The clinical utility and diagnostic implementation of human subject cell transdifferentiation followed by RNA sequencing.

RNA sequencing (RNA-seq) has recently been used in translational research settings to facilitate diagnoses of Mendelian disorders. A significant obstacle for clinical laboratories in adopting RNA-seq is the low or absent expression of a significant number of disease-associated genes/transcripts in clinically accessible samples. As this is especially problematic in neurological diseases, we developed a clinical diagnostic approach that enhanced the detection and evaluation of tissue-specific genes/transcripts through fibroblast-to-neuron cell transdifferentiation. The approach is designed specifically to suit clinical implementation, emphasizing simplicity, cost effectiveness, turnaround time, and reproducibility. For clinical validation, we generated induced neurons (iNeurons) from 71 individuals with primary neurological phenotypes recruited to the Undiagnosed Diseases Network. The overall diagnostic yield was 25.4%. Over a quarter of the diagnostic findings benefited from transdifferentiation and could not be achieved by fibroblast RNA-seq alone. This iNeuron transcriptomic approach can be effectively integrated into diagnostic whole-transcriptome evaluation of individuals with genetic disorders.

TMEM161B regulates cerebral cortical gyration, Sonic Hedgehog signaling, and ciliary structure in the developing central nervous system.

Sonic hedgehog signaling regulates processes of embryonic development across multiple tissues, yet factors regulating context-specific Shh signaling remain poorly understood. Exome sequencing of families with polymicrogyria (disordered cortical folding) revealed multiple individuals with biallelic deleterious variants in TMEM161B, which encodes a multi-pass transmembrane protein of unknown function. Tmem161b null mice demonstrated holoprosencephaly, craniofacial midline defects, eye defects, and spinal cord patterning changes consistent with impaired Shh signaling, but were without limb defects, suggesting a CNS-specific role of Tmem161b. Tmem161b depletion impaired the response to Smoothened activation in vitro and disrupted cortical histogenesis in vivo in both mouse and ferret models, including leading to abnormal gyration in the ferret model. Tmem161b localizes non-exclusively to the primary cilium, and scanning electron microscopy revealed shortened, dysmorphic, and ballooned ventricular zone cilia in the Tmem161b null mouse, suggesting that the Shh-related phenotypes may reflect ciliary dysfunction. Our data identify TMEM161B as a regulator of cerebral cortical gyration, as involved in primary ciliary structure, as a regulator of Shh signaling, and further implicate Shh signaling in human gyral development.

The Finances of Neurology in a Major Children's Hospital.

Child neurology programs can be net margin generators for children's hospitals. The relative value unit (RVU) expectations for child neurologists are heavily influenced by proceduralists (neurophysiologists, Botox injectors, and so forth) and means in most RVU data sets are not realistic expectations for Evaluation and Management coding, outpatient neurologists. Yet each neurologist has a net revenue/expense ratio of 1.97 for a hospital neurology enterprise, so each of the neurologists generates nearly twice their salary for the hospital. Downstream revenue is even more impressive. Each neurologist generates about $2,000,000.00 in downstream revenue per year.

Neurology in a Pandemic.

The adaption of online or virtual technologies to deliver care, to meet professionally, and to interview has transformed child neurology. Although these technologies were brought to bear out of necessity, it is hoped that in a postpandemic world, these useful tools will continue to benefit the field. Here we discuss the tools and their future.

Novel Treatments and Clinical Research in Child Neurology.

The molecular understanding of the pathogenic mechanisms responsible for neurologic diseases of children has led to a remarkable period of research that addresses the root causes of diseases. The promise of this research has been realized with cures and treatments that correct underlying deficiencies. The breakneck rate at which new research is being proposed promises to usher in a transformation of child neurology from a diagnostic and supportive field into an interventional one. Training child neurology residents in clinical research and therapeutic intervention is increasingly important to assure the ongoing ability to support research discoveries and treatment.

Clinical Profile and Long-Term Outcome in Neonatal Cerebral Sinus Venous Thrombosis.

