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Matsumoto S, Uchiumi T, Noda N, Ueyanagi Y, Hotta T, Kang D. Droplet digital polymerase chain reaction to measure heteroplasmic m.3243A>G mitochondrial mutations. Lab Med 2024; 55:227-233. [PMID: 37478467 PMCID: PMC10920975 DOI: 10.1093/labmed/lmad063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/23/2023] Open
Abstract
OBJECTIVE Different mitochondrial DNA genotypes can coexist in a cell population as well as in a single cell, a condition known as heteroplasmy. Here, we accurately determined the heteroplasmy levels of the m.3243A>G mutation, which is the most frequently identified mutation in patients with mitochondrial diseases, using droplet digital polymerase chain reaction (ddPCR). METHODS The m.3243A>G heteroplasmy levels in artificial heteroplasmy controls mixed with various proportions of wild-type and mutant plasmids were measured using ddPCR, PCR-restriction fragment length polymorphism, and Sanger sequencing. The m.3243A>G heteroplasmy levels in DNA, extracted from the peripheral blood of patients with suspected mitochondrial disease and healthy subjects, were determined using ddPCR. RESULTS The accuracy of the ddPCR method was high. The lower limit of detection was 0.1%, which indicated its higher sensitivity compared with other methods. The m.3243A>G heteroplasmy levels in peripheral blood, measured using ddPCR, correlated inversely with age at the time of analysis. The m.3243A>G mutation may be overlooked in the peripheral blood-derived DNA of elderly people, as patients >60 years of age have heteroplasmy levels <10%, which is difficult to detect using methods other than the highly sensitive ddPCR. CONCLUSION ddPCR may be considered an accurate and sensitive method for measuring m.3243 A>G heteroplasmy levels of mitochondrial DNA.
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Affiliation(s)
- Shinya Matsumoto
- Department of Clinical Chemistry and Laboratory Medicine, Kyushu University Hospital, Fukuoka, Japan
| | - Takeshi Uchiumi
- Department of Clinical Chemistry and Laboratory Medicine, Kyushu University Hospital, Fukuoka, Japan
- Department of Clinical Chemistry and Laboratory Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
- Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Nozomi Noda
- Department of Clinical Chemistry and Laboratory Medicine, Kyushu University Hospital, Fukuoka, Japan
| | - Yasushi Ueyanagi
- Department of Clinical Chemistry and Laboratory Medicine, Kyushu University Hospital, Fukuoka, Japan
| | - Taeko Hotta
- Department of Clinical Chemistry and Laboratory Medicine, Kyushu University Hospital, Fukuoka, Japan
| | - Dongchon Kang
- Department of Clinical Chemistry and Laboratory Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
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2
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Cox BC, Pearson JY, Mandrekar J, Gavrilova RH. The clinical spectrum of MELAS and associated disorders across ages: a retrospective cohort study. Front Neurol 2023; 14:1298569. [PMID: 38156086 PMCID: PMC10753009 DOI: 10.3389/fneur.2023.1298569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 11/20/2023] [Indexed: 12/30/2023] Open
Abstract
Objective Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) is a severe multisystemic disease, although some have a milder phenotype. We aimed to evaluate the clinical spectrum of this disease from MELAS patients to asymptomatic carriers and identify predictors of severity. Methods We reviewed 81 patients, who had MELAS or had positive genetics without meeting clinical criteria. Patients who met criteria including lactic acidosis, encephalomyopathy, and stroke-like episodes (SLE) were categorized as MELAS, symptomatic non-MELAS, and asymptomatic. MELAS was further categorized as "standard-onset" if the first stroke-like episode (SLE) occurred before age 40 or "late-onset." Results Eighty-one patients were included: 42 MELAS (13 late-onset), 30 symptomatic non-MELAS, and 9 asymptomatic. MELAS patients had lower BMI at onset (mean 18.6 vs. 25.1 asymptomatic and 22.0 symptomatic non-MELAS, p < 0.05). There was a trend toward higher serum heteroplasmy in MELAS compared to symptomatic non-MELAS and asymptomatic (means 39.3, 29.3, and 21.8% p = 0.09). Symptomatic non-MELAS had more sensorineural hearing loss as first presenting symptom (51.6% vs. 24.4%, p < 0.05). MELAS had higher prevalence of seizures (88.1% vs. 16.7%, p < 0.05) and shorter survival from onset to death (50% mortality at 25 years vs. 10%, p < 0.05). Late-onset MELAS had longer disease duration from first symptom to first SLE (mean 16.6 vs. 9.3 yrs) and also lived longer (mean age at death 62 vs. 30). Standard-onset MELAS had more neurologic involvement at onset than late-onset (51.7% vs. 15.4%). Late-onset patients had more prevalent diabetes (69.2% vs. 13.8%) and nephropathy (53.8% vs. 10.3%). Patients with late-onset MELAS also had more organ systems involved (mean 4.1 vs. 2.7, p < 0.05). There was a trend toward higher heteroplasmy levels in standard-onset (mean 44.8% vs. 25.3%, p = 0.18). Discussion Our study highlights the spectrum of MELAS. The lower BMI in MELAS at presentation as well as higher rates of sensorineural hearing loss as initial symptom in symptomatic non-MELAS may be useful clinical markers. While many patients present before age 40 with SLE, some can present with SLE later in life. Standard onset MELAS is more likely to present with neurologic symptoms. Late-onset is more likely to suffer diabetes or nephropathy and have more organ systems involved.
