Epidemiology and natural history of POLG disease in Norway: a nationwide cohort study.

OBJECTIVE: To investigate the prevalence and natural history of POLG disease in the Norwegian population. METHODS: A national, population-based, retrospective study using demographic, clinical, and genetic data of patients with genetically confirmed POLG disease. The patients were diagnosed between 2002 and 2022, and were included into the Norwegian POLG Patient Registry. Patients were stratified according to age at disease onset (early <12 years, juvenile to adult 12-40 years, late ≥40 years) and resident region. RESULTS: Ninety-one patients were included. The point prevalence of POLG disease was 1:149,253. Birth prevalence was 1:48,780. Median age at clinical onset was 16 years (range: 2 months to 70 years). Onset occurred early in 35% (32 out of 91), juvenile-adult in 55% (50 out of 91) and late in 10% (9 out of 91). A distinct seasonal pattern in disease onset was observed, with 57% (52 out of 91) presenting between May and August. Forty-five patients (49%) had acute exacerbations that required intensive care, and this affected 72% of those in the early-onset group. The mortality rate was 54% (49 out of 91), with a median time from disease onset to death of 3 years (range: 1 month to 36 years). INTERPRETATION: We provide the point prevalence and birth prevalence of POLG disease in the first nationwide study in which epidemiological and clinical data were integrated. Seasonal variations in clinical onset may offer valuable insights into disease mechanisms and modifying factors. The findings from this study are crucial for quantifying the disease burden, and contribute to evidence-based healthcare planning.

Musculoskeletal Chronic Graft versus Host Disease-A Rare Complication to Allogeneic Hematopoietic Stem Cell Transplant: A Case-Based Report and Review of the Literature.

Musculoskeletal graft versus host disease (GVHD) is a rare manifestation of chronic GVHD (cGVHD) following allogeneic hematopoietic stem cell transplantation (allo-HSCT). Left untreated, the disease can cause extensive damage to muscle tissue and joints. We describe a 62-year-old male with musculoskeletal GVHD and generalized muscle pain and stiffness. In addition, we performed a systemic literature review based on published cases of musculoskeletal GVHD between 1983 and 2019. We identified 85 cases, 62% male and 38% female with an age of 4-69 years and median age of 39 years at diagnosis. The majority of patients (72%) also had manifestations of cGVHD in at least one other organ system, most frequently the skin (52%), followed by oropharyngeal mucosa (37%), and pulmonary and gastrointestinal tract (GI tract) (21%). We conclude that, while musculoskeletal cGVHD is a rare complication of allo-HSCT, it remains a serious and debilitating risk that must be considered in patients with muscle pain, muscle weakness, joint stiffness, and tissue inflammation. Early intervention is critical for the patient's prognosis.

Patient-specific neural progenitor cells derived from induced pluripotent stem cells offer a promise of good models for mitochondrial disease.

Mitochondria are the primary generators of ATP in eukaryotic cells through the process of oxidative phosphorylation. Mitochondria are also involved in several other important cellular functions including regulation of intracellular Ca2+, cell signaling and apoptosis. Mitochondrial dysfunction causes disease and since it is not possible to perform repeated studies in humans, models are essential to enable us to investigate the mechanisms involved. Recently, the discovery of induced pluripotent stem cells (iPSCs), made by reprogramming adult somatic cells (Takahashi and Yamanaka 2006; Yamanaka and Blau 2010), has provided a unique opportunity for studying aspects of disease mechanisms in patient-specific cells and tissues. Reprogramming cells to neuronal lineage such as neural progenitor cells (NPCs) generated from the neural induction of reprogrammed iPSCs can thus provide a useful model for investigating neurological disease mechanisms including those caused by mitochondrial dysfunction. In addition, NPCs display a huge clinical potential in drug screening and therapeutics.

Polymerase gamma-related mitochondrial disorder. / Polymerase gamma-relatert mitokondriesykdom.

DNA Polymerase gamma (POLG) is an enzyme that replicates and repairs mitochondrial DNA. Mutations in the gene that codes for the catalytic subunit of the enzyme, the POLG gene, are one of the most common causes of mitochondrial disease. POLG-related disorders can have overlapping phenotypes and affect a number of organ systems, and first onset may occur at any age. The disease group can serve as a paradigm for understanding mitochondrial diseases in general.

Genomic medicine must reduce, not compound, health inequities: the case for hauora-enhancing genomic resources for New Zealand.

