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Background and purpose: Clinical outcome information on patients with neuromuscular diseases (NMDs) who have been infected with SARS‐CoV‐2 is limited. The aim of this study was to determine factors associated with the severity of COVID‐19 outcomes in people with NMDs. Methods: Cases of NMD, of any age, and confirmed/presumptive COVID‐19, submitted to the International Neuromuscular COVID‐19 Registry up to 31 December 2021, were included. A mutually exclusive ordinal COVID‐19 severity scale was defined as follows: (1) no hospitalization; (2) hospitalization without oxygenation; (3) hospitalization with ventilation/oxygenation; and (4) death. Multivariable ordinal logistic regression analyses were used to estimate odds ratios (ORs) for severe outcome, adjusting for age, sex, race/ethnicity, NMD, comorbidities, baseline functional status (modified Rankin scale [mRS]), use of immunosuppressive/immunomodulatory medication, and pandemic calendar period. Results: Of 315 patients from 13 countries (mean age 50.3 [±17.7] years, 154 [48.9%] female), 175 (55.5%) were not hospitalized, 27 (8.6%) were hospitalized without supplemental oxygen, 91 (28.9%) were hospitalized with ventilation/supplemental oxygen, and 22 (7%) died. Higher odds of severe COVID‐19 outcomes were observed for: age ≥50 years (50–64 years: OR 2.4, 95% confidence interval [CI] 1.33–4.31; >64 years: OR 4.16, 95% CI 2.12–8.15; both vs. <50 years); non‐White race/ethnicity (OR 1.81, 95% CI 1.07–3.06; vs. White); mRS moderately severe/severe disability (OR 3.02, 95% CI 1.6–5.69; vs. no/slight/moderate disability); history of respiratory dysfunction (OR 3.16, 95% CI 1.79–5.58); obesity (OR 2.24, 95% CI 1.18–4.25); ≥3 comorbidities (OR 3.2, 95% CI 1.76–5.83; vs. ≤2; if comorbidity count used instead of specific comorbidities); glucocorticoid treatment (OR 2.33, 95% CI 1.14–4.78); and Guillain–Barré syndrome (OR 3.1, 95% CI 1.35–7.13; vs. mitochondrial disease). Conclusions: Among people with NMDs, there is a differential risk of COVID‐19 outcomes according to demographic and clinical characteristics. These findings could be used to develop tailored management strategies and evidence‐based recommendations for NMD patients. [ABSTRACT FROM AUTHOR]

A rapidly expanding catalog of neurogenetic disorders has encouraged a diagnostic shift towards early clinical whole exome sequencing (WES). Adult primary mitochondrial diseases (PMDs) frequently exhibit neurological manifestations that overlap with other nervous system disorders. However, mitochondrial DNA (mtDNA) is not routinely analyzed in standard clinical WES bioinformatic pipelines. We reanalyzed 11,424 exomes, enriched with neurological diseases, for pathogenic mtDNA variants. Twenty-four different mtDNA mutations were detected in 64 exomes, 11 of which were considered disease causing based on the associated clinical phenotypes. These findings highlight the diagnostic uplifts gained by analyzing mtDNA from WES data in neurological diseases. ANN NEUROL 2021;89:1240-1247. [ABSTRACT FROM AUTHOR]

Over the past two decades there has been increased interest in orphan drug development for rare diseases. However, hurdles to clinical trial design for these disorders remain. This phase 1a/1b study addressed several challenges, while evaluating the safety and tolerability of the novel oral molecule KL1333 in healthy volunteers and subjects with primary mitochondrial disease. KL1333 aims to normalize the NAD+:NADH ratio that is critical for ATP production. The trial incorporated innovative design elements with potential translatability to other rare diseases including patient involvement, adaptive design and exploratory objectives, all of which have subsequently informed the protocol of an ongoing phase 2, pivotal efficacy study of KL1333. Results indicate KL1333 is safe and well tolerated, with dose-dependent gastrointestinal side effects, and validate potential novel outcome measures in primary mitochondrial disease including the 30-s Sit to Stand, and the patient-reported fatigue scales. Importantly, the data from the trial support efficacy of KL1333 based on improvements in fatigue and functional strength and endurance. Furthermore, the study highlights the value in using phase 1 studies to capture data that helps optimize later phase efficacy trial design., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Guarantors of Brain.)

Primary mitochondrial diseases, with diverse systemic manifestations, often present with auditory impairments due to mitochondrial dysfunction. This study provides an in-depth exploration of auditory deficits in primary mitochondrial diseases, highlighting the impact of various pathogenic variants on both cochlea and neural/central auditory functions. An observational study involving 72 adults with primary mitochondrial diseases was conducted. Participants underwent extensive audiological evaluations including pure-tone audiometry, tympanometry, acoustic reflex thresholds, quick speech-in-noise test, listening in spatialized noise-sentences test, auditory-evoked brainstem responses and distortion product otoacoustic emissions. Multivariate analysis of covariance and logistic regression analyses assessed the influence of various pathogenic DNA variants, accounting for age, cognitive status via the Montreal Cognitive Assessment and disease severity through the Newcastle Mitochondrial Disease Adult Scale. Participants with the pathogenic m.3243A>G/T variants (m.3243A>G n = 40; m.3243A>T n = 1) exhibited significant elevations in pure-tone audiometry thresholds, especially at high frequencies, suggesting cochlea involvement. Notably, the listening in spatialized noise-sentences test showed significant spatial processing deficits in the m.3243A>G/T group, possibly indicating a unique mutation-specific impact on central auditory processing. Auditory-evoked brainstem response results highlighted a higher likelihood of auditory brainstem response abnormalities in this group, further substantiating neural/central auditory pathway involvement. This study emphasizes the heterogeneous nature of hearing impairment in primary mitochondrial diseases, with a genotype-phenotype correlation, particularly in the m.3243A>G/T group. These insights advocate for personalized, genotype-specific auditory assessments and targeted management strategies. Conventional hearing aids and cochlear implants are ineffective for those with central auditory dysfunctions related to mitochondrial mutations. There is an urgent need for innovative rehabilitation strategies catering for both cochlear and neural/central auditory pathways., Competing Interests: The authors report no competing interests., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Guarantors of Brain.)

