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The Lancet. Neurology Jul 2021Mitochondrial diseases are some of the most common inherited neurometabolic disorders, and major progress has been made in our understanding, diagnosis, and treatment of... (Review)
Review
Mitochondrial diseases are some of the most common inherited neurometabolic disorders, and major progress has been made in our understanding, diagnosis, and treatment of these conditions in the past 5 years. Development of national mitochondrial disease cohorts and international collaborations has changed our knowledge of the spectrum of clinical phenotypes and natural history of mitochondrial diseases. Advances in high-throughput sequencing technologies have altered the diagnostic algorithm for mitochondrial diseases by increasingly using a genetics-first approach, with more than 350 disease-causing genes identified to date. While the current management strategy for mitochondrial disease focuses on surveillance for multisystem involvement and effective symptomatic treatment, new endeavours are underway to find better treatments, including repurposing current drugs, use of novel small molecules, and gene therapies. Developments made in reproductive technology offer women the opportunity to prevent transmission of DNA-related mitochondrial disease to their children.
Topics: DNA, Mitochondrial; Genetic Therapy; High-Throughput Nucleotide Sequencing; Humans; Mitochondrial Diseases; Mutation
PubMed: 34146515
DOI: 10.1016/S1474-4422(21)00098-3 -
International Journal of Molecular... Jan 2021Mitochondria are ubiquitous intracellular organelles found in almost all eukaryotes and involved in various aspects of cellular life, with a primary role in energy... (Review)
Review
Mitochondria are ubiquitous intracellular organelles found in almost all eukaryotes and involved in various aspects of cellular life, with a primary role in energy production. The interest in this organelle has grown stronger with the discovery of their link to various pathologies, including cancer, aging and neurodegenerative diseases. Indeed, dysfunctional mitochondria cannot provide the required energy to tissues with a high-energy demand, such as heart, brain and muscles, leading to a large spectrum of clinical phenotypes. Mitochondrial defects are at the origin of a group of clinically heterogeneous pathologies, called mitochondrial diseases, with an incidence of 1 in 5000 live births. Primary mitochondrial diseases are associated with genetic mutations both in nuclear and mitochondrial DNA (mtDNA), affecting genes involved in every aspect of the organelle function. As a consequence, it is difficult to find a common cause for mitochondrial diseases and, subsequently, to offer a precise clinical definition of the pathology. Moreover, the complexity of this condition makes it challenging to identify possible therapies or drug targets.
Topics: Animals; DNA, Mitochondrial; Energy Metabolism; Humans; Mitochondria; Mitochondrial Diseases; Mitochondrial Proteins; Models, Molecular; Mutation; Protein Conformation
PubMed: 33435522
DOI: 10.3390/ijms22020586 -
Journal of Parkinson's Disease 2021Mitochondrial dysfunction represents a well-established player in the pathogenesis of both monogenic and idiopathic Parkinson's disease (PD). Initially originating from... (Review)
Review
Mitochondrial dysfunction represents a well-established player in the pathogenesis of both monogenic and idiopathic Parkinson's disease (PD). Initially originating from the observation that mitochondrial toxins cause PD, findings from genetic PD supported a contribution of mitochondrial dysfunction to the disease. Here, proteins encoded by the autosomal recessively inherited PD genes Parkin, PTEN-induced kinase 1 (PINK1), and DJ-1 are involved in mitochondrial pathways. Additional evidence for mitochondrial dysfunction stems from models of autosomal-dominant PD due to mutations in alpha-synuclein (SNCA) and leucine-rich repeat kinase 2 (LRRK2). Moreover, patients harboring alterations in mitochondrial polymerase gamma (POLG) often exhibit signs of parkinsonism. While some molecular studies suggest that mitochondrial dysfunction is a primary event in PD, others speculate that it is the result of impaired mitochondrial clearance. Most recent research even implicated damage-associated molecular patterns released from non-degraded mitochondria in neuroinflammatory processes in PD. Here, we summarize the manifold literature dealing with mitochondria in the context of PD. Moreover, in light of recent advances in the field of personalized medicine, patient stratification according to the degree of mitochondrial impairment followed by mitochondrial enhancement therapy may hold potential for at least a subset of genetic and idiopathic PD cases. Thus, in the second part of this review, we discuss therapeutic approaches targeting mitochondrial dysfunction with the aim to prevent or delay neurodegeneration in PD.
Topics: Animals; Humans; Mitochondrial Diseases; Parkinson Disease
PubMed: 33074190
DOI: 10.3233/JPD-201981 -
Cell Apr 2020Mitochondrial diseases are clinically heterogeneous disorders caused by a wide spectrum of mutations in genes encoded by either the nuclear or the mitochondrial genome.... (Review)
Review
Mitochondrial diseases are clinically heterogeneous disorders caused by a wide spectrum of mutations in genes encoded by either the nuclear or the mitochondrial genome. Treatments for mitochondrial diseases are currently focused on symptomatic management rather than improving the biochemical defect caused by a particular mutation. This review focuses on the latest advances in the development of treatments for mitochondrial disease, both small molecules and gene therapies, as well as methods to prevent transmission of mitochondrial disease through the germline.
