| 1. |
- Müller, Kathrin, et al.
(author)
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De novo mutations in SOD1 are a cause of ALS
- 2022
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In: Journal of Neurology, Neurosurgery and Psychiatry. - : BMJ Publishing Group Ltd. - 0022-3050 .- 1468-330X. ; 93, s. 201-206
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Journal article (peer-reviewed)abstract
- Objective: The only identified cause of amyotrophic lateral sclerosis (ALS) are mutations in a number of genes found in familial cases but also in sporadic cases. De novo mutations occurring in a parental gonadal cell, in the zygote or postzygotic during embryonal development can result in an apparently sporadic/isolated case of ALS later in life. We searched for de novo mutations in SOD1 as a cause of ALS.Methods: We analysed peripheral-blood exome, genome and Sanger sequencing to identify deleterious mutations in SOD1 in 4000 ALS patients from Germany, South Korea and Sweden. Parental kinship was confirmed using highly polymorphic microsatellite markers across the genome. Medical genealogical and clinical data were reviewed and compared with the literature.Results: We identified four sporadic ALS cases with de novo mutations in SOD1. They aggregate in hot-spot codons earlier found mutated in familial cases. Their phenotypes match closely what has earlier been reported in familial cases with pathogenic mutations in SOD1. We also encountered familial cases where de novo mutational events in recent generations may have been involved.Conclusions: De novo mutations are a cause of sporadic ALS and may also be underpinning smaller families with few affected ALS cases. It was not possible to ascertain if the origin of the de novo mutations was parental germline, zygotic or postzygotic during embryonal development. All ALS patients should be offered genetic counselling and genetic screening, the challenges of variant interpretation do not outweigh the potential benefits including earlier confirmed diagnosis and possible bespoken therapy.Data availability statement: Data are available upon reasonable request. All data relevant to the study are included in the article or uploaded as supplementary information.
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| 2. |
- Nordin, Angelica, et al.
(author)
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Sequence variations in C9orf72 downstream of the hexanucleotide repeat region and its effect on repeat-primed PCR interpretation : a large multinational screening study
- 2017
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In: Amyotrophic Lateral Sclerosis and Frontotemporal Degeneration. - : Informa UK Limited. - 2167-8421 .- 2167-9223. ; 18:3-4, s. 256-264
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Journal article (peer-reviewed)abstract
- A large GGGGCC-repeat expansion mutation (HREM) in C9orf72 is the most common known cause of ALS and FTD in European populations. Sequence variations immediately downstream of the HREM region have previously been observed and have been suggested to be one reason for difficulties in interpreting RP-PCR data. Our objective was to determine the properties of these sequence variations with regard to prevalence, the range of variation, and effect on disease prognosis. We screened a multi-national cohort (n = 6981) for the HREM and samples with deviant RP-PCR curves were identified. The deviant samples were subsequently sequenced to determine sequence alteration. Our results show that in the USA and European cohorts (n = 6508) 10.7% carried the HREM and 3% had a sequence variant, while no HREM or sequence variants were observed in the Japanese cohort (n = 473). Sequence variations were more common on HREM alleles; however, certain population specific variants were associated with a non-expanded allele. In conclusion, we identified 38 different sequence variants, most located within the first 50 bp downstream of the HREM region. Furthermore, the presence of an HREM was found to be coupled to a lower age of onset and a shorter disease survival, while sequence variation did not have any correlation with these parameters.
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| 3. |
- Akimoto, Chizuru, et al.
