Truncating SRCAP variants outside the Floating-Harbor syndrome locus cause a distinct neurodevelopmental disorder with a specific DNA methylation signature.

Truncating variants in exons 33 and 34 of the SNF2-related CREBBP activator protein (SRCAP) gene cause the neurodevelopmental disorder (NDD) Floating-Harbor syndrome (FLHS), characterized by short stature, speech delay, and facial dysmorphism. Here, we present a cohort of 33 individuals with clinical features distinct from FLHS and truncating (mostly de novo) SRCAP variants either proximal (n = 28) or distal (n = 5) to the FLHS locus. Detailed clinical characterization of the proximal SRCAP individuals identified shared characteristics: developmental delay with or without intellectual disability, behavioral and psychiatric problems, non-specific facial features, musculoskeletal issues, and hypotonia. Because FLHS is known to be associated with a unique set of DNA methylation (DNAm) changes in blood, a DNAm signature, we investigated whether there was a distinct signature associated with our affected individuals. A machine-learning model, based on the FLHS DNAm signature, negatively classified all our tested subjects. Comparing proximal variants with typically developing controls, we identified a DNAm signature distinct from the FLHS signature. Based on the DNAm and clinical data, we refer to the condition as "non-FLHS SRCAP-related NDD." All five distal variants classified negatively using the FLHS DNAm model while two classified positively using the proximal model. This suggests divergent pathogenicity of these variants, though clinically the distal group presented with NDD, similar to the proximal SRCAP group. In summary, for SRCAP, there is a clear relationship between variant location, DNAm profile, and clinical phenotype. These results highlight the power of combined epigenetic, molecular, and clinical studies to identify and characterize genotype-epigenotype-phenotype correlations.

Sphingosine Phosphate Lyase Is Upregulated in Duchenne Muscular Dystrophy, and Its Inhibition Early in Life Attenuates Inflammation and Dystrophy in Mdx Mice.

Duchenne muscular dystrophy (DMD) is a congenital myopathy caused by mutations in the dystrophin gene. DMD pathology is marked by myositis, muscle fiber degeneration, and eventual muscle replacement by fibrosis and adipose tissue. Satellite cells (SC) are muscle stem cells critical for muscle regeneration. Sphingosine-1-phosphate (S1P) is a bioactive sphingolipid that promotes SC proliferation, regulates lymphocyte trafficking, and is irreversibly degraded by sphingosine phosphate lyase (SPL). Here, we show that SPL is virtually absent in normal human and murine skeletal muscle but highly expressed in inflammatory infiltrates and degenerating fibers of dystrophic DMD muscle. In mdx mice that model DMD, high SPL expression is correlated with dysregulated S1P metabolism. Perinatal delivery of the SPL inhibitor LX2931 to mdx mice augmented muscle S1P and SC numbers, reduced leukocytes in peripheral blood and skeletal muscle, and attenuated muscle inflammation and degeneration. The effect on SC was also observed in SCID/mdx mice that lack mature T and B lymphocytes. Transcriptional profiling in the skeletal muscles of LX2931-treated vs. control mdx mice demonstrated changes in innate and adaptive immune functions, plasma membrane interactions with the extracellular matrix (ECM), and axon guidance, a known function of SC. Our cumulative findings suggest that by raising muscle S1P and simultaneously disrupting the chemotactic gradient required for lymphocyte egress, SPL inhibition exerts a combination of muscle-intrinsic and systemic effects that are beneficial in the context of muscular dystrophy.

Targeted Treatments for Inherited Neuromuscular Diseases of Childhood.