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Affiliation(s)
- Benjamin C. Cox
- Department of Neurology, College of Medicine, Mayo Clinic, Rochester, MN, United States
| | - Jennifer Y. Pearson
- Department of Neurology, College of Medicine, Mayo Clinic, Rochester, MN, United States
| | - Jay Mandrekar
- Department of Health Sciences Research, College of Medicine, Mayo Clinic, Rochester, MN, United States
| | - Ralitza H. Gavrilova
- Department of Neurology, College of Medicine, Mayo Clinic, Rochester, MN, United States
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Hong S, Kim S, Kim K, Lee H. Clinical Approaches for Mitochondrial Diseases. Cells 2023; 12:2494. [PMID: 37887337 PMCID: PMC10605124 DOI: 10.3390/cells12202494] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 10/18/2023] [Accepted: 10/19/2023] [Indexed: 10/28/2023] Open
Abstract
Mitochondria are subcontractors dedicated to energy production within cells. In human mitochondria, almost all mitochondrial proteins originate from the nucleus, except for 13 subunit proteins that make up the crucial system required to perform 'oxidative phosphorylation (OX PHOS)', which are expressed by the mitochondria's self-contained DNA. Mitochondrial DNA (mtDNA) also encodes 2 rRNA and 22 tRNA species. Mitochondrial DNA replicates almost autonomously, independent of the nucleus, and its heredity follows a non-Mendelian pattern, exclusively passing from mother to children. Numerous studies have identified mtDNA mutation-related genetic diseases. The consequences of various types of mtDNA mutations, including insertions, deletions, and single base-pair mutations, are studied to reveal their relationship to mitochondrial diseases. Most mitochondrial diseases exhibit fatal symptoms, leading to ongoing therapeutic research with diverse approaches such as stimulating the defective OXPHOS system, mitochondrial replacement, and allotropic expression of defective enzymes. This review provides detailed information on two topics: (1) mitochondrial diseases caused by mtDNA mutations, and (2) the mechanisms of current treatments for mitochondrial diseases and clinical trials.