BACKGROUND: Neonatal cerebral sinus venous thrombosis (CSVT) causes high morbidity and mortality. Factors associated with either favorable or unfavorable long-term outcomes have not been clearly established. This study aimed to determine the factors involved in long-term neurological outcomes in patients with neonatal CSVT. METHODS: This was a retrospective cohort study of patients with neonatal CSVT at a single institution. Clinical factors associated with long-term neurological outcomes were examined. RESULTS: A total of 67 patients met study inclusion criteria for radiologically confirmed neonatal CSVT. The mean patient follow-up duration was four years (range one week to 16 years, median six years). We observed a favorable neurological outcome defined by a pediatric stroke outcome measures (PSOM) score of 0 to 0.5 in 26 (53%) of osurviving patients at follow-up. An unfavorable neurological outcome as defined by PSOM score >0.5 was observed in 23 survivors (47%). Death was reported in 18 (27%) patients, of which 10 patients died due to direct complications of CSVT. Congential heart disease and genetic disease were associated with significantly increased odds for all-cause death. Cardiorespiratory failure and altered mental status during the initial neurological examination were significantly associated with increased odds of death due to CSVT. Among surviving patients, higher PSOM scores were associated with premature birth (i.e., gestational age < 37 weeks), traumatic birth, site of thrombosis in the straight sinus, site of thrombosis in the internal cerebral veins, and hemorrhagic infarct. In contrast, lower PSOM scores were associated with a normal neurological examination at presentation, thrombosis in only superficial sinuses, and hemorrhage without infarct. There was no statistically significant association between the type and duration of CSVT treatment. CONCLUSIONS: The major factors influencing outcome of neonates following CSVT included comorbid medical conditions, abnormal neurological examination at presentation, location of venous thrombosis, and type of cerebral injury. These results can help guide further studies in neonatal CSVT aiming to decrease morbidity and mortality with the goal of improving long-term neurological outcomes.

Neurocutaneous Melanocytosis and Leptomeningeal Melanoma.

Neurocutaneous melanocytosis (NCM) is a disorder characterized by multiple or large congenital nevi and excessive proliferation of melanocytes in the leptomeninges and brain parenchyma. The majority of NCM is a result of somatic mosaicism due to a single postzygotic mutation in codon 61 of NRAS. Patients with NCM are at high risk of developing leptomeningeal melanoma. The prognosis for leptomeningeal melanoma is poor with no known effective treatment options. We describe the clinical features, treatment, and outcome of 4 children with NCM and leptomeningeal melanoma and discuss the latest molecular findings and treatment options for this rare condition.

Case report of prenatal bilateral cerebellar infarction: implications for social-behavioral functioning.

Objective: Complete prenatal cerebellar infarction is rare and few reports exist documenting developmental outcomes. We report outcome data on a child who sustained a stroke to the bilateral cerebellar hemispheres at 25 weeks gestation, and was subsequently seen for follow-up neuropsychological evaluations at ages 5 years, 5 months and 7 years, 9 months. Method: Retrospective chart review. Results: Findings from the initial evaluation at age 5 were consistent with a diagnosis of intellectual disability based on developmental testing and parent-reported adaptive behavior. Deficits in social communication, relatedness, and reciprocity were identified, though diagnosis of an autism-spectrum disorder (ASD) was deferred given the difficulty of interpreting these findings in the context of his physical and cognitive disabilities. Re-assessment at age 7 included comprehensive autism assessment, and a diagnosis of ASD was confirmed. Neuropsychological testing revealed minimal developmental skill progression over the assessment interval. Conclusions: These findings add to growing evidence that the cerebellum plays an important role in social development, and that early cerebellar injury may represent an acquired pathway for ASD. Complex medical histories may obscure or delay diagnosis of ASD, highlighting the importance of early evaluation using a multidisciplinary approach.

Open-label use of highly purified CBD (Epidiolex®) in patients with CDKL5 deficiency disorder and Aicardi, Dup15q, and Doose syndromes.

