scholarly journals Ancient mitochondrial DNA pathogenic variants putatively associated with mitochondrial disease

2020 ◽  
Author(s):  
Draga Toncheva ◽  
Dimitar Serbezov ◽  
Sena Karachanak-Yankova ◽  
Desislava Nesheva
Keyword(s):  
Mitochondrial Dna ◽  
Mitochondrial Disease ◽  
Novel Mutation ◽  
Mitochondrial Diseases ◽  
Type Model ◽  
Human Populations ◽  
Neolithic Period ◽  
Pathogenic Variants ◽  
Pathogenic Effect ◽  
Mtdna Variants

AbstractMitochondrial DNA variants associated with diseases are widely studied in contemporary populations, but their prevalence has not yet been investigated in ancient populations. The publicly available AmtDB database contains 1443 ancient mtDNA Eurasian genomes from different periods. The objective of this study was to use this data to establish the presence of pathogenic mtDNA variants putatively associated with mitochondrial diseases in ancient populations. The clinical significance, pathogenicity prediction and contemporary frequency of mtDNA variants were determined using online platforms. The analyzed ancient mtDNAs contain six variants designated as being “confirmed pathogenic” in modern patients. The oldest of these, m.7510T>C in the MT-TS1 gene, was found in a sample from the Neolithic period dated 5800-5400 BCE. All six have well established clinical association, and their pathogenic effect is corroborated by very low population frequencies in contemporary populations. In addition, ten variants designated as possibly or likely pathogenic were detected. The oldest of these were two variants in the MT-TD gene, m.7543A>G and m.7554G>A, from Neolithic samples dated 8205-7700 BCE. A novel mutation in contemporary populations, m.4440G>A in the MT-TM gene, is established in 12 ancient mtDNA samples from different periods ranging from 2800 BCE to 920 CE. The pathogenic effect of these possibly/likely pathogenic mutations is not yet well established, and further research is warranted. All detected mutations putatively associated with mitochondrial disease in ancient mtDNA samples are in tRNA coding genes. Most of these mutations are in a mt-tRNA type (Model 2) that is characterized by loss of D-loop/T-loop interaction. Seven mutations are located in CS-Anticodon stem, 4 are located in AS-Acceptor stem, 2 in TS-TΨC stem, and single mutations are found in DL-Dihydrouridine Loop, CL-Anticodon Loop and DS-Dihydrouridine stem. Exposing pathogenic variants in ancient human populations expands our understanding of their origin.

scholarly journals Tinnitus in patients with hearing loss due to mitochondrial DNA pathogenic variants

2018 ◽  
Vol 275 (8) ◽  
pp. 1979-1985 ◽  
Author(s):  
Urszula Lechowicz ◽  
Agnieszka Pollak ◽  
Danuta Raj-Koziak ◽  
Beata Dziendziel ◽  
Piotr Henryk Skarżyński ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Mitochondrial Dna ◽  
Visual Analogue Scale ◽  
Analogue Scale ◽  
Medical Problem ◽  
Polish Population ◽  
Pathogenic Variants ◽  
Individual Perception ◽  
Characteristic Features ◽  
Mtdna Variants

Abstract Purpose Tinnitus described as individual perception of phantom sound constitutes a significant medical problem and has become an essential subject of many studies conducted worldwide. In the study, we aimed to examine the prevalence of tinnitus among Polish hearing loss (HL) patients with identified mitochondrial DNA (mtDNA) variants. Methods Among the selected group of unrelated HL patients with known mtDNA pathogenic variants, two questionnaires were conducted, i.e. Tinnitus Handicap Inventory translated into Polish (THI-POL) and Visual Analogue Scale (VAS) for measuring subjectively perceived tinnitus loudness, distress, annoyance and possibility of coping with this condition (VASs). Pathogenic mtDNA variants were detected with real-time PCR and sequencing of the whole mtDNA. Results This is the first extensive tinnitus characterization using THI-POL and VASs questionnaires in HL patients due to mtDNA variants. We have established the prevalence of tinnitus among the studied group at 23.5%. We found that there are no statistically significant differences in the prevalence of tinnitus and its characteristic features between HL patients with known HL mtDNA variants and the general Polish population. In Polish HL patients with tinnitus, m.7511T>C was significantly more frequent than in patients without tinnitus. We observed that the prevalence of tinnitus is lower in Polish patients with m.1555A>G as compared to other available data. Conclusions Our data suggest that the mtDNA variants causative of HL may affect tinnitus development but this effect seems to be ethnic-specific.

