Search

Cytoplasmic and nuclear iron-sulfur (Fe-S) enzymes that are essential for genome maintenance and replication depend on the cytoplasmic Fe-S assembly (CIA) machinery for cluster acquisition. The core of the CIA machinery consists of a complex of CIAO1, MMS19 and FAM96B. The physiological consequences of loss of function in the components of the CIA pathway have thus far remained uncharacterized. Our study revealed that patients with biallelic loss of function in CIAO1 developed proximal and axial muscle weakness, fluctuating creatine kinase elevation, and respiratory insufficiency. In addition, they presented with CNS symptoms including learning difficulties and neurobehavioral comorbidities, along with iron deposition in deep brain nuclei, mild normocytic to macrocytic anemia, and gastrointestinal symptoms. Mutational analysis revealed reduced stability of the variants compared with WT CIAO1. Functional assays demonstrated failure of the variants identified in patients to recruit Fe-S recipient proteins, resulting in compromised activities of DNA helicases, polymerases, and repair enzymes that rely on the CIA complex to acquire their Fe-S cofactors. Lentivirus-mediated restoration of CIAO1 expression reversed all patient-derived cellular abnormalities. Our study identifies CIAO1 as a human disease gene and provides insights into the broader implications of the cytosolic Fe-S assembly pathway in human health and disease., Introduction Iron-sulfur (Fe-S) clusters are ancient and evolutionarily conserved prosthetic groups with unique chemical properties that enable the proteins that contain them (Fe-S proteins) to function in several essential cellular [...]

Arthrogryposis is a heterogenous condition with a wide variety of etiological causes. It has been subdivided clinically based on the presence of additional features. Dominant gain of function (GoF) pathogenic variants in PIEZO2 have been associated with several forms of arthrogryposis. Previous reports have focused on diagnosis and clinical features. We report a three‐generation family with four affected individuals with a known pathogenic GoF change p.(Glu2727del) in PIEZO2. All family members presented at birth with distal arthrogryposis and ophthalmoplegia but have varied in their subsequent clinical course with differences in mobility and joint restriction. In the longer term, other features have presented including dysphagia, back pain and spinal stenosis‐like symptoms, raised intraocular pressure, and progressive restrictive lung disease. As far as we know, this is the first report detailing the longitudinal follow‐up of a three‐generation family which highlights potential long‐term complications in patients with PIEZO2‐related arthrogryposis. We present this family to demonstrate the importance of long‐term follow‐up for the clinical management of this group of patients. [ABSTRACT FROM AUTHOR]

For patients affected by Facioscapulohumeral dystrophy (FSHD), alternate methods for increasing physical activity engagement that may benefit shoulder function and wider health are needed. Arm cycling has been proposed as a potential method for achieving this although dosage parameters and evidence is limited. The aim of this study was to conduct a pilot study evaluating the effect of a single intermittent arm cycling exercise programme on people affected by FSHD. People with confirmed genetic diagnosis of FSHD between the ages 18–60 years were recruited to attend a single session for the exercise intervention (5 exercise efforts lasting 2 minutes each with 30 seconds of rest between each effort). Prior to exercise, measures of shoulder function (Oxford shoulder score), strength and range of movement were recorded. During the exercise participants were video recorded to quantify range of movement and extract movement profile features. Participants comments were recorded and followed up four days later to check for adverse events. Fifteen participants, (6F:9M) were recruited with median (IQR) Oxford Shoulder Scores of 25 (18 to 39). All participants successfully completed the exercise intervention with only transient symptoms consistent with exercise being reported and achieving a median (IQR) rate of perceived exertion scores of 13 (12 to 13). Movement profile data was available for 12 out of 15 participants and suggests that exercise intensity did not compromise movement. An association between strength and shoulder function (R2 = 0.5147), Rate of perceived exertion (RPE) of the final effort against shoulder function and strength (R2 = 0.2344 and 0.1743 respectively) was identified. Participant comments were positive regarding the exercise intervention. Our study demonstrates that an intermittent arm cycling programme is feasible for people affected by FSHD. Further work is needed to evaluate physiological responses to exercise across variations in programme variables and equipment set up in a larger sample of people affected by FSHD. [ABSTRACT FROM AUTHOR]

