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Heath O, Hammerl E, Spitzinger A, Wortmann SB. Ending an Odyssey? The Psychosocial Experiences of Parents after the Genetic Diagnosis of a Mitochondrial Disease in Children. J Pers Med 2024; 14:523. [PMID: 38793105 PMCID: PMC11122152 DOI: 10.3390/jpm14050523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Revised: 05/02/2024] [Accepted: 05/09/2024] [Indexed: 05/26/2024] Open
Abstract
Obtaining a genetic diagnosis of a primary mitochondrial disease (PMD) is often framed as a diagnostic odyssey. Yet, even after receiving a diagnosis, parents of affected children experience ongoing therapeutic and prognostic uncertainty and considerable psychosocial challenges. Semi-structured interviews (N = 24) were conducted with parents of 13 children (aged 2-19 years) with a genetically confirmed PMD. Paternal (N = 11) and maternal (N = 13) perspectives were obtained, and thematic analysis was performed on all interviews. A genetic diagnosis was valuable and empowering for parents, despite eliciting varied emotional responses. While the diagnosis helped focus management decisions, families often felt overwhelmed and unsupported in navigating the healthcare system. Most parents reported a serious impact on their romantic relationship. The sources of social support varied, with a preference for established friendship and family support networks over disease-specific community support groups. Most parents favored prenatal genetic testing in the event of a future pregnancy. This study provides insight into the lived experiences of parents after a genetic diagnosis of PMD in their children. The findings draw awareness to supportive care needs and highlight important gaps that should be addressed to ensure that parents feel supported within a holistic framework of management for PMDs.
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Affiliation(s)
- Oliver Heath
- University Children’s Hospital, Salzburger Landeskliniken (SALK), Paracelsus Medical University (PMU), Müllner Hauptstrasse 48, 5020 Salzburg, Austria; (O.H.); (E.H.); (A.S.)
| | - Emma Hammerl
- University Children’s Hospital, Salzburger Landeskliniken (SALK), Paracelsus Medical University (PMU), Müllner Hauptstrasse 48, 5020 Salzburg, Austria; (O.H.); (E.H.); (A.S.)
| | - Anna Spitzinger
- University Children’s Hospital, Salzburger Landeskliniken (SALK), Paracelsus Medical University (PMU), Müllner Hauptstrasse 48, 5020 Salzburg, Austria; (O.H.); (E.H.); (A.S.)
- Institut für Klinische Psychologie der UK für Psychiatrie, Psychotherapie und Psychosomatik der PMU, 5020 Salzburg, Austria
| | - Saskia B. Wortmann
- University Children’s Hospital, Salzburger Landeskliniken (SALK), Paracelsus Medical University (PMU), Müllner Hauptstrasse 48, 5020 Salzburg, Austria; (O.H.); (E.H.); (A.S.)
- Nijmegen Centre for Mitochondrial Disorders (NCMD), Amalia Children’s Hospital, Radboudumc, 6525 Nijmegen, The Netherlands
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2
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Ozlu C, Messahel S, Minassian B, Kayani S. Mitochondrial encephalopathies and myopathies: Our tertiary center's experience. Eur J Paediatr Neurol 2024; 50:31-40. [PMID: 38583367 DOI: 10.1016/j.ejpn.2024.03.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Revised: 03/12/2024] [Accepted: 03/22/2024] [Indexed: 04/09/2024]
Abstract
Mitochondrial diseases have a heterogeneous phenotype and can result from mutations in the mitochondrial or nuclear genomes, constituting a diagnostically and therapeutically challenging group of disorders. We report our center's experience with mitochondrial encephalopathies and myopathies with a cohort of 50 genetically and phenotypically diverse patients followed in the Neurology clinic over the last ten years. Seventeen patients had mitochondrial DNA mutations, presented over a wide range of ages with seizures, feeding difficulties, extraocular movements abnormalities, and had high rates of stroke-like episodes and regression. Twenty-seven patients had nuclear DNA mutations, presented early in life with feeding difficulty, failure-to-thrive, and seizures, and had high proportions of developmental delay, wheelchair dependence, spine abnormalities and dystonia. In six patients, a mutation could not be identified, but they were included for having mitochondrial disease confirmed by histopathology, enzyme analysis and clinical features. These patients had similar characteristics to patients with nuclear DNA mutations, suggesting missed underlying mutations in the nuclear genome. Management was variable among patients, but outcomes were universally poor with severe disability in all cases. Therapeutic entryways through elucidation of disease pathways and remaining unknown genes are acutely needed.