In the past decade, the number of genes linked to neuromuscular diseases of childhood has expanded dramatically, and this genetic information is forming the basis for gene-specific and even mutation-specific therapies. At the forefront of these advances are the two recently approved treatments for spinal muscular atrophy: one, an antisense oligonucleotide that modifies splicing of the SMN2 gene, and, the other, a gene therapy vector that delivers the SMN1 gene to motor neurons, both of which are allowing patients to acquire developmental milestones previously unseen in this fatal disease. This review highlights these advances and emerging targeted therapies for Duchenne muscular dystrophy and centronuclear myopathy, while also covering enzyme replacement therapy and small molecule-based targeted therapies for conditions such as Pompe's disease and congenital myasthenic syndromes. With these and other newer techniques for targeted correction of genetic defects, such as CRISPR/Cas9, there is now hope that treatments for many more genetic diseases of the nervous system will follow in the near future.

Pathogenic WDFY3 variants cause neurodevelopmental disorders and opposing effects on brain size.

The underpinnings of mild to moderate neurodevelopmental delay remain elusive, often leading to late diagnosis and interventions. Here, we present data on exome and genome sequencing as well as array analysis of 13 individuals that point to pathogenic, heterozygous, mostly de novo variants in WDFY3 (significant de novo enrichment P = 0.003) as a monogenic cause of mild and non-specific neurodevelopmental delay. Nine variants were protein-truncating and four missense. Overlapping symptoms included neurodevelopmental delay, intellectual disability, macrocephaly, and psychiatric disorders (autism spectrum disorders/attention deficit hyperactivity disorder). One proband presented with an opposing phenotype of microcephaly and the only missense-variant located in the PH-domain of WDFY3. Findings of this case are supported by previously published data, demonstrating that pathogenic PH-domain variants can lead to microcephaly via canonical Wnt-pathway upregulation. In a separate study, we reported that the autophagy scaffolding protein WDFY3 is required for cerebral cortical size regulation in mice, by controlling proper division of neural progenitors. Here, we show that proliferating cortical neural progenitors of human embryonic brains highly express WDFY3, further supporting a role for this molecule in the regulation of prenatal neurogenesis. We present data on Wnt-pathway dysregulation in Wdfy3-haploinsufficient mice, which display macrocephaly and deficits in motor coordination and associative learning, recapitulating the human phenotype. Consequently, we propose that in humans WDFY3 loss-of-function variants lead to macrocephaly via downregulation of the Wnt pathway. In summary, we present WDFY3 as a novel gene linked to mild to moderate neurodevelopmental delay and intellectual disability and conclude that variants putatively causing haploinsufficiency lead to macrocephaly, while an opposing pathomechanism due to variants in the PH-domain of WDFY3 leads to microcephaly.

Serial prenatal and postnatal MRI of dystroglycanopathy in a patient with familial B3GALNT2 mutation.

The dystroglycanopathies are a heterogeneous group of conditions, with mutations in B3GALNT2 described in association with congenital muscular dystrophy. The serial prenatal MRI findings in this disorder have not been well described. We present sequential prenatal and postnatal MRI findings in a boy with compound heterozygous mutations in B3GALNT2, as well as the MRI findings of his two siblings with similar mutations. These findings provide new insight into the molecular pathogenesis and neurodevelopment of congenital muscular dystrophy.

Novel KIF7 missense substitutions in two patients presenting with multiple malformations and features of acrocallosal syndrome.

We present two children who both had two missense mutations in the Kinesin Family Member 7 (KIF7) gene. A seven year old female with severe developmental delays, failure to thrive and growth retardation, infantile spasms, a cardiac vascular ring and right-sided aortic arch, imperforate anus, hydronephrosis with a right renal cyst, syndactyly and abnormal white matter was a compound heterozygote for c.3365C > G, predicting p.(Ser1122Trp) that was maternally inherited and c.2482G > A, predicting p.(Val828Met) that was paternally inherited. An eight year old female with severe developmental delays, epilepsy, left postaxial polydactyly of the hand and abnormalities of brain development including hydrocephalus, pachygyria and absence of the body and splenium of the corpus callous was a compound heterozygote for c.461G > A, predicting p.(Arg154Gln) and c.2959 G > A, predicting p.(Glu987Lys) that was maternally inherited and her father was unavailable for testing. The presentations in these children include features of acrocallosal syndrome, such as hypoplasia of the corpus callosum, enlarged ventricles, facial dysmorphism with a prominent forehead and broad halluces in the first child, but included atypical findings for individuals previously reported to have truncating mutations in KIF7, including imperforate anus, infantile spasms and severe growth retardation. We conclude that these phenotypes may result from the KIF7 sequence variants and abnormal hedgehog signaling, but that the full spectrum of KIF7-associated features remains to be determined.