Objective: The North Star Ambulatory Assessment (NSAA) is a validated 17-item functional rating scale and widely used to assess motor function in boys with Duchenne muscular dystrophy (DMD). The SARS-CoV-2 pandemic and subsequent Government 'lockdown' resulted in no face-to-face clinic visits hence the motor abilities were not monitored. The aim was to investigate whether the NSAA was feasible and reliable by video assessment. Method: Ten ambulant DMD boys were selected from the electronic hospital records. Two physiotherapists scored the boys' NSAA independently and the intraclass correlation coefficient was used to assess agreement. The video scores were compared to two previous NSAA in-clinic scores. Results: Mean scores (SD) for clinic visit one were 22.6 (4.19) and clinic visit two 21.8 (5.3). The two physiotherapists video mean scores were 20.6 (5.66) for physiotherapist 1 and 20.6 (6.53) for physiotherapist 2. The intraclass correlation coefficient was 0.98 (95% CI 0.93–1.00) for the total NSAA and 1.00 (95% CI 1.00 to 1.00) for the rise time. The mean decline in score from clinic visit one (−12 months) to video assessment was 2.0 (2.8SD). Conclusion: The results from the study suggest that video NSAA is partially feasible and reliable. [ABSTRACT FROM AUTHOR]

Importance: Corticosteroids improve strength and function in boys with Duchenne muscular dystrophy. However, there is uncertainty regarding the optimum regimen and dosage.Objective: To compare efficacy and adverse effects of the 3 most frequently prescribed corticosteroid regimens in boys with Duchenne muscular dystrophy.Design, Setting, and Participants: Double-blind, parallel-group randomized clinical trial including 196 boys aged 4 to 7 years with Duchenne muscular dystrophy who had not previously been treated with corticosteroids; enrollment occurred between January 30, 2013, and September 17, 2016, at 32 clinic sites in 5 countries. The boys were assessed for 3 years (last participant visit on October 16, 2019).Interventions: Participants were randomized to daily prednisone (0.75 mg/kg) (n = 65), daily deflazacort (0.90 mg/kg) (n = 65), or intermittent prednisone (0.75 mg/kg for 10 days on and then 10 days off) (n = 66).Main Outcomes and Measures: The global primary outcome comprised 3 end points: rise from the floor velocity (in rise/seconds), forced vital capacity (in liters), and participant or parent global satisfaction with treatment measured by the Treatment Satisfaction Questionnaire for Medication (TSQM; score range, 0 to 100), each averaged across all study visits after baseline. Pairwise group comparisons used a Bonferroni-adjusted significance level of .017.Results: Among the 196 boys randomized (mean age, 5.8 years [SD, 1.0 years]), 164 (84%) completed the trial. Both daily prednisone and daily deflazacort were more effective than intermittent prednisone for the primary outcome (P < .001 for daily prednisone vs intermittent prednisone using a global test; P = .017 for daily deflazacort vs intermittent prednisone using a global test) and the daily regimens did not differ significantly (P = .38 for daily prednisone vs daily deflazacort using a global test). The between-group differences were principally attributable to rise from the floor velocity (0.06 rise/s [98.3% CI, 0.03 to 0.08 rise/s] for daily prednisone vs intermittent prednisone [P = .003]; 0.06 rise/s [98.3% CI, 0.03 to 0.09 rise/s] for daily deflazacort vs intermittent prednisone [P = .017]; and -0.004 rise/s [98.3% CI, -0.03 to 0.02 rise/s] for daily prednisone vs daily deflazacort [P = .75]). The pairwise comparisons for forced vital capacity and TSQM global satisfaction subscale score were not statistically significant. The most common adverse events were abnormal behavior (22 [34%] in the daily prednisone group, 25 [38%] in the daily deflazacort group, and 24 [36%] in the intermittent prednisone group), upper respiratory tract infection (24 [37%], 19 [29%], and 24 [36%], respectively), and vomiting (19 [29%], 17 [26%], and 15 [23%]).Conclusions and Relevance: Among patients with Duchenne muscular dystrophy, treatment with daily prednisone or daily deflazacort, compared with intermittent prednisone alternating 10 days on and 10 days off, resulted in significant improvement over 3 years in a composite outcome comprising measures of motor function, pulmonary function, and satisfaction with treatment; there was no significant difference between the 2 daily corticosteroid regimens. The findings support the use of a daily corticosteroid regimen over the intermittent prednisone regimen tested in this study as initial treatment for boys with Duchenne muscular dystrophy.Trial Registration: ClinicalTrials.gov Identifier: NCT01603407. [ABSTRACT FROM AUTHOR]