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Affiliation(s)
- Seongho Hong
- Korea Mouse Phenotyping Center, Seoul National University, Seoul 08826, Republic of Korea;
- Department of Medicine, Korea University College of Medicine, Seoul 02708, Republic of Korea
| | - Sanghun Kim
- Laboratory Animal Resource and Research Center, Korea Research Institute of Bioscience and Biotechnology, Cheongju 28116, Republic of Korea;
- College of Veterinary Medicine and Research Institute of Veterinary Medicine, Chungbuk National University, Cheongju 28644, Republic of Korea
| | - Kyoungmi Kim
- Department of Biomedical Sciences, Korea University College of Medicine, Seoul 02841, Republic of Korea
- Department of Physiology, Korea University College of Medicine, Seoul 02841, Republic of Korea
| | - Hyunji Lee
- Department of Medicine, Korea University College of Medicine, Seoul 02708, Republic of Korea
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Wang A, Zhao J, Zhao Y, Yan Y. Late-onset MELAS syndrome in a 46-year-old man with initial symptom of chest tightness: a case report. Eur Heart J Case Rep 2023; 7:ytad441. [PMID: 37767231 PMCID: PMC10519872 DOI: 10.1093/ehjcr/ytad441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Revised: 08/14/2023] [Accepted: 08/30/2023] [Indexed: 09/29/2023]
Abstract
Background Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-like episodes (MELAS) syndrome is a rare mitochondrial disorder caused by mutations in mitochondrial DNA, resulting in impaired energy production and affecting multiple organs. We present a suspected MELAS syndrome case with the initial symptom of chest tightness. Case summary A 46-year-old man sought medical attention due to progressively worsening chest tightness during physical activity. He had been receiving treatment for type 2 diabetes for 15 years. One year ago, he presented with symptoms of hearing impairment. Transthoracic echocardiography revealed increased thickness of the left ventricular wall. Serum protein electrophoresis showed no evidence of light-chain amyloidosis, and the 99mTc-3,3-diphosphono-1,2-propanodicarboxylic acid scan showed no definite uptake in the heart muscle. The patient's head magnetic resonance imaging (MRI) indicated lacunar infarcts. The lactate threshold test was positive. The biopsy of the skeletal muscle showed broken red fibre infiltration on modified Gomori trichrome staining, and electron microscopy revealed signs of mitochondrial cardiomyopathy, including mild mitochondrial swelling, lipid accumulation, and myofibril damage. A whole-exome genetic test was used to detect the m.3243A>G mutation in the MT-TL1 gene. Based on these findings, MELAS syndrome was the most probable diagnosis. Discussion The patient presented with chest tightness in adulthood, without any accompanying psychoneurological symptoms. However, the patient presented with other symptoms, including diabetes mellitus, hearing loss, abnormal lactate levels, ischaemic lesions on head MRI, and left ventricular hypertrophy. By identifying a mutation in the MT-TL1 gene and conducting a muscle biopsy, the diagnosis of MELAS syndrome was definitively confirmed.
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Affiliation(s)
- Ai Wang
- Department of Cardiology, Zhongshan Hospital, Fudan University, 180 Fenglin Road, Shanghai 200032, China
| | - Ji Zhao
- Department of Cardiology, Zhongshan Hospital, Fudan University, 180 Fenglin Road, Shanghai 200032, China
| | - Yun Zhao
- Department of Cardiovascular Surgery, Shanghai Geriatric Medical Center, 2560 Chunshen Road, Shanghai 201104, China
| | - Yan Yan
- Department of Cardiology, Zhongshan Hospital, Fudan University, 180 Fenglin Road, Shanghai 200032, China
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Selvam P, Jain A, Abbott J, Ahuja AS, Cheema A, Bruno KA, Atwal H, Forghani I, Caulfield T, Atwal PS. Molecular Modeling and Phenotypic Description of a Patient with a Novel Exonic Deletion of GALNS with Resultant Morquio Syndrome with Two Successful Pregnancies. Mol Syndromol 2022; 13:282-289. [PMID: 36158053 PMCID: PMC9421684 DOI: 10.1159/000519326] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Accepted: 08/30/2021] [Indexed: 01/03/2023] Open
Abstract
In this report, we describe phenotypic features of a patient with mucopolysaccharidosis type IVA (Morquio syndrome) harboring a novel exon 1 deletion in GALNS with enzymatic confirmation consistent with Morquio syndrome. To our knowledge, this is the first reported case of this variant. Additionally, we protein modelled wild-type GALNS and the pathogenic variant with an exon 1 deletion for comparative analysis using statistical mechanics methods described herein. We demonstrate that, even when the protein is translated, the mutation would affect protein stability and function via homodimer interaction modifications. Lastly, given the patient's 2 successful pregnancies, data about the management of pregnancies in mucopolysaccharidoses are reviewed, and we discuss the management of pregnancy in patients with Morquio syndrome.