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Affiliation(s)
- Can Ozlu
- University of Texas Southwestern Medical Center ,Dallas, TX, USA; Children's Medical Center, Dallas, TX, USA
| | | | - Berge Minassian
- University of Texas Southwestern Medical Center ,Dallas, TX, USA; Children's Medical Center, Dallas, TX, USA
| | - Saima Kayani
- University of Texas Southwestern Medical Center ,Dallas, TX, USA; Children's Medical Center, Dallas, TX, USA.
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3
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Fancello V, Fancello G, Palma S, Monzani D, Genovese E, Bianchini C, Ciorba A. The Role of Primary Mitochondrial Disorders in Hearing Impairment: An Overview. Medicina (B Aires) 2023; 59:medicina59030608. [PMID: 36984609 PMCID: PMC10058207 DOI: 10.3390/medicina59030608] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 03/06/2023] [Accepted: 03/16/2023] [Indexed: 03/22/2023] Open
Abstract
Background. Defects of mitochondrial DNA (mtDNA) involved in the function of the mitochondrial electron transport chain can result in primary mitochondrial diseases (PMDs). Various features can influence the phenotypes of different PMDs, with relevant consequences on clinical presentation, including the presence of hearing impairment. This paper aims to describe the hearing loss related to different PMDs, and when possible, their phenotype. Methods. A systematic review was performed according to PRISMA guidelines, searching Medline until December 2022. A total of 485 papers were identified, and based on specified criteria, 7 were included in this study. Results. A total of 759 patients affected by PMDs and hearing loss were included. The age of patients ranged from 2 days to 78 years old, and the male-to-female ratio was 1.3:1. The percentage of subjects affected by hearing loss was 40.8%, (310/759), and in most cases, hearing impairment was described as sensorineural, bilateral, symmetrical, and progressive, with different presentations depending on age and syndrome severity. Conclusions. PMDs are challenging conditions with different clinical phenotypes. Hearing loss, especially when bilateral and progressive, may represent a red flag; its association with other systemic disorders (particularly neuromuscular, ocular, and endocrine) should alert clinicians, and confirmation via genetic testing is mandatory nowadays.
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Affiliation(s)
- Virginia Fancello
- ENT & Audiology Unit, Department of Neurosciences, University Hospital of Ferrara, 44124 Ferrara, Italy
- Correspondence: (V.F.); (S.P.)
| | - Giuseppe Fancello
- Department of Otorhinolaryngology, Careggi University Hospital, 50134 Florence, Italy
| | - Silvia Palma
- ENT & Audiology Department, University of Modena and Reggio Emilia, 41100 Modena, Italy
- Correspondence: (V.F.); (S.P.)
| | - Daniele Monzani
- ENT & Audiology Department, University of Verona, 37134 Verona, Italy
| | - Elisabetta Genovese
- ENT & Audiology Department, University of Modena and Reggio Emilia, 41100 Modena, Italy
| | - Chiara Bianchini
- ENT & Audiology Unit, Department of Neurosciences, University Hospital of Ferrara, 44124 Ferrara, Italy
| | - Andrea Ciorba
- ENT & Audiology Unit, Department of Neurosciences, University Hospital of Ferrara, 44124 Ferrara, Italy
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4
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Mandal AK. Mitochondrial targeting of potent nanoparticulated drugs in combating diseases. J Biomater Appl 2022; 37:614-633. [PMID: 35790487 DOI: 10.1177/08853282221111656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Mitochondrial dysfunction, characterized by the electron transport chain (ETC) leakage and reduced adenosine tri-phosphate synthesis, occurs primarily due to free radicals -induced mutations in either the mitochondrial deoxyribonucleic acid (mtDNA) or nuclear (n) DNA caused by pathogenic infections, toxicant exposures, adverse drug-effects, or other environmental exposures, leading to secondary dysfunction affecting ischemic, diabetic, cancerous, and degenerative diseases. In these concerns, mitochondria-targeted remedies may include a significant role in the protection and treatment of mitochondrial function to enhance its activity. Coenzyme Q10 pyridinol and pyrimidinol antioxidant analogues and other potent drug-compounds for their multifunctional radical quencher and other anti-toxic activities may take a significant therapeutic effectivity for ameliorating mitochondrial dysfunction. Moreover, the encapsulation of these bioactive ligands-attached potent compounds in vesicular system may enable them a superb biological effective for the treatment of mitochondria-targeted dysfunction-related diseases with least side effects. This review depicts mainly on mitochondrial enzymatic dysfunction and their amelioration by potent drugs with the usages of nanoparticulated delivery system against mitochondria-affected diseases.
