Childhood Onset Research Articles

Neurocognitive disorder in Myotonic dystrophy type 1

Cognitive deficits and abnormal cognitive aging have been associated with Myotonic dystrophy type 1 (DM1), but the knowledge of the extent and progression of decline is limited. The aim of this study was to examine the prevalence of signs of neurocognitive disorder (mild cognitive impairment and dementia) in adult patients with DM1. A total of 128 patients with childhood, juvenile, adult, and late onset DM1 underwent a screening using the Montreal Cognitive Assessment (MoCA). Demographic and clinical information was collected. The results revealed that signs of neurocognitive disorder were relatively rare among the participants. However, 23.8 % of patients with late onset DM1 (aged over 60 years) scored below MoCA cut-off (=23), and this group also scored significantly worse compared to patients with adult onset. Age at examination were negatively correlated with MoCA scores, although it only explained a small portion of the variation in test results. Other demographic and clinical factors showed no association with MoCA scores. In conclusion, our findings indicate a low prevalence of signs of neurocognitive disorder in adult patients with DM1, suggesting that cognitive deficits rarely progress to severe disorders over time. However, the performance of patients with late onset DM1 suggests that this phenotype warrants further exploration in future studies, including longitudinal and larger sample analyses.

Deciding Without Data: A Case for Inclusion of Adults with Childhood Onset Disease in the Palliative Care Literature

Deciding Without Data: A Case for Inclusion of Adults with Childhood Onset Disease in the Palliative Care Literature

Cardiovascular risk in young people with childhood onset systemic lupus erythematosus

Cardiovascular risk in young people with childhood onset systemic lupus erythematosus

Incidences of newly diagnosed childhood diabetes and onset severity: a multicenter regional study in Thailand over two decades and during the COVID-19 pandemic.

While global incidence rates (IR) of childhood diabetes are increasing, there is a notable lack of current informationon theincidence of childhood-onset diabetesin Thailand. This study aims to illustrate the age-standardized IR and types of childhood diabetes using multicenter regional data in Northern Thailand from 2005 to 2022 and to assess the impact of the COVID-19 pandemic. Data on newly diagnosed childhood diabetes were retrospectively collected between 2005 and 2016 and prospectively recorded for all incident cases between 2016 and 2022. The capture-recapture method was applied to estimate the completeness of ascertainment. The age-standardized IR of diabetes was calculated. The IR of diabetes and the prevalence/severity of DKA at onset were compared between the pre-pandemic and pandemic periods. Among 210 patients, type 1 diabetes (T1D) accounted for 56.2 %, type 2 diabetes (T2D) for 39 %, and other types for 4.8 %. The T1D age-standardized IR significantly increased from 0.30 in 2005 to 3.11/100,000 person/year in 2022, mirroring the T2D trend, which increased from 0.33 to 3.15/100,000 person/year. The average T1D age-standardized IR, including the prevalence/severity of DKA at diagnosis, did not significantly differ between the pre-pandemic and pandemic periods (2.11 vs. 2.36/100,000 person/year, p-value=0.67). However, the average T2D age-standardized IR significantly increased from 0.83 to 2.15/100,000 person/year during the pandemic (p-value=0.0057). This study highlights an increased incidence of childhood T1D and T2D in Northern Thailand over a two-decade period. Notably, during the COVID-19 pandemic, the T1D incidence remained stable, while a significant rise in T2D incidence was observed.

Inherited KDM6AA649T facilitates tumor-immune escape and exacerbates colorectal signet-ring cell carcinoma outcomes.

Childhood onset of colorectal signet-ring cell carcinoma (CR-SRCC) is extremely rare and featured as highly malignant with poor prognosis. Here we reported a CR-SRCC case of 11-year-old boy with a novel inherited X-linked KDM6AA694T mutation. The H3K27me3 demethylase KDM6A was frequently mutated in varieties of tumors and acts as a tumor suppressor. In vivo H3K27me3 demethylation assay demonstrated that KDM6AA694T had dampened H3K27me3 demethylase activity. Overexpression of KDM6AA694T in SRCC cell line KATO3 promoted cell proliferation, invasion and migration, which were further confirmed in vivo by constructing orthotopic tumor growth and lung metastasis model. Besides, expression of KDM6AA694T in immune cells suppresses inflammatory macrophage response and effector T cell response. In conclusion, we characterized a novel inherited KDM6AA694T mutant from a childhood-onset SRCC case and demonstrated that the mutant with impaired H3K27me3 demethylase activity could potentiate tumor malignancy and suppress antitumor immunity.

