Remediation of Perceptual Deficits in Progressive Auditory Neuropathy: A Case Study.

BACKGROUND: Auditory neuropathy (AN) is a hearing disorder that affects neural activity in the VIIIth cranial nerve and central auditory pathways. Progressive forms have been reported in a number of neurodegenerative diseases and may occur as a result of both the deafferentiation and desynchronisation of neuronal processes. The purpose of this study was to describe changes in auditory function over time in a patient with axonal neuropathy and to explore the effect of auditory intervention. METHODS: We tracked auditory function in a child with progressive AN associated with Charcot-Marie-Tooth (Type 2C) disease, evaluating hearing levels, auditory-evoked potentials, and perceptual abilities over a 3-year period. Furthermore, we explored the effect of auditory intervention on everyday listening and neuroplastic development. RESULTS: While sound detection thresholds remained constant throughout, both electrophysiologic and behavioural evidence suggested auditory neural degeneration over the course of the study. Auditory brainstem response amplitudes were reduced, and perception of auditory timing cues worsened over time. Functional hearing ability (speech perception in noise) also deteriorated through the first 1.5 years of study until the child was fitted with a "remote-microphone" listening device, which subsequently improved binaural processing and restored speech perception ability to normal levels. CONCLUSIONS: Despite the deterioration of auditory neural function consistent with peripheral axonopathy, sustained experience with the remote-microphone listening system appeared to produce neuroplastic changes, which improved the patient's everyday listening ability-even when not wearing the device.

Rare homozygous disease-associated sequence variants in children with spinal muscular atrophy: a phenotypic description and review of the literature.

5q-associated spinal muscular atrophy (SMA) is the most common autosomal recessive neurological disease. Depletion in functional SMN protein leads to dysfunction and irreversible degeneration of the motor neurons. Over 95 % of individuals with SMA have homozygous exon 7 deletions in the SMN1 gene. Most of the remaining 4-5 % are compound heterozygous for deletion and a disease-associated sequence variant in the non-deleted allele. Individuals with SMA due to bi-allelic SMN1 sequence variants have rarely been reported. Data regarding their clinical phenotype, disease progression, outcome and treatment response are sparse. This study describes six individuals from three families, all with homozygous sequence variants in SMN1, and four of whom received treatment with disease-modifying therapies. We also describe the challenges faced during the diagnostic process and intrafamilial phenotypic variability observed between siblings.

Practical approach to the child presenting with acute generalised weakness.

Acute generalised muscle weakness in children is a paediatric emergency with a broad differential diagnosis. A careful history and neurologic examination guides timely investigation and management. We review some of the more common causes of acute generalised muscle weakness in children, highlighting key history and examination findings, along with an approach to lesion localisation to guide differential diagnosis and further investigation.

Pilot study of a virtual weight management program for Duchenne muscular dystrophy.

INTRODUCTION/AIMS: Young people with Duchenne muscular dystrophy (DMD) are at increased risk of obesity. Weight management is important to families; however, several barriers exist. This pilot study aimed to investigate the feasibility and acceptability of a co-designed weight management program for DMD. METHODS: The Supporting Nutrition and Optimizing Wellbeing Program (SNOW-P) was a single-arm diet and behavior weight management intervention delivered via weekly telehealth/phone visits over 6 weeks to young people with DMD and obesity (body mass index (BMI) ≥95th percentile) and their caregivers. Using an online survey, caregivers of boys with DMD were consulted on the structure and topics delivered in SNOW-P. Primary outcomes were feasibility and acceptability; secondary outcomes were weight, physical function, and quality of life at 6- and 12-weeks follow-up. RESULTS: Of nineteen eligible participants, eight were enrolled (median age 11.4 years, range 4.9-15.8), and seven completed the program. Visit attendance was high (88%-100%); most participants reported high satisfaction and that participation was easy. Suggested changes included online and visual DMD-specific resources. At 6-weeks, median change in weight z-scores was -0.01 (IQR: -0.23, 0.17) indicating that on average, weight gain tracked as expected for age. Waist circumference measured by caregivers lacked accuracy and the completion rate of caregiver-reported secondary outcome measures (e.g., food diaries) was low. DISCUSSION: A co-designed, telehealth/phone weight management program appeared to be feasible and acceptable in a small group of boys with DMD. An adapted, hybrid telehealth and face-to-face program is recommended for efficacy testing.

