A recurrent de novo splice site variant involving DNM1 exon 10a causes developmental and epileptic encephalopathy through a dominant-negative mechanism.

Heterozygous pathogenic variants in DNM1 cause developmental and epileptic encephalopathy (DEE) as a result of a dominant-negative mechanism impeding vesicular fission. Thus far, pathogenic variants in DNM1 have been studied with a canonical transcript that includes the alternatively spliced exon 10b. However, after performing RNA sequencing in 39 pediatric brain samples, we find the primary transcript expressed in the brain includes the downstream exon 10a instead. Using this information, we evaluated genotype-phenotype correlations of variants affecting exon 10a and identified a cohort of eleven previously unreported individuals. Eight individuals harbor a recurrent de novo splice site variant, c.1197-8G>A (GenBank: NM_001288739.1), which affects exon 10a and leads to DEE consistent with the classical DNM1 phenotype. We find this splice site variant leads to disease through an unexpected dominant-negative mechanism. Functional testing reveals an in-frame upstream splice acceptor causing insertion of two amino acids predicted to impair oligomerization-dependent activity. This is supported by neuropathological samples showing accumulation of enlarged synaptic vesicles adherent to the plasma membrane consistent with impaired vesicular fission. Two additional individuals with missense variants affecting exon 10a, p.Arg399Trp and p.Gly401Asp, had a similar DEE phenotype. In contrast, one individual with a missense variant affecting exon 10b, p.Pro405Leu, which is less expressed in the brain, had a correspondingly less severe presentation. Thus, we implicate variants affecting exon 10a as causing the severe DEE typically associated with DNM1-related disorders. We highlight the importance of considering relevant isoforms for disease-causing variants as well as the possibility of splice site variants acting through a dominant-negative mechanism.

Delineating clinical and developmental outcomes in STXBP1-related disorders.

STXBP1-related disorders are among the most common genetic epilepsies and neurodevelopmental disorders. However, the longitudinal epilepsy course and developmental end points, have not yet been described in detail, which is a critical prerequisite for clinical trial readiness. Here, we assessed 1281 cumulative patient-years of seizure and developmental histories in 162 individuals with STXBP1-related disorders and established a natural history framework. STXBP1-related disorders are characterized by a dynamic pattern of seizures in the first year of life and high variability in neurodevelopmental trajectories in early childhood. Epilepsy onset differed across seizure types, with 90% cumulative onset for infantile spasms by 6 months and focal-onset seizures by 27 months of life. Epilepsy histories diverged between variant subgroups in the first 2 years of life, when individuals with protein-truncating variants and deletions in STXBP1 (n = 39) were more likely to have infantile spasms between 5 and 6 months followed by seizure remission, while individuals with missense variants (n = 30) had an increased risk for focal seizures and ongoing seizures after the first year. Developmental outcomes were mapped using milestone acquisition data in addition to standardized assessments including the Gross Motor Function Measure-66 Item Set and the Grasping and Visual-Motor Integration subsets of the Peabody Developmental Motor Scales. Quantification of end points revealed high variability during the first 5 years of life, with emerging stratification between clinical subgroups. An earlier epilepsy onset was associated with lower developmental abilities, most prominently when assessing gross motor development and expressive communication. We found that individuals with neonatal seizures or early infantile seizures followed by seizure offset by 12 months of life had more predictable seizure trajectories in early to late childhood compared to individuals with more severe seizure presentations, including individuals with refractory epilepsy throughout the first year. Characterization of anti-seizure medication response revealed age-dependent response over time, with phenobarbital, levetiracetam, topiramate and adrenocorticotropic hormone effective in reducing seizures in the first year of life, while clobazam and the ketogenic diet were effective in long-term seizure management. Virtual clinical trials using seizure frequency as the primary outcome resulted in wide range of trial success probabilities across the age span, with the highest probability in early childhood between 1 year and 3.5 years. In summary, we delineated epilepsy and developmental trajectories in STXBP1-related disorders using standardized measures, providing a foundation to interpret future therapeutic strategies and inform rational trial design.

Motor training for young children with cerebral palsy: A single-blind randomized controlled trial.

