NGLY1 deficiency: a prospective natural history study.

N-glycanase 1 (NGLY1) deficiency is a debilitating, ultra-rare autosomal recessive disorder caused by loss of function of NGLY1, a cytosolic enzyme that deglycosylates other proteins. It is characterized by severe global developmental delay and/or intellectual disability, hyperkinetic movement disorder, transient elevation of transaminases, (hypo)alacrima and progressive, diffuse, length-dependent sensorimotor polyneuropathy. A prospective natural history study (NHS) was conducted to elucidate clinical features and disease course. Twenty-nine participants were enrolled (15 onsite, 14 remotely) and followed for up to 32 months, representing ~29% of the ~100 patients identified worldwide. Participants exhibited profound developmental delays, with almost all developmental quotients below 20 on the Mullen Scales of Early Learning, well below the normative score of 100. Increased difficulties with sitting and standing suggested decline in motor function over time. Most patients presented with (hypo)alacrima and reduced sweat response. Pediatric quality of life was poor except for emotional function. Language/communication and motor skill problems including hand use were reported by caregivers as the most bothersome symptoms. Levels of the substrate biomarker, GlcNAc-Asn (aspartylglucosamine; GNA), were consistently elevated in all participants over time, independent of age. Liver enzymes were elevated for some participants but improved especially in younger patients and did not reach levels indicating severe liver disease. Three participants died during the study period. Data from this NHS informs selection of endpoints and assessments for future clinical trials for NGLY1 deficiency interventions. Potential endpoints include GNA biomarker levels, neurocognitive assessments, autonomic and motor function (particularly hand use), (hypo)alacrima and quality of life.

Mutations in the Na(+)/citrate cotransporter NaCT (SLC13A5) in pediatric patients with epilepsy and developmental delay.

Mutations in the SLC13A5 gene that codes for the Na(+)/citrate cotransporter, NaCT, are associated with early onset epilepsy, developmental delay and tooth dysplasia in children. In the present study we identify additional SLC13A5 mutations in nine epilepsy patients from six families. To better characterize the syndrome, families with affected children answered questions about the scope of illness and treatment strategies. There are currently no effective treatments, but some anti-epileptic drugs targeting the GABA system reduce seizure frequency. Acetazolamide, a carbonic anhydrase inhibitor and atypical anti-seizure medication decreases seizures in 4 patients. In contrast to previous reports, the ketogenic diet and fasting produce worsening of symptoms. The effects of the mutations on NaCT transport function and protein expression were examined by transient transfections of COS-7 cells. There was no transport activity from any of the mutant transporters, although some of the mutant transporter proteins were present on the plasma membrane. The structural model of NaCT suggests that these mutations can affect helix packing or substrate binding. We tested various treatments, including chemical chaperones and low temperatures, but none improve transport function in the NaCT mutants. Interestingly, coexpression of NaCT and the mutants results in decreased protein expression and activity of the wild-type transporter, indicating functional interaction. In conclusion, our study has identified additional SLC13A5 mutations in patients with chronic epilepsy starting in the neonatal period, with the mutations producing inactive Na(+)/citrate transporters.

Impact of an Interactive, Animation-Based Electroencephalography Curriculum on Learner Confidence and Knowledge.

BACKGROUND: There is a national need for innovative electroencephalography (EEG) education with efficacy evaluated by rigorous statistical analysis. We created a dynamic, online resource that includes a series of animated videos at a single academic medical center. METHODS: For the animations and interactive module, we used VideoScribe and Articulate, respectively. The module comprised three chapters: (1) Origin & Technical Aspects of EEG, (2) Normal Adult EEG in Wakefulness & Sleep, and (3) Abnormal EEG, with appendices on artifacts, variants, activation procedures, seizure/epilepsy classification, and neonatal/pediatric EEG. The curriculum and knowledge assessments were reviewed independently by two fellowship-trained physicians before distribution. Linear mixed-effects models with bootstrapping were used to compare paired pre- and post-tests as well as Likert scale questionnaires. RESULTS: Forty-nine learners participated in the pretest survey; 38 matched participants completed post-tests (78%). Learners across fields perceived benefit (100% would recommend to colleagues), indicated improved self-efficacy (P < 0.0001), and performed better on post-test knowledge assessments (54.1 vs 88.2%, P < 0.0001). In the neurology providers subgroup (n = 20), pretest scores correlated with years in training (Spearman r = 0.52, P = 0.039), neurology rotations (r = 0.70, P = 0.003), epilepsy/EEG rotations (r = 0.6, P = 0.014), and EEG teaching hours (r = 0.62, P = 0.01); content knowledge and self-efficacy improvement for neurology providers remained significant in a multivariate model adjusting for these covariates. CONCLUSIONS: This animation-based, interactive EEG module proved effective in elevating learner confidence and knowledge across several medical specialties and training levels. Further study across institutions and subspecialties is needed to substantiate broad applicability, but our data appear promising for early EEG learners.

Use of Flow Cytometry for Diagnosis of Epilepsy Associated With Homozygous PIGW Variants.

BACKGROUND: Biallelic variants in PIGW have been suggested to cause infantile spasms and hyperphosphatasia. PIGW encodes for a protein involved in the third step of glycosylphosphatidylinositol (GPI) synthesis. GPI anchored proteins are increasingly recognized as important structures for cellular interactions and neuronal development. METHODS: Molecular testing of PIGW was performed followed by fluorescence activating cell sorting analysis of granulocytes, lymphocytes, and monocytes, and compared to controls. FINDINGS: An infant was homozygous for variants in PIGW (c.199C>G; p.Pro67Ala) with an associated phenotype of infantile spasms, myoclonic seizures, cortical visual impairment, developmental delay, and minor dysmorphic features. Alkaline phosphatase levels ranged from normal to mildly elevated. Flow cytometric studies showed significantly decreased expression of important GPIs, providing functional evidence of pathogenicity. CONCLUSION: Our data provide further evidence of a novel autosomal recessive PIGW-related epilepsy disorder. Flow cytometry provided functional evidence of the pathogenicity of homozygous variants of uncertain significance in PIGW, and supports the use of flow cytometry as a functional tool to demonstrate decreased surface expression of GPI anchored proteins in individuals with variants of unknown significance.

Relationship between reaction time variability and motor skill development in ADHD.

Slower and more variable reaction times to computerized tasks have been documented in children diagnosed with attention deficit/hyperactivity disorder (ADHD). Recent research supports a role for attentional lapses in generating abnormally variable and slow responses. However, given the association between ADHD and impairments in motor control, we hypothesized that slower or more variable reaction times might also correlate with motor development. The aim of this case-control study was to explore the relationship between motor function, reaction speed and variability, and ADHD. After comprehensive educational and clinical assessments, motor skill development was evaluated in 35 children ages 9 to 14 (19 with ADHD) using the Physical and Neurological Examination for Subtle Signs (PANESS) test battery. Finger-sequencing speed and variability were quantified with goniometers. Reaction times were measured with 20 trials each of computerized simple and choice (binary) tasks. Compared to healthy controls, children with ADHD had slower and more variable reaction times, and these findings correlated with impaired motor development (PANESS) and slow and variable finger sequencing (goniometers). Further studies of motor development in ADHD may identify factors influencing speed and variability of reaction times.