(author)
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A blinded international study on the reliability of genetic testing for GGGGCC-repeat expansions in C9orf72 reveals marked differences in results among 14 laboratories
- 2014
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In: Journal of Medical Genetics. - : BMJ. - 0022-2593 .- 1468-6244. ; 51:6, s. 419-424
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Journal article (peer-reviewed)abstract
- Background The GGGGCC-repeat expansion in C9orf72 is the most frequent mutation found in patients with amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Most of the studies on C9orf72 have relied on repeat-primed PCR (RP-PCR) methods for detection of the expansions. To investigate the inherent limitations of this technique, we compared methods and results of 14 laboratories. Methods The 14 laboratories genotyped DNA from 78 individuals (diagnosed with ALS or FTD) in a blinded fashion. Eleven laboratories used a combination of amplicon-length analysis and RP-PCR, whereas three laboratories used RP-PCR alone; Southern blotting techniques were used as a reference. Results Using PCR-based techniques, 5 of the 14 laboratories got results in full accordance with the Southern blotting results. Only 50 of the 78 DNA samples got the same genotype result in all 14 laboratories. There was a high degree of false positive and false negative results, and at least one sample could not be genotyped at all in 9 of the 14 laboratories. The mean sensitivity of a combination of amplicon-length analysis and RP-PCR was 95.0% (73.9-100%), and the mean specificity was 98.0% (87.5-100%). Overall, a sensitivity and specificity of more than 95% was observed in only seven laboratories. Conclusions Because of the wide range seen in genotyping results, we recommend using a combination of amplicon-length analysis and RP-PCR as a minimum in a research setting. We propose that Southern blotting techniques should be the gold standard, and be made obligatory in a clinical diagnostic setting.
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| 4. |
- Andersson, Maria, 1969-, et al.
(author)
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Moral Distress, Health and Intention to Leave: Critical Care Nurses’ Perceptions During COVID-19 Pandemic
- 2023
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In: Sage Open Nursing. - : SAGE Publications Inc.. - 2377-9608. ; 9
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Journal article (peer-reviewed)abstract
- Introduction: Moral distress increases the risk that critical care nurses will lose the ability to provide quality nursing care.Aims: To describe person-related conditions and perceptions of moral distress, health and intention to leave among critical care nurses in intensive care units, and to examine the relationship between person-related conditions, moral distress, health and intention to leave.Method: Cross-sectional, with 220 critical care nurses in 15 Swedish ICUs, and data gathered via a self-reported questionnaire.Results: Highest moral distress scores were reported in futile care and poor teamwork and 21% reported entertaining an intention to leave. Self-reported health was lower than before the COVID-19 pandemic and 4.1% reported pronounced exhaustion disorder. Self-reported health, reduced capacity to tolerate demands under time pressure, emotional instability or irritability, physical weakness, or being more easily fatigued and with decreased well-being were factors that had a relationship with futile care. Sleeping problems and intention to leave had a relationship with poor teamwork.Conclusions: Different strategies are needed to reduce moral distress and the leadership is crucial for managing crises such as the COVID-19 pandemic.
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| 5. |
- Andersson, Maria, et al.
(author)
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The four domains of the person-centred practice framework from the perspective of critical care nurses in intensive care units during a pandemic
- 2023
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In: Intensive & Critical Care Nursing. - : Elsevier. - 0964-3397 .- 1532-4036. ; 78
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Journal article (peer-reviewed)abstract
- Objectives: The aim was to describe the Person-Centred Practice Framework’s four domains (prerequisites, care environment, person-centred processes, and person-centred outcomes) through the perspectives of critical care nurses working in intensive care units during the second year of the COVID-19 pandemic. Furthermore, the aim was to investigate the relationships between prerequisites, care environment, person-centred processes, and person-centred outcomes. Design/methods: A cross-sectional study involving questionnaires. Prerequisites were measured using person- related conditions, the care environment by using the Person-Centred Climate Questionnaire–Staff version, the person-centred processes by using the Person-Centred Care Assessment Tool and person-centred outcomes were measured with one question about present health and well-being and by using Self-rated Exhaustion Disorder. Descriptive and analytic statistics were used. Data was collected from July 2021 to November 2021. Setting: Critical care nurses (n =217) working in 15 Swedish adult intensive care units. Results: Participants’ average length of experience in intensive care units was 14 years, and most participants experienced increased nursing care responsibilities. They perceived the climate as safe but had limitations in terms of its everydayness and community. Participants perceived the organisations both supported and hindered personalized care. Most participants experienced a variety of exhaustion symptoms, and their health had positive relationship with community. Conclusion: By showing how prerequisites, care environment, person-centred process influences critical care nurses’ health and well-being, organisations might identify aspects in the work environment that require targeted interventions to reach healthy workplaces. Implications for clinical practice: To preserve the health and well-being of critical care nurses and to flourish as humans in their professional roles, they need to interact with and form relationships with their colleagues, patients, and relatives. Organisations should have a person-centred approach for every individual in the workforce to harness each critical care nurses’ knowledge and skills for individuals to growth in their roles.