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Affiliation(s)
| | | | | | - Abhimanyu S. Ahuja
- Charles E. Schmidt College of Medicine, Florida Atlantic University, Boca Raton, Florida, USA
| | | | | | | | - Irman Forghani
- Dr. John T. Macdonald Foundation Department of Human Genetics, Miller School of Medicine, University of Miami, Miami, Florida, USA
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Stefanetti R, Ng Y, Errington L, Blain A, McFarland R, Gorman GS. L-arginine in Mitochondrial Encephalopathy, Lactic Acidosis, and Stroke-like Episodes: A Systematic Review. Neurology 2022; 98:e2318-e2328. [PMID: 35428733 PMCID: PMC9202525 DOI: 10.1212/wnl.0000000000200299] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Accepted: 02/15/2022] [Indexed: 12/02/2022] Open
Abstract
Background and Objectives Stroke management in the context of primary mitochondrial disease is clinically challenging, and the best treatment options for patients with stroke-like episodes remain uncertain. We sought to perform a systematic review of the safety and efficacy of l-arginine use in the acute and prophylactic management of stroke-like episodes in patients with mitochondrial disease. Methods The systematic review was registered in PROSPERO (CRD42020181230). We searched 6 databases from inception to January 15, 2021: MEDLINE, Embase, Scopus, Web of Science, CINAHL, and ClinicalTrials.gov. Original articles and registered trials available, in English, reporting l-arginine use in the acute or prophylactic management of stroke-like episodes in patients with genetically confirmed mitochondrial disease were eligible for inclusion. Data on safety and treatment response were extracted and summarized by multiple observers. Risk of bias was assessed by the methodologic quality of case reports, case series, and a risk-of-bias checklist for nonrandomized studies. Quality of evidence was synthesized with the Oxford Centre for Evidence-Based Medicine Levels of Evidence and Grade of Recommendations. The predetermined main outcome measures were clinical response to l-arginine treatment, adverse events, withdrawals, and deaths (on treatment and/or during follow-up), as defined by the author. Results Thirty-seven articles met inclusion criteria (0 randomized controlled trials; 3 open-label; 1 retrospective cohort; 33 case reports/case series) (N = 91 patients; 86% m.3243A>G). In the case reports, 54% of patients reported a positive clinical response to acute l-arginine, of which 40% were concomitantly treated with antiepileptic drugs. Improved headache at 24 hours was the greatest reported benefit in response to IV l-arginine in the open-label trials (31 of 39, 79%). In 15 of 48 patients (31%) who positively responded to prophylactic l-arginine, antiepileptic drugs were either used (7 of 15) or unreported (8 of 15). Moderate adverse events were reported in the follow-up of both IV and oral l-arginine treatment, and 11 patients (12%) died during follow-up or while on prophylactic treatment. Discussion The available evidence is of poor methodologic quality and classified as Level 5. IV and oral l-arginine confers no demonstrable clinical benefit in either the acute or prophylactic treatment of mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes, with more robust controlled trials required to assess its efficacy and safety profile.
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Fan HC, Lee HF, Yue CT, Chi CS. Clinical Characteristics of Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-Like Episodes. Life (Basel) 2021; 11:life11111111. [PMID: 34832987 PMCID: PMC8617702 DOI: 10.3390/life11111111] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 10/11/2021] [Accepted: 10/16/2021] [Indexed: 12/12/2022] Open
Abstract
Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome, a maternally inherited mitochondrial disorder, is characterized by its genetic, biochemical and clinical complexity. The most common mutation associated with MELAS syndrome is the mtDNA A3243G mutation in the MT-TL1 gene encoding the mitochondrial tRNA-leu(UUR), which results in impaired mitochondrial translation and protein synthesis involving the mitochondrial electron transport chain complex subunits, leading to impaired mitochondrial energy production. Angiopathy, either alone or in combination with nitric oxide (NO) deficiency, further contributes to multi-organ involvement in MELAS syndrome. Management for MELAS syndrome is amostly symptomatic multidisciplinary approach. In this article, we review the clinical presentations, pathogenic mechanisms and options for management of MELAS syndrome.
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Affiliation(s)
- Hueng-Chuen Fan
- Department of Pediatrics, Tungs’ Taichung Metroharbor Hospital, Wuchi, Taichung 435, Taiwan; (H.-C.F.); (C.-T.Y.)