AIM: To compare the effect of iMOVE (Intensive Mobility training with Variability and Error) therapy with dose-matched conventional therapy on gross motor development and secondary outcomes in young children with cerebral palsy. METHOD: This single-blind, randomized controlled trial included repeated assessments of gross motor function (using the Gross Motor Function Measure) and secondary outcomes during a 12- to 24-week intervention phase and at three follow-up points after treatment. Treatment was delivered three times per week in both groups. Forty-two children aged 12 to 36 months were stratified by age and motor function to ensure equivalence between groups at baseline. RESULTS: Thirty-six children completed treatment and follow-up phases. Treatment fidelity was high and adherence was equivalent between groups (77.3% conventional therapy, 76.2% iMOVE). There were no group differences on the primary (gross motor function after 12 weeks p = 0.18; after 24 weeks p = 0.94) or any secondary (postural control p = 0.88, caregiver satisfaction p = 0.52, child engagement p = 0.98) measure after treatment or at the follow-up points. However, one-third of total participants exceeded predicted change after 12 weeks and 77% exceeded predicted change after 24 weeks of treatment. INTERPRETATION: Our observations indicate a potential dose-response effect of rehabilitation therapy. We further demonstrated that individual therapeutic ingredients can be manipulated. When delivered consistently, both iMOVE and conventional therapy interventions might both be more effective than standard care. WHAT THIS PAPER ADDS: Those receiving iMOVE therapy demonstrated more independent practice time, error, and child-initiation than those receiving the dose-matched control. iMOVE therapy was not superior to the control (conventional physical) therapy. Most participants exceeded predicted change after 24 weeks of treatment.

Agreement Between the Gross Motor Ability Estimator-2 and the Gross Motor Ability Estimator-3 in Young Children With Cerebral Palsy.

PURPOSE: The purpose of this study was to determine the agreement between Gross Motor Ability Estimator-2 (GMAE-2) and Gross Motor Ability Estimator-3 (GMAE-3) calculations of Gross Motor Function Measure-66 (GMFM-66) scores in infants and young children with cerebral palsy. METHODS: Data from 53 children 5 to 53 months of age were analyzed. Agreement between GMFM-66 scores using the GMAE-2 and the GMAE-3 was calculated using Bland-Altman plots and interclass correlation coefficients (ICCs). Eleven participants who had at least 1 GMFM-66 score of less than 25 using either method were identified for further analysis. RESULTS: The average difference between GMFM-66 scores was 0.27 for all participants and 0.63 for the subset of lower-scoring participants. Good agreement was found for GMFM-66 scores for all participants (ICC = 0.998) and for subset of lower-scoring participants (ICC = 0.879). CONCLUSIONS: High levels of agreement exist between the GMAE-2 and the GMAE-3, which suggests that scores are comparable using either algorithm.

Tethered cord release in patients after open fetal myelomeningocele closure: intraoperative neuromonitoring data and patient outcomes.

PURPOSE: The purpose of the study was to better understand the clinical course and impact of tethered cord release surgery on patients who have previously undergone open spinal dysraphism closure in utero. METHODS: This is a single-center retrospective observational study on patients undergoing tethered cord release after having previously had open fetal myelomeningocele (MMC) closure. All patients underwent tethered cord release surgery with a single neurosurgeon. A detailed analysis of the patients' preoperative presentation, intraoperative neuromonitoring (IONM) data, and postoperative course was performed. RESULTS: From 2009 to 2021, 51 patients who had previously undergone fetal MMC closure had tethered cord release surgery performed. On both preoperative and postoperative manual motor testing, patients were found to have on average 2 levels better than would be expected from the determined anatomic level from fetal imaging. The electrophysiologic functional level was found on average to be 2.5 levels better than the anatomical fetal level. Postoperative motor levels when tested on average at 4 months were largely unchanged when compared to preoperative levels. Unlike the motor signals, 46 (90%) of patients had unreliable or undetectable lower extremity somatosensory evoked potentials (SSEPs) prior to the tethered cord release. CONCLUSION: Tethered cord surgery can be safely performed in patients after open fetal MMC closure without clinical decline in manual motor testing. Patients often have functional nerve roots below the anatomic level. Sensory function appears to be more severely affected in patients leading to a consistent motor-sensory imbalance.

The relationship between family empowerment and fine motor, gross motor and cognitive skills in young children with cerebral palsy.