A phase 2 open-label study of the safety and efficacy of weekly dosing of ATL1102 in patients with non-ambulatory Duchenne muscular dystrophy and pharmacology in mdx mice.

BACKGROUND: ATL1102 is a 2'MOE gapmer antisense oligonucleotide to the CD49d alpha subunit of VLA-4, inhibiting expression of CD49d on lymphocytes, reducing survival, activation and migration to sites of inflammation. Children with DMD have dystrophin deficient muscles susceptible to contraction induced injury, which triggers the immune system, exacerbating muscle damage. CD49d is a biomarker of disease severity in DMD, with increased numbers of high CD49d expressing T cells correlating with more severe and progressive weakess, despite corticosteroid treatment. METHODS: This Phase 2 open label study assessed the safety, efficacy and pharmacokinetic profile of ATL1102 administered as 25 mg weekly by subcutaneous injection for 24 weeks in 9 non-ambulatory boys with DMD aged 10-18 years. The main objective was to assess safety and tolerability of ATL1102. Secondary objectives included the effect of ATL1102 on lymphocyte numbers in the blood, functional changes in upper limb function as assessed by Performance of Upper Limb test (PUL 2.0) and upper limb strength using MyoGrip and MyoPinch compared to baseline. RESULTS: Eight out of nine participants were on a stable dose of corticosteroids. ATL1102 was generally safe and well tolerated. No serious adverse events were reported. There were no participant withdrawals from the study. The most commonly reported adverse events were injection site erythema and skin discoloration. There was no statistically significant change in lymphocyte count from baseline to week 8, 12 or 24 of dosing however, the CD3+CD49d+ T lymphocytes were statistically significantly higher at week 28 compared to week 24, four weeks past the last dose (mean change 0.40x109/L 95%CI 0.05, 0.74; p = 0.030). Functional muscle strength, as measured by the PUL2.0, EK2 and Myoset grip and pinch measures, and MRI fat fraction of the forearm muscles were stable throughout the trial period. CONCLUSION: ATL1102, a novel antisense drug being developed for the treatment of inflammation that exacerbates muscle fibre damage in DMD, appears to be safe and well tolerated in non-ambulant boys with DMD. The apparent stabilisation observed on multiple muscle disease progression parameters assessed over the study duration support the continued development of ATL1102 for the treatment of DMD. TRIAL REGISTRATION: Clinical Trial Registration. Australian New Zealand Clinical Trials Registry Number: ACTRN12618000970246.

Geographic Expansion of Japanese Encephalitis Virus to Australia: Neuroinflammatory Sequelae and Consideration of Immunomodulation.

We report a child from Southern Australia (New South Wales) who presented during a La Niña event with encephalopathy and acute flaccid paralysis. Magnetic resonance imaging suggested Japanese encephalitis (JE). Steroids and intravenous immunoglobulin did not improve symptoms. Therapeutic plasma exchange (TPE) resulted in rapid improvement and tracheostomy decannulation. Our case illustrates the complex pathophysiology of JE, its' geographic expansion into Southern Australia and potential use of TPE for neuroinflammatory sequelae.

Fracture risk and impact in boys with Duchenne muscular dystrophy: A retrospective cohort study.

INTRODUCTION/AIMS: Boys with Duchenne muscular dystrophy (DMD) are at increased risk of fracture. This study investigated the incidence of fractures, factors contributing to risk of first fracture with emphasis on body mass index (BMI), and the impact of fractures on functional capacity in an Australian cohort of boys with DMD. METHODS: A retrospective cohort study included boys with DMD who attended a pediatric neuromuscular clinic from 2011 to 2018. Information regarding fractures, anthropometry measurements, body composition and functional assessment was collected. Factors associated with first fracture risk were analyzed with Cox-proportional hazards. Longitudinal analysis of function post-fracture was also conducted. RESULTS: This study included 155 boys with DMD. At least one fracture occurred in 71 (45%) boys; overall incidence of fractures was 399-per-10,000 persons-years. The first fracture was vertebral in 55%; 41% had non-vertebral fractures and 4% had both. Vertebral fractures occurred in significantly older (12.28 vs 9.28 y) boys with longer exposure to glucocorticoids (5.45 vs 2.50 y) compared to non-vertebral fractures. Boys with a history of fracture(s) had a steeper rate of functional decline (measured by Northstar Ambulatory Assessment score) than those with no recorded fractures. DISCUSSION: A high fracture burden was observed in a large Australian cohort of boys with DMD. Further investigation is required to understand preventative strategies and modifiable risk factors to reduce the incidence of fractures in DMD. The impact on fractures on ambulatory capacity should be closely monitored.