Topics: Animals; DNA, Mitochondrial; Genetic Therapy; Genome, Mitochondrial; Humans; Mitochondria; Mitochondrial Diseases; Mutation; NAD; Reactive Oxygen Species
PubMed: 32220313
DOI: 10.1016/j.cell.2020.02.051 -
Deutsches Arzteblatt International Nov 2021Mitochondrial disorders are among the most common heritable diseases, with an overall lifetime risk of approximately one in 1500. Nonetheless, their diagnosis is often... (Review)
Review
BACKGROUND
Mitochondrial disorders are among the most common heritable diseases, with an overall lifetime risk of approximately one in 1500. Nonetheless, their diagnosis is often missed because of their extreme phenotypic and genotypic heterogeneity.
METHODS
This review is based on publications retrieved by a selective literature search on the clinical features, genetics, pathogenesis, diagnosis, and treatment of mitochondrial diseases.
RESULTS
Pathogenic defects of energy metabolism have been described to date in over 400 genes. Only a small number of these genes lie in the mitochondrial DNA; the corresponding diseases are either maternally inherited or of sporadic distribution. The remaining disease-associated genes are coded in nuclear DNA and cause diseases that are inherited according to Mendelian rules, mostly autosomal recessive. The most severely involved organs are generally those with the highest energy requirements, including the brain, the sensory epithelia, and the extraocular, cardiac, and skeletal musculature. Typical manifestations include epileptic seizures, stroke-like episodes, hearing loss, retinopathy, external ophthalmoparesis, exercise intolerance, and diabetes mellitus. More than two manifestations of these types should arouse suspicion of a disease of energy metabolism. The severity of mitochondrial disorders ranges from very severe disease, already evident in childhood, to relatively mild disease arising in late adulthood. The diagnosis is usually confirmed with molecular-genetic methods. Symptomatic treatment can improve patients' quality of life. The only disease-modifying treatment that has been approved to date is idebenone for the treatment of Leber hereditary optic neuropathy. Intravitreal gene therapy has also been developed for the treatment of this disease; its approval by the European Medicines Agency is pending.
CONCLUSION
Patients with mitochondrial diseases have highly varied manifestations and can thus present to physicians in practically any branch of medicine. A correct diagnosis is the prerequisite for genetic counseling and for the initiation of personalized treatment.
Topics: Adult; DNA, Mitochondrial; Humans; Mitochondrial Diseases; Optic Atrophy, Hereditary, Leber; Quality of Life
PubMed: 34158150
DOI: 10.3238/arztebl.m2021.0251 -
Journal of Internal Medicine Jun 2020Mitochondrial disease presenting in childhood is characterized by clinical, biochemical and genetic complexity. Some children are affected by canonical syndromes, but... (Review)
Review
Mitochondrial disease presenting in childhood is characterized by clinical, biochemical and genetic complexity. Some children are affected by canonical syndromes, but the majority have nonclassical multisystemic disease presentations involving virtually any organ in the body. Each child has a unique constellation of clinical features and disease trajectory, leading to enormous challenges in diagnosis and management of these heterogeneous disorders. This review discusses the classical mitochondrial syndromes presenting most frequently in childhood and then presents an organ-based perspective including systems less frequently linked to mitochondrial disease, such as skin and hair abnormalities and immune dysfunction. An approach to diagnosis is then presented, encompassing clinical evaluation and biochemical, neuroimaging and genetic investigations, and emphasizing the problem of phenocopies. The impact of next-generation sequencing is discussed, together with the importance of functional validation of novel genetic variants never previously linked to mitochondrial disease. The review concludes with a brief discussion of currently available and emerging therapies. The field of mitochondrial medicine has made enormous strides in the last 30 years, with approaching 400 different genes across two genomes now linked to primary mitochondrial disease. However, many important questions remain unanswered, including the reasons for tissue specificity and variability of clinical presentation of individuals sharing identical gene defects, and a lack of disease-modifying therapies and biomarkers to monitor disease progression and/or response to treatment.