scholarly journals Generation of somatic mitochondrial DNA-replaced cells for mitochondrial dysfunction treatment

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hideki Maeda ◽  
Daisuke Kami ◽  
Ryotaro Maeda ◽  
Akira Shikuma ◽  
Satoshi Gojo
Keyword(s):  
Mitochondrial Dna ◽  
Mitochondrial Dysfunction ◽  
Mitochondrial Disease ◽  
Respiratory Function ◽  
Disease Patient ◽  
Mitochondrial Diseases ◽  
Wild Type ◽  
Mutant Genotype ◽  
Isolated Mitochondria ◽  
Wide Range

AbstractMitochondrial diseases currently have no cure regardless of whether the cause is a nuclear or mitochondrial genome mutation. Mitochondrial dysfunction notably affects a wide range of disorders in aged individuals, including neurodegenerative diseases, cancers, and even senescence. Here, we present a procedure to generate mitochondrial DNA-replaced somatic cells with a combination of a temporal reduction in endogenous mitochondrial DNA and coincubation with exogeneous isolated mitochondria. Heteroplasmy in mitochondrial disease patient-derived fibroblasts in which the mutant genotype was dominant over the wild-type genotype was reversed. Mitochondrial disease patient-derived fibroblasts regained respiratory function and showed lifespan extension. Mitochondrial membranous components were utilized as a vehicle to deliver the genetic materials into endogenous mitochondria-like horizontal genetic transfer in prokaryotes. Mitochondrial DNA-replaced cells could be a resource for transplantation to treat maternal inherited mitochondrial diseases.

scholarly journals Generation of Somatic Mitochondrial DNA-Replaced Cells for Mitochondrial Dysfunction Treatment

2020 ◽  
Author(s):  
Hideki Maeda ◽  
Daisuke Kami ◽  
Ryotaro Maeda ◽  
Akira Shikuma ◽  
Satoshi Gojo
Keyword(s):  
Mitochondrial Dna ◽  
Mitochondrial Dysfunction ◽  
Mitochondrial Disease ◽  
Pluripotent Stem Cells ◽  
Disease Patient ◽  
Mitochondrial Diseases ◽  
Wild Type ◽  
Mutant Genotype ◽  
Wide Range

AbstractMitochondrial diseases currently have no cure regardless of whether the cause is a nuclear or mitochondrial genome mutation. Mitochondrial dysfunction notably affects a wide range of disorders in aged individuals, including neurodegenerative diseases, cancers, and even senescence. Here, we present a procedure to generate mitochondrial DNA-replaced somatic cells with a combination of a temporal reduction in endogenous mitochondrial DNA and coincubation with exogeneous isolated mitochondria. Heteroplasmy in mitochondrial disease patient-derived fibroblasts in which the mutant genotype was dominant over the wild-type genotype was reversed over the long term, even inducing the production of pluripotent stem cells from the mitochondrial DNA-replaced cells to maintain the genotype without a reversion to the original. Both mitochondrial disease patient-derived and aged fibroblasts could regain respiratory function and showed lifespan extension. Mitochondrial membranous components were utilized as a vehicle to deliver the genetic materials into endogenous mitochondria-like horizontal genetic transfer in prokaryotes. The mitochondrial DNA-replaced cells could be a resource for transplantation to treat not only mitochondrial diseases, but also senescence-related diseases.

scholarly journals Mitochondrial DNA: Hotspot for Potential Gene Modifiers Regulating Hypertrophic Cardiomyopathy

