Mutations disrupting neuritogenesis genes confer risk for cerebral palsy

Uncertainties Regarding Cerebral Palsy Diagnosis: Opportunities to Clarify the Consensus Definition

Background and Objectives

We have established that physicians, including neurologists, variably diagnose cerebral palsy (CP) when using the most recent CP definition from 2006. We also know that child neurologists and neurodevelopmentalists view themselves to be optimally suited to diagnose CP based on their training backgrounds. Therefore, to reduce variability in CP diagnosis, our objective was to elucidate uncertainties child neurologists and neurodevelopmentalists may have regarding practical application of the 2006 definition.

Methods

We conducted a cross-sectional survey of child neurologists and neurodevelopmentalists built into a discussion seminar at the 2022 Child Neurology Society (CNS) Annual Meeting, the largest professional meeting of these specialists in North America. Seminar attendees were provided the 2006 definition and asked whether they had any uncertainties about the practical application of the definition across 4 hypothetical clinical vignettes. A group of national and international CP leaders then processed these data through iterative discussions to develop recommendations for clarifying the 2006 definition.

Results

The seminar was attended by 50% of all conference attendees claiming CME (202/401). Of the 164 closing survey respondents, 145 (88%) expressed uncertainty regarding the clinical application of the 2006 definition. These uncertainties focused on 1) age, both regarding the minimum and maximum ages of brain disturbance or motor symptom onset (67/164, 41%), and 2) interpretation of the term "nonprogressive" (48/164, 29%). Almost all respondents (157/164, 96%) felt that we should revise the 2006 consensus definition of CP.

Discussion

To address the most common CP diagnostic uncertainties we identified, we collectively propose 4 points of clarification to the 2006 definition: 1) motor symptoms/signs should be present by 2 years old; 2) CP can and should be diagnosed as early as possible; 3) the clinical motor disability phenotype should be nonprogressive through 5 years old; and 4) a CP diagnosis should be re-evaluated if motor disability is progressive or absent by 5 years old. We anticipate that clarifying the 2006 definition of CP in this manner could address the uncertainties we identified among child neurologists and neurodevelopmentalists and reduce the diagnostic variability that currently exists.

Early intensive rehabilitation reverses locomotor disruption, decrease brain inflammation and induces neuroplasticity following experimental Cerebral Palsy

BACKGROUND

Cerebral Palsy (CP) is a major cause of motor and cognitive disability in children due to injury to the developing brain. Early intensive sensorimotor rehabilitation has been shown to change brain structure and reduce CP symptoms severity. We combined environmental enrichment (EE) and treadmill training (TT) to observe the effects of a one-week program of sensorimotor stimulation (EETT) in animals exposed to a CP model and explored possible mechanisms involved in the functional recovery.

METHODS

Pregnant Wistar rats were injected with Lipopolysaccharide (LPS - 200 µg/kg) intraperitoneally at embryonic days 18 and 19. At P0, pups of both sexes were exposed to 20' anoxia at 37 °C. From P2 to P21, hindlimbs were restricted for 16 h/day during the dark cycle. EETT lasted from P21 to P27. TT - 15 min/day at 7 cm/s. EE - 7 days in enriched cages with sensorimotor stimulus. Functional 3D kinematic gait analysis and locomotion were analyzed. At P28, brains were collected for ex-vivo MRI and histological assessment. Neurotrophins and key proteins involved in CNS function were assessed by western blotting.

RESULTS

CP model caused gross and skilled locomotor disruption and altered CNS neurochemistry. EETT reversed locomotor dysfunction with minor effects over gait kinematics. EETT also decreased brain inflammation and glial activation, preserved myelination, upregulated BDNF signaling and modulated the expression of proteins involved in excitatory synaptic function in the brain and spinal cord.

CONCLUSIONS

Using this translational approach based on intensive sensorimotor rehabilitation, we highlight pathways engaged in the early developmental processes improving neurological recovery observed in CP.