- Department of Medical Research, Tungs’ Taichung Metroharbor Hospital, Wuchi, Taichung 435, Taiwan
- Department of Rehabilitation, Jen-Teh Junior College of Medicine, Nursing and Management, Miaoli 356, Taiwan
- Department of Life Sciences, Agricultural Biotechnology Center, National Chung Hsing University, Taichung 402, Taiwan
| | - Hsiu-Fen Lee
- Department of Pediatrics, Taichung Veterans General Hospital, Taichung 407, Taiwan;
| | - Chen-Tang Yue
- Department of Pediatrics, Tungs’ Taichung Metroharbor Hospital, Wuchi, Taichung 435, Taiwan; (H.-C.F.); (C.-T.Y.)
| | - Ching-Shiang Chi
- Department of Pediatrics, Tungs’ Taichung Metroharbor Hospital, Wuchi, Taichung 435, Taiwan; (H.-C.F.); (C.-T.Y.)
- Correspondence: ; Tel.: +886-4-26581919-4301
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Atwal PS, Midei M, Adams D, Fay A, Heerinckx F, Milner P. The infantile neuroaxonal dystrophy rating scale (INAD-RS). Orphanet J Rare Dis 2020; 15:195. [PMID: 32727524 PMCID: PMC7392694 DOI: 10.1186/s13023-020-01479-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 07/21/2020] [Indexed: 11/10/2022] Open
Abstract
Background INAD is an autosomal recessive neurogenetic disorder caused by biallelic pathogenic variants in PLA2G6. The downstream enzyme, iPLA2, plays a critical role in cell membrane homeostasis by helping to regulate levels of phospholipids. The clinical presentation occurs between 6 months and 3 years with global developmental regression, hypotonia, and progressive spastic tetraparesis. Progression is often rapid, resulting in severe spasticity, visual impairment, and cognitive decline, with many children not surviving past the first decade of life. To date, no accepted tool for assessing the severity of INAD exists; other commonly used scales (e.g. CHOP-INTEND, Modified Ashworth, Hammersmith Functional Motor Scale) do not accurately gauge the current severity of INAD, nor are they sensitive/specific enough to monitor disease progression. Finally, these other scales are not appropriate, because they do not address the combination of CNS, peripheral nerve, and visual pathology that occurs in children with INAD. Methods We have developed and validated a structured neurological examination for INAD (scored out of 80). The examination includes six main categories of pediatric developmental evaluation: 1) gross motor-and-truncal-stability skills, 2) fine motor skills, 3) bulbar function, 4) ocular function, 5) temporo-frontal function, and, 6) Functional evaluation of the autonomic nervous system. A cohort of patients diagnosed with INAD were followed prospectively to validate the score against disease severity and disease progression. Results We show significant correlation between the total neurological assessment score and months since symptom onset with a statistically significant (p = 6.7 × 10− 07) correlation between assessment score and disease onset. As hypothesized, the coefficient of months-since-symptom-onset is strongly negative, indicating a negative correlation between total score and months since symptom onset. Conclusion We have developed and validated a novel neurological assessment score in INAD that demonstrates strong correlation with disease severity and disease progression.
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Affiliation(s)
| | | | - Darius Adams
- Atlantic Medical Group, Morris Township, NJ, USA
| | - Alexander Fay
- University of California San Francisco (UCSF), San Francisco, CA, USA
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Late-onset Mitochondrial Encephalopathy, Lactic Acidosis, and Stroke-like Episodes Presenting With Auditory Agnosia. Neurologist 2019; 24:90-92. [PMID: 31045719 DOI: 10.1097/nrl.0000000000000229] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
INTRODUCTION Mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) is a multisystemic mitochondrial disorder that usually presents in childhood. Patients can have a wide array of neurological symptoms when presenting with stroke-like episodes, and imaging characteristics during the episodes can overlap with different neurological disorders. CASE REPORT A 61-year-old woman presented with communication difficulties consistent with auditory agnosia and was found to have bitemporal abnormalities on imaging that first raised the concern for herpes simplex virus encephalitis. Further work-up, in conjunction with the patient's past medical and family history, suggested a mitochondrial disorder. Mitochondrial full genome analysis revealed m.3243A>G variant in the MT-TL1 gene, with 6% heteroplasmy in blood leading to a diagnosis of MELAS. CONCLUSIONS MELAS is a disorder with clinical variability. Neuroimaging studies during stroke-like episodes in MELAS can provide significant clues to the underlying disorder. Although patients typically present in childhood, the first stroke-like episode can occur later in life in some patients, potentially related to a lower heteroplasmy level.