Delivering multidisciplinary neuromuscular care for children via telehealth.

INTRODUCTION/AIMS: In response to coronavirus disease 2019 (COVID-19) pandemic restrictions int 2020, our face-to-face (F2F) multidisciplinary neuromuscular clinic (NMC) transitioned to widespread use of telehealth (TH). This study aimed to (1) understand parent/guardian, child, and clinician perceptions of TH; (2) examine TH-related changes in clinical activity; and (3) use these findings to inform a future model of care for the NMC. METHODS: A clinical audit was undertaken to examine clinical activity throughout 2018-2020. Online surveys were distributed to clinicians and parents of children attending the NMC via TH in 2020. A working group of clinicians created a checklist to guide a future hybrid model of TH and F2F care. RESULTS: Total clinical activity in 2020 was maintained from previous years; 62.8% of all appointments occurred via TH, and 82.3% of patients attended NMC by TH at least once. Ninety-nine parents (30.6% response rate), 52 children, and 17 clinicians (77% response rate) responded to the survey. All groups reported better interaction when F2F compared to TH. Eighty percent of parents identified advantages of TH and reported lower levels of stress. A lack of "hands-on" physical assessment was identified by parents and clinicians as a TH limitation. Most families (68.1% of parents; 58.8% of children) and all clinicians indicated a preference for a mix of TH and F2F NMC appointments in the future. DISCUSSION: This study has informed a checklist to guide future TH use in a new hybrid model of care. Further investigation is required to assess health impacts of TH use in pediatric neuromuscular care.

Clinical practice guideline for the management of paediatric Charcot-Marie-Tooth disease.

BACKGROUND AND OBJECTIVES: Charcot-Marie-Tooth disease (CMT) is the most common inherited neuropathy and often presents during childhood. Guidelines for the optimal management of common problems experienced by individuals with CMT do not exist, for either children or adults. We formed the Paediatric CMT Best Practice Guidelines Consortium to develop evidence and consensus-based recommendations for the clinical management of children and adolescents with CMT, with the primary objective of promoting optimal, standardised care globally. METHODS: Development of this clinical practice guideline involved a series of systematic reviews covering 10 clinical questions, modified Delphi methodology involving an international panel of clinicians to generate consensus where evidence did not exist, and application of the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach to evaluate the body of literature and formulate recommendations. RESULTS: The final guideline includes three evidence-based and 31 consensus-based recommendations. They encompass the management of muscle weakness, balance and mobility impairment, sensory symptoms, muscle cramps, impaired upper limb function, respiratory impairment, maintenance of joint range of motion and non-surgical management of joint deformity. Consensus was not achieved in some management areas, reflecting differences in practice between clinicians and healthcare settings, and highlighting the need for further research. CONCLUSIONS: This clinical practice guideline provides practical and implementable guidance on the management of common clinical problems experienced by children with CMT and advocates for improved access to multidisciplinary care. Successful dissemination and implementation of these recommendations will be critical in ensuring their application across multiple healthcare settings.

Onasemnogene abeparvovec in spinal muscular atrophy: an Australian experience of safety and efficacy.