BACKGROUND: Family empowerment in families of young children with cerebral palsy (CP) is an important consideration because the first few years of life can be overwhelming for parents. The purpose of this research was to investigate the relationship between family empowerment, fine motor (FM), gross motor (GM) and cognitive development in children with CP who were under 3 years of age. METHODS: Forty-one children with a mean age of 23.8 months participated in this study. The Family Empowerment Scale (FES) was completed by the participants' parents, whereas the FM, GM and cognitive subscales of the Bayley Scales of Infant and Toddler Development Third edition (B-III) were administered by physical therapists. RESULTS: Statistically significant positive correlations were found between the FES total and B-III raw scores for FM, GM and cognitive subscales with coefficients ranging from 0.35 to 0.41. Significant relationships were also found between the FES Community subscale and the B-III FM, GM and cognitive subscales. CONCLUSIONS: This study provides evidence of a relationship between family empowerment and FM, GM and cognitive abilities in young children with CP, with a greater severity of impairments related to lower levels of caregiver empowerment.

Psychometric outcome measures in beta-propeller protein-associated neurodegeneration (BPAN).

BACKGROUND: Beta-propeller protein-associated neurodegeneration (BPAN) is a rare neurodegenerative disorder characterized by iron accumulation in the brain with spectrum of neurodevelopmental and movement phenotypes. In anticipation of future clinical trials and to inform clinical care, there is an unmet need to capture the phenotypic diversity of this rare disorder and better define disease subtypes. METHODS: A total of 27 individuals with BPAN were included in our natural history study, from which traditional outcome measures were obtained in 18 subjects. Demographic and diagnostic information, along with acquisition of basic developmental skills and overall neurologic severity were extracted from the medical records. Functional outcome measures were administered at the time of the evaluation or applied retrospectively at the last clinical encounter for patients who were not able to travel for in person. Based on age and functional level, the following assessments were administered: Leiter-3, Gross Motor Function Measure (GMFM)-66 Item Sets, Vineland-3, and Peabody-2. RESULTS: Overall, cognitive function was more impaired compared to gross motor function. Onset of symptoms of BPAN within the first 6 months of life was associated with decreased gain of ambulation and gain of spoken language (ambulation: log-rank test p = 0.0015; gain of first word: p = 0.0015). There was no difference in age at seizure onset by age at initial symptom onset (p = 0.8823). Collection of prospective outcome measures was limited by attention and behavior in our patient population, reinforcing the complexity of phenotype assessment and inadequacy of available standardized tests. Overall, gross motor and adaptive behavior assessments were better able to capture the dynamic range of function across the BPAN population than the fine motor and non-verbal cognitive tests. Floor effects were noted across outcome measures in a subset of individuals for cognitive and adaptive behavior tests. CONCLUSION: Our data suggest the distinct phenotypes of BPAN: a severe, early onset form and an attenuated form with higher cognitive capabilities. Early age at onset was a key factor in predicting future neurologic impairment.

Infants at risk for physical disability may be identified by measures of postural control in supine.

BACKGROUND: Early detection of delay or impairment in motor function is important to guide clinical management and inform prognosis during a critical window for the development of motor control in children. The purpose of this study was to investigate the ability of biomechanical measures of early postural control to distinguish infants with future impairment in motor control from their typically developing peers. METHODS: We recorded postural control from infants lying in supine in several conditions. We compared various center of pressure metrics between infants grouped by birth status (preterm and full term) and by future motor outcome (impaired motor control and typical motor control). RESULTS: One of the seven postural control metrics-path length-was consistently different between groups for both group classifications and for the majority of conditions. CONCLUSIONS: Quantitative measures of early spontaneous infant movement may have promise to distinguish early in life between infants who are at risk for motor impairment or physical disability and those who will demonstrate typical motor control. Our observation that center of pressure path length may be a potential early marker of postural instability and motor control impairment needs further confirmation and further investigation to elucidate the responsible neuromotor mechanisms. IMPACT: The key message of this article is that quantitative measures of infant postural control in supine may have promise to distinguish between infants who will demonstrate future motor impairment and those who will demonstrate typical motor control. One of seven postural control metrics-path length-was consistently different between groups. This metric may be an early marker of postural instability in infants at risk for physical disability.

The relationship between the Family Empowerment Scale and Gross Motor Function Measure-66 in Young Children with cerebral palsy.