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| 6. |
- Andersson-Sköld, Yvonne, 1957-, et al.
(author)
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Development of the SUNRA Tool to Improve Regional and Local Sustainability of the Transportation Sector
- 2022
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In: Sustainability. - : MDPI AG. - 2071-1050. ; 14:18, s. 11275-
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Journal article (peer-reviewed)abstract
- To fulfil the global sustainable development goals (SDGs), achieving sustainable development is becoming urgent, not least in the transportation sector. In response to this, the sustainability framework Sustainability National Road Administrations (SUNRA) was developed to contribute to improving the sustainability performance of national road administrations across Europe. In the present study, the framework has been tested, applied and further developed to be applicable for target setting and follow-up at the project level at both the Swedish Transport Administration (STA) and at municipal levels. The aim was a framework relevant for investment, re-investments, maintenance and operation projects and also to make it more user applicable. The study also investigated how the framework can contribute to sustainability, identified drivers and barriers for applying the framework and examined whether the framework can be applied and adapted to projects of different complexities. The adaptations and developments were done in collaboration between researchers and practitioners. The results show that the framework could easily be used and adapted for investment, re-investment, maintenance and operation projects in the planning stage, as well as for small municipal establishments, construction or reconstruction of residential areas and frequent maintenance. The framework contributes to increased awareness on sustainability, and it provides a common structure and transparency on how infrastructure project goals/targets are set and fulfilled. The framework can also be applied to follow the fulfilment of the goals/targets and thereby adapt the project to better fulfil the goals. Identified barriers include the lack of obligations and lack of experience in using sustainability frameworks.
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| 7. |
- Engström, Åsa, et al.
(author)
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Institutional Constraints as an Obstacle for Prioritizing Nursing Interventions During the COVID-19 Pandemic—Critical Care Nurses’ Experiences
- 2022
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In: Sage Open Nursing. - : Sage Publications. - 2377-9608. ; 8
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Journal article (peer-reviewed)abstract
- Introduction: The demands of the pandemic such as staff shortages and limited resources combined with new guidelines regarding infection control may have required the prioritizing of nursing interventions.Objectives: The aim of this study was to describe critical care nurses’ experiences of prioritizing nursing interventions for patients with COVID-19 in intensive care units (ICUs) during the pandemic.Method: A qualitative descriptive study was gathered from open-ended questions included in a cross-sectional online questionnaire. Characteristics were presented using descriptive statistics, and open-ended questions were analyzed using qualitative content analysis with an inductive approach. The study was conducted in Sweden and focused on critical care nurses working in ICUs during spring 2021 and the second year of the COVID-19 pandemic.Results: During the COVID-19 pandemic, 87% of the critical care nurses had provided orientations for new co-workers, and 52% had supervised intensive care nursing students. In all, 70 answered the question of whether they had prioritized nursing care differently during the pandemic; 86% reported that they had and 14% had not. The qualitative analysis resulted in one theme, Institutional constraints as an obstacle for nursing interventions, with three categories: Prioritizing lifesaving interventions, Performing nursing interventions less frequently, and Not able to provide the nursing care I wish to provide.Conclusion: Institutional constraints as an obstacle for nursing interventions is the overall theme. It illustrates how critical care nurses have been forced to prioritize, thereby not being able to provide the nursing interventions they wanted to do provide, and it describes their feelings in this situation. The nurses need recovery and possibilities for reflection. The organization must also recover and not only return to how it was before the pandemic but also to learn from recent events and take actions to reduce the long-term effects on staffing.