OBJECTIVE: We studied our collective open-label, compassionate use experience in using cannabidiol (CBD) to treat epilepsy in patients with CDKL5 deficiency disorder and Aicardi, Doose, and Dup15q syndromes. METHODS: We included patients aged 1-30 years with severe childhood-onset epilepsy who received CBD for ≥10 weeks as part of multiple investigator-initiated expanded access or state access programs for a compassionate prospective interventional study: CDKL5 deficiency disorder (n = 20), Aicardi syndrome (n = 19), Dup15q syndrome (n = 8), and Doose syndrome (n = 8). These patients were treated at 11 institutions from January 2014 to December 2016. RESULTS: The percent change in median convulsive seizure frequency for all patients taking CBD in the efficacy group decreased from baseline [n = 46] to week 12 (51.4% [n = 35], interquartile range (IQR): 9-85%) and week 48 (59.1% [n = 27], IQR: 14-86%). There was a significant difference between the percent changes in monthly convulsive seizure frequency during baseline and week 12, χ2(2) = 22.9, p = 0.00001, with no difference in seizure percent change between weeks 12 and 48. Of the 55 patients in the safety group, 15 (27%) withdrew from extended observation by week 144: 4 due to adverse effects, 9 due to lack of efficacy, 1 withdrew consent, and 1 was lost to follow-up. SIGNIFICANCE: This open-label drug trial provides class III evidence for the long-term safety and efficacy of CBD administration in patients with treatment-resistant epilepsy (TRE) associated with CDKL5 deficiency disorder and Aicardi, Dup15q, and Doose syndromes. Adjuvant therapy with CBD showed similar safety and efficacy for these four syndromes as reported in a diverse population of TRE etiologies. This study extended analysis of the prior report from 12 weeks to 48 weeks of efficacy data and suggested that placebo-controlled randomized trials should be conducted to formally assess the safety and efficacy of CBD in these epileptic encephalopathies.

Evaluation of Safety in Exceeding Maximum Adult Doses of Commonly Used Second-Generation Antiepileptic Drugs in Pediatric Patients.

OBJECTIVE: Pediatric patients often require larger doses of antiepileptic drug (AED) than adults in order to attain therapeutic serum concentrations and/or achieve seizure control. Safety and efficacy data are often extrapolated from adult literature; hence, optimal dosage may only be determined anecdotally or based on expert opinion. With limited pediatric dosing guidelines, milligrams per day that are based on weight may exceed the maximum adult dose. The primary objective of this study is to evaluate the safety of exceeding maximum doses as specified by the US Food and Drug Administration or manufacturers of commonly used AEDs in pediatric patients. METHODS: This study is a single-center, retrospective analysis of all pediatric patients seen in the outpatient clinic between October 2010 and October 2014 who were prescribed a dose that exceeds the maximum approved dose of oxcarbazepine, zonisamide, topiramate, levetiracetam, lamotrigine, or clobazam. Baseline demographics (ie, sex, age, race/ethnicity, weight, height, diagnosis), serum drug concentrations, and appropriate laboratory tests were collected. Side effects were reviewed. RESULTS: During the 4-year study period, 41,137 prescriptions were included. A total of 2% of prescriptions exceeded the maximum dose of 1 of the included AEDs. The most common AED prescribed above the maximum dose was levetiracetam (53%), whereas lamotrigine was the least common (6%). The largest doses prescribed exceeded the maximum by 3-fold (i.e., levetiracetam dose of 9000 mg/day). CONCLUSION: It appears safe to use doses exceeding the maximum approved dose of the evaluated AEDs in pediatric patients, with appropriate counseling and monitoring for adverse effects.

Platelet-Activating Factor Acetylhydrolase and Brain Development.

The heterotrimeric brain platelet-activating factor acetylhydrolase (PAFAH1B1) contains two catalytic subunits and a regulatory subunit. This complex plays important, surprising roles in brain development and in spermatogenesis. The regulatory subunit, PAFAH1B1 (LIS1 protein), is critically regulated and when deficient leads to the devastating human neurological disorder Lissencephaly, or smooth brain. The role of the protein in brain development is not the catalysis of platelet-activating factor, rather the entire brain platelet-activating factor acetylhydrolase complex serves a signaling role, coordinating important pathways in brain development. The role of this complex in spermatogenesis was not foreseen, but appears to function to regulate a critical level of the PAFAH1B1 protein, such that too much of this protein or too little of this protein can lead to a disruption of spermatogenesis. Brain platelet-activating factor is thus a signaling complex, important for brain development and for spermatogenesis.

Whole-exome sequencing identifies compound heterozygous mutations in WDR62 in siblings with recurrent polymicrogyria.