Genetic investigations in cerebral palsy

The original description of cerebral palsy (CP) contained case histories suggesting that perinatal environmental stressors resulted in brain injury and neurodevelopmental disability. While there are clear associations between environmental impact on brain development and CP, recent studies indicate an 11% to 40% incidence of monogenic conditions in patients given a diagnosis of CP. A genetic diagnosis supports the delivery of personalized medicine. In this review, we describe how the Wnt pathway exemplifies our understanding of pathophysiology related to a gene variant (CTNNB1) found in some children diagnosed with CP. We cover studies undertaken to establish the baseline prevalence of monogenic conditions in populations attending CP clinics. We list factors indicating increased likelihood of a genomic diagnosis; and we highlight the need for a comprehensive, accurate, genotype-phenotype reference data set to aid variant interpretation in CP cohorts. We also consider the wider societal implications of genomic management of CP including significance of the diagnostic label, benefits and pitfalls of a genetic diagnosis, logistics, and cost.

The Genetic Puzzle of Cerebral Palsy: Results of a Monocentric Study

BACKGROUND

Cerebral palsy (CP) is the most frequent cause of motor impairment in children. Although perinatal asphyxia was long considered to be the leading cause of CP, recent studies demonstrate its causation in only around one in 10 individuals with CP. Instead, genetic causes are increasingly demonstrated. We systematically performed clinical phenotyping and genetic investigations in a monocentric CP cohort, aiming to gain insight into the contribution of genetic variants in CP and its different subtypes.

METHODS

Chromosomal microarray and/or trio exome sequencing were systematically performed in 337 individuals with CP between September 2017 and August 2022. Deep phenotyping was performed through clinical multidisciplinary evaluation and review of medical files.

RESULTS

Genetic analyses resulted in an overall diagnostic yield of 38.3% (129 of 337). In cases with one or more comorbidities (intellectual disability, epilepsy, autism spectrum disorder), the yield increased to almost 50%. Functional enrichment analysis showed over-representation of the following pathways: genetic imprinting, DNA modification, liposaccharide metabolic process, neuron projection guidance, and axon development.

CONCLUSIONS

Genetic analyses in our CP cohort, the largest monocentric study to date, demonstrated a diagnostic yield of 38.3%, highlighting the importance of genetic testing in CP. The diagnosis of a genetic disorder is essential for prognosis and clinical follow-up, as well as for family counseling. Pathway analysis points to dysregulation of general developmental and metabolic processes as well as neuronal development and function. Unraveling the role of these pathways in CP pathogenesis is instrumental for the identification of CP candidate genes as well as potential therapeutic targets.

Inhibition of GSK3α,β rescues cognitive phenotypes in a preclinical mouse model of CTNNB1 syndrome

CTNNB1 syndrome is a rare monogenetic disorder caused by CTNNB1 de novo pathogenic heterozygous loss-of-function variants that result in cognitive and motor disabilities. Treatment is currently lacking; our study addresses this critical need. CTNNB1 encodes β-catenin which is essential for normal brain function via its dual roles in cadherin-based synaptic adhesion complexes and canonical Wnt signal transduction. We have generated a Ctnnb1 germline heterozygous mouse line that displays cognitive and motor deficits, resembling key features of CTNNB1 syndrome in humans. Compared with wild-type littermates, Ctnnb1 heterozygous mice also exhibit decreases in brain β-catenin, β-catenin association with N-cadherin, Wnt target gene expression, and Na/K ATPases, key regulators of changes in ion gradients during high activity. Consistently, hippocampal neuron functional properties and excitability are altered. Most important, we identify a highly selective inhibitor of glycogen synthase kinase (GSK)3α,β that significantly normalizes the phenotypes to closely meet wild-type littermate levels. Our data provide new insights into brain molecular and functional changes, and the first evidence for an efficacious treatment with therapeutic potential for individuals with CTNNB1 syndrome.