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| 8. |
- Fredholm, Angelica, et al.
(author)
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Learning in intensive care during the COVID-19 pandemic - postgraduate critical care nursing students’ experiences
- 2022
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In: International Journal of Medical Education. - : NLM (Medline). - 2042-6372. ; 13, s. 335-344
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Journal article (peer-reviewed)abstract
- Objectives: This study explored postgraduate critical care nursing students' experiences of learning in the ICU during the COVID-19 pandemic and to understand these experiences in relation to self-directed learning and professional development. Methods: An explorative qualitative design was used. Eight postgraduate critical care nursing students from two different universities were interviewed. Questions focused on learning, supervision, ethically difficult situations, issues regarding communication, as well as the impact of the pandemic on students' health. Interviews thematically analyzed, and further analyzed using a theoretical framework focusing self-directed learning and professional development containing the concepts of autonomy, authenticity, and attachment. Results: The result consists of three themes: 1) Attachment with subthemes Attachment to the patient, Attachment to family and friends, Attachment to the ICU-context, and Attachment to the clinical supervisor. 2) Authenticity with subthemes Experiencing a varying degree of authenticity, Clinical reasoning about how to prioritize care. 3) Autonomy with subthemes Being just a student - with limited responsibility, taking responsibility, and having worries regarding one's professional development. Conclusion: Findings show the need for participation in the ICU community of practice without the demands and responsibility of full participation. Students need to be given the opportunity to form a relationship with practice. For attachment, participation, and consequently professional development to take place, there is need for inviting students to be a part of the team even during such straining circumstances as an ongoing pandemic. These findings can advance the understanding of how to organize clinical education during future crisis such as a new pandemic.
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| 9. |
- Koch Frisén, Angelica, et al.
(author)
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Prospective evaluation of 6895 groin hernia repairs in women
- 2005
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In: British Journal of Surgery. - : Oxford University Press (OUP). - 0007-1323 .- 1365-2168. ; 92:12, s. 1553-1558
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Journal article (peer-reviewed)abstract
- Background: Although 8 per cent of groin hernia repairs are performed in women, there is little published literature relating specifically to women. This study compared differences in outcome between women and men after groin hernia repair.Methods: Data collected prospectively in the Swedish Hernia Register between 1992 and 2003 were analysed, including 6895 groin hernia repairs in women and 83 753 in men.Results: A higher proportion of emergency operations was carried out in women (16.9 per cent) than men (5.0 per cent), leading to bowel resection in 16.6 and 5.6 per cent respectively. During reoperation femoral hernias were found in 41.6 per cent of the women who were diagnosed with a direct or indirect inguinal hernia at the primary operation. The corresponding proportion for men was 4.6 per cent. The hernia repair was not classified as a standard operation (e.g. Shouldice, Lichtenstein, Plug/Mesh, TAPP/TEP) in 38.2 per cent of women and 11.2 per cent of men. Women had a significantly higher risk of reoperation for recurrence than men, and techniques associated with the lowest risk for reoperation in men had the highest risk in women.Conclusion: A greater proportion of women than men require emergency groin hernia repair, with consequently higher rates of bowel resection, complications and death. Surgical techniques developed for use in men may put women at unnecessary risk. Copyright © 2005 British Journal of Surgery Society Ltd. Published by John Wiley & Sons Ltd.
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| 10. |
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| 11. |
- Nordin, Angelica, et al.