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5
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Doherty TM, Gruffi C, Overby P. Failed Emergence After Pediatric Epilepsy Surgery: Is Propofol-Related Infusion Syndrome to Blame? Cureus 2021; 13:e19414. [PMID: 34909331 PMCID: PMC8660594 DOI: 10.7759/cureus.19414] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/01/2021] [Indexed: 12/18/2022] Open
Abstract
Propofol infusion syndrome was first reported in the literature by Bray in 1998. He described a series of fatal outcomes after a presenting constellation of symptoms observed in pediatric patients who had received prolonged propofol infusions. Profound metabolic acidosis and bradycardia are the disease’s hallmark features, which can further develop expeditiously to rhabdomyolysis, renal failure, and heart failure. It has been subsequently theorized that a triggering mechanism or a precipitating factor sets up the progressive physiologic spiral which can ensue. The name of the disease was expanded to Propofol Related Infusion Syndrome (PRIS), as propofol alone was no longer considered the culprit. The disease process is rare and can present with an insidious onset in some cases, causing much speculation of whether there is a proper grasp of the disease entity in its entirety as currently reported. The case discussed in this article depicts an adverse neurologic outcome following a craniotomy for temporal lobectomy in a child with lesional epilepsy. Since there was no obvious causative factor for these findings, PRIS became a diagnosis that was robustly discussed among the involved services.
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Affiliation(s)
- Tara M Doherty
- Pediatric Anesthesiology, Westchester Medical Center, Valhalla, USA
| | - Catherine Gruffi
- Pediatric Anesthesiology, Westchester Medical Center, Valhalla, USA
| | - Philip Overby
- Pediatric Neurology, Westchester Medical Center, Valhalla, USA
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6
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Akiyama N, Shimura M, Yamazaki T, Harashima H, Fushimi T, Tsuruoka T, Ebihara T, Ichimoto K, Matsunaga A, Saito-Tsuruoka M, Yatsuka Y, Kishita Y, Kohda M, Namba A, Kamei Y, Okazaki Y, Kosugi S, Ohtake A, Murayama K. Prenatal diagnosis of severe mitochondrial diseases caused by nuclear gene defects: a study in Japan. Sci Rep 2021; 11:3531. [PMID: 33574353 PMCID: PMC7878886 DOI: 10.1038/s41598-021-81015-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 12/28/2020] [Indexed: 12/05/2022] Open
Abstract
Prenatal diagnoses of mitochondrial diseases caused by defects in nuclear DNA (nDNA) or mitochondrial DNA have been reported in several countries except for Japan. The present study aimed to clarify the status of prenatal genetic diagnosis of mitochondrial diseases caused by nDNA defects in Japan. A comprehensive genomic analysis was performed to diagnose more than 400 patients, of which, 13 families (16 cases) had requested prenatal diagnoses. Eight cases diagnosed with wild type homozygous or heterozygous variants same as either of the heterozygous parents continued the pregnancy and delivered healthy babies. Another eight cases were diagnosed with homozygous, compound heterozygous, or hemizygous variants same as the proband. Of these, seven families chose to terminate the pregnancy, while one decided to continue the pregnancy. Neonatal- or infantile-onset mitochondrial diseases show severe phenotypes and lead to lethality. Therefore, such diseases could be candidates for prenatal diagnosis with careful genetic counseling, and prenatal testing could be a viable option for families.