The Hexokinase 1 5'-UTR Mutation in Charcot-Marie-Tooth 4G Disease Alters Hexokinase 1 Binding to Voltage-Dependent Anion Channel-1 and Leads to Dysfunctional Mitochondrial Calcium Buffering.

Demyelinating Charcot-Marie-Tooth 4G (CMT4G) results from a recessive mutation in the 5'UTR region of the Hexokinase 1 (HK1) gene. HK participates in mitochondrial calcium homeostasis by binding to the Voltage-Dependent Anion Channel (VDAC), through its N-terminal porin-binding domain. Our hypothesis is that CMT4G mutation results in a broken interaction between mutant HK1 and VDAC, disturbing mitochondrial calcium homeostasis. We studied a cohort of 25 CMT4G patients recruited in the French gypsy population. The disease was characterized by a childhood onset, an intermediate demyelinating pattern, and a significant phenotype leading to becoming wheelchair-bound by the fifth decade of life. Co-IP and PLA studies indicated a strong decreased interaction between VDAC and HK1 in the patients' PBMCs and sural nerve. We observed that either wild-type HK1 expression or a peptide comprising the 15 aa of the N-terminal wild-type HK1 administration decreased mitochondrial calcium release in HEK293 cells. However, mutated CMT4G HK1 or the 15 aa of the mutated HK1 was unable to block mitochondrial calcium release. Taken together, these data show that the CMT4G-induced modification of the HK1 N-terminus disrupts HK1-VDAC interaction. This alters mitochondrial calcium buffering that has been shown to be critical for myelin sheath maintenance.

COVID-19 and Asthma Onset in Children.

Respiratory viral infections increase risk of asthma in infants and children. Infection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus can cause severe lung inflammation and prolonged respiratory symptoms. We sought to determine whether SARS-CoV-2 infection modified pediatric incident asthma risk. This retrospective cohort study examined children ages 1 to 16 within the Children's Hospital of Philadelphia Care Network who received polymerase chain reaction (PCR) testing for SARS-CoV-2 between March 1, 2020 and February 28, 2021. Multivariable Cox regression models assessed the hazard ratio of new asthma diagnosis between SARS-CoV-2 PCR positive and SARS-CoV-2 PCR negative groups within an 18-month observation window. Models were adjusted for demographic characteristics, socioeconomic variables, and atopic comorbidities. There were 27 423 subjects included in the study. In adjusted analyses, SARS-CoV-2 PCR positivity had no significant effect on the hazard of new asthma diagnosis (hazard ratio [HR]: 0.96; P = .79). Black race (HR: 1.49; P = .004), food allergies (HR: 1.26; P = .025), and allergic rhinitis (HR: 2.30; P < .001) significantly increased the hazard of new asthma diagnosis. Preterm birth (HR: 1.48; P = .005) and BMI (HR: 1.13; P < .001) significantly increased the hazard of new asthma diagnosis for children <5 years old. SARS-CoV-2 PCR positivity was not associated with new asthma diagnosis in children within the observation period, although known risk factors for pediatric asthma were confirmed. This study informs the prognosis and care of children with a history of SARS-CoV-2 infection.

Detailed Clinical Features of PTPRQ-Associated Hearing Loss Identified in a Large Japanese Hearing Loss Cohort.

The PTPRQ gene has been identified as one of the genes responsible for non-syndromic sensorineural hearing loss (SNHL), and assigned as DFNA73 and DFNB84. To date, about 30 causative PTPRQ variants have been reported to cause SNHL. However, the detailed clinical features of PTPRQ-associated hearing loss (HL) remain unclear. In this study, 15,684 patients with SNHL were enrolled and genetic analysis was performed using massively parallel DNA sequencing (MPS) for 63 target deafness genes. We identified 17 possibly disease-causing PTPRQ variants in 13 Japanese patients, with 15 of the 17 variants regarded as novel. The majority of variants identified in this study were loss of function. Patients with PTPRQ-associated HL mostly showed congenital or childhood onset. Their hearing levels at high frequency deteriorated earlier than that at low frequency. The severity of HL progressed from moderate to severe or profound HL. Five patients with profound or severe HL received cochlear implantation, and the postoperative sound field threshold levels and discrimination scores were favorable. These findings will contribute to a greater understanding of the clinical features of PTPRQ-associated HL and may be relevant in clinical practice.