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Veitia RA. How the most common mitochondrial DNA mutation (m.3243A>G) vanishes from leukocytes: a mathematical model. Hum Mol Genet 2019; 27:1565-1571. [PMID: 29474538 DOI: 10.1093/hmg/ddy063] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 02/15/2018] [Indexed: 01/24/2023] Open
Abstract
Mitochondrial diseases may be caused by alterations of the mitochondrial genome. The pathogenic variant m.3243A>G is one of the most frequent causes of mitochondrial disease and the most common mitochondrial DNA mutation. Patients with a variant in mitochondrial DNA can have a mixture of mutated and wild-type genomes (heteroplasmy). In the case of the pathogenic variant m.3243A>G, the degree of heteroplasmy (H) correlates to some extent with the severity of the disease. Several longitudinal studies, where H is measured at two different time-points, have shown an annual decline in leukocyte H values. Thus far, only an exponential decay of H with time has been noted but a mechanistic model is lacking. Here, I describe a deterministic mathematical model that accounts for the decline of H in leukocytes based on selective mechanisms acting at the stem cell level. The 'inverted-sigmoid' model provides estimates of at-birth H levels closer to those observed in post-mitotic tissues, such as skeletal muscle, than the estimates provided by an exponential decay. The new model never leads to predictions of H > 100% and provides a stronger correlation between at-birth H values in leukocytes and the scores of the Newcastle Mitochondrial Disease Scale for Adults, which can be of practical utility. This model could be extended to other mitochondrial DNA disease-causing variants.
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Affiliation(s)
- Reiner A Veitia
- Institut Jacques Monod, Université Paris Diderot, Paris, France
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11
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Mohammad AN, Bruno KA, Hines S, Atwal PS. Type 1 sialidosis presenting with ataxia, seizures and myoclonus with no visual involvement. Mol Genet Metab Rep 2018; 15:11-14. [PMID: 30023283 PMCID: PMC6047061 DOI: 10.1016/j.ymgmr.2017.12.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 12/28/2017] [Accepted: 12/28/2017] [Indexed: 12/14/2022] Open
Abstract
Sialidosis is an autosomal recessive lysosomal storage disease caused by pathogenic variants in NEU1 which encodes lysosomal sialidase (neuraminidase 1). Lysosomal neuraminidase catalyzes the removal of terminal sialic acid molecules from glycolipids, glycoproteins and oligosaccharides. Sialidosis is classified into two types, based on phenotype and age of onset. Patients with the milder type 1 typically present late, usually in the second or third decade, with myoclonus, ataxia and visual defects. Type 2 is more severe and presents earlier with coarse facial features, developmental delay, hepatosplenomegaly and dysostosis multiplex. Presentation and severity of the disease are related to whether lysosomal sialidase is inactive or there is some residual activity. Diagnosis is suspected based on clinical features and increased urinary bound sialic acid excretion and confirmed by genetic testing showing pathogenic variants in NEU1. We report a patient with type 1 sialidosis who presented mainly with ataxia and both generalized and myoclonic seizures but no visual involvement. Whole exome sequencing of the proband detected compound heterozygous likely pathogenic variants (S182G and G227R) in NEU1.