Acute Flaccid Myelitis of Unknown Etiology in California, 2012-2015.

IMPORTANCE: There has been limited surveillance for acute flaccid paralysis in North America since the regional eradication of poliovirus. In 2012, the California Department of Public Health received several reports of acute flaccid paralysis cases of unknown etiology. OBJECTIVE: To quantify disease incidence and identify potential etiologies of acute flaccid paralysis cases with evidence of spinal motor neuron injury. DESIGN, SETTING, AND PARTICIPANTS: Case series of acute flaccid paralysis in patients with radiological or neurophysiological findings suggestive of spinal motor neuron involvement reported to the California Department of Public Health with symptom onset between June 2012 and July 2015. Patients meeting diagnostic criteria for other acute flaccid paralysis etiologies were excluded. Cerebrospinal fluid, serum samples, nasopharyngeal swab specimens, and stool specimens were submitted to the state laboratory for infectious agent testing. MAIN OUTCOMES AND MEASURES: Case incidence and infectious agent association. RESULTS: Fifty-nine cases were identified. Median age was 9 years (interquartile range [IQR], 4-14 years; 50 of the cases were younger than 21 years). Symptoms that preceded or were concurrent included respiratory or gastrointestinal illness (n = 54), fever (n = 47), and limb myalgia (n = 41). Fifty-six patients had T2 hyperintensity of spinal gray matter on magnetic resonance imaging and 43 patients had cerebrospinal fluid pleocytosis. During the course of the initial hospitalization, 42 patients received intravenous steroids; 43, intravenous immunoglobulin; and 13, plasma exchange; or a combination of these treatments. Among 45 patients with follow-up data, 38 had persistent weakness at a median follow-up of 9 months (IQR, 3-12 months). Two patients, both immunocompromised adults, died within 60 days of symptom onset. Enteroviruses were the most frequently detected pathogen in either nasopharynx swab specimens, stool specimens, serum samples (15 of 45 patients tested). No pathogens were isolated from the cerebrospinal fluid. The incidence of reported cases was significantly higher during a national enterovirus D68 outbreak occurring from August 2014 through January 2015 (0.16 cases per 100,000 person-years) compared with other monitoring periods (0.028 cases per 100,000 person-years; P <.001). CONCLUSIONS AND RELEVANCE: In this series of patients identified in California from June 2012 through July 2015, clinical manifestations indicated a rare but distinct syndrome of acute flaccid paralysis with evidence of spinal motor neuron involvement. The etiology remains undetermined, most patients were children and young adults, and motor weakness was prolonged.

Analysis of Gender Discrepancies in Leadership Roles and Recognition Awards in the Child Neurology Society.