OBJECTIVE: To provide a greater understanding of the tolerability, safety and clinical outcomes of onasemnogene abeparvovec in real-world practice, in a broad population of infants with spinal muscular atrophy (SMA). METHODS: A prospective cohort study of children with SMA treated with onasemnogene abeparvovec at Sydney Children's Hospital Network, Australia was conducted from August 2019 to November 2021. Safety outcomes included clinical and laboratory evaluations. Efficacy assessments included World Health Organisation (WHO) motor milestones, oral and swallowing abilities, and requirements for respiratory support. The implementation of a model of care for onasemnogene abeparvovec administration in health practice is described. RESULTS: 21 children were treated (age range, 0.65-24 months; body weight range, 2.5-12.5 kg) and 19/21 (90.4%) had previous nusinersen. Transient treatment-related side effects occurred in all children; vomiting (100%), transaminitis (57%) and thrombocytopaenia (33%). Incidence of moderate/severe transaminitis was significantly greater in infants weighing ≥8 kg compared with <8 kg (p < 0.05). Duration of prednisolone following treatment was prolonged (mean 87.5 days, range 57-274 days). 16/21 (76%) children gained at least one WHO motor milestone. Stabilisation or improvement in bulbar or respiratory function was observed in 20/21 (95.2%) patients. Implementation challenges were mitigated by developing standard operating procedures and facilitating exchange of knowledge. INTERPRETATION: This study provides real-world evidence to inform treatment decisions and guide therapeutic expectations for onasemnogene abeparvovec and combination therapy for SMA in health practice, especially for children weighing ≥8 kg receiving higher vector loads. Proactive clinical and laboratory surveillance is essential to facilitate individualised management of risks.

The Responsiveness of Gait and Balance Outcomes to Disease Progression in Friedreich Ataxia.

To identify gait and balance measures that are responsive to change during the timeline of a clinical trial in Friedreich ataxia (FRDA), we administered a battery of potential measures three times over a 12-month period. Sixty-one ambulant individuals with FRDA underwent assessment of gait and balance at baseline, 6 months and 12 months. Outcomes included GAITRite® spatiotemporal gait parameters; Biodex Balance System Postural Stability Test (PST) and Limits of Stability; Berg Balance Scale (BBS); Timed 25-Foot Walk Test; Dynamic Gait Index (DGI); SenseWear MF Armband step and energy activity; and the Friedreich Ataxia Rating Scale Upright Stability Subscale (FARS USS). The standardised response mean (SRM) or correlation coefficients were reported as effect size indices for comparison of internal responsiveness. Internal responsiveness was also analysed in subgroups. SenseWear Armband daily step count had the largest effect size of all the variables over 6 months (SRM = -0.615), while the PST medial-lateral index had the largest effect size (SRM = 0.829) over 12 months. The FARS USS (SRM = 0.824) and BBS (SRM = -0.720) were the only outcomes able to detect change over 12 months in all subgroups. The DGI was the most responsive outcome in children, detecting a mean change of -2.59 (95% CI -3.52 to -1.66, p < 0.001, SRM = -1.429). In conclusion, the FARS USS and BBS are highly responsive and can detect change in a wide range of ambulant individuals with FRDA. However, therapeutic effects in children may be best measured by the DGI.

[Evidence based guidelines. Diagnosis and management of Guillain-Barré syndrome in ten steps]. / Guía basada en la evidencia. Diagnóstico y manejo del síndrome de Guillain-Barré en diez pasos.

Guillain-Barré syndrome (GBS) is a rare, but potentially fatal, immune-mediated disease of the peripheral nerves and nerve roots that is usually triggered by infections. The incidence of GBS can therefore increase during outbreaks of infectious diseases, as was seen during the Zika virus epidemics in 2013 in French Polynesia and in 2015 in Latin America. Diagnosis and management of GBS can be complicated as its clinical presentation and disease course are heterogeneous, and no international clinical guidelines are currently available. To support clinicians, especially in the context of an outbreak, we have developed a globally applicable guideline for the diagnosis and management of GBS. The guideline is based on current literature and expert consensus, and has a ten-step structure to facilitate its use in clinical practice. We first provide an introduction to the diagnostic criteria, clinical variants and differential diagnoses of GBS. The ten steps then cover early recognition and diagnosis of GBS, admission to the intensive care unit, treatment indication and selection, monitoring and treatment of disease progression, prediction of clinical course and outcome, and management of complications and sequelae.