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Affiliation(s)
- Nana Akiyama
- Center for Medical Genetics, Chiba Children's Hospital, Chiba, Japan.,Department of Medical Genetics/Medical Ethics, Kyoto University School of Public Health, Kyoto, Japan
| | - Masaru Shimura
- Department of Metabolism, Chiba Children's Hospital, 579-1 Heta-cho, Midori-ku, Chiba, 266-0007, Japan
| | - Taro Yamazaki
- Department of Pediatrics, Faculty of Medicine, Saitama Medical University, Saitama, Japan
| | - Hiroko Harashima
- Department of Pediatrics, Faculty of Medicine, Saitama Medical University, Saitama, Japan.,Department of Clinical Genomics, Faculty of Medicine, Saitama Medical University, Saitama, Japan
| | - Takuya Fushimi
- Department of Metabolism, Chiba Children's Hospital, 579-1 Heta-cho, Midori-ku, Chiba, 266-0007, Japan
| | - Tomoko Tsuruoka
- Department of Neonatology, Chiba Children's Hospital, Chiba, Japan
| | - Tomohiro Ebihara
- Department of Neonatology, Chiba Children's Hospital, Chiba, Japan
| | - Keiko Ichimoto
- Department of Metabolism, Chiba Children's Hospital, 579-1 Heta-cho, Midori-ku, Chiba, 266-0007, Japan
| | - Ayako Matsunaga
- Department of Metabolism, Chiba Children's Hospital, 579-1 Heta-cho, Midori-ku, Chiba, 266-0007, Japan
| | - Megumi Saito-Tsuruoka
- Department of Clinical Genomics, Faculty of Medicine, Saitama Medical University, Saitama, Japan.,Center for Intractable Diseases, Saitama Medical University Hospital, Saitama, Japan
| | - Yukiko Yatsuka
- Diagnostics and Therapeutics of Intractable Diseases, Intractable Disease Research Center, Graduate School of Medicine, Juntendo University, Tokyo, Japan
| | - Yoshihito Kishita
- Diagnostics and Therapeutics of Intractable Diseases, Intractable Disease Research Center, Graduate School of Medicine, Juntendo University, Tokyo, Japan.,Department of Life Science, Faculty of Science and Engineering, Kindai University, Osaka, Japan
| | - Masakazu Kohda
- Diagnostics and Therapeutics of Intractable Diseases, Intractable Disease Research Center, Graduate School of Medicine, Juntendo University, Tokyo, Japan
| | - Akira Namba
- Department of Clinical Genomics, Faculty of Medicine, Saitama Medical University, Saitama, Japan.,Center for Intractable Diseases, Saitama Medical University Hospital, Saitama, Japan.,Department of Obstetrics and Gynecology, Saitama Medical University Hospital, Saitama, Japan
| | - Yoshimasa Kamei
- Department of Obstetrics and Gynecology, Saitama Medical University Hospital, Saitama, Japan
| | - Yasushi Okazaki
- Diagnostics and Therapeutics of Intractable Diseases, Intractable Disease Research Center, Graduate School of Medicine, Juntendo University, Tokyo, Japan
| | - Shinji Kosugi
- Department of Medical Genetics/Medical Ethics, Kyoto University School of Public Health, Kyoto, Japan
| | - Akira Ohtake
- Department of Pediatrics, Faculty of Medicine, Saitama Medical University, Saitama, Japan. .,Department of Clinical Genomics, Faculty of Medicine, Saitama Medical University, Saitama, Japan. .,Center for Intractable Diseases, Saitama Medical University Hospital, Saitama, Japan.
| | - Kei Murayama
- Center for Medical Genetics, Chiba Children's Hospital, Chiba, Japan. .,Department of Metabolism, Chiba Children's Hospital, 579-1 Heta-cho, Midori-ku, Chiba, 266-0007, Japan. .,Diagnostics and Therapeutics of Intractable Diseases, Intractable Disease Research Center, Graduate School of Medicine, Juntendo University, Tokyo, Japan.
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7
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Aryamvally A, Myers MF, Huang T, Slone J, Pilipenko V, Hartmann JE. Mitochondrial replacement therapy: Genetic counselors' experiences, knowledge, and opinions. J Genet Couns 2021; 30:828-837. [PMID: 33469959 DOI: 10.1002/jgc4.1382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 11/13/2020] [Accepted: 12/21/2020] [Indexed: 11/08/2022]
Abstract
Mitochondrial disorders affect at least 1 in 5,000 individuals worldwide and are often incurable and fatal. Mitochondrial replacement therapy (MRT) is an in vitro fertilization technique used to prevent the transmission of mitochondrial disorders. Currently, MRT is the only approach that provides mothers who carry a pathogenic variant in their mitochondrial DNA (mtDNA), the opportunity to have a biological child without a mitochondrial disease. MRT involves the combination of nuclear DNA from the egg of the carrier mother and the cytoplasm from an oocyte donor, which contains healthy mitochondria. While MRT was approved for use in the UK in 2015, the ban on congressional funding for research on 'heritable genetic modification' has made MRT unavailable within the US borders. This survey-based study aimed to describe genetic counselors' experience, knowledge, and opinions about MRT. Additionally, we also assessed whether genetic counselors' comfort discussing MRT with patients, and feelings about clinical use of MRT in the United States changed after providing information about MRT compared with baseline. Responses were received from 139 genetic counselors in North America. Findings indicate low awareness and knowledge about MRT among participants. However, more participants expressed comfort with discussing MRT with patients and more participants were able to form opinions about statements about MRT after they were provided with information about MRT. This study is the first to assess genetic counselors' opinions toward MRT and suggests the need for more education about novel technologies such as MRT among genetic counselors.