Complications during Adolescence Predict Mortality in Young Adults with Childhood Onset Type 1 Diabetes

Objective. Microvascular complications increase the risk of cardiovascular disease and premature death in adults with type 1 diabetes. We examined the association between microvascular complications during adolescence, including cardiac autonomic nerve dysfunction and subsequent mortality. Research Design and Methods. We undertook data linkage with the Australian National Death Index in a cohort of 409 adolescents (diagnosed between 1973 and 1993), 48% male, median age at final complications assessment 17.4 years (interquartile range: 16.0–18.9), followed longitudinally for median 22.3 years (21.0–23.4) from diagnosis. Generalized estimating equations (GEE) were used to examine associations between mortality and adolescent complications. Mortality risk was calculated as standardized mortality ratio (SMR). Results. At final adolescent visit, 20% had CAN abnormality, 30% abnormal pupillary response, 20% albuminuria, 40% early elevation of albumin excretion rate (AER) and 45% retinopathy. Data linkage 8–13 years later showed 14 were deceased (3% of cohort), 57% male, median age 28.3 years (24.8–32.9). Acute or chronic diabetes complications accounted for 25% of deaths. In multivariable GEE, elevated AER (OR 4.54, 1.23–16.80, p=0.030), pupillary abnormality (OR 4.27, 1.20–15.22, p=0.023), systolic blood pressure SDS (OR 2.17, 1.26–3.74, p=0.005) and CAN (OR 4.65, 1.03–21.0, p=0.045) predicted mortality. HbA1c was not significant. SMR was 2.5 (1.4–4.2) and was higher in females (SMR 3.5, 1.3–7.8) but not in males (SMR 2.1, 0.9–4.0). Conclusion. Mortality in young adults with type 1 diabetes is predicted by subclinical markers of autonomic neuropathy and elevated AER during adolescence, but not glycemia. Mortality was over twice that of the background population in females but not in males.

Childhood Onset Amyotrophic Lateral Sclerosis Associated with SPTLC2 Gain-of-Function Pathogenic Variants: Clinical, Genetic, and Biochemical Insights (P4-8.001)

Childhood Onset Amyotrophic Lateral Sclerosis Associated with SPTLC2 Gain-of-Function Pathogenic Variants: Clinical, Genetic, and Biochemical Insights (P4-8.001)

A rare case of bilateral keratoconus and granular corneal dystrophy managed with contact lens

Keratoconus (KC) is a bilateral, non-inflammatory, progressive thinning disorder of the cornea that results in high irregular astigmatism, distortion, and poor vision. Granular corneal dystrophy (GCD) is an autosomal dominant stromal dystrophy with onset in childhood that involves the entire cornea. KC associated with GCD is a rare combination that could occur due to abnormal synthetic activity of keratocytes and degeneration of defective basal epithelial cells. This case report shows the management of KC associated with GCD – an uncommon condition.

Gamma activity in Autism Spectrum Disorder: Enhanced response to visual input

IntroductionAutism spectrum disorder (ASD) is a childhood onset neurodevelopmental condition, that leads to permanent disability in a high proportion of cases. ASD is associated with a heterogeneous symptom presentation, which - besides social interaction and communication difficulties - encompasses altered sensory reactivity, including excessive hyper-sensitivity to stimuli, especially in the visual domain. Meta-analyses of fMRI studies revealed increased reactivity in visual task conditions in the temporal and occipital brain regions. Neural oscillations in the EEG gamma band are viewed as a candidate neurobiological marker for higher order sensory and perceptual processes, and social interactions.ObjectivesWe investigated changes in gamma activity in the EEG in the eyes open (EO) vs. eyes closed (EC) condition in order to identify the neurobiological underpinning of the enhanced sensitivity to visual input in ASD as compared to typically developing (TD) subjects.MethodsEEGs were obtained in EC and EO condition in ASD (N=23) and TD subjects (N=24) in an ongoing study. For EEG recording we used a high-density 128-channel BioSemi system, with 0.5 Hz frequency resolution. The spectral power in the gamma band (30-100Hz) was quantified by the power spectral density. To investigate whether changes in the gamma band were linked to changes in arousal instead of enhanced visual processing, we also examined alterations in the alpha band (8-13Hz) in the EO condition. Spectral power changes were determined for each EEG channel by computing the difference between the EC and EO conditions (EO-EC).ResultsSpectral power in the gamma band showed changes in the opposite direction in the two study groups: ASD subjects manifested significant (p&lt;0.05) increase, while TD subjects had a decrease in the EO vs. EC condition in the temporal and occipital brain regions. By contrast, the changes in the alpha band were similar, with both groups exhibiting a spectral power decrease in the EO compared to the EC condition.ConclusionsIn ASD, an enhancement of gamma activity is present in the EO as compared to the EC condition in the posterior brain areas. These brain areas are involved in the processing of visual information, and gamma activity is considered as a measure of perceptual processes. Thus, the gamma alterations in the EO vs. EC condition may underlie the hyper-sensitivity symptoms to visual stimuli in ASD, and EEG can offer a simple to use tool to delineate the neurobiological foundation of the symptom presentation.Funding statement: Hungarian Brain Research program,#NAP2022-I-4/2022Disclosure of InterestNone Declared