(author)
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Extensive size variability of the GGGGCC expansion in C9orf72 in both neuronal and non-neuronal tissues in 18 patients with ALS or FTD
- 2015
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In: Human Molecular Genetics. - : Oxford University Press (OUP). - 0964-6906 .- 1460-2083. ; 24:11, s. 3133-3142
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Journal article (peer-reviewed)abstract
- A GGGGCC-repeat expansion in C9orf72 is the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) among Caucasians. However, little is known about the variability of the GGGGCC expansion in different tissues and whether this correlates with the observed phenotype. Here, we used Southern blotting to estimate the size of hexanucleotide expansions in C9orf72 in neural and non-neural tissues from 18 autopsied ALS and FTD patients with repeat expansion in blood. Digitalization of the Southern blot images allowed comparison of repeat number, smear distribution and expansion band intensity between tissues and between patients. We found marked intra-individual variation of repeat number between tissues, whereas there was less variation within each tissue group. In two patients, the size variation between tissues was extreme, with repeat numbers below 100 in all studied non-neural tissues, whereas expansions in neural tissues were 20-40 times greater and in the same size range observed in neural tissues of the other 16 patients. The expansion pattern in different tissues could not distinguish between diagnostic groups and no correlation was found between expansion size in frontal lobe and occurrence of cognitive impairment. In ALS patients, a less number of repeats in the cerebellum and parietal lobe correlated with earlier age of onset and a larger number of repeats in the parietal lobe correlated with a more rapid progression. In 43 other individuals without repeat expansion in blood, we find that repeat sizes up to 15 are stable, as no size variation between blood, brain and spinal cord was found.
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| 12. |
- Nordin, Angelica, 1982-
(author)
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Genetic and functional studies of hereditary myopathy with lactic acidosis
- 2011
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Doctoral thesis (other academic/artistic)abstract
- Hereditary myopathy with lactic acidosis (HML, OMIM#255125) is an autosomal recessive disorder which originates from Västerbotten and Ångermanland in the Northern part of Sweden. HML is characterized by severe exercise intolerance which manifests with tachycardia, dyspnea, muscle pain, cramps, elevated lactate and pyruvate levels, weakness and myoglobinuria. The symptoms arise from malfunction of the energy metabolism in skeletal muscles with defects in several important enzymes involved in the TCA cycle and the electron transport chain. All affected proteins contain iron-sulfur (Fe-S) clusters, which led to the suggestion that the disease was caused by malfunctions in either the transportation, assembly or processing of Fe-S clusters. The aim of my thesis was to identify the disease causing gene of HML and to investigate the underlying disease-mechanisms. In paper I we identified a disease-critical region on chromosome 12; a region containing 16 genes. One of the genes coded for the Fe-S cluster assembly protein ISCU and an intronic base pair substitution (g.7044G>C) was identified in the last intron of this gene. The mutation gave rise to the insertion of intron sequence into the mRNA, leading to a protein containing 15 abberant amino acids and a premature stop. In paper II we investigated why a mutation in an evolutionary well conserved protein with a very important cellular role, which in addition is expressed in almost all tissues, gives rise to a muscle-restricted phenotype. Semi-quantitative RT-PCR analysis showed that the mutant transcript constituted almost 80% of total ISCU mRNA in muscle, while in both heart and liver the normal splice form was dominant. We could also show that, in mice, complete absence of Iscu protein was coupled with early embryonic death, further emphasizing the importance of the protein in all tissues. These data strongly suggested that tissue-specific splicing was the main mechanism responsible for the muscle-specific phenotype of HML. In paper III the splicing mechanisms that give rise to the mutant ISCU transcript was further investigated. We identified three proteins; PTBP1, IGF2BP1 and RBM39, that could bind to the region containing the mutation and could affect the splicing pattern of ISCU in an in vitro system. PTBP1 repressed the inclusion of the intronic sequence, while IGF2BP1 and RBM39 repressed the total ISCU mRNA level though the effect was more pronounced for the normal transcript. Moreover, IGF2BP1 and RBM39 were also able to reverse the effect of PTBP1. IGF2BP1, though not a splicing factor, had higher affinity for the mutant sequence. This suggested that the mutation enables IGF2BP1 binding, thereby preventing the PTBP1 induced repression seen in the normal case. In conclusion, we have determined the genetic cause of HML, identifying a base pair substitution in the last intron of the ISCU gene that gives rise to abnormally spliced transcript. The muscle-specific phenotype was also analyzed and tissue-specific splicing was identified as the main disease-mechanism. Furthermore, nuclear factors with ability to affect the splicing pattern of the mutant ISCU gene were identified. This work has thoroughly investigated the fundamental disease mechanisms, thus providing deeper understanding for this hereditary myopathy.