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Affiliation(s)
| | - Melanie F Myers
- Divison of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.,College of Medicine, University of Cincinnati, Cincinnati, OH, USA
| | - Taosheng Huang
- Divison of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.,College of Medicine, University of Cincinnati, Cincinnati, OH, USA
| | - Jesse Slone
- Divison of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Valentina Pilipenko
- Divison of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Julianne E Hartmann
- Divison of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
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8
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Set KK, Sen K, Huq AHM, Agarwal R. Mitochondrial Disorders of the Nervous System: A Review. Clin Pediatr (Phila) 2019; 58:381-394. [PMID: 30607979 DOI: 10.1177/0009922818821890] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Kallol K Set
- 1 Dayton Children's Hospital, Dayton, OH, USA.,2 Wright State University Boonshoft School of Medicine, Dayton, OH, USA
| | - Kuntal Sen
- 3 Children's Hospital of Michigan, Detroit, MI, USA.,4 Wayne State University School of Medicine, Detroit, MI, USA
| | - A H M Huq
- 3 Children's Hospital of Michigan, Detroit, MI, USA.,4 Wayne State University School of Medicine, Detroit, MI, USA
| | - Rajkumar Agarwal
- 1 Dayton Children's Hospital, Dayton, OH, USA.,2 Wright State University Boonshoft School of Medicine, Dayton, OH, USA
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9
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Alfadhel M, Babiker A. Inborn errors of metabolism associated with hyperglycaemic ketoacidosis and diabetes mellitus: narrative review. Sudan J Paediatr 2018; 18:10-23. [PMID: 30166758 DOI: 10.24911/sjp.2018.1.3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Inborn errors of metabolism (IEM) are heterogeneous group of disorders that might present in the clinics or emergency departments in different phenotypes, and one of these is a diabetes scenario. Diabetes is the most common endocrine disorder among children. The mechanism of how IEM could lead to diabetes is unclear; however, the postulated pathogenesis consists of three mechanisms: 1) accumulation of toxic substance in the gland, ruining structure and normal functionality, 2) disturbing energy availability required for hormone synthesis and 3) defect of complex molecules. The differential diagnosis of IEM associated with hyperglycaemic ketoacidosis and diabetes include: organic acidemias specifically propionic acidemia, methylmalonic acidemia, isovaleric acidemia, hereditary hemochromatosis, aceruloplasminemia, holocarboxylase synthetase deficiency, β-ketothiolase deficiency and finally, cystinosis, Rogers syndrome (thiamine-responsive megaloblastic anaemia) and congenital disorders of glycosylation type Ia. Clinical approach will help in ready diagnosis and treatment for IEM disorders in early detection of diabetes. In this review, we will discuss the differential diagnosis, clinical features and diagnostic approaches of IEM presenting as hyperglycaemic ketoacidosis and diabetes.