BACKGROUND AND OBJECTIVES: Gender disparities have been demonstrated across several medical specialties, including neurology. Although women have comprised most of the child neurology trainees since 2007, it is not apparent whether this demographic shift is reflected in the Child Neurology Society (CNS) awards and leadership. This study aimed to evaluate the differences in gender representation among leadership positions and award recipients within the CNS. The primary outcome measure was the total number of board of director (BOD) positions or awards given by gender each year. METHODS: A retrospective review of publicly available data was conducted on CNS members, post-training award recipients, and BOD positions, including nomination records, from 1972 to 2023. Data abstracted were restricted to gender to preserve member and nominee anonymity. Gender identification and consensus were determined through a combination of strategies and study members. Data analysis included descriptive statistics, Pearson χ2 test, and the exact binomial test to compare gender proportions and the probability of being underrepresented in awards, leadership, and nominations over time. Data are presented according to the Strengthening the Reporting of Observational Studies in Epidemiology guidelines. RESULTS: From 1972 to 2023, women represented 29% (44/152) of the BOD positions and 26% (61/236) of post-training award recipients presented by the CNS. Despite the increase in the proportion of women in child neurology, the overall gap in gender representation in leadership positions remains broadly stable. Only 13% (4/32) of CNS presidents have been women, a significant underrepresentation (95% CI 2.3%-52%, p < 0.004), although the representation of women in nonpresidential positions increased from 2003 to 2023. Women are also underrepresented as overall awardees (95% CI 12%-38%, p < 0.00001) except for the Philip R. Dodge Young Investigator Award, which is an investigator-initiated application. DISCUSSION: Women remain underrepresented at the highest levels of recognition in child neurology despite representing most of the field. Reasons for disparities are known to be multifactorial and likely include gender bias and structural sexism. We present several discussion topics that seek to rationalize this disparity and provide suggestions for improving diversity, equity, and inclusion for leadership roles and awards.

Quantitative MRI analysis in children with multiple sclerosis: a multicenter feasibility pilot study.

BACKGROUND: Pediatric multiple sclerosis (MS) is a rare disorder with significant consequences. Quantitative MRI measurements may provide significant insights, however multicenter collaborative studies are needed given the small numbers of subjects. The goal of this study is to demonstrate feasibility and evaluate lesion volume (LV) characteristics in a multicenter cohort of children with MS. METHODS: A common MRI-scanning guideline was implemented at six member sites of the U.S. Network of Pediatric MS Centers of Excellence. We included in this study the first ten scans performed at each site on patients meeting the following inclusion criteria: pediatric RRMS within 3 years of disease onset, examination within 1 month of MRI and no steroids 1 month prior to MRI. We quantified T2 number, T2-LV and individual lesion size in a total of 53 MRIs passing quality control procedures and assessed gadolinium-enhancing lesion number and LV in 55 scans. We studied MRI measures according to demographic features including age, race, ethnicity and disability scores, controlling for disease duration and treatment duration using negative binomial regression and linear regression. RESULTS: The mean number of T2 lesions was 24.30 ± 19.68 (range:1-113) and mean gadolinium-enhancing lesion count was 1.85 ± 5.84, (range:0-32). Individual lesion size ranged from 14.31 to 55750.60 mm3. Non-white subjects had higher T2-LV (unadjusted pT2-LV = 0.028; adjusted pT2-LV = 0.044), and maximal individual T2-LV (unadjusted pMax = 0.007; adjusted pMax = 0.011) than white patients. We also found a trend toward larger mean lesion size in males than females (p = 0.07). CONCLUSION: Assessment of MRI lesion LV characteristics is feasible in a multicenter cohort of children with MS.

Diagnostic yield of pediatric and prenatal exome sequencing in a diverse population.

The diagnostic yield of exome sequencing (ES) has primarily been evaluated in individuals of European ancestry, with less focus on underrepresented minority (URM) and underserved (US) patients. We evaluated the diagnostic yield of ES in a cohort of predominantly US and URM pediatric and prenatal patients suspected to have a genetic disorder. Eligible pediatric patients had multiple congenital anomalies and/or neurocognitive disabilities and prenatal patients had one or more structural anomalies, disorders of fetal growth, or fetal effusions. URM and US patients were prioritized for enrollment and underwent ES at a single academic center. We identified definitive positive or probable positive results in 201/845 (23.8%) patients, with a significantly higher diagnostic rate in pediatric (26.7%) compared to prenatal patients (19.0%) (P = 0.01). For both pediatric and prenatal patients, the diagnostic yield and frequency of inconclusive findings did not differ significantly between URM and non-URM patients or between patients with US status and those without US status. Our results demonstrate a similar diagnostic yield of ES between prenatal and pediatric URM/US patients and non-URM/US patients for positive and inconclusive results. These data support the use of ES to identify clinically relevant variants in patients from diverse populations.