Potential clinical applications of advanced genomic analysis in cerebral palsy

Cerebral palsy (CP) has historically been attributed to acquired insults, but emerging research suggests that genetic variations are also important causes of CP. While microarray and whole-exome sequencing based studies have been the primary methods for establishing new CP-gene relationships and providing a genetic etiology for individual patients, the cause of their condition remains unknown for many patients with CP. Recent advancements in genomic technologies offer additional opportunities to uncover variations in human genomes, transcriptomes, and epigenomes that have previously escaped detection. In this review, we outline the use of these state-of-the-art technologies to address the molecular diagnostic challenges experienced by individuals with CP. We also explore the importance of identifying a molecular etiology whenever possible, given the potential for genomic medicine to provide opportunities to treat patients with CP in new and more precise ways.

Application of multiple mosaic callers improves post-zygotic mutation detection from exome sequencing data

PURPOSE

The gold standard for identification of post-zygotic variants (PZVs) is droplet digital polymerase chain reaction or high-depth sequencing across multiple tissues types. These approaches are yet to be systematically implemented for monogenic disorders. We developed PZV detection pipelines for correct classification of de novo variants.

METHOD

Our pipelines detect PZV in parents (gonosomal mosaicism [pGoM]) and children (somatic mosaicism, "M3"). We applied them to research exome sequencing (ES) data from the Australian Cerebral Palsy Biobank (n = 145 trios) and Simons Simplex Collection (n = 405 families). Candidate mosaic variants were validated using deep amplicon sequencing or droplet digital polymerase chain reaction.

RESULTS

69.2% (M3trio), 63.9% (M3single), and 92.7% (pGoM) of detected variants were validated, with 48.6%, 56.7%, and 26.2% of variants, respectively, meeting strict criteria for mosaicism. In the Australian Cerebral Palsy Biobank, 16.6% of probands and 20.7% of parents had at least 1 true-positive somatic or pGoM variant, respectively. A large proportion of PZVs detected in Simons Simplex Collection parents (79.8%) and child (94.5%) were not previously reported. We reclassified 3.7% to 8.0% of germline de novo variants as mosaic.

CONCLUSION

Many PZVs were incorrectly classified as germline variants or missed by previous approaches. Systematic application of our pipelines could increase genetic diagnostic rate, improve estimates of recurrence risk in families, and benefit novel disease gene identification.

Genetic pathways in cerebral palsy: a review of the implications for precision diagnosis and understanding disease mechanisms

ABSTRACT

Cerebral palsy is a diagnostic term utilized to describe a group of permanent disorders affecting movement and posture. Patients with cerebral palsy are often only capable of limited activity, resulting from non-progressive disturbances in the fetal or neonatal brain. These disturbances severely impact the child's daily life and impose a substantial economic burden on the family. Although cerebral palsy encompasses various brain injuries leading to similar clinical outcomes, the understanding of its etiological pathways remains incomplete owing to its complexity and heterogeneity. This review aims to summarize the current knowledge on the genetic factors influencing cerebral palsy development. It is now widely acknowledged that genetic mutations and alterations play a pivotal role in cerebral palsy development, which can be further influenced by environmental factors. Despite continuous research endeavors, the underlying factors contributing to cerebral palsy remain are still elusive. However, significant progress has been made in genetic research that has markedly enhanced our comprehension of the genetic factors underlying cerebral palsy development. Moreover, these genetic factors have been categorized based on the identified gene mutations in patients through clinical genotyping, including thrombosis, angiogenesis, mitochondrial and oxidative phosphorylation function, neuronal migration, and cellular autophagy. Furthermore, exploring targeted genotypes holds potential for precision treatment. In conclusion, advancements in genetic research have substantially improved our understanding of the genetic causes underlying cerebral palsy. These breakthroughs have the potential to pave the way for new treatments and therapies, consequently shaping the future of cerebral palsy research and its clinical management. The investigation of cerebral palsy genetics holds the potential to significantly advance treatments and management strategies. By elucidating the underlying cellular mechanisms, we can develop targeted interventions to optimize outcomes. A continued collaboration between researchers and clinicians is imperative to comprehensively unravel the intricate genetic etiology of cerebral palsy.