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Affiliation(s)
- Majid Alfadhel
- Genetics Division, Department of Paediatrics, King Abdullah Specialized Children's Hospital, Riyadh, Saudi Arabia.,King Abdullah International Medical Research Centre and King Saud bin Abdulaziz University for Health Sciences, Ministry of National Guard-Health Affairs, King Abdulaziz Medical City, Riyadh, Saudi Arabia
| | - Amir Babiker
- King Abdullah International Medical Research Centre and King Saud bin Abdulaziz University for Health Sciences, Ministry of National Guard-Health Affairs, King Abdulaziz Medical City, Riyadh, Saudi Arabia.,Endocrinology Division, Department of Paediatrics, King Abdullah Specialized Children's Hospital, Riyadh, Saudi Arabia
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10
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Poulton J, Finsterer J, Yu-Wai-Man P. Genetic Counselling for Maternally Inherited Mitochondrial Disorders. Mol Diagn Ther 2018; 21:419-429. [PMID: 28536827 DOI: 10.1007/s40291-017-0279-7] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The aim of this review was to provide an evidence-based approach to frequently asked questions relating to the risk of transmitting a maternally inherited mitochondrial disorder (MID). We do not address disorders linked with disturbed mitochondrial DNA (mtDNA) maintenance, causing mtDNA depletion or multiple mtDNA deletions, as these are autosomally inherited. The review addresses questions regarding prognosis, recurrence risks and the strategies available to prevent disease transmission. The clinical and genetic complexity of maternally inherited MIDs represent a major challenge for patients, their relatives and health professionals. Since many of the genetic and pathophysiological aspects of MIDs remain unknown, counselling of affected patients and at-risk family members remains difficult. MtDNA mutations are maternally transmitted or, more rarely, they are sporadic, occurring de novo (~25%). Females carrying homoplasmic mtDNA mutations will transmit the mutant species to all of their offspring, who may or may not exhibit a similar phenotype depending on modifying, secondary factors. Females carrying heteroplasmic mtDNA mutations will transmit a variable amount of mutant mtDNA to their offspring, which can result in considerable phenotypic heterogeneity among siblings. The majority of mtDNA rearrangements, such as single large-scale deletions, are sporadic, but there is a small risk of recurrence (~4%) among the offspring of affected women. The range and suitability of reproductive choices for prospective mothers is a complex area of mitochondrial medicine that needs to be managed by experienced healthcare professionals as part of a multidisciplinary team. Genetic counselling is facilitated by the identification of the underlying causative genetic defect. To provide more precise genetic counselling, further research is needed to clarify the secondary factors that account for the variable penetrance and the often marked differential expressivity of pathogenic mtDNA mutations both within and between families.
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Affiliation(s)
- Joanna Poulton
- Nuffield Department of Obstetrics and Gynaecology, University of Oxford, Oxford, UK
| | - Josef Finsterer
- Krankenanstalt Rudolfstiftung, Postfach 20, 1180, Vienna, Austria.
| | - Patrick Yu-Wai-Man
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK.,Newcastle Eye Centre, Royal Victoria Infirmary, Newcastle upon Tyne, UK.,NIHR Biomedical Research Centre, Moorfields Eye Hospital and UCL Institute of Ophthalmology, London, UK.,Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, UK
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11
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Bianco B, Montagna E. The advances and new technologies for the study of mitochondrial diseases. EINSTEIN-SAO PAULO 2017; 14:291-3. [PMID: 27462900 PMCID: PMC4943364 DOI: 10.1590/s1679-45082016md3561] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 12/21/2015] [Indexed: 11/29/2022] Open
Abstract
Genetic mitochondrial disorders are responsible for the most common inborn errors of metabolism, caused by mutations in either nuclear genes or in mitochondrial DNA. This article presents the prokaryotic origin of the organelle and the relation between nuclear and mitochondrial genomes, as well as current evolutionary models for such mechanisms. It also addresses the structure of mitochondrial genes, their expression pattern, clinical features of gene defects, risk of transmission and current techniques to avoid these events in assisted human reproduction. Finally, it discusses the ethical implications of these possibilities.
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Affiliation(s)
- Bianca Bianco
- Faculdade de Medicina do ABC, Santo André, SP, Brazil
| | - Erik Montagna
- Faculdade de Medicina do ABC, Santo André, SP, Brazil
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12
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Krieg E, Calderwood L, Campion M, Krepkovich KE. Confirmed versus suspected: The social significance of a genetic or non-genetic diagnosis of mitochondrial disease. Mitochondrion 2016; 28:60-6. [PMID: 27017995 DOI: 10.1016/j.mito.2016.03.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2015] [Revised: 02/02/2016] [Accepted: 03/23/2016] [Indexed: 01/29/2023]
Abstract
This study assessed attitudes and beliefs regarding the importance of a genetic versus non-genetic diagnosis within the mitochondrial disease community. Survey respondents were categorized into two groups - those with a genetic diagnosis, and those with a non-genetic diagnosis of mitochondrial disease. We found that while both groups perceive problems with the support available to adult mitochondrial disease patients, the non-genetic group experiences less medical and social support due to lack of a definitive diagnosis. Understanding the efficacy of existing resources for mitochondrial disease sub-groups will allow for the development or improvement of resources designed to meet patient needs.