BACKGROUND: Cerebral palsy (CP) is the most common cause of motor disability in children. A concept to consider in order to meet the needs of children with CP and their families is family empowerment. Family empowerment can be defined as the process by which families acquire the skills, knowledge and resources to allow them to gain control and improve the quality of their lives. The relationship between gross motor function and family empowerment may be important because children with CP vary so widely in their ability to perform motor skills, which may affect their family's levels of empowerment. The purpose of this research was to investigate the relationship between the Family Empowerment Scale (FES) and Gross Motor Function Measure-66 (GMFM-66) in children with CP who were under 3 years of age. METHODS: Forty-one children with a mean age of 23.8 months participated in this study. The FES was completed by the participants' parents or regular caregivers and includes a total score and subscales of empowerment in the family, in service situations and in community/political environments. The GMFM-66 was administered by a physical therapist and consists of a total score of gross motor function (GMFM-66) and subscores for Dimension B (sitting), Dimension C (crawling and kneeling), Dimension D (standing) and Dimension E (walking, running and jumping). RESULTS: Statistically significant positive correlations were found between the FES total and GMFM (total score and Dimensions B-E) with coefficients varying from 0.43-0.62. Significant relationships were also found between most subscales of the FES and the GMFM-66. CONCLUSIONS: This study provides evidence of a relationship between family empowerment and gross motor function in young children with CP and suggests that caregivers of children with higher gross motor function report higher levels of self-efficacy.

The Use of Dynamic Weight Support with Principles of Infant Learning in a Child with Cerebral Palsy: A Case Report.

AIMS: Typical infant movement is characterized by a high degree of motor exploration, error, and variability. However, children with cerebral palsy (CP) often cannot create these experiences due to their neuromotor impairments. The purpose of this case study is to describe a 6-month course of physical therapy (PT) incorporating principles of infant motor learning using dynamic weight support (DWS) in a child with CP. METHODS: The child was a 27-month-old girl with diplegic CP who functioned at Gross Motor Function Classification System Level IV. The child received 68 PT sessions over a six-month period. DWS was used during therapy to encourage motor practice. The therapy area was arranged to encourage active exploration, motor variability, and error experience. Gross motor function, postural control, parent perception of performance, and parent satisfaction were measured before, during, and after the course of therapy. RESULTS: Gross motor function increased during the treatment beyond the level predicted from natural progression. Postural control fluctuated and demonstrated no appreciable improvement. Parent-perceived performance and satisfaction improved on three of four goals. CONCLUSIONS: Using DWS to incorporate principles of infant learning may have facilitated the development of gross motor skills in a child with diplegic CP.

Linear and Nonlinear Measures of Postural Control in a Toddler With Cerebral Palsy: Brief Report.

PURPOSE: The purpose of this study was to describe changes in linear and nonlinear measures of postural control along with motor outcomes in a young child with cerebral palsy. SUMMARY OF KEY POINTS: Posturography in sitting and standing, the Gross Motor Function Measure-66 (GMFM-66), and the Early Clinical Assessment of Balance (ECAB) were performed prior to, during, and after physical therapy. The child demonstrated independent sitting throughout the study and developed independent standing during the study. He made improvements in the GMFM-66 and ECAB throughout the study. Higher average values were found in all linear and nonlinear measures in standing when compared to sitting, which may indicate less predictable movement due to less experience with standing. RECOMMENDATIONS FOR CLINICAL PRACTICE: Greater variability and lower predictability in postural control likely reflect early stages of skill acquisition. Research is needed to understand the optimal levels of movement variability and predictability.

iMOVE: Intensive Mobility training with Variability and Error compared to conventional rehabilitation for young children with cerebral palsy: the protocol for a single blind randomized controlled trial.

