| 1. |
- Björkman, Kristoffer, et al.
(författare)
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Broad phenotypic variability in patients with complex I deficiency due to mutations in NDUFS1 and NDUFV1.
- 2015
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Ingår i: Mitochondrion. - : Elsevier BV. - 1872-8278 .- 1567-7249. ; 21, s. 33-40
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Tidskriftsartikel (refereegranskat)abstract
- We report clinical, metabolic, genetic and neuroradiological findings in five patients from three different families with isolated complex I deficiency. Genetic analysis revealed mutations in NDUFS1 in three patients and in NDUFV1 in two patients. Four of the mutations are novel and affect amino acid residues that either are invariant among species or conserved in their properties. The presented clinical courses are characterized by leukoencephalopathy or early death and expand the already heterogeneous phenotypic spectrum. A literature review was performed, showing that patients with mutations in NDUFS1 in general have a worse prognosis than patients with mutations in NDUFV1.
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| 2. |
- Björkman, Kristoffer, et al.
(författare)
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Clinical course of patients with single large-scale mtDNA deletions and childhood onset anemia
- 2022
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Ingår i: 14th European Paediatric Neurology Society Congress, Glasgow, UK (ISBN 978-3-00-072065-9).
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Objective: To add to our knowledge of the clinical spectrum of patients with single large-scale mitochondrial DNA (mtDNA) deletion and childhood onset anemia. Methods: Retrospective collection of clinical data from medical records for patients, both living and deceased, with a single large-scale mtDNA deletion from seven mitochondrial disease centers in five countries. Statistical analysis with descriptive methods and Kaplan-Meier survival analysis. Results: Seventeen patients matching the genetic criterium and with anemia onset before six years of age. Exocrine pancreatic insufficiency was only seen in five patients in this group. Multiple organs were involved in all patients, with the most common non-hematologic ones being skeletal muscle, central nervous system, endocrine, eyes, gastrointestinal system, kidneys, hearing, liver and heart. Psychomotor retardation was seen in ten patients, hearing impairment in nine patients, failure to thrive in eight patients. Eight later developed Kearns-Sayre syndrome. Eleven patients were deceased, with a median age at death of 7.5 years. Conclusions: The classically described phenotype of patients with large-scale mtDNA deletions and early onset anemia is Pearson marrow-pancreas syndrome, characterized by sideroblastic anemia and exocrine pancreas dysfunction. Only a minority of our patients fulfill the original criteria of Pearson syndrome though. Involvement of other organs than the pancreas is more common. The clinical course vary, but multi-system impact is the rule and life-expectancy is low. Early onset anemia in patients with large-scale mtDNA deletions is most frequently not associated with exocrine pancreas dysfunction. Better knowledge of the phenotype is helpful for diagnosis and more accurate prognosis.
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| 3. |
- Björkman, Kristoffer, et al.
(författare)
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Genotype-phenotype correlations in patients with complex I deficiency due to mutations in NDUFS1 and NDUFV1
- 2014
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Ingår i: Euromit 2014, 15-19 juni, Tampere, Finland.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Objectives: To study genotype-phenotype correlations in genes encoding complex I electron input module subunits. Materials and methods: We studied five patients with isolated complex I deficiency, three with NDUFS1 mutations and two with NDUFV1 mutations. A literature review of all reported cases of mutations in the affected genes was performed. Results: The literature review revealed pathological mutations in NDUFS1 for 18 patients in 17 families and correspondingly in NDUFV1 for 26 patients in 19 families. Unpublished clinical data for our five patients were added. Our study showed quite variable clinical courses; death before two years of age was seen in 41% of patients while 18% were alive at seven years. There was a significant difference between the NDUFS1 and NDUFV1 groups for clinical onset and life-span. Mutations in NDUFS1 were linked to a worse clinical course with earlier onset and earlier death. Conclusions: Genotype-phenotype correlations in patients with mutations affecting the genes that encode the electron input module of complex I vary, but patients with NDUFS1 mutation tend to have a worse clinical course than patients with NDUFV1 mutation. Identifying the mutations is of importance for accurate prognostic information and genetic counseling.