2020 ◽  
Vol 9 (8) ◽  
pp. 2349 ◽  
Author(s):  
Parisa K. Kargaran ◽  
Jared M. Evans ◽  
Sara E. Bodbin ◽  
James G. W. Smith ◽  
Timothy J. Nelson ◽  
...  
Keyword(s):  
Mitochondrial Dna ◽  
Hypertrophic Cardiomyopathy ◽  
Mitochondrial Genome ◽  
Treatment Options ◽  
Mitochondrial Diseases ◽  
Efficient Treatment ◽  
Novel Treatments ◽  
Sarcomeric Mutations ◽  
Patient Families ◽  
Mtdna Variants

Hypertrophic cardiomyopathy (HCM) is a prevalent and untreatable cardiovascular disease with a highly complex clinical and genetic causation. HCM patients bearing similar sarcomeric mutations display variable clinical outcomes, implying the involvement of gene modifiers that regulate disease progression. As individuals exhibiting mutations in mitochondrial DNA (mtDNA) present cardiac phenotypes, the mitochondrial genome is a promising candidate to harbor gene modifiers of HCM. Herein, we sequenced the mtDNA of isogenic pluripotent stem cell-cardiomyocyte models of HCM focusing on two sarcomeric mutations. This approach was extended to unrelated patient families totaling 52 cell lines. By correlating cellular and clinical phenotypes with mtDNA sequencing, potentially HCM-protective or -aggravator mtDNA variants were identified. These novel mutations were mostly located in the non-coding control region of the mtDNA and did not overlap with those of other mitochondrial diseases. Analysis of unrelated patients highlighted family-specific mtDNA variants, while others were common in particular population haplogroups. Further validation of mtDNA variants as gene modifiers is warranted but limited by the technically challenging methods of editing the mitochondrial genome. Future molecular characterization of these mtDNA variants in the context of HCM may identify novel treatments and facilitate genetic screening in cardiomyopathy patients towards more efficient treatment options.

scholarly journals Ancient mitochondrial DNA pathogenic variants putatively associated with mitochondrial disease

PLoS ONE ◽  
2020 ◽  
Vol 15 (9) ◽  
pp. e0233666
Author(s):  
Draga Toncheva ◽  
Dimitar Serbezov ◽  
Sena Karachanak-Yankova ◽  
Desislava Nesheva
Keyword(s):  
Mitochondrial Dna ◽  
Mitochondrial Disease ◽  
Pathogenic Variants

scholarly journals Diagnosing pediatric mitochondrial disease: lessons from 2,000 exomes

2021 ◽  
Author(s):  
Sarah L Stenton ◽  
Masaru Shimura ◽  
Dorota Piekutowska-Abramczuk ◽  
Peter Freisinger ◽  
Felix Distelmaier ◽  
...  
Keyword(s):  
Precision Medicine ◽  
Molecular Diagnosis ◽  
Mitochondrial Disease ◽  
Mitochondrial Diseases ◽  
Improve Patient Care ◽  
Disease Genes ◽  
Common Denominator ◽  
Functional Studies ◽  
Pathogenic Variants ◽  
Genes Encoding

Background: The spectrum of mitochondrial disease is genetically and phenotypically diverse, resulting from pathogenic variants in over 400 genes, with aerobic energy metabolism defects as a common denominator. Such heterogeneity poses a significant challenge in making an accurate diagnosis, critical for precision medicine. Methods: In an international collaboration initiated by the European Network for Mitochondrial Diseases (GENOMIT) we recruited 2,023 pediatric patients at 11 specialist referral centers between October 2010 and January 2021, accumulating exome sequencing and HPO-encoded phenotype data. An exome-wide search for variants in known and potential novel disease genes, complemented by functional studies, followed ACMG guidelines. Results: 1,109 cases (55%) received a molecular diagnosis, of which one fifth have potential disease-modifying treatments (236/1,109, 21%). Functional studies enabled diagnostic uplift from 36% to 55% and discovery of 62 novel disease genes. Pathogenic variants were identified within genes encoding mitochondrial proteins or RNAs in 801 cases (72%), while, given extensive phenotype overlap, the remainder involved proteins targeted to other cellular compartments. To delineate genotype-phenotype associations, our data was complemented with registry and literature data to develop GENOMITexplorer, an open access resource detailing patient- (n=3,940), gene- (n=427), and variant-level (n=1,492) associations (prokischlab.github.io/GENOMITexplorer/). Conclusions: Reaching a molecular diagnosis was essential for implementation of precision medicine and clinical trial eligibility, underlining the need for genome-wide screening given inability to accurately define mitochondrial diseases clinically. Key to diagnostic success were functional studies, encouraging early acquisition of patient-derived tissues and routine integration of high-throughput functional data to improve patient care by uplifting diagnostic rate.