BACKGROUND: Cerebral palsy (CP) is the most common cause of physical disability in children. The best opportunity to maximize lifelong independence is early in motor development when there is the most potential for neuroplastic change, but how best to optimize motor ability during this narrow window remains unknown. We have systematically developed and pilot-tested a novel intervention that incorporates overlapping principles of neurorehabilitation and infant motor learning in a context that promotes upright mobility skill and postural control development. The treatment, called iMOVE therapy, was designed to allow young children with CP to self-initiate motor learning experiences similar to their typically developing peers. This manuscript describes the protocol for a subsequent clinical trial to test the efficacy of iMOVE therapy compared to conventional therapy on gross motor development and other secondary outcomes in young children with CP. METHODS: The study is a single-blind randomized controlled trial. Forty-two participants with CP or suspected CP between the ages of 1-3 years will be randomized to receive either the iMOVE or conventional therapy group. Distinguishing characteristics of each group are detailed. Repeated measures of gross motor function will be collected throughout the 12-24 week intervention phase and at three follow-up points over one year post therapy. Secondary outcomes include measures of postural control, physical activity, participation and caregiver satisfaction. DISCUSSION: This clinical trial will add to a small, but growing, body of literature on early interventions to optimize the development of motor control in young children with CP. The information learned will inform clinical practice of early treatment strategies and may contribute to improving the trajectory of motor development and reducing lifelong physical disability in individuals with CP. TRIAL REGISTRATION: ClinicalTrials.gov identifier NCT02340026 . Registered January 16, 2015.

Use of Hippotherapy With a Boy After Traumatic Brain Injury: A Case Study.

PURPOSE: The purpose of this case report was to describe the use of hippotherapy with a boy who sustained a brain injury. KEY POINTS: A 13-year-old boy, 6 months after traumatic brain injury received 12 physical therapy sessions, which included hippotherapy. Improvements were noted in balance, strength, gross motor skills, gait speed, functional mobility, and reported participation. SUMMARY: Hippotherapy used with a 13-year-old boy after traumatic brain injury may have had a positive effect in the body structure, activity, and participation domains.

Barriers to bicycle helmet use in young children in an urban elementary school.

PURPOSE: Traumatic brain injury is a leading cause of death in bicycle crashes. The factors associated with bicycle helmet use in young children with diverse ethnic and socioeconomic backgrounds have not been studied. The purpose of this study was to identify barriers to helmet use in young children in an urban elementary school. DESIGN: Qualitative content analysis with semistructured interviews, observational field notes, and artifacts. SETTING: Urban elementary school. PARTICIPANTS: Seventeen students whose age ranged from 5 to 7 years and whose ethnic background was identified as African American (14) or Caucasian (3). METHOD: Children participated in a brain safety fair that included presentations and activities. Semistructured, pre- and postexperience interviews were completed. Observations of the students participating in the activities and reflective art projects from the students were collected. RESULTS: The analysis found the following barriers to helmet use: (a) lack of access to a helmet, (b) poor fit of helmets due to hairstyles, and (c) lack of knowledge regarding helmet use. CONCLUSION: The present study suggests that the issue of helmet design and comfort for younger children with variable hairstyles needs to be addressed in order to increase helmet use in this population.

Preliminary assessment of a standardized vision screening guideline in a pediatric inpatient rehabilitation unit.

OBJECTIVE: This study aimed to evaluate the impact of a standardized vision screen guideline on occupational therapy vision screens in a pediatric inpatient rehabilitation unit. METHODS: Charts of patients admitted to a pediatric inpatient rehabilitation before guideline implementation (n = 47) versus charts after implementation (n = 47) were randomly, retrospectively reviewed to explore differences in visual skills screened and use of standardized assessments. RESULTS: Significant improvements (p < = 0.05) were found in the number of visual skills screened (p = 0.034), use of standardized assessments (p = 0.005), and screening of the specific visual skills of accommodative amplitude (p = 0.05), suppression (p = 0.015), and double vision (p < 0.001). CONCLUSION: Implementation of a standardized vision screen guideline improved the frequency of vision screens during occupational therapy evaluations in a pediatric inpatient rehabilitation unit. The use of standardized assessments may also improve the quality of vision screens by encouraging staff to complete more comprehensive vision screens, including screening more visual skills, and by prompting use of standardized assessments, which can improve accuracy of screening procedures.

Locomotor learning in infants at high risk for cerebral palsy: A study protocol.