Relapse severity and recovery in early pediatric multiple sclerosis.

BACKGROUND: Factors determining severity and recovery of early demyelinating events in pediatric multiple sclerosis (MS) patients are unknown. OBJECTIVE: The objective of this study was to characterize the severity and recovery of early demyelinating events in pediatric MS. METHODS: Multivariate logistic regression was performed to determine predictors of severe (versus mild/moderate) relapses and poor or fair (versus complete) recovery in patients aged 18 years or less with MS or clinically isolated syndrome (CIS). RESULTS: Optic nerve involvement (OR 4.30, 95% CI 1.50-12.3, p = 0.007) was associated with a severe initial demyelinating event (IDE), while non-White race (OR 2.55, 95% CI 0.87-7.49, p = 0.088), localization to the cerebral hemispheres (OR 7.94, 95% CI 0.86-73.8, p = 0.068), or encephalopathy (OR 8.70, 95% CI 0.86-88.0, p = 0.067) showed a trend towards increased IDE severity. A similar association with race was found for severe second events. A severe IDE (OR 6.90, 95% CI 2.47-19.3, p < 0.001) was associated with incomplete IDE recovery, with similar trends for second and third events. Incomplete recovery from the first event predicted incomplete second event recovery (OR 3.36, 95% CI 0.98-11.6, p = 0.055). CONCLUSIONS: These results may help identify children at risk for a more aggressive disease course.

Vitamin D status is associated with relapse rate in pediatric-onset multiple sclerosis.

OBJECTIVE: We sought to determine if vitamin D status, a risk factor for multiple sclerosis, is associated with the rate of subsequent clinical relapses in pediatric-onset multiple sclerosis. METHODS: This is a retrospective study of patients with pediatric-onset multiple sclerosis or clinically isolated syndrome who were consecutively recruited into a prospective cohort at their clinical visit at the pediatric multiple sclerosis center of University of California, San Francisco or State University of New York at Stony Brook. Of 171 eligible patients, 134 (78%) with multiple sclerosis/clinically isolated syndrome were included in the cohort; a further 24 were excluded from this analysis due to lack of available serum (n = 7) or lack of follow-up (n = 17). Serum 25-hydroxyvitamin D(3) levels were measured and were adjusted to reflect a deseasonalized value. The adjusted serum 25-hydroxyvitamin D(3) level was the primary predictor in a multivariate negative binomial regression model in which the main outcome measure was the number of subsequent relapses. RESULTS: Among the 110 subjects, the mean unadjusted 25-hydroxyvitamin D(3) level was 22 +/- 9 ng/ml. After adjustment for age, gender, race, ethnicity, disease duration, disease-modifying therapy, and length of follow-up, every 10 ng/ml increase in the adjusted 25-hydroxyvitamin D(3) level was associated with a 34% decrease in the rate of subsequent relapses (incidence rate ratio, 0.66; 95% confidence interval, 0.46-0.95; p = 0.024). INTERPRETATION: Lower serum 25-hydroxyvitamin D(3) levels are associated with a substantially increased subsequent relapse rate in pediatric-onset multiple sclerosis or clinically isolated syndrome, providing rationale for a randomized controlled trial of vitamin D supplementation.

Treatment of hypokalemic periodic paralysis with topiramate.

Hypokalemic periodic paralysis (hypoPP), the most common form of periodic paralysis, is a disorder characterized by attacks of transient muscle weakness associated with a drop in serum potassium level.The mainstay of treatment is potassium supplementation and drugs that inhibit the enzyme carbonic anhydrase. In this report we describe 11-year-old twins with hypoPP who were treated with topiramate, an anti-epileptic drug known to have carbonic anhydrase inhibitory properties. The patients experienced a decrease in the severity of their attacks upon initiation of treatment. Topiramate may warrant further investigation as a treatment option in hypoPP.