scholarly journals Epilepsy in Mitochondrial Diseases—Current State of Knowledge on Aetiology and Treatment

Children ◽  
2021 ◽  
Vol 8 (7) ◽  
pp. 532
Author(s):  
Dorota Wesół-Kucharska ◽  
Dariusz Rokicki ◽  
Aleksandra Jezela-Stanek
Keyword(s):  
Oxidative Phosphorylation ◽  
Mitochondrial Dysfunction ◽  
Mitochondrial Disease ◽  
Clinical Picture ◽  
Poor Prognosis ◽  
Treatment Options ◽  
Mitochondrial Diseases ◽  
Energy Deficit ◽  
Atp Production ◽  
Current State

Mitochondrial diseases are a heterogeneous group of diseases resulting from energy deficit and reduced adenosine triphosphate (ATP) production due to impaired oxidative phosphorylation. The manifestation of mitochondrial disease is usually multi-organ. Epilepsy is one of the most common manifestations of diseases resulting from mitochondrial dysfunction, especially in children. The onset of epilepsy is associated with poor prognosis, while its treatment is very challenging, which further adversely affects the course of these disorders. Fortunately, our knowledge of mitochondrial diseases is still growing, which gives hope for patients to improve their condition in the future. The paper presents the pathophysiology, clinical picture and treatment options for epilepsy in patients with mitochondrial disease.

The champions' mitochondria: is it genetically determined? A review on mitochondrial DNA and elite athletic performance

2011 ◽  
Vol 43 (13) ◽  
pp. 789-798 ◽  
Author(s):  
Nir Eynon ◽  
María Morán ◽  
Ruth Birk ◽  
Alejandro Lucia
Keyword(s):  
Mitochondrial Dna ◽  
Endurance Exercise ◽  
Current Knowledge ◽  
Geographic Origin ◽  
Aerobic Performance ◽  
East African ◽  
Athletic Status ◽  
The Status ◽  
Genetically Determined ◽  
Mtdna Variants

Aerobic ATP generation by the mitochondrial respiratory oxidative phosphorylation system (OXPHOS) is a vital metabolic process for endurance exercise. Notably, mitochondrial DNA (mtDNA) codifies 13 of the 83 polypeptides implied in the respiratory chain. As such, there is a strong rationale for identifying an association between mtDNA variants and “aerobic” (endurance) exercise phenotypes. The aim of this review is to summarize current knowledge on the association between mtDNA, nuclear genes involved in mitochondriogenesis, and elite endurance athletic status. Several studies in nonathletic people have demonstrated an association between certain mtDNA lineages and aerobic performance, characterized by maximal oxygen uptake (V̇o2max). Whether mtDNA haplogroups are also associated with the status of being an elite endurance athlete is more controversial, with differences between studies arising from the different ethnic backgrounds of the athletic cohorts (Caucasian of mixed geographic origin, Asiatic, or East African).

scholarly journals Mitochondrial DNA Replacement Techniques to Prevent Human Mitochondrial Diseases

2021 ◽  
Vol 22 (2) ◽  
pp. 551
Author(s):  
Luis Sendra ◽  
Alfredo García-Mares ◽  
María José Herrero ◽  
Salvador F. Aliño
Keyword(s):  
Mitochondrial Dna ◽  
Nuclear Dna ◽  
Genetic Disorders ◽  
Mitochondrial Diseases ◽  
Legal Regulation ◽  
Donor Oocyte ◽  
Legal Position ◽  
Ethical And Legal Issues ◽  
Mitochondrial Replacement Techniques ◽  
Do So