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| 4. |
- Björkman, Kristoffer, et al.
(författare)
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Phenotypic spectrum and clinical course of single large-scale mitochondrial DNA deletion disease in the paediatric population: a multicentre study.
- 2021
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Ingår i: Journal of Medical Genetics. - : BMJ. - 0022-2593 .- 1468-6244. ; 60:1, s. 65-73
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Tidskriftsartikel (refereegranskat)abstract
- Background Large-scale mitochondrial DNA deletions (LMD) are a common genetic cause of mitochondrial disease and give rise to a wide range of clinical features. Lack of longitudinal data means the natural history remains unclear. This study was undertaken to describe the clinical spectrum in a large cohort of patients with paediatric disease onset. Methods A retrospective multicentre study was performed in patients with clinical onset <16 years of age, diagnosed and followed in seven European mitochondrial disease centres. Results A total of 80 patients were included. The average age at disease onset and at last examination was 10 and 31 years, respectively. The median time from disease onset to death was 11.5 years. Pearson syndrome was present in 21%, Kearns-Sayre syndrome spectrum disorder in 50% and progressive external ophthalmoplegia in 29% of patients. Haematological abnormalities were the hallmark of the disease in preschool children, while the most common presentations in older patients were ptosis and external ophthalmoplegia. Skeletal muscle involvement was found in 65% and exercise intolerance in 25% of the patients. Central nervous system involvement was frequent, with variable presence of ataxia (40%), cognitive involvement (36%) and stroke-like episodes (9%). Other common features were pigmentary retinopathy (46%), short stature (42%), hearing impairment (39%), cardiac disease (39%), diabetes mellitus (25%) and renal disease (19%). Conclusion Our study provides new insights into the phenotypic spectrum of childhood-onset, LMD-associated syndromes. We found a wider spectrum of more prevalent multisystem involvement compared with previous studies, most likely related to a longer time of follow-up.
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| 5. |
- Burda, P, et al.
(författare)
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Characterization and review of MTHFD1 deficiency: four new patients, cellular delineation and response to folic and folinic acid treatment.
- 2015
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Ingår i: Journal of Inherited Metabolic Disease. - : Wiley. - 0141-8955 .- 1573-2665. ; 38:5, s. 863-872
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Tidskriftsartikel (refereegranskat)abstract
- In the folate cycle MTHFD1, encoded by MTHFD1, is a trifunctional enzyme containing 5,10-methylenetetrahydrofolate dehydrogenase, 5,10-methenyltetrahydrofolate cyclohydrolase and 10-formyltetrahydrofolate synthetase activity. To date, only one patient with MTHFD1 deficiency, presenting with hyperhomocysteinemia, megaloblastic anaemia, hemolytic uremic syndrome (HUS) and severe combined immunodeficiency, has been identified (Watkins et al J Med Genet 48:590-2, 2011). We now describe four additional patients from two different families. The second patient presented with hyperhomocysteinemia, megaloblastic anaemia, HUS, microangiopathy and retinopathy; all except the retinopathy resolved after treatment with hydroxocobalamin, betaine and folinic acid. The third patient developed megaloblastic anaemia, infection, autoimmune disease and moderate liver fibrosis but not hyperhomocysteinemia, and was successfully treated with a regime that included and was eventually reduced to folic acid. The other two, elder siblings of the third patient, died at 9weeks of age with megaloblastic anaemia, infection and severe acidosis and had MTFHD1 deficiency diagnosed retrospectively. We identified a missense mutation (c.806C>T, p.Thr296Ile) and a splice site mutation (c.1674G>A) leading to exon skipping in the second patient, while the other three harboured a missense mutation (c.146C>T, p.Ser49Phe) and a premature stop mutation (c.673G>T, p.Glu225*), all of which were novel. Patient fibroblast studies revealed severely reduced methionine formation from [(14)C]-formate, which did not increase in cobalamin supplemented culture medium but was responsive to folic and folinic acid. These additional cases increase the clinical spectrum of this intriguing defect, provide in vitro evidence of disturbed methionine synthesis and substantiate the effectiveness of folic or folinic acid treatment.