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Affiliation(s)
- Ahmed N. Mohammad
- Dept. of Clinical Genomics, Mayo Clinic, Jacksonville, FL, United States
- Center for Individualized Medicine, Mayo Clinic, Jacksonville, FL, United States
| | - Katelyn A. Bruno
- Dept. of Cardiovascular Diseases, Mayo Clinic, Jacksonville, FL, United States
| | - S. Hines
- Center for Individualized Medicine, Mayo Clinic, Jacksonville, FL, United States
| | - Paldeep S. Atwal
- Dept. of Clinical Genomics, Mayo Clinic, Jacksonville, FL, United States
- Center for Individualized Medicine, Mayo Clinic, Jacksonville, FL, United States
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Goel H, Szczepanczyk K, Mirza FS. Late-Onset Melas with Midd: An Uncommon Age of Presentation. AACE Clin Case Rep 2018. [DOI: 10.4158/ep171955.cr] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Langdahl J, Larsen M, Frost M, Andersen P, Yderstraede K, Vissing J, Dunø M, Thomassen M, Frederiksen A. Lecocytes mutation load declines with age in carriers of the m.3243A>G mutation: A 10-year Prospective Cohort. Clin Genet 2018; 93:925-928. [DOI: 10.1111/cge.13201] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 12/14/2017] [Accepted: 12/15/2017] [Indexed: 01/30/2023]
Affiliation(s)
- J.H. Langdahl
- Department of Clinical Genetics; Odense University Hospital; Odense Denmark
- Institute of Clinical Research; University of Southern Denmark; Odense Denmark
- Department of Endocrinology; Hospital of Southwest Jutland; Esbjerg Denmark
| | - M. Larsen
- Department of Clinical Genetics; Odense University Hospital; Odense Denmark
- Institute of Clinical Research; University of Southern Denmark; Odense Denmark
| | - M. Frost
- Institute of Clinical Research; University of Southern Denmark; Odense Denmark
- Department of Internal Medicine; Kolding Hospital; Kolding Denmark
| | - P.H. Andersen
- Department of Endocrinology; Hospital of Southwest Jutland; Esbjerg Denmark
| | - K.B. Yderstraede
- Department of Endocrinology; Odense University Hospital; Odense Denmark
| | - J. Vissing
- Copenhagen Neuromuscular Center; Rigshospitalet; Copenhagen Denmark
| | - M. Dunø
- Department of Clinical Genetics; Rigshospitalet; Copenhagen Denmark
| | - M. Thomassen
- Department of Clinical Genetics; Odense University Hospital; Odense Denmark
- Institute of Clinical Research; University of Southern Denmark; Odense Denmark
| | - A.L. Frederiksen
- Department of Clinical Genetics; Odense University Hospital; Odense Denmark
- Institute of Clinical Research; University of Southern Denmark; Odense Denmark
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Atwal H, Gass J, Blackburn P, Atwal P. The clinical heterogeneity of late-onset MELAS. Mol Genet Metab Rep 2017; 11:30. [PMID: 28443237 PMCID: PMC5394211 DOI: 10.1016/j.ymgmr.2017.04.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Accepted: 04/08/2017] [Indexed: 11/18/2022] Open
Affiliation(s)
- H.K. Atwal
- Department of Pharmacy, Mayo Clinic, Jacksonville, FL, United States
- Corresponding author.
| | - J. Gass
- Department of Clinical Genomics, Center for Individualized Medicine, Mayo Clinic, Jacksonville, FL, United States
| | - P.R. Blackburn
- Department of Clinical Genomics, Center for Individualized Medicine, Mayo Clinic, Jacksonville, FL, United States
| | - P.S. Atwal
- Department of Clinical Genomics, Center for Individualized Medicine, Mayo Clinic, Jacksonville, FL, United States
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Finsterer J, Zarrouk-Mahjoub S. Low blood heteroplasmy-rate may cause late-onset MELAS. Mol Genet Metab Rep 2017; 10:100. [PMID: 28224084 PMCID: PMC5295506 DOI: 10.1016/j.ymgmr.2017.01.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 01/27/2017] [Indexed: 11/11/2022] Open
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16
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Onset of MELAS due to the m.3243A > G mutation is early if the large phenotypic variability is considered. Mol Genet Metab Rep 2017; 10:23. [PMID: 27995079 PMCID: PMC5156606 DOI: 10.1016/j.ymgmr.2016.12.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 12/02/2016] [Indexed: 11/29/2022] Open
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17
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Gass J, Atwal HK, Atwal PS. Late-onset mitochondrial encephalomyopathy with lactic acid and stroke-like episodes (MELAS), defining symptomology. Mol Genet Metab Rep 2017; 10:51. [PMID: 28116243 PMCID: PMC5233920 DOI: 10.1016/j.ymgmr.2017.01.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Accepted: 01/04/2017] [Indexed: 10/29/2022] Open
Affiliation(s)
- J Gass
- Department of Clinical Genomics, Center for Individualized Medicine, Mayo Clinic, Jacksonville, FL, United States
| | - H K Atwal
- Department of Pharmacy, Mayo Clinic, Jacksonville, FL, United States
| | - P S Atwal
- Department of Clinical Genomics, Center for Individualized Medicine, Mayo Clinic, Jacksonville, FL, United States
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