Clinical exome sequencing uncovers genetic disorders in neonates with suspected hypoxic-ischemic encephalopathy: A retrospective analysis

Hypoxic-ischemic encephalopathy (HIE) occurs in up to 7 out of 1000 births and accounts for almost a quarter of neonatal deaths worldwide. Despite the name, many newborns with HIE have little evidence of perinatal hypoxia. We hypothesized that some infants with HIE have genetic disorders that resemble encephalopathy. We reviewed genetic results for newborns with HIE undergoing exome or genome sequencing at a clinical laboratory (2014-2022). Neonates were included if they had a diagnosis of HIE and were delivered ≥35 weeks. Neonates were excluded for cardiopulmonary pathology resulting in hypoxemia or if neuroimaging suggested postnatal hypoxic-ischemic injury. Of 24 patients meeting inclusion criteria, six (25%) were diagnosed with a genetic condition. Four neonates had variants at loci linked to conditions with phenotypic features resembling HIE, including KIF1A, GBE1, ACTA1, and a 15q13.3 deletion. Two additional neonates had variants in genes not previously associated with encephalopathy, including DUOX2 and PTPN11. Of the six neonates with a molecular diagnosis, two had isolated HIE without apparent comorbidities to suggest a genetic disorder. Genetic diagnoses were identified among neonates with and without sentinel labor events, abnormal umbilical cord gasses, and low Apgar scores. These results suggest that genetic evaluation is clinically relevant for patients with perinatal HIE.

[Neurodevelopment and neuroprotection in young children]

In France, the most pessimistic estimates put the prevalence of neurodevelopmental disorders (NDD) at 15 % of births. The two largest populations of newborns at highest risk of NDD are premature babies and babies born into siblings with one or more infants who already have an autism spectrum disorder or another NDD. The high prevalence of these disorders justifies a health promotion policy, centred on the child and his or her family. Prevention is based on the early identification of high-risk factors, by informing families and training pregnancy and early childhood professionals, and implementing perinatal prevention protocols for high-risk newborns (antenatal corticosteroid therapy and magnesium sulfate for women at risk of preterm delivery before 32 weeks, developmental care, therapeutic hypothermia for full-term infants with early neonatal encephalopathy presumed to be anoxic). Preventing the severity of NDD depends on their early identification, as early as possible in the highest plastic "1000 days" developmental window, a smooth flow of diagnosis and care for mothers and children, and the establishment of an ecosystem that includes multi-modal early intervention, at the best in multi-disciplinary teams such as the early medical and social action centres, support for families through guidance programs and inclusion in the community, first in day-care centers and then in nursery schools.

Improving access to exome sequencing in a medically underserved population through the Texome Project

PURPOSE

Genomic medicine can end diagnostic odysseys for patients with complex phenotypes; however, limitations in insurance coverage and other systemic barriers preclude individuals from accessing comprehensive genetics evaluation and testing.

METHODS

The Texome Project is a 4-year study that reduces barriers to genomic testing for individuals from underserved and underrepresented populations. Participants with undiagnosed, rare diseases who have financial barriers to obtaining exome sequencing (ES) clinically are enrolled in the Texome Project.

RESULTS

We highlight the Texome Project process and describe the outcomes of the first 60 ES results for study participants. Participants received a genetic evaluation, ES, and return of results at no cost. We summarize the psychosocial or medical implications of these genetic diagnoses. Thus far, ES provided molecular diagnoses for 18 out of 60 (30%) of Texome participants. Plus, in 11 out of 60 (18%) participants, a partial or probable diagnosis was identified. Overall, 5 participants had a change in medical management.

CONCLUSION

To date, the Texome Project has recruited a racially, ethnically, and socioeconomically diverse cohort. The diagnostic rate and medical impact in this cohort support the need for expanded access to genetic testing and services. The Texome Project will continue reducing barriers to genomic care throughout the future study years.