Polymicrogyria is a disorder of neuronal development resulting in structurally abnormal cerebral hemispheres characterized by over-folding and abnormal lamination of the cerebral cortex. Polymicrogyria is frequently associated with severe neurologic deficits including intellectual disability, motor problems, and epilepsy. There are acquired and genetic causes of polymicrogyria, but most patients with a presumed genetic etiology lack a specific diagnosis. Here we report using whole-exome sequencing to identify compound heterozygous mutations in the WD repeat domain 62 (WDR62) gene as the cause of recurrent polymicrogyria in a sibling pair. Sanger sequencing confirmed that the siblings both inherited 1-bp (maternal allele) and 2-bp (paternal allele) frameshift deletions, which predict premature truncation of WDR62, a protein that has a role in early cortical development. The probands are from a non-consanguineous family of Northern European descent, suggesting that autosomal recessive PMG due to compound heterozygous mutation of WDR62 might be a relatively common cause of PMG in the population. Further studies to identify mutation frequency in the population are needed.

Recurrent partial rhombencephalosynapsis and holoprosencephaly in siblings with a mutation of ZIC2.

Rhombencephalosynapsis (RES) is a rare congenital brain malformation typically identified by magnetic resonance imaging and characterized by fusion of the cerebellar hemispheres and dentate nuclei and vermian agenesis or hypogenesis. Although RES is frequently found in conjunction with other brain malformations and/or congenital anomalies, no specific molecular etiology has been discovered to date and no animal models exist. We identified two half sisters with alobar or semi-lobar holoprosencephaly (HPE) and partial RES, suggesting that genes linked to HPE may also contribute to RES. A deletion of seven base pairs in exon one of the ZIC2 gene (c.392_98del7) was identified in each of the two half sisters with HPE and partial RES. To identify genetic causes of RES and to assess whether genes identified in HPE have a role in RES, we tested 11 additional individuals with RES by high-resolution chromosome analysis, chromosomal microarray analysis, and sequencing of four HPE genes. No mutations in ZIC2 or in other genes that cause HPE were identified, suggesting that mutation of ZIC2 is a rare cause of, or contributor to, RES associated with HPE. In addition, an individual with a complex rearrangement of chromosome 22q13.3 and RES was identified, suggesting the presence of a dosage-sensitive gene that may contribute to RES in this region.

Bilateral in utero cerebellar infarction.

We report a case of complete bilateral cerebellar infarction diagnosed in utero by routine prenatal ultrasound and magnetic resonance imaging in a 26-week-old fetus. This posterior fossa ischemic stroke with secondary hemorrhage caused transient obstructive hydrocephalus and likely occurred subsequent to vertebrobasilar artery thrombosis. Such posterior fossa ischemic insults diagnosed in utero are rare with scarce clinical reports. The serial imaging characteristics, clinical, and developmental implications of this case are reviewed.

Differential interaction of the Pafah1b alpha subunits with the Reelin transducer Dab1.

The Reelin signaling pathway controls radial neuronal migration and maturation in the developing brain. The platelet activating factor (PAF) acetyl hydrolase 1b (Pafah1b) complex is also involved in multiple aspects of brain development. We previously showed that the Reelin pathway and the Pafah1b complex interact genetically and biochemically. Lis1, the regulatory subunit of Pafah1b interacts with phosphoDab1, an essential mediator of Reelin signaling. Compound mutants carrying mutations in both, the Reelin pathway and Lis1 exhibit hydrocephalus, a phenotype that is suppressed by mutations in the gene encoding the Alpha2 subunit of Pafah1b. This subunit, like the Alpha1 catalytic subunit of Pafah1b also binds the Reelin receptor VLDLR. Here we investigated the molecular interactions of the Pafah1b catalytic subunits with Dab1. We found that Alpha2 coprecipitates with Dab1 from brain extracts of normal and reeler mutant mice lacking Reelin, and from cell-free extracts containing normal or a phosphorylation mutant form of Dab1, suggesting that Dab1 phosphorylation is not necessary for binding to Alpha2. This interaction is specific for Alpha2 and not Alpha1, and depends on a unique tyrosine residue of Alpha2. Biochemical assays using mutant mice lacking Alpha2 further demonstrated that this subunit is not required for Reelin-induced Dab1 phosphorylation. However, increasing amounts of Alpha2 in a cell-free system disrupted the formation of Dab1-Lis1 complexes without affecting the association of Dab1 with VLDLR. Our data suggest that the Alpha2 subunit may play a modulatory role in the formation of protein complexes that affect brain development and hydrocephalus.