Topics: Child; Humans; Mitochondria; Mitochondrial Diseases; Mutation; Phenotype
PubMed: 32176382
DOI: 10.1111/joim.13054 -
Mitochondrion Jan 2022Although mitochondrial dysfunction is the known cause of primary mitochondrial disease, mitochondrial dysfunction is often difficult to measure and prove, especially... (Review)
Review
Although mitochondrial dysfunction is the known cause of primary mitochondrial disease, mitochondrial dysfunction is often difficult to measure and prove, especially when biopsies of affected tissue are not available. In order to identify blood biomarkers of mitochondrial dysfunction, we reviewed studies that measured blood biomarkers in genetically, clinically or biochemically confirmed primary mitochondrial disease patients. In this way, we were certain that there was an underlying mitochondrial dysfunction which could validate the biomarker. We found biomarkers of three classes: 1) functional markers measured in blood cells, 2) biochemical markers of serum/plasma and 3) DNA markers. While none of the reviewed single biomarkers may perfectly reveal all underlying mitochondrial dysfunction, combining biomarkers that cover different aspects of mitochondrial impairment probably is a good strategy. This biomarker panel may assist in the diagnosis of primary mitochondrial disease patients. As mitochondrial dysfunction may also play a significant role in the pathophysiology of multifactorial disorders such as Alzheimer's disease and glaucoma, the panel may serve to assess mitochondrial dysfunction in complex multifactorial diseases as well and enable selection of patients who could benefit from therapies targeting mitochondria.
Topics: Biomarkers; Humans; Mitochondrial Diseases
PubMed: 34740866
DOI: 10.1016/j.mito.2021.10.008 -
International Journal of Molecular... Oct 2022Primary mitochondrial diseases are relatively common inborn errors of energy metabolism, with a combined prevalence of 1 in 4300. These disorders typically affect... (Review)
Review
Primary mitochondrial diseases are relatively common inborn errors of energy metabolism, with a combined prevalence of 1 in 4300. These disorders typically affect tissues with high energy requirements, including the brain. Epilepsy affects >1% of the worldwide population, making it one of the most common neurological illnesses; it may be the presenting feature of a mitochondrial disease, but is often part of a multisystem clinical presentation. The major genetic causes of mitochondrial epilepsy are mutations in mitochondrial DNA and in the nuclear-encoded gene POLG. Treatment of mitochondrial epilepsy may be challenging, often representing a poor prognostic feature. This narrative review will cover the most recent advances in the field of mitochondrial epilepsy, from pathophysiology and genetic etiologies to phenotype and treatment options.
Topics: Humans; Neurologists; Mitochondrial Diseases; DNA, Mitochondrial; Epilepsy; Mitochondria; Mutation
PubMed: 36362003
DOI: 10.3390/ijms232113216 -
The Journal of Clinical Investigation Jan 2022Vaccination affords protection from disease by activating pathogen-specific immune cells and facilitating the development of persistent immunologic memory toward the... (Review)
Review
Vaccination affords protection from disease by activating pathogen-specific immune cells and facilitating the development of persistent immunologic memory toward the vaccine-specific pathogen. Current vaccine regimens are often based on the efficiency of the acute immune response, and not necessarily on the generation of memory cells, in part because the mechanisms underlying the development of efficient immune memory remain incompletely understood. This Review describes recent advances in defining memory T cell metabolism and how metabolism of these cells might be altered in patients affected by mitochondrial diseases or metabolic syndrome, who show higher susceptibility to recurrent infections and higher rates of vaccine failure. It discusses how this new understanding could add to the way we think about immunologic memory, vaccine development, and cancer immunotherapy.
Topics: Animals; Cancer Vaccines; Humans; Immunologic Memory; Memory T Cells; Metabolic Syndrome; Mitochondrial Diseases; Neoplasms; Vaccination
PubMed: 34981777
DOI: 10.1172/JCI148546 -
FEBS Letters Apr 2021Mitochondrial disorders are among the most frequent inborn errors of metabolism, their primary cause being the dysfunction of the oxidative phosphorylation system... (Review)
Review
Mitochondrial disorders are among the most frequent inborn errors of metabolism, their primary cause being the dysfunction of the oxidative phosphorylation system (OXPHOS). OXPHOS is composed of the electron transport chain (ETC), formed by four multimeric enzymes and two mobile electron carriers, plus an ATP synthase [also called complex V (cV)]. The ETC performs the redox reactions involved in cellular respiration while generating the proton motive force used by cV to synthesize ATP. OXPHOS biogenesis involves multiple steps, starting from the expression of genes encoded in physically separated genomes, namely the mitochondrial and nuclear DNA, to the coordinated assembly of components and cofactors building each individual complex and eventually the supercomplexes. The genetic cause underlying around half of the diagnosed mitochondrial disease cases is currently known. Many of these cases result from pathogenic variants in genes encoding structural subunits or additional factors directly involved in the assembly of the ETC complexes. Here, we review the historical and most recent findings concerning the clinical phenotypes and the molecular pathological mechanisms underlying this particular group of disorders.
Topics: Adenosine Triphosphate; Animals; DNA, Mitochondrial; Electron Transport; Electron Transport Chain Complex Proteins; Humans; Mitochondria; Mitochondrial Diseases
PubMed: 33159691
DOI: 10.1002/1873-3468.13995