Objective: To describe age and time at key stages in the Duchenne muscular dystrophy (DMD) prediagnosis pathway at selected centres to identify opportunities for service improvement.Design: A multicentre retrospective national audit.Setting: Nine tertiary neuromuscular centres across the UK and Ireland. A prior single-centre UK audit of 20 patients with no DMD family history provided benchmark criteria.Patients: Patients with a definitive diagnosis of DMD documented within 3 years prior to December 2018 (n=122).Main Outcome Measures: Mean age (months) at four key stages in the DMD diagnostic pathway and mean time (months) of presentational and diagnostic delay, and time from first reported symptoms to definitive diagnosis. Type of symptoms was also recorded.Results: Overall, mean age at definitive diagnosis, age at first engagement with healthcare professional (HCP) and age at first reported symptoms were 53.9±29.7, 49.9±28.9 and 36.4±26.8 months, respectively. The presentational delay and time to diagnosis were 21.1 (±21.1) and 4.6 (±7.9) months, respectively. The mean time from first reported symptoms to definitive diagnosis was 24.2±20.9. The percentages of patients with motor and/or non-motor symptoms recorded were 88% (n=106/121) and 47% (n=57/121), respectively.Conclusions: Majority of data mirrored the benchmark audit. However, while the time to diagnosis was shorter, a presentational delay was observed. Failure to recognise early symptoms of DMD could be a contributing factor and represents an unmet need in the diagnosis pathway. Methods determining how to improve this need to be explored. [ABSTRACT FROM AUTHOR]

The objective of this study was to assess the face validity of a disease model evaluating the cost-effectiveness of ataluren for the treatment of nonsense mutation Duchenne muscular dystrophy (nmDMD). This was a Delphi panel study comprising of physicians with first-hand experience of ataluren for the treatment of nmDMD. Consensus was sought for previously unvalidated model data, including patient health status and quality of life measured using the Health Utility Index (HUI), mortality, informal caregiving, and the expected benefit of early ataluren treatment across four states: (1) ambulatory, (2) non-ambulatory, not yet requiring ventilation support, (3) non-ambulatory, night-time ventilation support, and (4) non-ambulatory, full-time ventilation support. Nine experts from five countries participated in the Delphi panel. Consensus was obtained for all questions after three panel rounds (except for two HUI-questions concerning hand function [dexterity]). Consensus HUI-derived utilities for state (1) were 1.0000 for ataluren on top of best supportive care (BSC) and 0.7337 for BSC alone. Corresponding estimates for state (2) were 0.3179 and 0.2672, for state (3) 0.1643 and 0.0913, and for state (4) −0.0732 and −0.1163. Consensus mortality rates for states (1), (2), and (3) were 4%, 13%, and 33%, and life expectancy in state (4) was agreed to be 3 years. Panelists further agreed that two informal caregivers typically provide day-to-day care/support to patients with nmDMD, and that starting treatment with ataluren at 2 versus 5 years of age would be expected to delay loss of ambulation by an additional 2 years, and initiation of night-time and full-time ventilation support by an additional 3 years, respectively. The main limitation concerns the size of the Delphi panel, govern primarily by the rarity of the disease. This study confirms the face validity of key clinical parameters and assumptions underlying the ataluren cost-effectiveness model. [ABSTRACT FROM AUTHOR]