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| 6. |
- Darin, Niklas, 1964, et al.
(författare)
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Benign mitochondrial myopathy with exercise intolerance in a large multigeneration family due to a homoplasmic m.3250T>C mutation in MTTL1.
- 2017
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Ingår i: European journal of neurology. - : Wiley. - 1468-1331 .- 1351-5101. ; 24:4, s. 587-593
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Tidskriftsartikel (refereegranskat)abstract
- Most mitochondrial disorders with onset in early childhood are progressive and involve multiple organs. The m.3250T>C mutation in MTTL1 has previously been described in a few individuals with a possibly riboflavin-responsive myopathy and an association with sudden infant death syndrome was suspected. We describe a large family with this mutation and evaluate the effect of riboflavin treatment.Medical data were collected with the help of a standardized data collection form. Sanger sequencing was used to screen for variants in mitochondrial DNA and the proportion of the mutation was analyzed in different tissues. Biochemical and muscle morphological investigations of muscle tissue were performed in two individuals. The effect of riboflavin treatment was evaluated in two individuals.Thirteen family members experienced exercise intolerance with fatigue and weakness. Inheritance was maternal with 100% penetrance. The course was either static or showed improvement over time. There was no evidence of other organ involvement except for a possible mild transient cardiac enlargement in one child. Muscle investigations showed isolated complex I deficiency and mitochondrial proliferation. The level of m.3250T>C was apparently 100%, i.e. homoplasmic, in all examined tissues. Riboflavin treatment showed no effect in any treated family member and there have been no cases of sudden infant death in this family.This study illustrates the importance of considering mitochondrial disorders in the work-up of individuals with exercise intolerance and provides a better understanding of the phenotype associated with the m.3250T>C mutation in MTTL1.
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| 7. |
- Darin, Niklas, 1964, et al.
(författare)
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Functional analysis of a novel POL gamma A mutation associated with a severe perinatal mitochondrial encephalomyopathy
- 2021
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Ingår i: Neuromuscular Disorders. - : Elsevier BV. - 0960-8966. ; 31:4, s. 348-358
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Tidskriftsartikel (refereegranskat)abstract
- Mutations in the mitochondrial DNA polymerase gamma catalytic subunit (POL. A) compromise the stability of mitochondrial DNA (mtDNA) by leading to mutations, deletions and depletions in mtDNA. Patients with mutations in POL gamma A often differ remarkably in disease severity and age of onset. In this work we have studied the functional consequence of POL gamma A mutations in a patient with an uncommon and a very severe disease phenotype characterized by prenatal onset with intrauterine growth restriction, lactic acidosis from birth, encephalopathy, hepatopathy, myopathy, and early death. Muscle biopsy identified scattered COX-deficient muscle fibers, respiratory chain dysfunction and mtDNA depletion. We identified a novel POL.A mutation (p.His1134Tyr) in trans with the previously identified p.Thr251Ile/Pro587Leu double mutant. Biochemical characterization of the purified recombinant POL gamma A variants showed that the p.His1134Tyr mutation caused severe polymerase dysfunction. The p.Thr251Ile/Pro587Leu mutation caused reduced polymerase function in conditions of low dNTP concentration that mimic postmitotic tissues. Critically, when p.His1134Tyr and p.Thr251Ile/Pro587Leu were combined under these conditions, mtDNA replication was severely diminished and featured prominent stalling. Our data provide a molecular explanation for the patients mtDNA depletion and clinical features, particularly in tissues such as brain and muscle that have low dNTP concentration. (c) 2021 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)
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| 8. |
- Darin, Niklas, 1964, et al.