Long-Term Safety, Immunologic Response, and Imaging Outcomes following Neural Stem Cell Transplantation for Pelizaeus-Merzbacher Disease.

Four boys with Pelizaeus-Merzbacher disease, an X-linked leukodystrophy, underwent transplantation with human allogeneic central nervous system stem cells (HuCNS-SC). Subsequently, all subjects were followed for an additional 4 years in this separate follow-up study to evaluate safety, neurologic function, magnetic resonance imaging (MRI) data, and immunologic response. The neurosurgical procedure, immunosuppression, and HuCNS-SC transplantation were well tolerated and all four subjects were alive at the conclusion of the study period. At year 2, all subjects exhibited diffusion MRI changes at the implantation sites as well as in more distant brain regions. There were persistent, increased signal changes in the three patients who were studied up to year 5. Two of four subjects developed donor-specific HLA alloantibodies, demonstrating that neural stem cells can elicit an immune response when injected into the CNS, and suggesting the importance of monitoring immunologic parameters and identifying markers of engraftment in future studies.

Pediatric multiple sclerosis.

Diagnosing multiple sclerosis (MS) in a child is challenging because of the limited diagnostic criteria and their overlap with acute disseminated encephalomyelitis. Pediatric-onset MS patients are more likely to be male, have seizures, and have brainstem and cerebellar symptoms than adults, and are less likely to have spinal cord symptoms than adults. They mostly experience a relapsing-remitting course. Their initial brain MRI shows more frequent involvement of the posterior fossa, less well-defined ovoid lesions, and more confluent lesions that decrease over time in patients with prepubertal onset, making early diagnosis even more difficult. Although disability progression is slower than in adults, pediatric onset MS leads to significant disability at a younger age and may be worse in non-white patients (up to 50% in North America). The rareness of pediatric-onset MS has precluded enrollment in clinical trials. Thus, children are receiving off-label adult therapies without clear evidence of their effectiveness and limited knowledge of their tolerability.

Presynaptic congenital myasthenic syndrome with altered synaptic vesicle homeostasis linked to compound heterozygous sequence variants in RPH3A.

BACKGROUND: Monogenic defects of synaptic vesicle (SV) homeostasis have been implicated in many neurologic diseases, including autism, epilepsy, and movement disorders. In addition, abnormal vesicle exocytosis has been associated with several endocrine dysfunctions. METHODS: We report an 11 year old girl with learning disabilities, tremors, ataxia, transient hyperglycemia, and muscle fatigability responsive to albuterol sulfate. Failure of neuromuscular transmission was confirmed by single fiber electromyography. Electron microscopy of motor nerve terminals revealed marked reduction in SV density, double-membrane-bound sacs containing SVs, abundant endosomes, and degenerative lamellar bodies. The patient underwent whole exome sequencing (WES) and relevant sequence variants were expressed and studied in a mammalian cell line. RESULTS: Chromosomal microarray studies and next generation sequencing (NGS) of mitochondrial DNA were unrevealing; however, NGS of genomic DNA showed two rare sequence variants in the gene encoding rabphilin 3a (RPH3A). The paternally inherited variant c.806 G>A (p.Arg269Gln) involves a substitution of a conserved residue in the linker region, while the maternally inherited variant c.1390 G>T (p.Val464Leu) involves a conserved amino acid substitution in the highly conserved C2A region. Expression studies revealed that p.Arg269Gln strongly impairs the binding of rabphilin 3a to 14-3-3, which is a proposed regulator of synaptic transmission and plasticity. In contrast, the binding of rabphilin 3a to 14-3-3 is only marginally impaired by p.Val464Leu; thus, the pathogenic role of p.Val464Leu remains unclear. CONCLUSION: In summary, we report a patient with a multisystem neurologic disorder and altered SV regulation attributed to defects in RPH3A, which grants further studies of this gene in human disorders of synaptic transmission.