Investigating nutritional status and body composition in children with cerebral palsy; the Eat, Sleep Play-CP study

Cerebral palsy (CP), or to use the Te Reo term “Hōkai Nukurangi”, is an umbrella name for a group of permanent neurodevelopmental disorders, affecting movement and posture(1), and is the most common childhood onset physical disability globally. The available literature on the nutritional status of children with CP describes high rates of malnutrition, however data appears to be skewed towards children of higher levels of impairment impacting functional independence. Less is known about the nutritional status of children with lower levels of impairment. The aim of the “Eat, Sleep, Play-CP” study was to evaluate total energy intake, total protein intake and the timing of protein intake in relation to physical activity for children with CP across all functional levels living in Aotearoa New Zealand. Children with CP aged 5-12 years were invited to participate in an observational assessment of dietary intake using parent reported 24-hour dietary recall (Intake 24) on three non-consecutive days, accompanied by a questionnaire capturing self-reported sleep and physical activity patterns. Body composition was assessed via whole body dual energy X-ray absorptiometry scan. Nine participants (6 males, median age: 10 years, n = 2 Māori), across Gross Motor Function Classification System levels I-IV, and Eating and Drinking Classification System levels I-III took part in the study. The median total energy intake was 7267kJ/d (range 5355-10731.96kJ/d), and median protein intake was 67g/d (range 49-111g/d). According to the Nutrient Reference Values for Australia and New Zealand (NRV)(2), 3 of the 9 participants (33%) were within the recommended range for energy intake according to their age and reported physical activity levels. Of the other 6, 4 were below and 2 were above the recommended ranges. All 9 met the recommended protein intake (NRV). Participants had a median percentage body fat of 40% (range 20-46%), and non-fat mass of 58% (range 52-76%). Five participants fell within the overweight or obese range for their age and sex, three of whom were within the recommended range of total energy daily intake according to NRVs. This outcome may indicate that for some children with CP, recommendations could be over-estimating the actual requirements. These early results may bring in to question current practice around guidance for energy intake requirements for children with CP and their whānau to support healthy body composition. Further investigations are needed to establish whether specific energy intake guidelines are required for children with CP.

Novel SGCE Mutation in a Patient With Myoclonus-Dystonia: A Case Report.

Characterize the presentation, workup, and management of SGCE myoclonus-dystonia, a rare genetic condition, in a patient with atypical presenting symptoms and no family history of movement abnormalities. A woman with myoclonus and dystonia was identified based on clinical history and physical examination. Workup was conducted to determine the cause of her symptoms, including whole-exome sequencing. Myoclonus-dystonia is associated with more than 100 distinct mutations in MYC/DYT-SGCE that account for only half of the total myoclonus-dystonia patients. As such, this case required intensive genetic analyses rather than screening only for a small subset of well-characterized mutations. Childhood onset myoclonus and worsening dystonia with age were identified in a young woman. She underwent screening for common causes of twitching movements, followed by whole-exome sequencing which identified a de novo novel variant in the SGCE gene, resulting in a diagnosis of SGCE myoclonus-dystonia. Myoclonus-dystonia should be considered in patients with symptoms of head and upper extremity myoclonus early in life, especially with co-occurring dystonia, even in the absence of a family history of similar symptoms. Diagnosis of this condition should take place using sequencing, as new mutations continue to be discovered.

Analysis of the Relationship between Psychiatric and Addiction-Related Disorders in Patients of an Outpatient Addiction Treatment Clinic for Children and Adolescents.