Background: Mitochondrial DNA (mtDNA) diseases are a group of maternally inherited genetic disorders caused by a lack of energy production. Currently, mtDNA diseases have a poor prognosis and no known cure. The chance to have unaffected offspring with a genetic link is important for the affected families, and mitochondrial replacement techniques (MRTs) allow them to do so. MRTs consist of transferring the nuclear DNA from an oocyte with pathogenic mtDNA to an enucleated donor oocyte without pathogenic mtDNA. This paper aims to determine the efficacy, associated risks, and main ethical and legal issues related to MRTs. Methods: A bibliographic review was performed on the MEDLINE and Web of Science databases, along with searches for related clinical trials and news. Results: A total of 48 publications were included for review. Five MRT procedures were identified and their efficacy was compared. Three main risks associated with MRTs were discussed, and the ethical views and legal position of MRTs were reviewed. Conclusions: MRTs are an effective approach to minimizing the risk of transmitting mtDNA diseases, but they do not remove it entirely. Global legal regulation of MRTs is required.

Abstract 17097: Non-Synonymous Mitochondrial DNA Variants Are Common in Myocardial Tissue of Heart Failure Patients

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Pappu Ananya ◽  
Michael Binder ◽  
Yang Wanjun ◽  
Rebecca McClellan ◽  
Brittney Murray ◽  
...  
Keyword(s):  
Heart Failure ◽  
Mitochondrial Dna ◽  
Nuclear Dna ◽  
Left Ventricular ◽  
Individual Risk ◽  
Myocardial Tissue ◽  
Mtdna Mutation ◽  
Mtdna Mutations ◽  
Ventricular Tissue ◽  
Mtdna Variants

Introduction: Mitochondrial heart disease due to pathogenic mitochondrial DNA (mtDNA) mutations can present as hypertrophic or dilated cardiomyopathy, ventricular arrhythmias and conduction disease. It is estimated that the mutation rate of mtDNA is 10 to 20-fold higher than that of nuclear DNA genes due to damage from reactive oxygen species released as byproducts during oxidative phosphorylation. When a new mtDNA mutation arises, it creates an intracellular heteroplasmic mixture of mutant and normal mtDNAs, called heteroplasmy. Heteroplasmy levels can vary in various tissues and examining mtDNA variants in blood may not be representative for the heart. The frequency of pathogenic mtDNA variants in myocardial tissues in unknown. Hypothesis: Human ventricular tissue may contain mtDNA mutations which can lead to alterations in mitochondrial function and increase individual risk for heart failure. Methods: Mitochondrial DNA was isolated from 61 left ventricular myocardial samples obtained from failing human hearts at the time of transplantation. mtDNA was sequenced with 23 primer pairs. In silico prediction of non-conservative missense variants was performed via PolyPhen-2. Heteroplasmy levels of variants predicted to be pathogenic were quantified using allele-specific ARMS-PCR. Results: We identified 21 mtDNA non-synonymous variants predicted to be pathogenic in 17 hearts. Notably, one heart contained four pathogenic mtDNA variants (ATP6: p.M104; ND5: p.P265S; ND4: p.N390S and p.L445F). Heteroplasmy levels exceeded 90% for all four variants in myocardial tissue and were significantly lower in blood. No pathogenic mtDNA variants were identified in 44 hearts. Hearts with mtDNA mutations had higher levels of myocardial GDF-15 (growth differentiation factor-15; 6.2±2.3 vs. 1.3±0.18, p=0.045), an established serum biomarker in various mitochondrial diseases. Conclusions: Non-synonymous mtDNA variants predicted to be pathogenic are common in human left ventricular tissue and may be an important modifier of the heart failure phenotype. Future studies are necessary to correlate myocardial mtDNA mutations with cardiovascular outcomes and to assess whether serum GDF-15 allows identifying patients with myocardial mtDNA mutations.

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