Consistent chromosome abnormalities identify novel polymicrogyria loci in 1p36.3, 2p16.1-p23.1, 4q21.21-q22.1, 6q26-q27, and 21q2.

Polymicrogyria is a malformation of cortical development characterized by loss of the normal gyral pattern, which is replaced by many small and infolded gyri separated by shallow, partly fused sulci, and loss of middle cortical layers. The pathogenesis is unknown, yet emerging data supports the existence of several loci in the human genome. We report on the clinical and brain imaging features, and results of cytogenetic and molecular genetic studies in 29 patients with polymicrogyria associated with structural chromosome rearrangements. Our data map new polymicrogyria loci in chromosomes 1p36.3, 2p16.1-p23, 4q21.21-q22.1, 6q26-q27, and 21q21.3-q22.1, and possible loci in 1q44 and 18p as well. Most and possibly all of these loci demonstrate incomplete penetrance and variable expressivity. We anticipate that these data will serve as the basis for ongoing efforts to identify the causal genes located in these regions.

Pafah1b2 mutations suppress the development of hydrocephalus in compound Pafah1b1; Reln and Pafah1b1; Dab1 mutant mice.

Reelin, an extracellular protein that signals through the Dab1 adapter protein, and Lis1 regulate neuronal migration and cellular layer formation in the brain. Loss of Reelin and reduction in Lis1 activity in mice or humans results in the disorganization of cortical structures. Lis1, the product of the Pafah1b1 gene associates with Alpha1 (the product of the Pafah1b3 gene) and Alpha2 (the product of the Pafah1b2 gene) to form the Pafah1b heterotrimeric complex. This complex interacts biochemically and genetically with the Reelin pathway, however, the role of Alpha1 and Alpha2 in brain development is poorly understood. We previously demonstrated that compound mutations of Pafah1b1 with genes in Reelin pathway result in layering defects and the appearance of hydrocephalus in double mutant mice. Here, we generate triple mouse mutants to investigate the effect of individual Pafah1b Alpha subunits on cellular layer formation and hydrocephalus. We found that Pafah1b3 mutations exacerbate the layering defects, whereas Pafah1b2 mutations strongly suppress the hydrocephalus phenotype of compound mutant mice. The data indicate that the two Pafah1b Alpha subunits have profoundly different effects on brain development and interact in a significantly different manner with the Reelin signaling pathway.

Speech delay and autism spectrum behaviors are frequently associated with duplication of the 7q11.23 Williams-Beuren syndrome region.

PURPOSE: Williams-Beuren syndrome is among the most well-characterized microdeletion syndromes, caused by recurrent de novo microdeletions at 7q11.23 mediated by nonallelic homologous recombination between low copy repeats flanking this critical region. However, the clinical phenotype associated with reciprocal microduplication of this genomic region is less well described. We investigated the molecular, clinical, neurodevelopmental, and behavioral features of seven patients with dup(7)(q11.23), including two children who inherited the microduplication from one of their parents, to more fully characterize this emerging microduplication syndrome. METHODS: Patients were identified by array-based comparative genomic hybridization. Clinical examinations were performed on seven affected probands, and detailed cognitive and behavioral evaluations were carried out on four of the affected probands. RESULTS: Our findings confirm initial reports of speech delay seen in patients with dup(7)(q11.23) and further delineate and expand the phenotypic spectrum of this condition to include communication, social interactions, and repetitive interests that are often observed in individuals diagnosed with autism spectrum disorders. CONCLUSIONS: Array-based comparative genomic hybridization is a powerful means of detecting genomic imbalances and identifying molecular etiologies in the clinic setting, including genomic disorders such as Williams-Beuren syndrome and dup(7)(q11.23). We propose that dup(7)(q11.23) syndrome may be as frequent as Williams-Beuren syndrome and a previously unrecognized cause of language delay and behavioral abnormalities. Indeed, these individuals may first be referred for evaluation of autism, even if they do not ultimately meet diagnostic criteria for an autism spectrum disorder.