Dual diagnosis is used in addiction medicine to refer to the co-occurrence of an addiction-related disorder and another psychiatric disorder in the same individual. Adolescence is a key period for the development of both mental disorders and addictions. The aim of this study is to describe the relationships between psychiatric and addiction-related disorders in patients of the Outpatient Addiction Treatment Clinic for Children and Adolescents at the 1st Faculty of Medicine, Charles University in Prague in 2015-2022. Data were retrospectively analyzed from the hospital's medical system, which collects basic diagnostic data on patients. Descriptive statistics and cluster analysis were performed to identify relationships between psychiatric and addiction-related disorders. Of the 450 patients, 153 patients (34%) met the criteria for dual diagnosis. The most common addiction-related disorders were mental and behavioural disorders due to the use of cannabinoids (35%) and internet gaming disorder (35%). The most common psychiatric diagnoses were behavioural and emotional disorders with usual onset in childhood and adolescence (64%), with a lower prevalence in girls than in boys. These findings may be important for the diagnosis and treatment of risky behaviours and addictions in children and adolescents.

PDE10A Mutation as an Emerging Cause of Childhood-Onset Hyperkinetic Movement Disorders: A Review of All Published Cases.

Cyclic nucleotide phosphodiesterase (PDE) enzymes catalyze the breakdown of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP), which act as intracellular second messengers for signal transduction pathways and modulate various processes in the central nervous system. Recent discoveries that mutations in genes encoding different PDEs, including PDE10A, are responsible for rare forms of chorea in children led to the recognition of an emerging role of PDEs in the field of pediatric movement disorders. A comprehensive literature review of all reported cases of PDE10A mutations in PubMed and Web of Science was performed in English. We included eight studies, describing 31 patients harboring a PDE10A mutation and exhibiting a hyperkinetic movement disorder with onset in infancy or childhood. Mutations in both GAF-A, GAF-B regulatory domains and outside the GAF domains of the PDE10A gene have been reported to cause hyperkinetic movement disorders. In general, patients with homozygous mutations in either GAF-A domain of PDE10A present with a more severe phenotype and at an earlier age but without any extensive abnormalities of the striata compared with patients with dominant variants in GAF-B domain, indicating that dominant and recessive mutations have different pathogenic mechanisms. PDE10A plays a key role in regulating control of striato-cortical movement. Comprehension of the molecular mechanisms within the cAMP and cGMP signaling systems caused by PDE10A mutations may inform novel therapeutic strategies that could alleviate symptoms in young patients affected by these rare movement disorders.

Estimation of the Age of the Kashubian-Specific Pathogenic NPHS2 Variant Responsible for Hereditary Steroid-Resistant Nephrotic Syndrome Points to Its Recent Local Origin

Steroid-resistant nephrotic syndrome (SRNS) is a highly heterogenic kidney disorder resulting from genetic abnormalities or immune system dysfunction affecting the establishment and maintenance of the glomerular filtration barrier. The most common cause of genetic SRNS is biallelic pathogenic variants in NPHS2 gene, especially in individuals with an infantile or childhood onset. The type of the NPHS2 defect implies the course of the disease and the stage of its onset and differs across populations. In a cohort of Polish patients with SRNS, a unique profile of the disease-related NPHS2 variants was identified in patients from northern Poland inhabited by Kashubs, a minority West-Slavic ethnic group known for a local increase of the frequency of several pathogenic variants. Among Kashubian families, the compound heterozygotes c.686G&gt;A/c.1032delT and a single c.1032delT homozygote were the only underlying cause of SRNS. The restricted, Kashubian-only pattern of c.1032delT occurrence, suggesting the founder effect, prompted us to conduct a detailed analysis of its haplotype background to estimate the age of the c.1032delT origin. Eight Kashubian SRNS families were genotyped using the Infinium Global Screening Array-24. The haplotype background analysis was performed using an in-house pipeline designed to solve the phase of the heterozygous genotype data. The age of the c.1032delT mutation was calculated using the gamma method based on the genetic length of ancestral haplotypes shared between two or more individuals carrying this variant. The results of our study indicated a very recent origin of the c.1032delT mutation (~240 years). Genetic screening performed in the general Polish population control corroborates the assumption that the mutation occurred on the specific Kashubian haplotype background. The identification of ancestry-specific Kashubian pathogenic variant can help to develop effective screening and diagnostic strategies as a part of personalized medicine approach in the region.

Epileptic spasms in clusters without hypsarrhythmia in infancy and childhood: A single age-dependent type of epilepsy or well-defined epileptic syndrome?