(författare)
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Mitochondrial myopathy with exercise intolerance and retinal dystrophy in a sporadic patient with a G583A mutation in the mt tRNA(phe) gene
- 2006
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Ingår i: Neuromuscular disorders : NMD. - : Elsevier BV. - 0960-8966 .- 1873-2364. ; 16:8, s. 504-6
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Tidskriftsartikel (refereegranskat)abstract
- We describe a second patient with the 583G>A mutation in the tRNA(phe) gene of mitochondrial DNA (mtDNA). This 17-year-old girl had a mitochondrial myopathy with exercise intolerance and an asymptomatic retinopathy. Muscle investigations showed occasional ragged red fibers, 30% cytochrome c oxidase (COX)-negative fibers, and reduced activities of complex I+IV in the respiratory chain. The mutation was heteroplasmic (79%) in muscle but undetectable in other tissues. Analysis of single muscle fibers revealed a significantly higher level of mutated mtDNA in COX-negative fibers. Our study indicates that the 583G>A mutation is pathogenic and expands the clinical spectrum of this mutation.
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| 9. |
- Grønborg, Sabine, et al.
(författare)
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Leukoencephalopathy due to Complex II Deficiency and Bi-Allelic SDHB Mutations: Further Cases and Implications for Genetic Counselling.
- 2016
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Ingår i: JIMD reports. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 2192-8304. ; 33, s. 69-77
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Tidskriftsartikel (refereegranskat)abstract
- Isolated complex II deficiency is a rare cause of mitochondrial disease and bi-allelic mutations in SDHB have been identified in only a few patients with complex II deficiency and a progressive neurological phenotype with onset in infancy. On the other hand, heterozygous SDHB mutations are a well-known cause of familial paraganglioma/pheochromocytoma and renal cell cancer. Here, we describe two additional patients with respiratory chain deficiency due to bi-allelic SDHB mutations. The patients' clinical, neuroradiological, and biochemical phenotype is discussed according to current knowledge on complex II and SDHB deficiency and is well in line with previously described cases, thus confirming the specific neuroradiological presentation of complex II deficiency that recently has emerged. The patients' genotype revealed one novel SDHB mutation, and one SDHB mutation, which previously has been described in heterozygous form in patients with familial paraganglioma/pheochromocytoma and/or renal cell cancer. This is only the second example in the literature where one specific SDHx mutation is associated with both recessive mitochondrial disease in one patient and familial paraganglioma/pheochromocytoma in others. Due to uncertainties regarding penetrance of different heterozygous SDHB mutations, we argue that all heterozygous SDHB mutation carriers identified in relation to SDHB-related leukoencephalopathy should be referred to relevant surveillance programs for paraganglioma/pheochromocytoma and renal cell cancer. The diagnosis of complex II deficiency due to SDHB mutations therefore raises implications for genetic counselling that go beyond the recurrence risk in the family according to an autosomal recessive inheritance.
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| 10. |
- Horvath, Rita, et al.
(författare)
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Molecular basis of infantile reversible cytochrome c oxidase deficiency myopathy.
- 2009
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Ingår i: Brain : a journal of neurology. - : Oxford University Press (OUP). - 1460-2156. ; 132:Pt 11, s. 3165-74
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Tidskriftsartikel (refereegranskat)abstract
- Childhood-onset mitochondrial encephalomyopathies are usually severe, relentlessly progressive conditions that have a fatal outcome. However, a puzzling infantile disorder, long known as 'benign cytochrome c oxidase deficiency myopathy' is an exception because it shows spontaneous recovery if infants survive the first months of life. Current investigations cannot distinguish those with a good prognosis from those with terminal disease, making it very difficult to decide when to continue intensive supportive care. Here we define the principal molecular basis of the disorder by identifying a maternally inherited, homoplasmic m.14674T>C mt-tRNA(Glu) mutation in 17 patients from 12 families. Our results provide functional evidence for the pathogenicity of the mutation and show that tissue-specific mechanisms downstream of tRNA(Glu) may explain the spontaneous recovery. This study provides the rationale for a simple genetic test to identify infants with mitochondrial myopathy and good prognosis.
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