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| 13. |
- Nordin, Anna, et al.
(author)
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Intensive Care Managers' Experiences of the COVID-19 Pandemic: A Dramatic Change of the Intensive Care Landscape
- 2023
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In: Journal of Nursing Management. - : Wiley-Hindawi. - 0966-0429 .- 1365-2834.
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Journal article (peer-reviewed)abstract
- Aim. To describe intensive care managers' experiences of premises and resources of care in intensive care units during the COVID-19 pandemic.Background. Intensive care units (ICUs) were enormously pressured during the COVID-19 pandemic from many ill patients, requiring advanced care. Hospital and community volunteers increased staff strength. Obligatorily, recruitments were also conducted using transfer of staff from different hospital departments. However, there is little knowledge about intensive care managers' (ICMs) experiences of leadership during the COVID-19 pandemic.Methods. A qualitative descriptive study was conducted from March to April 2022. Semistructured interviews were held with 12 ICMs who were purposively sampled from the ICU in ten Swedish hospitals. Data were analysed using qualitative content analysis.Results. Two themes emerged: a dramatic change of the intensive care landscape and we could handle more than we thought, but at a steep price. Participants described that the ICUs had to perform extraordinary changes at a very fast pace, which initially created a sense of cohesion. Training and introduction to war-like conditions associated with uncertainty meant that ICMs had to support ICU staff in prioritising interventions. Participants described how ICUs stood strong against a pandemic, but stress, worries, and anxiety took a heavy toll on ICU staff and ICMs. The pandemic eroded the resilience in ICUs. Participants described a deterioration in health and said that sick leaves and resignations occurred.Conclusion. Our findings show ICMs' experiences as a field of tension between resources and demands, whereby the changes created a heavy burden that left intensive care weakened.Implications for Nursing Management. Findings emphasised the importance of creating working conditions using human resources and materials in order to rebuild resilience in intensive care with the ability to conduct safe patient care.
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| 14. |
- Nordin, Anna, 1972-, et al.
(author)
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Measuring moral distress in Swedish intensive care: Psychometric and descriptive results
- 2023
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In: Intensive & Critical Care Nursing. - : Elsevier. - 0964-3397 .- 1532-4036. ; 76
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Journal article (peer-reviewed)abstract
- Objectives: To investigate the construct validity and psychometric properties of the Swedish version of the Moral Distress Scale–Revised and to describe moral distress in an intensive care context.Research Methodology/Design: The Italian Moral Distress Scale–Revised was translated and semantically adjusted to the Swedish intensive care context. A web survey with 14 moral distress items, as well as three additional and eight background questions was answered by critical care nurses (N = 71) working in intensive care units during the second year of the coronavirus disease pandemic. Inferential and descriptive statistics were used to investigate the Italian four-factor model and to examine critical care nurses’ moral distress.Results: The result shows a factor model of four components differing from the previous model. Critical care nurses demonstrated significant differences in moral distress regarding priorities compared to before the pandemic, type of household; experience as critical care nurses and whether they had supervised students during the pandemic.Conclusion: The component structure might have originated from the specific situation critical care nurses perceived during the pandemic. The health care organisations’ role in preventing and healing the effects of moral distress is important for managers to understand.Implications for clinical practice: Moral distress is common in intensive care and it is necessary to use valid instrument when measuring it. A psychometrical investigation of the Swedish version of the Moral Distress Scale–Revised, adapted for intensive care shows need for further semantic and cultural adaptation. Perceived priorities during the pandemic, household type, supervising during the pandemic and working experience were related to critical care nurses’ experience of moral distress and managers need to be aware of conditions that may trigger such a response.