ObjectiveIn this study, we present the electroclinical features and outcomes of 92 patients with epileptic spasms (ES) in clusters without modified or classical hypsarrhythmia that started in either in infancy or in childhood; we compared both groups in terms of electroclinical features, etiology, treatment, evolution, and outcome. MethodsBetween June 2000 and July 2022, 92 patients met the electroclinical diagnostic criteria of ES in clusters without hypsarrhythmia. Patients with ES associated with other epileptic encephalopathies including West Syndrome, as well as those with the specific etiology of ES and developmental and epileptic encephalopathy associated with CDKL5 were excluded. ResultsThe patients were divided into two groups based on the age at ES onset: those with ES onset before (Group 1) and those with ES onset after 2 years of age (Group 2). The features of ES and the type of associated seizures before and after ES onset, as well as the interictal and ictal EEG and electromyography findings were similar in both groups. The etiologies were mainly structural (40.2%), genetic (11.9%), and unknown (44.6%) in majority of the patients in both groups. Thirty-one patients were seizure-free, while in the remaining patients the seizures continued. Nine patients (9.8%) with unilateral structural lesions underwent surgery with good results. The neurological abnormalities and developmental findings prior to ES onset depended on the underlying etiology. ConclusionOur series of patients may represent a well-defined epileptic syndrome or type of epilepsy with onset in infancy or childhood characterized by ES in clusters without hypsarrhythmia associated with focal and generalized seizures and EEG paroxysms without neurological deterioration.

The Impact of Non-Seizure Symptoms in Dravet Syndrome and Lennox–Gastaut Syndrome

Dravet syndrome (DS) and Lennox–Gastaut syndrome (LGS) are developmental and epileptic encephalopathies (DEE) that onset in childhood, and persist lifelong. In both, non-seizure symptoms (NSS) include intellectual disability, psychiatric symptoms, speech and communication difficulties, motor and gait difficulties, appetite and eating difficulties, autism spectrum characteristics, attention deficit hyperactivity disorder, and sleep disorders. The NSS impact health-related quality of life (HRQoL) for the affected individual and the caregiver, considering personal time, sleep, finances, energy, and family and social relationship. In this industry-sponsored symposium, three leading ex-perts in DEEs discussed NSS, and how properly assessing and tracking these can lead to more informed understanding of an individual’s needs. This can help to guide treat-ment for NSS and, subsequently, increase HRQoL for both the individual and their caregivers.

Development of a functional outcome measure for riboflavin transporter deficiency.

Riboflavin transporter deficiency (RTD) is a progressive inherited neuropathy of childhood onset, characterised clinically by pontobulbar palsy, sensory ataxia, sensorineural deafness, muscle weakness, optic atrophy and respiratory failure. A robust and responsive functional outcome measure is essential for future clinical trials of disease-modifying therapies including genetic therapies. The Charcot-Marie-Tooth disease Pediatric Scale (CMTPedS) is a well-validated outcome measure for CMT and related neuropathies, and might have utility for measuring disease progression in individuals with RTD. However, the CMTPedS requires modifications to account for phenotypic differences between children with CMT and RTD. The aim of this study was to develop a functional outcome measure based on the CMTPedS for specific use in individuals with RTD. The CMTPedS data collected over the last 10 years in individuals with RTD attending the Peripheral Neuropathy Management Clinic at the Children's Hospital at Westmead (Sydney, Australia) were reviewed to evaluate each item within the CMTPedS. A literature review of articles published until September 2021 for functional outcome measures generated an item pool for pilot testing. The results of this pilot testing, alongside analysis of existing CMTPedS item scores in the RTD cohort, informed the modification of the CMTPedS. CMTPedS data were reviewed for eight individuals over the past 10 years. Two items were identified as requiring modification or removal and additional items of proximal strength and function needed to be considered. Six studies were identified in the literature review, and five items were selected for pilot testing. 'Shoulder internal rotation' and the '30-s sit to stand test' were added as proximal measures of strength and function. The composite balance item comprising nine tasks in the CMTPedS showed a ceiling effect and was replaced with the single 'Feet apart on a line eyes open' balance item. 'Pinprick sensation' was removed due to a floor effect. This study provides preliminary evidence that the Riboflavin Transporter Deficiency Pediatric Scale (RTDPedS) is a functional outcome measure covering strength, upper and lower limb function, balance and mobility for individuals with RTD to assess disease severity and progression in clinical trials and cohort studies.