El síndrome de Guillain-Barré (SGB) es una enfermedad inmunológica del nervio periférico y las raíces nerviosas, poco frecuente, potencialmente mortal y que suele desencadenarse por infecciones. La incidencia del SGB puede aumentar durante el brote de enfermedades infecciosas, tal como se observó en las epidemias del virus Zika en la Polinesia Francesa en 2013 y en América Latina en 2015. El diagnóstico y el manejo clínico del SGB pueden ser complicados ya que su presentación y el curso de la enfermedad son heterogéneos, y actualmente no se cuenta con guías clínicas internacionales. Para respaldar a los médicos, especialmente en el contexto de un brote de una enfermedad infecciosa, hemos desarrollado una guía clínica aplicable en todo el mundo para el diagnóstico y el tratamiento del SGB. La guía se basa en literatura actualizada y el consenso de expertos, y tiene una estructura de diez pasos para facilitar su uso en la práctica clínica. Inicialmente, brindamos una introducción a los criterios de diagnóstico, variantes clínicas y diagnósticos diferenciales del SGB. Los diez pasos luego abordan el reconocimiento y el diagnóstico temprano del SGB, la admisión a la unidad de cuidados intensivos, indicación y selección de tratamiento, seguimiento y tratamiento de la progresión de la enfermedad, predicción del curso clínico, resultados y tratamiento de complicaciones y secuelas.

Guía basada en la evidencia. Diagnóstico y manejo del síndrome de Guillain-Barré en diez pasos / Evidence based guidelines. Diagnosis and management of Guillain-Barré syndrome in ten steps

Resumen El síndrome de Guillain-Barré (SGB) es una enfermedad inmunológica del nervio periférico y las raíces nerviosas, poco frecuente, potencialmente mortal y que suele desencadenarse por infecciones. La incidencia del SGB puede aumentar durante el brote de enfermedades infecciosas, tal como se observó en las epidemias del virus Zika en la Polinesia Francesa en 2013 y en América Latina en 2015. El diagnóstico y el manejo clínico del SGB pueden ser complicados ya que su presentación y el curso de la enfermedad son heterogéneos, y actualmente no se cuenta con guías clínicas internacionales. Para respaldar a los médicos, especialmente en el contexto de un brote de una enfermedad infecciosa, hemos desarrollado una guía clínica aplicable en todo el mundo para el diagnóstico y el tratamiento del SGB. La guía se basa en literatura actualizada y el consenso de expertos, y tiene una estructura de diez pasos para facilitar su uso en la práctica clínica. Inicialmente, brindamos una introducción a los criterios de diagnóstico, variantes clínicas y diagnósticos diferenciales del SGB. Los diez pasos luego abordan el reconocimiento y el diagnóstico temprano del SGB, la admisión a la unidad de cuidados intensivos, indicación y selección de tratamiento, seguimiento y tratamiento de la progresión de la enfermedad, predicción del curso clínico, resultados y tratamiento de complicaciones y secuelas.

Abstract Guillain-Barré syndrome (GBS) is a rare, but potentially fatal, immune-mediated disease of the peripheral nerves and nerve roots that is usually triggered by infections. The incidence of GBS can therefore increase during outbreaks of infectious diseases, as was seen during the Zika virus epidemics in 2013 in French Polynesia and in 2015 in Latin America. Diagnosis and management of GBS can be complicated as its clinical presentation and disease course are heterogeneous, and no international clinical guidelines are currently available. To support clinicians, especially in the context of an outbreak, we have developed a globally applicable guideline for the diagnosis and management of GBS. The guideline is based on current literature and expert consensus, and has a ten-step structure to facilitate its use in clinical practice. We first provide an introduction to the diag nostic criteria, clinical variants and differential diagnoses of GBS. The ten steps then cover early recognition and diagnosis of GBS, admission to the intensive care unit, treatment indication and selection, monitoring and treatment of disease progression, prediction of clinical course and outcome, and management of complications and sequelae.

Determining the Validity of Conducting Rating Scales in Friedreich Ataxia through Video.