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| 15. |
- Nordin, Angelica, 1982-, et al.
(author)
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The defective splicing caused by the ISCU intron mutation in patients with myopathy with lactic acidosis is repressed by PTBP1 but can be de-repressed by IGF2BP1
- 2012
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In: Human Mutation. - : Hindawi Limited. - 1059-7794 .- 1098-1004. ; 33:3, s. 467-470
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Journal article (peer-reviewed)abstract
- Hereditary myopathy with lactic acidosis (HML) is caused by an intron mutation in the iron-sulfur cluster assembly gene ISCU which leads to the activation of cryptic splice sites and the retention of part of intron 4. This incorrect splicing is more pronounced in muscle than in other tissues, resulting in a muscle-specific phenotype. In this study, we identified five nuclear factors that interact with the sequence harboring the mutation and analyzed their effect on the splicing of the ISCU gene. The identification revealed three splicing factors, SFRS14, RBM39 and PTBP1, and two additional RNA binding factors, matrin 3 (MATR3) and IGF2BP1. IGF2BP1 showed a preference for the mutant sequence, whereas the other factors showed similar affinity for both sequences. PTBP1 was found to repress the defective splicing of ISCU, resulting in a drastic loss of mutant transcripts. In contrast, IGF2BP1 and RBM39 shifted the splicing ratio toward the incorrect splice form.
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| 16. |
- Nordin, Angelica, 1982-, et al.
(author)
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Tissue-specific splicing of ISCU results in a skeletal muscle phenotype in myopathy with lactic acidosis, while complete loss of ISCU results in early embryonic death in mice
- 2011
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In: Human Genetics. - : Springer Science and Business Media LLC. - 0340-6717 .- 1432-1203. ; 129:4, s. 371-378
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Journal article (peer-reviewed)abstract
- Hereditary myopathy with lactic acidosis (HML) is caused by an intron mutation in the iron-sulphur cluster assembly gene (ISCU) leading to incorporation of intron sequence into the mRNA. This results in a deficiency of Fe-S cluster proteins, affecting the TCA cycle and the respiratory chain. The proteins involved in the Fe-S machinery are evolutionary conserved and shown to be fundamental in all organisms examined. ISCU is expressed at high levels in numerous tissues in mammals, including high metabolic tissues like the heart, suggesting that a drastic mutation in the ISCU gene would be damaging to all energy-demanding organs. In spite of this, the symptoms in patients with HML are restricted to skeletal muscle, and it has been proposed that splicing events may contribute to the muscle specificity. In this study we confirm that a striking difference in the splicing pattern of mutant ISCU exists between different tissues. The highest level of incorrectly spliced ISCU mRNA was found in skeletal muscle, while the normal splice form predominated in patient heart. The splicing differences were also reflected at a functional level, where loss of Fe-S cluster carrying enzymes and accumulation of iron were present in muscle, but absent in other tissues. We also show that complete loss of ISCU in mice results in early embryonic death. The mice data confirm a fundamental role for ISCU in mammals and further support tissue-specific splicing as the major mechanism limiting the phenotype to skeletal muscle in HML.
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| 17. |
- Rawcliffe, Denise F. R., et al.