Multiple pterygium syndrome (MPS) disorders are a phenotypically and genetically heterogeneous group of conditions characterized by multiple joint contractures (arthrogryposis), pterygia (joint webbing) and other developmental defects. MPS is most frequently inherited in an autosomal recessive fashion but X‐linked and autosomal dominant forms also occur. Advances in genomic technologies have identified many genetic causes of MPS‐related disorders and genetic diagnosis requires large targeted next generation sequencing gene panels or genome‐wide sequencing approaches. Using the Illumina TruSightOne clinical exome assay, we identified a recurrent heterozygous missense substitution in TPM2 (encoding beta tropomyosin) in three unrelated individuals. This was confirmed to have arisen as a de novo event in the two patients with parental samples. TPM2 mutations have previously been described in association with a variety of dominantly inherited neuromuscular phenotypes including nemaline myopathy, congenital fibre‐type disproportion, distal arthrogryposis and trismus pseudocamptodactyly, and in a patient with autosomal recessive Escobar syndrome and a nemaline myopathy. The three cases reported here had overlapping but variable features. Our findings expand the range of TMP2‐related phenotypes and indicate that de novo TMP2 mutations should be considered in isolated cases of MPS‐related conditions. [ABSTRACT FROM AUTHOR]

Objective: The Global FKRP Registry is a database for individuals with conditions caused by mutations in the Fukutin‐Related Protein (FKRP) gene: limb girdle muscular dystrophy R9 (LGMDR9, formerly LGMD2I) and congenital muscular dystrophies MDC1C, Muscle–Eye–Brain Disease and Walker–Warburg Syndrome. The registry seeks to further understand the natural history and prevalence of FKRP‐related conditions; aid the rapid identification of eligible patients for clinical studies; and provide a source of information to clinical and academic communities. Methods: Registration is patient‐initiated through a secure online portal. Data, reported by both patients and their clinicians, include: age of onset, presenting symptoms, family history, motor function and muscle strength, respiratory and cardiac function, medication, quality of life and pain. Results: Of 663 registered participants, 305 were genetically confirmed LGMDR9 patients from 23 countries. A majority of LGMDR9 patients carried the common mutation c.826C > A on one or both alleles; 67.9% were homozygous and 28.5% were compound heterozygous for this mutation. The mean ages of symptom onset and disease diagnosis were higher in individuals homozygous for c.826C > A compared with individuals heterozygous for c.826C > A. This divergence was replicated in ages of loss of running ability, wheelchair‐dependence and ventilation assistance; consistent with the milder phenotype associated with individuals homozygous for c.826C > A. In LGMDR9 patients, 75.1% were currently ambulant and 24.6%, nonambulant (unreported in 0.3%). Cardiac impairment was reported in 23.2% (30/129). Interpretation: The Global FKRP Registry enables the collection of patient natural history data, which informs academics, healthcare professionals and industry. It represents a trial‐ready cohort of individuals and is centrally placed to facilitate recruitment to clinical studies. [ABSTRACT FROM AUTHOR]

Background: Defects in glycosylation of alpha-dystroglycan (α-DG) cause autosomal-recessive disorders with wide clinical and genetic heterogeneity, with phenotypes ranging from congenital muscular dystrophies to milder limb girdle muscular dystrophies. Patients show variable reduction of immunoreactivity to antibodies specific for glycoepitopes of α-DG on a muscle biopsy. Recessive mutations in 18 genes, including guanosine diphosphate mannose pyrophosphorylase B (GMPPB), have been reported to date. With no specific clinical and pathological handles, diagnosis requires parallel or sequential analysis of all known genes.Methods: We describe clinical, genetic and biochemical findings of 21 patients with GMPPB-associated dystroglycanopathy.Results: We report eight novel mutations and further expand current knowledge on clinical and muscle MRI features of this condition. In addition, we report a consistent shift in the mobility of beta-dystroglycan (β-DG) on Western blot analysis of all patients analysed by this mean. This was only observed in patients with GMPPB in our large dystroglycanopathy cohort. We further demonstrate that this mobility shift in patients with GMPPB was due to abnormal N-linked glycosylation of β-DG.Conclusions: Our data demonstrate that a change in β-DG electrophoretic mobility in patients with dystroglycanopathy is a distinctive marker of the molecular defect in GMPPB. [ABSTRACT FROM AUTHOR]