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Affiliation(s)
- Elizabeth Krieg
- Boston University School of Medicine, Genetic Counseling Program, Boston, USA.
| | - Laurel Calderwood
- Boston University School of Medicine, Genetic Counseling Program, Boston, USA
| | - MaryAnn Campion
- Boston University School of Medicine, Genetic Counseling Program, Boston, USA
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13
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Otten ABC, Smeets HJM. Evolutionary defined role of the mitochondrial DNA in fertility, disease and ageing. Hum Reprod Update 2015; 21:671-89. [PMID: 25976758 DOI: 10.1093/humupd/dmv024] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Accepted: 04/22/2015] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND The endosymbiosis of an alpha-proteobacterium and a eubacterium a billion years ago paved the way for multicellularity and enabled eukaryotes to flourish. The selective advantage for the host was the acquired ability to generate large amounts of intracellular hydrogen-dependent adenosine triphosphate. The price was increased reactive oxygen species (ROS) inside the eukaryotic cell, causing high mutation rates of the mitochondrial DNA (mtDNA). According to the Muller's ratchet theory, this accumulation of mutations in asexually transmitted mtDNA would ultimately lead to reduced reproductive fitness and eventually extinction. However, mitochondria have persisted over the course of evolution, initially due to a rapid, extreme evolutionary reduction of the mtDNA content. After the phylogenetic divergence of eukaryotes into animals, fungi and plants, differences in evolution of the mtDNA occurred with different adaptations for coping with the mutation burden within these clades. As a result, mitochondrial evolutionary mechanisms have had a profound effect on human adaptation, fertility, healthy reproduction, mtDNA disease manifestation and transmission and ageing. An understanding of these mechanisms might elucidate novel approaches for treatment and prevention of mtDNA disease. METHODS The scientific literature was investigated to determine how mtDNA evolved in animals, plants and fungi. Furthermore, the different mechanisms of mtDNA inheritance and of balancing Muller's ratchet in these species were summarized together with the consequences of these mechanisms for human health and reproduction. RESULTS Animal, plant and fungal mtDNA have evolved differently. Animals have compact genomes, little recombination, a stable number of genes and a high mtDNA copy number, whereas plants have larger genomes with variable gene counts, a low mtDNA copy number and many recombination events. Fungal mtDNA is somewhere in between. In plants, the mtDNA mutation rate is kept low by effective ROS defence and efficient recombination-mediated mtDNA repair. In animal mtDNA, these mechanisms are not or less well-developed and the detrimental mutagenesis events are controlled by a high mtDNA copy number in combination with a genetic bottleneck and purifying selection during transmission. The mtDNA mutation rates in animals are higher than in plants, which allow mobile animals to adapt more rapidly to various environmental conditions in terms of energy production, whereas static plants do not have this need. Although at the level of the species, these mechanisms have been extremely successful, they can have adverse effects for the individual, resulting, in humans, in severe or unpredictably segregating mtDNA diseases, as well as fertility problems and unhealthy ageing. CONCLUSIONS Understanding the forces and processes that underlie mtDNA evolution among different species increases our knowledge on the detrimental consequences that individuals can have from these evolutionary end-points. Alternative outcomes in animals, fungi and plants will lead to a better understanding of the inheritance of mtDNA disorders and mtDNA-related fertility problems. These will allow the development of options to ameliorate, cure and/or prevent mtDNA diseases and mtDNA-related fertility problems.