BACKGROUND: The Friedreich Ataxia Rating Scale (FARS) and the Scale for the Assessment and Rating of Ataxia (SARA) are commonly used neurological rating scales in Friedreich ataxia (FRDA). The modified Friedreich Ataxia Rating Scale (mFARS) has been accepted as an appropriate outcome measure for clinical trials in FRDA. OBJECTIVES: The COVID-19 pandemic has resulted in limited face-to-face interactions with individuals involved in natural history studies and clinical trials. The aim of this study was to determine the validity of conducting the mFARS and SARA through video. METHODS: Individuals who had the mFARS administered face-to-face in the previous 6 months were invited to participate. Participants were sent instructions and asked to have a carer present to assist. The mFARS and SARA were then administered by video. Differences between face-to-face and video scores and the reliability between scores obtained face-to-face and by video were examined. RESULTS: The mFARS and SARA were conducted by video with 19 individuals. Excellent test-retest reliability was seen in the mFARS lower limb coordination (ICC = 0.96, 95% CI 0.90-0.98) and upright stability sections (ICC = 0.97, 95% CI 0.93-0.99), total mFARS (ICC = 0.97, 95% CI 0.92-0.99) and SARA scores (ICC = 0.98, 95% CI 0.95-0.99). CONCLUSIONS: Excellent test-retest reliability was demonstrated in the majority of the mFARS sections, and in the total mFARS and SARA scores, suggesting that video is a valid method of conducting these scales. This method enables inclusion of participants who are unable to travel to study sites. A larger cohort will be required to further validate the use of video mFARS and SARA for future studies.

The severe epilepsy syndromes of infancy: A population-based study.

OBJECTIVE: To study the epilepsy syndromes among the severe epilepsies of infancy and assess their incidence, etiologies, and outcomes. METHODS: A population-based cohort study was undertaken of severe epilepsies with onset before age 18 months in Victoria, Australia. Two epileptologists reviewed clinical features, seizure videos, and electroencephalograms to diagnose International League Against Epilepsy epilepsy syndromes. Incidence, etiologies, and outcomes at age 2 years were determined. RESULTS: Seventy-three of 114 (64%) infants fulfilled diagnostic criteria for epilepsy syndromes at presentation, and 16 (14%) had "variants" of epilepsy syndromes in which there was one missing or different feature, or where all classical features had not yet emerged. West syndrome (WS) and "WS-like" epilepsy (infantile spasms without hypsarrhythmia or modified hypsarrhythmia) were the most common syndromes, with a combined incidence of 32.7/100 000 live births/year. The incidence of epilepsy of infancy with migrating focal seizures (EIMFS) was 4.5/100 000 and of early infantile epileptic encephalopathy (EIEE) was 3.6/100 000. Structural etiologies were common in "WS-like" epilepsy (100%), unifocal epilepsy (83%), and WS (39%), whereas single gene disorders predominated in EIMFS, EIEE, and Dravet syndrome. Eighteen (16%) infants died before age 2 years. Development was delayed or borderline in 85 of 96 (89%) survivors, being severe-profound in 40 of 96 (42%). All infants with EIEE or EIMFS had severe-profound delay or were deceased, but only 19 of 64 (30%) infants with WS, "WS-like," or "unifocal epilepsy" had severe-profound delay, and only two of 64 (3%) were deceased. SIGNIFICANCE: Three quarters of severe epilepsies of infancy could be assigned an epilepsy syndrome or "variant syndrome" at presentation. In this era of genomic testing and advanced brain imaging, diagnosing epilepsy syndromes at presentation remains clinically useful for guiding etiologic investigation, initial treatment, and prognostication.

The effects of calf massage in boys with Duchenne muscular dystrophy: a prospective interventional study.

PURPOSE: We explored the effects of standardized calf massage in ambulant boys with Duchenne muscular dystrophy (DMD) using a prospective study design. MATERIALS AND METHODS: Twenty boys completed two study visits, 1 week apart. At both visits, each leg received a 10-min calf massage (intervention) and a 10-min control rest period (placebo) in randomized order. Muscle length of calf and hamstrings and gastrocnemius stiffness were measured by a blinded assessor before and after intervention and placebo. Measures of gait function (timed 10-m walk/run and spatio-temporal gait parameters); gastrocnemius muscle ultrasound findings; participant perception of leg pain, stiffness and effort of walking and general psychological well-being were also collected. RESULTS: Consistent significant small increases in muscle length of soleus, gastrocnemius and hamstrings were recorded post-massage, and gastrocnemius stiffness decreased. Small changes in gastrocnemius and soleus length only were also recorded following the control rest period. Gait function and general well-being remained stable throughout. Measurement across both study visits suggested that gains in muscle length may be cumulative with repeated massage. CONCLUSIONS: Calf massage is safe and associated with benefits to muscle length and stiffness for ambulant boys with DMD.Implications for RehabilitationIn a small sample of boys with Duchenne muscular dystrophy, calf massage was found to be safe, well-tolerated and associated with increased muscle length and decreased stiffness.The use of massage may assist in managing muscle length in boys with Duchenne muscular dystrophy.