(author)
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PTBP1 acts as a dominant repressor of the aberrant tissue-specific splicing of ISCU in hereditary myopathy with lactic acidosis
- 2018
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In: Molecular Genetics & Genomic Medicine. - : John Wiley & Sons. - 2324-9269. ; 6:6, s. 887-897
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Journal article (peer-reviewed)abstract
- Background: Hereditary myopathy with lactic acidosis (HML) is an autosomal recessive disease caused by an intron mutation in the iron-sulfur cluster assembly (ISCU) gene. The mutation results in aberrant splicing, where part of the intron is retained in the final mRNA transcript, giving rise to a truncated nonfunctional ISCU protein. Using an ISCU mini-gene system, we have previously shown that PTBP1 can act as a repressor of the mis-splicing of ISCU, where overexpression of PTBP1 resulted in a decrease of the incorrect splicing. In this study, we wanted to, in more detail, analyze the role of PTBP1 in the regulation of endogenous ISCU mis-splicing.Methods: Overexpression and knockdown of PTBP1 was performed in myoblasts from two HML patients and a healthy control. Quantification of ISCU mis-splicing was done by qRTPCR. Biotinylated ISCU RNA, representing wildtype and mutant intron sequence, was used in a pull-down assay with nuclear extracts from myoblasts. Levels of PTBP1 in human cell lines and mice tissues were analyzed by qRTPCR and western blot.Results: PTBP1 overexpression in HML patient myoblasts resulted in a substantial decrease of ISCU mis-splicing while knockdown of PTBP1 resulted in a drastic increase. The effect could be observed in both patient and control myoblasts. We could also show that PTBP1 interacts with both the mutant and wild-type ISCU intron sequence, but with a higher affinity to the mutant sequence. Furthermore, low levels of PTBP1 among examined mouse tissues correlated with high levels of incorrect splicing of ISCU.Conclusion: Our results show that PTBP1 acts as a dominant repressor of ISCU mis-splicing. We also show an inverse correlation between the levels of PTBP1 and ISCU mis-splicing, suggesting that the high level of mis-splicing in the skeletal muscle is primarily due to the low levels of PTBP1.
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| 18. |
- Tazelaar, Gijs H.P., et al.
(author)
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Whole genome sequencing analysis reveals post-zygotic mutation variability in monozygotic twins discordant for amyotrophic lateral sclerosis
- 2023
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In: Neurobiology of Aging. - : Elsevier. - 0197-4580 .- 1558-1497. ; 122, s. 76-87
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Journal article (peer-reviewed)abstract
- Amyotrophic lateral sclerosis is a heterogeneous, fatal neurodegenerative disease, characterized by motor neuron loss and in 50% of cases also by cognitive and/or behavioral changes. Mendelian forms of ALS comprise approximately 10-15% of cases. The majority is however considered sporadic, but also with a high contribution of genetic risk factors. To explore the contribution of somatic mutations and/or epigenetic changes to disease risk, we performed whole genome sequencing and methylation analyses using samples from multiple tissues on a cohort of 26 monozygotic twins discordant for ALS, followed by in-depth validation and replication experiments. The results of these analyses implicate several mechanisms in ALS pathophysiology, which include a role for de novo mutations, defects in DNA damage repair and accelerated aging.
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| 19. |
- van Rheenen, W, et al.
(author)
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Common and rare variant association analyses in amyotrophic lateral sclerosis identify 15 risk loci with distinct genetic architectures and neuron-specific biology
- 2021
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In: Nature genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 53:12, s. 1636-
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Journal article (peer-reviewed)abstract
- Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease with a lifetime risk of one in 350 people and an unmet need for disease-modifying therapies. We conducted a cross-ancestry genome-wide association study (GWAS) including 29,612 patients with ALS and 122,656 controls, which identified 15 risk loci. When combined with 8,953 individuals with whole-genome sequencing (6,538 patients, 2,415 controls) and a large cortex-derived expression quantitative trait locus (eQTL) dataset (MetaBrain), analyses revealed locus-specific genetic architectures in which we prioritized genes either through rare variants, short tandem repeats or regulatory effects. ALS-associated risk loci were shared with multiple traits within the neurodegenerative spectrum but with distinct enrichment patterns across brain regions and cell types. Of the environmental and lifestyle risk factors obtained from the literature, Mendelian randomization analyses indicated a causal role for high cholesterol levels. The combination of all ALS-associated signals reveals a role for perturbations in vesicle-mediated transport and autophagy and provides evidence for cell-autonomous disease initiation in glutamatergic neurons.
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