Publications by authors named "Gary D Clark"

Objective: The cannabidiol (CBD) Expanded Access Program provided compassionate access to CBD for patients with treatment-resistant epilepsy, including tuberous sclerosis complex (TSC), at 35 US epilepsy centers. Here, we present the long-term efficacy and safety outcomes for add-on CBD treatment in patients with TSC.

Methods: Patients received plant-derived, highly purified CBD (Epidiolex® 100 mg/mL, oral solution), increasing from 2 to 10 mg/kg/d to tolerance or maximum of 25-50 mg/kg/d.

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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.

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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 , which encodes a multi-pass transmembrane protein of unknown function. 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.

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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.

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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.

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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.

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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.

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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.

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Article Synopsis
  • Lamb-Shaffer syndrome (LAMSHF) is a rare neurodevelopmental disorder linked to genetic changes in the SOX5 gene, primarily through microdeletions, affecting brain development and function.
  • The study analyzed data from 41 new patients with different SOX5 alterations to better understand the genetic variations and their impact on clinical symptoms.
  • Findings revealed that while most genetic changes disrupt SOX5's ability to bind DNA, leading to varying degrees of intellectual disability and language delays, the severity of symptoms doesn't strongly correlate with specific genetic alterations.
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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. Retrospective chart review.

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Article Synopsis
  • This study focused on using cannabidiol (CBD) to treat severe epilepsy in patients with specific genetic disorders, including CDKL5 deficiency disorder, Aicardi, Doose, and Dup15q syndromes.
  • A total of 46 patients were assessed, showing a significant reduction in convulsive seizure frequency after 12 weeks (51.4%) and 48 weeks (59.1%) of treatment with CBD.
  • The research supports the long-term safety and efficacy of CBD for these hard-to-treat epilepsy syndromes and calls for more rigorous placebo-controlled trials to further validate these findings.
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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.

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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.

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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.

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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.

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Article Synopsis
  • A 26-week-old fetus was diagnosed in utero with complete bilateral cerebellar infarction using routine prenatal ultrasound and MRI.
  • This condition is associated with posterior fossa ischemic stroke, linked to a thrombosis in the vertebrobasilar artery, which led to temporary obstructive hydrocephalus.
  • Cases like this are uncommon, and the report discusses the imaging results and potential impacts on the fetus's clinical and developmental future.
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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.

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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.

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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.

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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.

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Reelin is an extracellular protein that directs the organization of cortical structures of the brain through the activation of two receptors, the very low-density lipoprotein receptor (VLDLR) and the apolipoprotein E receptor 2 (ApoER2), and the phosphorylation of Disabled-1 (Dab1). Lis1, the product of the Pafah1b1 gene, is a component of the brain platelet-activating factor acetylhydrolase 1b (Pafah1b) complex, and binds to phosphorylated Dab1 in response to Reelin. Here we investigated the involvement of the whole Pafah1b complex in Reelin signaling and cortical layer formation and found that catalytic subunits of the Pafah1b complex, Pafah1b2 and Pafah1b3, specifically bind to the NPxYL sequence of VLDLR, but not to ApoER2.

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Objectives: Our objectives were to (1) describe the clinical characteristics of and viruses isolated from patients who presented with neurologic symptoms associated with influenza A infection and were hospitalized at Texas Children's Hospital during October and November 2003 and (2) to raise awareness of the neurologic complications of influenza among US children.

Methods: We reviewed the medical and laboratory records of all children who were hospitalized with neurologic symptoms and who also had evidence of influenza virus infection by rapid antigen testing or viral isolation.

Results: Eight children aged 5 months to 9 years with neurologic complications associated with influenza A were identified.

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Recent genetic insight into the mechanisms of human brain malformation have allowed one to consider a classification of these disorders by the genetic disruption. In this article an attempt is made to classify human cortical dysplasias by the known genetic disruptions or insults that lead to them. The discussion of malformation is within the context of the embryologic processes that have thought to have gone awry.

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