Energy metabolism and mitochondrial defects in X-linked Charcot-Marie-Tooth (CMTX6) iPSC-derived motor neurons with the p.R158H PDK3 mutation.

Charcot-Marie-Tooth (CMT) is a group of inherited diseases clinically and genetically heterogenous, characterised by length dependent degeneration of axons of the peripheral nervous system. A missense mutation (p.R158H) in the pyruvate dehydrogenase kinase 3 gene (PDK3) has been identified as the genetic cause for an X-linked form of CMT (CMTX6) in two unrelated families. PDK3 is one of four PDK isoenzymes that regulate the activity of the pyruvate dehydrogenase complex (PDC). The balance between kinases (PDKs) and phosphatases (PDPs) determines the extend of oxidative decarboxylation of pyruvate to generate acetyl CoA, critically linking glycolysis and the energy producing Krebs cycle. We had shown the p.R158H mutation causes hyperactivity of PDK3 and CMTX6 fibroblasts show hyperphosphorylation of PDC, leading to reduced PDC activity and ATP production. In this manuscript we have generated induced pluripotent stem cells (iPSCs) by re-programming CMTX6 fibroblasts (iPSCCMTX6). We also have engineered an isogenic control (iPSCisogenic) and demonstrated that genetic correction of the p.R158H mutation reverses the CMTX6 phenotype. Patient-derived motor neurons (MNCMTX6) show increased phosphorylation of the PDC, energy metabolism defects and mitochondrial abnormalities, including reduced velocity of trafficking mitochondria in the affected axons. Treatment of the MNCMTX6 with a PDK inhibitor reverses PDC hyperphosphorylation and the associated functional deficits founds in the patient motor neurons, demonstrating that the MNCMTX6 and MNisogenic motor neurons provide an excellent neuronal system for compound screening approaches to identify drugs for the treatment of CMTX6.

Hyperinsulinaemic hypoglycaemia: A rare association of vanishing white matter disease.

We report two unrelated patients with infantile onset leukoencephalopathy with vanishing white matter (VWM) and hyperinsulinaemic hypoglycaemia. To our knowledge, this association has not been described previously. Both patients had compound heterozygous pathogenic variants in EIF2B4 detected on exome sequencing and absence of other variants which might explain the hyperinsulinism. Hypoglycaemia became apparent at 6 and 8 months, respectively, although in one patient, transient neonatal hypoglycaemia was also documented. One patient responded to diazoxide and the other was managed with continuous nasogastric feeding. We hypothesise that the pathophysiology of hyperinsulinism in VWM may involve dysregulation of transcription of genes related to insulin secretion.

Neuromyelitis Optica Spectrum Disorder and Anti-Aquaporin 4 Channel Immunoglobulin in an Australian Pediatric Demyelination Cohort.

Neuromyelitis optica spectrum disorder is uncommon in children, and often seronegative for aquaporin-4 immunoglobulin G (AQP4-IgG). We conducted a retrospective study of 67 children presenting to a single Australian center with acquired demyelinating syndromes over a 7-year period. All patients were tested for AQP4-IgG. Five children (7.5%) had neuromyelitis optica spectrum disorder. One child was seropositive for AQP4-IgG (1.5%) and had a relapsing disease course with mild residual deficits. She also had a concomitant motor axonal neuropathy that improved with immunosuppressive therapy. Of the remaining 4 children, 3 had a monophasic course and 1 a relapsing course. Two were tested for anti-myelin oligodendrocyte glycoprotein (anti-MOG) antibody and both were seropositive. This study confirms that neuromyelitis optica spectrum disorder is uncommon in children, and that AQP4-IgG seropositivity is rare. Anti-MOG antibodies should be tested in children with neuromyelitis optica spectrum disorder.