We conducted a prospective multinational study of muscle pathology using magnetic resonance imaging (MRI) in patients with limb-girdle muscular dystrophy 2I (LGMD2I). Thirty eight adult ambulant LGMD2I patients (19 male; 19 female) with genetically identical mutations (c.826C>A) in the fukutin-related protein (FKRP) gene were recruited. In each patient, T1-weighted (T1w) imaging was assessed by qualitative grading for 15 individual lower limb muscles and quantitative Dixon imaging was analysed on 14 individual lower limb muscles by region of interest analysis. We described the pattern and appearance of muscle pathology and gender differences, not previously reported for LGMD2I. Diffuse fat infiltration of the gastrocnemii muscles was demonstrated in females, whereas in males fat infiltration was more prominent in the medial than the lateral gastrocnemius (p = 0.05). In the anterior thigh of males, in contrast to females, median fat infiltration in the vastus medialis muscle (45.7%) exceeded that in the vastus lateralis muscle (11.2%) (p<0.005). MRI is non-invasive, objective and does not rely on patient effort compared to clinical and physical measures that are currently employed. We demonstrated (i) that the quantitative Dixon technique is an objective quantitative marker of disease and (ii) new observations of gender specific patterns of muscle involvement in LGMD2I. [ABSTRACT FROM AUTHOR]

Background: Outcome measures for clinical trials in neuromuscular diseases are typically based on physical assessments which are dependent on patient effort, combine the effort of different muscle groups, and may not be sensitive to progression over short trial periods in slow-progressing diseases. We hypothesised that quantitative fat imaging by MRI (Dixon technique) could provide more discriminating quantitative, patient-independent measurements of the progress of muscle fat replacement within individual muscle groups. Objective: To determine whether quantitative fat imaging could measure disease progression in a cohort of limb-girdle muscular dystrophy 2I (LGMD2I) patients over a 12 month period. Methods: 32 adult patients (17 male;15 female) from 4 European tertiary referral centres with the homozygous c.826C>A mutation in the fukutin-related protein gene (FKRP) completed baseline and follow up measurements 12 months later. Quantitative fat imaging was performed and muscle fat fraction change was compared with (i) muscle strength and function assessed using standardized physical tests and (ii) standard T1-weighted MRI graded on a 6 point scale. Results: There was a significant increase in muscle fat fraction in 9 of the 14 muscles analyzed using the quantitative MRI technique from baseline to 12 months follow up. Changes were not seen in the conventional longitudinal physical assessments or in qualitative scoring of the T1w images. Conclusions: Quantitative muscle MRI, using the Dixon technique, could be used as an important longitudinal outcome measure to assess muscle pathology and monitor therapeutic efficacy in patients with LGMD2I. [ABSTRACT FROM AUTHOR]

Aristaless-related homeobox (ARX) gene mutations cause a diverse spectrum of disorders of the human brain, including lissencephaly, various forms of epilepsy and non-syndromic mental retardation. We have identified a novel mutation, c.81C>G (p.Y27X), within the ARX gene in a family with two affected male cousins. One of the boys was diagnosed with an early infantile epileptic encephalopathy also known as Ohtahara syndrome, whereas his cousin had been diagnosed with West syndrome (WS). Both patients have normal genitalia and neither have lissencephaly. The ARX mutation identified is predicted to yield a severely truncated protein of only 26 amino acids and can be considered as a null mutation. Somewhat surprisingly, however, it does not yield the X-linked lissencephaly with ambiguous genitalia (XLAG) syndrome. We proposed that the ARX mRNA translation re-initiated at the next AUG codon at position c.121–123 (aa 41) and, thus, partly rescued these patients from XLAG. Our in vitro studies show that this N-terminally truncated ARX protein (p.M41_C562) is detected by western immunoblot in lysates from cells transiently transfected with an ARX over-expression construct containing the c.81C>G mutation. Although these findings widen the spectrum of clinical phenotypes because of mutations in the ARX gene, they also emphasize the molecular pathogenetic effect of individual mutations as well as the effect of genetic background resulting in intrafamilial clinical heterogeneity for these mutations. [ABSTRACT FROM AUTHOR]