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Affiliation(s)
- Auke B C Otten
- Department of Clinical Genetics, Unit Clinical Genomics, Maastricht University Medical Centre, PO box 616 (box 16), 6200 MD Maastricht, The Netherlands School for Oncology and Developmental Biology (GROW), Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Hubert J M Smeets
- Department of Clinical Genetics, Unit Clinical Genomics, Maastricht University Medical Centre, PO box 616 (box 16), 6200 MD Maastricht, The Netherlands School for Oncology and Developmental Biology (GROW), Maastricht University Medical Centre, Maastricht, The Netherlands
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Platt J, Cox R, Enns GM. Points to consider in the clinical use of NGS panels for mitochondrial disease: an analysis of gene inclusion and consent forms. J Genet Couns 2014; 23:594-603. [PMID: 24399097 DOI: 10.1007/s10897-013-9683-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Accepted: 12/12/2013] [Indexed: 12/21/2022]
Abstract
Mitochondrial next generation sequencing (NGS) panels offer single-step analysis of the numerous nuclear genes involved in the structure, function, and maintenance of mitochondria. However, the complexities of mitochondrial biology and genetics raise points for consideration in clinical use of these tests. To understand the current status of mitochondrial genetic testing, we assessed the gene offerings and consent forms of mitochondrial NGS panels available from seven US-based clinical laboratories. The NGS panels varied markedly in number of genes (101-1204 genes), and the proportion of genes causing "classic" mitochondrial diseases and their phenocopies ranged widely between labs (18 %-94 % of panel contents). All panels included genes not associated with classic mitochondrial diseases (6 %-28 % of panel contents), including genes causing adult-onset neurodegenerative disorders, cancer predisposition, and other genetic syndromes or inborn errors of metabolism. Five of the panels included genes that are not listed in OMIM to be associated with a disease phenotype (5 %-49 % of panel contents). None of the consent documents reviewed had options for patient preference regarding receipt of incidental findings. These findings raise points of discussion applicable to mitochondrial diagnostics, but also to the larger arenas of exome and genome sequencing, including the need to consider the boundaries between clinical and research testing, the necessity of appropriate informed consent, and the responsibilities of clinical laboratories and clinicians. Based on these findings, we recommend careful evaluation by laboratories of the genes offered on NGS panels, clear communication of the predicted phenotypes, and revised consent forms to allow patients to make choices about receiving incidental findings. We hope that our analysis and recommendations will help to maximize the considerable clinical utility of NGS panels for the diagnosis of mitochondrial disease.
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Affiliation(s)
- Julia Platt
- Department of Pediatrics, Lucile Packard Children's Hospital, Stanford University, 300 Pasteur Drive, H-315, Stanford, CA, 94305, USA,
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15
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Liang C, Ahmad K, Sue CM. The broadening spectrum of mitochondrial disease: shifts in the diagnostic paradigm. Biochim Biophys Acta Gen Subj 2013; 1840:1360-7. [PMID: 24239706 DOI: 10.1016/j.bbagen.2013.10.040] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Revised: 10/21/2013] [Accepted: 10/26/2013] [Indexed: 01/08/2023]
Abstract
BACKGROUND The diagnosis of mitochondrial disease requires a complex synthesis of clinical, biochemical, histological, and genetic investigations. An expanding number of mitochondrial diseases are being recognized, despite their phenotypic diversity, largely due to improvements in methods to detect mutations in affected individuals and the discovery of genes contributing to mitochondrial function. Improved understanding of the investigational pitfalls and the development of new laboratory methodologies that lead to a molecular diagnosis have necessitated the field to rapidly adopt changes to its diagnostic approach. SCOPE OF REVIEW We review the clinical, investigational and genetic challenges that have resulted in shifts to the way we define and diagnose mitochondrial disease. Incorporation of changes, including the use of fibroblast growth factor 21 (FGF-21) and next generation sequencing techniques, may allow affected patients access to earlier molecular diagnosis and management. MAJOR CONCLUSIONS There have been important shifts in the diagnostic paradigm for mitochondrial disease. Diagnosis of mitochondrial disease is no longer reliant on muscle biopsy alone, but should include clinical assessment accompanied by the use of serological biomarkers and genetic analysis. Because affected patients will be defined on a molecular basis, oligosymptomatic mutation carriers should be included in the spectrum of mitochondrial disease. Use of new techniques such as the measurement of serum FGF-21 levels and next-generation-sequencing protocols should simplify the diagnosis of mitochondrial disease. GENERAL SIGNIFICANCE Improvements in the diagnostic pathway for mitochondrial disease will result in earlier, cheaper and more accurate methods to identify patients with mitochondrial disease. This article is part of a Special Issue entitled Frontiers of Mitochondrial Research.
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Affiliation(s)
- Christina Liang
- Department of Neurology, Royal North Shore Hospital, St. Leonards, New South Wales 2065, Australia
| | - Kate Ahmad
- Department of Neurology, Royal North Shore Hospital, St. Leonards, New South Wales 2065, Australia
| | - Carolyn M Sue
- Department of Neurology, Royal North Shore Hospital, St. Leonards, New South Wales 2065, Australia; Department of Neurogenetics, Kolling Institute of Medical Research, Royal North Shore Hospital and the University of Sydney, St. Leonards, New South Wales 2065, Australia.
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Fair allocation of health-care resources: finding a model that does not disenfranchise users of genetic services. A commentary on Rogowski et al.... Eur J Hum Genet 2013; 22:1-2. [PMID: 23921538 DOI: 10.1038/ejhg.2013.170] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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