Precision medicine seeks to draw on data from both individuals and populations across disparate domains to influence and support diagnosis, management and prevention in healthcare at the level of the individual patient and their family/whanau. Central to this initiative is incorporating the effects of the inherent variation that lies within genomes and can influence health outcomes. Identifying and interpreting such variation requires an accurate, valid and representative dataset to firstly define what variants are present and then assess the potential relevance for the health of a person, their family/whanau and the wider community to which they belong. Globally the variation embedded within genomes differs enormously and has been shaped by the size, constitution, historical origins and evolutionary history of their source populations. Maori, and more broadly Pacific peoples, differ substantially in terms of genomic variation compared to the more closely studied European and Asian populations. In the absence of accurate genomic information from Maori and Pacific populations, the precise interpretation of genomic data and the success and benefits of genomic medicine will be disproportionately less for those Maori and Pacific peoples. In this viewpoint article we, as a group of healthcare professionals, researchers and scientists, present a case for assembling genomic resources that catalogue the characteristics of the genomes of New Zealanders, with an emphasis on peoples of Maori and Polynesian ancestry, as a healthcare imperative. In proposing the creation of these resources, we note that their governance and management must be led by iwi and Maori and Pacific representatives. Assembling a genomic resource must be informed by cultural concepts and values most especially understanding that, at a physical and spiritual level, whakapapa is embodied within the DNA of a person. Therefore DNA and genomic data that connects to whakapapa (genealogy) is considered a taonga (something precious and significant), and its storage, utilisation and interpretation is a culturally significant activity. Furthermore, such resources are not proposed to primarily enable comparisons between those with Maori and broader Pacific ancestries and other Aotearoa peoples but to place an understanding of the genetic contributors to their health outcomes in a valid context. Ongoing oversight and governance of such taonga by Maori and Pacific representatives will maximise hauora (health) while also minimising the risk of misuse of this information.

Phenotype-genotype correlations in Leigh syndrome: new insights from a multicentre study of 96 patients.

BACKGROUND: Leigh syndrome is a phenotypically and genetically heterogeneous mitochondrial disorder. While some genetic defects are associated with well-described phenotypes, phenotype-genotype correlations in Leigh syndrome are not fully explored. OBJECTIVE: We aimed to identify phenotype-genotype correlations in Leigh syndrome in a large cohort of systematically evaluated patients. METHODS: We studied 96 patients with genetically confirmed Leigh syndrome diagnosed and followed in eight European centres specialising in mitochondrial diseases. RESULTS: We found that ataxia, ophthalmoplegia and cardiomyopathy were more prevalent among patients with mitochondrial DNA defects. Patients with mutations in MT-ND and NDUF genes with complex I deficiency shared common phenotypic features, such as early development of central nervous system disease, followed by high occurrence of cardiac and ocular manifestations. The cerebral cortex was affected in patients with NDUF mutations significantly more often than the rest of the cohort. Patients with the m.8993T>G mutation in MT-ATP6 gene had more severe clinical and radiological manifestations and poorer disease outcome compared with patients with the m.8993T>C mutation. CONCLUSION: Our study provides new insights into phenotype-genotype correlations in Leigh syndrome and particularly in patients with complex I deficiency and with defects in the mitochondrial ATP synthase.

An evaluation of the genetic-matched pair study design using genome-wide SNP data from the European population.

Genetic matching potentially provides a means to alleviate the effects of incomplete Mendelian randomization in population-based gene-disease association studies. We therefore evaluated the genetic-matched pair study design on the basis of genome-wide SNP data (309,790 markers; Affymetrix GeneChip Human Mapping 500K Array) from 2457 individuals, sampled at 23 different recruitment sites across Europe. Using pair-wise identity-by-state (IBS) as a matching criterion, we tried to derive a subset of markers that would allow identification of the best overall matching (BOM) partner for a given individual, based on the IBS status for the subset alone. However, our results suggest that, by following this approach, the prediction accuracy is only notably improved by the first 20 markers selected, and increases proportionally to the marker number thereafter. Furthermore, in a considerable proportion of cases (76.0%), the BOM of a given individual, based on the complete marker set, came from a different recruitment site than the individual itself. A second marker set, specifically selected for ancestry sensitivity using singular value decomposition, performed even more poorly and was no more capable of predicting the BOM than randomly chosen subsets. This leads us to conclude that, at least in Europe, the utility of the genetic-matched pair study design depends critically on the availability of comprehensive genotype information for both cases and controls.