L account for the vast majority of cases with low CIII, and are associated with a wide range of neurological disorders. The gene coding for human tetratricopeptide 19 (TTC19) produces a poorly characterized protein thought to be involved in the correct assembly of CIII. Recently, mutations in TTC19 have been described in three unrelated Italian kindred in association with a severe neurodegenerative disease. Objectives: We studied a consanguineous Portuguese family where a severe neurometabolic disorder occurred in four siblings (three men and one woman) in association with a slowly progressive disorder characterized by dystonia of hands and feet, ataxic gait, severe olivo-ponto-cerebellar atrophy documented at brain MRI, and relentless psychiatric manifestations. Variability in age at onset and disease course was observed. Methods: The enzymatic activity of CIII was determined in muscle using a reported spectrophotometric method. Sequence analysis of genomic DNA was performed to identify disease-causing mutations in TTC19. Immunodetection analysis in muscle homogenate and skin fibroblasts allowed the detection of the amount TTC19 protein using a commercially available anti-TTC19 antibody. Results: In this family, we identified a novel homozygous TTC19 mutation predicting frameshift and early protein truncation. The mutation was heterozygous in parents and healthy siblings, and it was absent in ethnically-matched controls. The protein was undetectable in tissues by Western blot analyses. Conclusion: This is the fourth kindred presenting mutations in TTC19. The clinical phenotype of such condition is severe, embraces neurological and psychiatric symptoms, and represents a further example of autosomal recessive ataxia of metabolic origin.
- Bi-allelic LETM1 variants perturb mitochondrial ion homeostasis leading to a clinical spectrum with predominant nervous system involvementPublication . Kaiyrzhanov, Rauan; Mohammed, Sami E.M.; Maroofian, Reza; Husain, Ralf A.; Catania, Alessia; Torraco, Alessandra; Alahmad, Ahmad; Dutra-Clarke, Marina; Grønborg, Sabine; Sudarsanam, Annapurna; Vogt, Julie; Arrigoni, Filippo; Baptista, Julia; Haider, Shahzad; Feichtinger, René G.; Bernardi, Paolo; Zulian, Alessandra; Gusic, Mirjana; Efthymiou, Stephanie; Bai, Renkui; Bibi, Farah; Horga, Alejandro; Martinez-Agosto, Julian A.; Lam, Amanda; Manole, Andreea; Rodriguez, Diego-Perez; Durigon, Romina; Pyle, Angela; Albash, Buthaina; Dionisi-Vici, Carlo; Murphy, David; Martinelli, Diego; Bugiardini, Enrico; Allis, Katrina; Lamperti, Costanza; Reipert, Siegfried; Risom, Lotte; Laugwitz, Lucia; Di Nottia, Michela; McFarland, Robert; Vilarinho, Laura; Hanna, Michael; Prokisch, Holger; Mayr, Johannes A.; Bertini, Enrico Silvio; Ghezzi, Daniele; Østergaard, Elsebet; Wortmann, Saskia B.; Carrozzo, Rosalba; Haack, Tobias B.; Taylor, Robert W.; Spinazzola, Antonella; Nowikovsky, Karin; Houlden, HenryLeucine zipper-EF-hand containing transmembrane protein 1 (LETM1) encodes an inner mitochondrial membrane protein with an osmoregulatory function controlling mitochondrial volume and ion homeostasis. The putative association of LETM1 with a human disease was initially suggested in Wolf-Hirschhorn syndrome, a disorder that results from de novo monoallelic deletion of chromosome 4p16.3, a region encompassing LETM1. Utilizing exome sequencing and international gene-matching efforts, we have identified 18 affected individuals from 11 unrelated families harboring ultra-rare bi-allelic missense and loss-of-function LETM1 variants and clinical presentations highly suggestive of mitochondrial disease. These manifested as a spectrum of predominantly infantile-onset (14/18, 78%) and variably progressive neurological, metabolic, and dysmorphic symptoms, plus multiple organ dysfunction associated with neurodegeneration. The common features included respiratory chain complex deficiencies (100%), global developmental delay (94%), optic atrophy (83%), sensorineural hearing loss (78%), and cerebellar ataxia (78%) followed by epilepsy (67%), spasticity (53%), and myopathy (50%). Other features included bilateral cataracts (42%), cardiomyopathy (36%), and diabetes (27%). To better understand the pathogenic mechanism of the identified LETM1 variants, we performed biochemical and morphological studies on mitochondrial K+/H+ exchange activity, proteins, and shape in proband-derived fibroblasts and muscles and in Saccharomyces cerevisiae, which is an important model organism for mitochondrial osmotic regulation. Our results demonstrate that bi-allelic LETM1 variants are associated with defective mitochondrial K+ efflux, swollen mitochondrial matrix structures, and loss of important mitochondrial oxidative phosphorylation protein components, thus highlighting the implication of perturbed mitochondrial osmoregulation caused by LETM1 variants in neurological and mitochondrial pathologies.
- Complex III deficiency in a Portuguese family: expanding the clinical phenotypePublication . Nogueira, Célia; Nesti, Claudia; Meschini, M. Clara; Carrozzo, Rosalba; Barros, José; Sá, Maria José; Azevedo, Luisa; Santorelli, Filippo; Vilarinho, Laura
- Infantile-Onset Disorders of Mitochondrial Replication and Protein SynthesisPublication . Nogueira, Célia; Carrozzo, Rosalba; Vilarinho, Laura; Santorelli, FilippoMost inherited mitochondrial diseases in infants result from mutations in nuclear genes encoding proteins with specific functions targeted to the mitochondria rather than primary mutations in the mitochondrial DNA (mtDNA) itself. In the past decade, a growing number of syndromes associated with dysfunction resulting from tissue-specific depletion of mtDNA have been reported in infants. MtDNA depletion syndrome is transmitted as an autosomal recessive trait and causes respiratory chain dysfunction with prominent neurological, muscular, and hepatic involvement. Mendelian diseases characterized by defective mitochondrial protein synthesis and combined respiratory chain defects have also been described in infants and are associated with mutations in nuclear genes that encode components of the translational machinery. In the present work, we reviewed current knowledge of clinical phenotypes, their relative frequency, spectrum of mutations, and possible pathogenic mechanisms responsible for infantile disorders of oxidative metabolism involved in correct mtDNA maintenance and protein production.