Background: Physical disability in individuals with cerebral palsy (CP) creates lifelong mobility challenges and healthcare costs. Despite this, very little is known about how infants at high risk for CP learn to move and acquire early locomotor skills, which set the foundation for lifelong mobility. The objective of this project is to characterize the evolution of locomotor learning over the first 18 months of life in infants at high risk for CP. To characterize how locomotor skill is learned, we will use robotic and sensor technology to provide intervention and longitudinally study infant movement across three stages of the development of human motor control: early spontaneous movement, prone locomotion (crawling), and upright locomotion (walking). Study design: This longitudinal observational/intervention cohort study (ClinicalTrials.gov Identifier: NCT04561232) will enroll sixty participants who are at risk for CP due to a brain injury by one month post-term age. Study participation will be completed by 18 months of age. Early spontaneous leg movements will be measured monthly from 1 to 4 months of age using inertial sensors worn on the ankles for two full days each month. Infants who remain at high risk for CP at 4 months of age, as determined from clinical assessments of motor function and movement quality, will continue through two locomotor training phases. Prone locomotor training will be delivered from 5 to 9 months of age using a robotic crawl training device that responds to infant behavior in real-time. Upright locomotor training will be delivered from 9 to 18 months of age using a dynamic weight support system to allow participants to practice skills beyond their current level of function. Repeated assessments of locomotor skill, training characteristics (such as movement error, variability, movement time and postural control), and variables that may mediate locomotor learning will be collected every two months during prone training and every three months during upright training. Discussion: This study will develop predictive models of locomotor skill acquisition over time. We hypothesize that experiencing and correcting movement errors is critical to skill acquisition in infants at risk for CP and that locomotor learning is mediated by neurobehavioral factors outside of training.Project Number 1R01HD098364-01A1.ClinicalTrials.gov Identifier: NCT04561232.

Quantifying interaction with robotic toys in pre-term and full-term infants.

Infants born pre-term are at an increased risk for developmental, behavioral, and motor delay and subsequent disability. When these problems are detected early, clinical intervention can be effective at improving functional outcomes. Current methods of early clinical assessment are resource intensive, require extensive training, and do not always capture infants' behavior in natural play environments. We developed the Play and Neuro Development Assessment (PANDA) Gym, an affordable, mechatronic, sensor-based play environment that can be used outside clinical settings to capture infant visual and motor behavior. Using a set of classification codes developed from the literature, we analyzed videos from 24 pre-term and full-term infants as they played with each of three robotic toys designed to elicit different types of interactions-a lion, an orangutan, and an elephant. We manually coded for frequency and duration of toy interactions such as kicking, grasping, touching, and gazing. Pre-term infants gazed at the toys with similar frequency as full-term infants, but infants born full-term physically engaged more frequently and for longer durations with the robotic toys than infants born pre-term. While we showed we could detect differences between full-term and pre-term infants, further work is needed to determine whether differences seen were primarily due to age, developmental delays, or a combination.

Gross Motor Function in Pediatric Onset TUBB4A-Related Leukodystrophy: GMFM-88 Performance and Validation of GMFC-MLD in TUBB4A.

TUBB4A pathogenic variants are associated with a spectrum of neurologic impairments including movement disorders and leukodystrophy. With the development of targeted therapies, there is an urgent unmet need for validated tools to measure mobility impairment. Our aim is to explore gross motor function in a pediatric-onset TUBB4A-related leukodystrophy cohort with existing gross motor outcome tools. Gross Motor Function Measure-88 (GMFM-88), Gross Motor Function Classification System (GMFCS-ER), and Gross Motor Function Classification-Metachromatic Leukodystrophy (GMFC-MLD) were selected through face validity. Subjects with a confirmed clinical and molecular diagnosis of TUBB4A-related leukodystrophy were enrolled. Participants' sex, age, genotype, and age at disease onset were collected, together with GMFM-88 and concurrent GMFCS-ER and GMFC-MLD. Performances on each measure were compared. GMFM-88 floor effect was defined as total score below 20%. A total of 35 subjects participated. Median performance by GMFM-88 was 16.24% (range 0-97.31), with 42.9% (n = 15) of individuals performing above the floor. GMFM-88 Dimension A (Lying and Rolling) was the best-performing dimension in the GMFM-88 (n = 29 above the floor). All levels of the Classification Scales were represented, with the exception of the GMFC-MLD level 0. Evaluation by GMFM-88 was strongly correlated with the Classification Scales (Spearman correlations: GMFCS-ER:GMFM-88 r = 0.90; GMFC-MLD:GMFM-88 r = 0.88; GMFCS-ER:GMFC-MLD: r = 0.92). Despite overall observation of a floor effect, the GMFM-88 is able to accurately capture the performance of individuals with attenuated phenotypes. GMFM-88 Dimension A shows no floor effect. GMFC-MLD shows a strong correlation with GMFCS-ER and GMFM-88, supporting its use as an age-independent functional score in TUBB4A-related leukodystrophy.