Primary mitochondrial diseases (PMDs) are among the most common inherited neurological disorders. They are caused by pathogenic variants in mitochondrial or nuclear DNA that disrupt mitochondrial structure and/or function, leading to impaired oxidative phosphorylation (OXPHOS). One emerging subcategory of PMDs involves defective phospholipid (PL) metabolism. Cardiolipin (CL), the signature PL of mitochondria, resides primarily in the inner mitochondrial membrane, where it is biosynthesised and remodelled via multiple enzymes and is fundamental to several aspects of mitochondrial biology. Genes that contribute to CL biosynthesis have recently been linked with PMD. However, the pathophysiological mechanisms that underpin human CL-related PMDs are not fully characterised. Here, we report six individuals, from three independent families, harbouring biallelic variants in PTPMT1, a mitochondrial tyrosine phosphatase required for de novo CL biosynthesis. All patients presented with a complex, neonatal/infantile onset neurological and neurodevelopmental syndrome comprising developmental delay, microcephaly, facial dysmorphism, epilepsy, spasticity, cerebellar ataxia and nystagmus, sensorineural hearing loss, optic atrophy, and bulbar dysfunction. Brain MRI revealed a variable combination of corpus callosum thinning, cerebellar atrophy, and white matter changes. Using patient-derived fibroblasts and skeletal muscle tissue, combined with cellular rescue experiments, we characterise the molecular defects associated with mutant PTPMT1 and confirm the downstream pathogenic effects that loss of PTPMT1 has on mitochondrial structure and function. To further characterise the functional role of PTPMT1 in CL homeostasis, we established a zebrafish ptpmt1 knockout model associated with abnormalities in body size, developmental alterations, decreased total CL levels, and OXPHOS deficiency. Together, these data indicate that loss of PTPMT1 function is associated with a new autosomal recessive PMD caused by impaired CL metabolism, highlight the contribution of aberrant CL metabolism towards human disease, and emphasise the importance of normal CL homeostasis during neurodevelopment., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Guarantors of Brain.)

Primary mitochondrial diseases (PMDs) are a heterogeneous group of hereditary disorders characterized by an impairment of the mitochondrial respiratory chain. They are the most common group of genetic metabolic disorders, with a prevalence of 1 in 4,300 people. The presence of leukoencephalopathy is recognized as an important feature in many PMDs and can be a manifestation of mutations in both mitochondrial DNA (classic syndromes such as mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes; myoclonic epilepsy with ragged-red fibers [RRFs]; Leigh syndrome; and Kearns-Sayre syndrome) and nuclear DNA (mutations in maintenance genes such as POLG, MPV17, and TYMP; Leigh syndrome; and mitochondrial aminoacyl-tRNA synthetase disorders). In this chapter, PMDs associated with white matter involvement are outlined, including details of clinical presentations, brain MRI features, and elements of differential diagnoses. The current approach to the diagnosis of PMDs and management strategies are also discussed. A PMD diagnosis in a subject with leukoencephalopathy should be considered in the presence of specific brain MRI features (for example, cyst-like lesions, bilateral basal ganglia lesions, and involvement of both cerebral hemispheres and cerebellum), in addition to a complex neurologic or multisystem disorder. Establishing a genetic diagnosis is crucial to ensure appropriate genetic counseling, multidisciplinary team input, and eligibility for clinical trials., (Copyright © 2024 Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.)

Parkinson's disease is the second most common neurodegenerative disease. Mitochondrial dysfunction has been associated with neurodegeneration in Parkinson's disease, and several treatments targeting mitochondria have been tested in these patients to delay disease progression and tackle disease symptoms. Herein, we review available data from randomised, double-blind clinical studies that have investigated the role of compounds targeting mitochondria in idiopathic Parkinson's disease patients, with a view of providing patients and clinicians with a comprehensive and practical paper that can inform therapeutic interventions in this group of people. A total of 9 compounds have been tested in randomized clinical trials, but only exenatide has shown some promising neuroprotective and symptomatic effects. However, whether this evidence can be translated into daily clinical practice still needs to be confirmed. In conclusion, targeting mitochondrial dysfunction in Parkinson's disease is a promising therapeutic approach, although only one compound has shown a positive effect on Parkinson's disease progression and symptoms. New compounds have been investigated in animal models, and their efficacy needs to be confirmed in humans through robust, randomised, double-blind clinical trials., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)