Delineating clinical and developmental outcomes in STXBP1-related disorders.

STXBP1-related disorders are among the most common genetic epilepsies and neurodevelopmental disorders. However, the longitudinal epilepsy course and developmental endpoints have not yet been described in detail, which is a critical prerequisite for clinical trial readiness. Here, we assessed 1,281 cumulative patient-years of seizure and developmental histories in 162 individuals with STXBP1-related disorders and established a natural history framework. STXBP1-related disorders are characterized by a dynamic pattern of seizures in the first year of life and high variability in neurodevelopmental trajectories in early childhood. Epilepsy onset differed across seizure types, with 90% cumulative onset for infantile spasms by 6 months and focal-onset seizures by 27 months of life. Epilepsy histories diverged between variant subgroups in the first 2 years of life, when individuals with protein-truncating variants and deletions in STXBP1 (n=39) were more likely to have infantile spasms between 5 and 6 months followed by seizure remission, while individuals with missense variants (n=30) had an increased risk for focal seizures and ongoing seizures after the first year. Developmental outcomes were mapped using milestone acquisition data in addition to standardized assessments including the Gross Motor Function Measure-66 Item Set and the Grasping and Visual-Motor Integration subsets of the Peabody Developmental Motor Scales. Quantification of endpoints revealed high variability during the first five years of life, with emerging stratification between clinical subgroups, most prominently between individuals with and without infantile spasms. We found that individuals with neonatal seizures or early infantile seizures followed by seizure offset by 12 months of life had more predictable seizure trajectories in early to late childhood than compared to individuals with more severe seizure presentations, including individuals with refractory epilepsy throughout the first year. Characterization of anti-seizure medication response revealed age-dependent response over time, with phenobarbital, levetiracetam, topiramate, and adrenocorticotropic hormone effective in reducing seizures in the first year of life, while clobazam and the ketogenic diet were effective in long-term seizure management. Virtual clinical trials using seizure frequency as the primary outcome resulted in wide range of trial success probabilities across the age span, with the highest probability in early childhood between 1 year and 3.5 years. In summary, we delineated epilepsy and developmental trajectories in STXBP1-related disorders using standardized measures, providing a foundation to interpret future therapeutic strategies and inform rational trial design.

Exploration of Gross Motor Function in Aicardi-Goutières Syndrome.

Background: Aicardi-Goutières syndrome (AGS) is a rare genetic disorder characterized by a spectrum of motor abilities. While the Aicardi-Goutières syndrome severity score favors severely impacted individuals, there is an unmet need to define tools measuring function across the Aicardi-Goutières syndrome spectrum as potential outcome assessments for future clinical trials. Methods: Gross Motor Function Measure-88 (GMFM-88) and AGS Severity Scale were administered in individuals affected by Aicardi-Goutières syndrome (n = 71). We characterized the performance variability by genotype. Derived versions of the GMFM-88, including the GMFM-66, GMFM-66 item set (GMFM-66IS), and GMFM-66 Basal&Ceiling (GMFM-66BC) were calculated. The Aicardi-Goutières syndrome cohort was divided into severe (AGS Severity Scale score <4) or attenuated (≥4). Performance on the AGS Severity Scale highly correlated with total GMFM-88 scores (Spearman Correlation: R = 0.91). To assess variability of the GMFM-88 within genotypic subcohorts, interquartile ranges (IQRs) were compared. Results: GMFM-88 performance in the TREX1 cohort had least variability while the SAMHD1 cohort had the largest IQR (4.23 vs 81.8). Floor effect was prominent, with most evaluations scoring below 20% (n = 46, 64.79%), particularly in TREX1- and RNASEH2-cohorts. Performance by the GMFM-66, GMFM-66IS, and GMFM-66BC highly correlated with the full GMFM-88. The Aicardi-Goutières syndrome population represents a broad range of gross motor skills. Conclusions: This work identified the GMFM-88 as a potential clinical outcome assessment in subsets of the Aicardi-Goutières syndrome population but underscores the need for additional validation of outcome measures reflective of the diverse gross motor function observed in this population, including low motor function. When time is limited by resources or patient endurance, shorter versions of the GMFM-88 may be a reasonable alternative.