Development and validation of a stakeholder-driven, self-contained electronic informed consent platform for trio-based genomic research studies

Increasingly long and complex informed consents have yielded studies demonstrating comparatively low participant comprehension and satisfaction with traditional face-to-face approaches. In parallel, interest in electronic consents for clinical and research genomics has steadily increased, yet limited data are available for trio-based genomic discovery studies. We describe the design, development, implementation, and validation of an electronic iConsent application for trio-based genomic research deployed to support genomic studies of cerebral palsy. iConsent development incorporated stakeholder perspectives including researchers, patient advocates, institutional review board members, and genomic data-sharing considerations. The iConsent platform integrated principles derived from prior electronic consenting research and elements of multimedia learning theory. Participant comprehension was assessed in an interactive teachback format. The iConsent application achieved nine of ten proposed desiderata for effective patient-focused electronic consenting for genomic research. Overall, participants demonstrated high comprehension and retention of key human subjects' considerations. Enrollees reported high levels of satisfaction with the iConsent, and we found that participant comprehension, iConsent clarity, privacy protections, and study goal explanations were associated with overall satisfaction. Although opportunities exist to optimize iConsent, we show that such an approach is feasible, can satisfy multiple stakeholder requirements, and can realize high participant satisfaction and comprehension while increasing study reach.

Comprehensive whole-genome sequence analyses provide insights into the genomic architecture of cerebral palsy

We performed whole-genome sequencing (WGS) in 327 children with cerebral palsy (CP) and their biological parents. We classified 37 of 327 (11.3%) children as having pathogenic/likely pathogenic (P/LP) variants and 58 of 327 (17.7%) as having variants of uncertain significance. Multiple classes of P/LP variants included single-nucleotide variants (SNVs)/indels (6.7%), copy number variations (3.4%) and mitochondrial mutations (1.5%). The COL4A1 gene had the most P/LP SNVs. We also analyzed two pediatric control cohorts (n = 203 trios and n = 89 sib-pair families) to provide a baseline for de novo mutation rates and genetic burden analyses, the latter of which demonstrated associations between de novo deleterious variants and genes related to the nervous system. An enrichment analysis revealed previously undescribed plausible candidate CP genes (SMOC1, KDM5B, BCL11A and CYP51A1). A multifactorial CP risk profile and substantial presence of P/LP variants combine to support WGS in the diagnostic work-up across all CP and related phenotypes.

Gain-of-Function KIDINS220 Variants Disrupt Neuronal Development and Cause Cerebral Palsy

BACKGROUND

Kinase D-interacting substrate of 220 kDa (KIDINS220) is a multifunctional scaffolding protein essential for neuronal development. It has been implicated in neurological diseases with either autosomal dominant (AD) or autosomal recessive (AR) inheritance patterns. The molecular mechanisms underlying the AR/AD dual nature of KIDINS220 remain elusive, posing challenges to genetic interpretation and clinical interventions. Moreover, increased KIDINS220 exhibited neurotoxicity, but its role in neurodevelopment remains unclear.

OBJECTIVE

The aim was to investigate the genotype-phenotype correlations of KIDINS220 and elucidate its pathophysiological role in neuronal development.

METHODS

Whole-exome sequencing was performed in a four-generation family with cerebral palsy. CRISPR/Cas9 was used to generate KIDINS220 mutant cell lines. In utero electroporation was employed to investigate the effect of KIDINS220 variants on neurogenesis in vivo.

RESULTS

We identified in KIDINS220 a pathogenic nonsense variant (c.4177C > T, p.Q1393*) that associated with AD cerebral palsy. We demonstrated that the nonsense variants located in the terminal exon of KIDINS220 are gain-of-function (GoF) variants, which enable the mRNA to escape nonsense-mediated decay and produce a truncated yet functional KIDINS220 protein. The truncated protein exhibited significant resistance to calpain and consequently accumulated within cells, resulting in the hyperactivation of Rac1 and defects in neuronal development.

CONCLUSIONS

Our findings demonstrate that the location of variants within KIDINS220 plays a crucial role in determining inheritance patterns and corresponding clinical outcomes. The proposed interaction between Rac1 and KIDINS220 provides new insights into the pathogenesis of cerebral palsy, implying potential therapeutic perspectives. © 2023 International Parkinson and Movement Disorder Society.

A Cross-Sectional Study Examining the Relationship Between Malnutrition and Gross Motor Function in Cerebral Palsy

Introduction Cerebral palsy (CP) characterizes a range of permanent, nonprogressive symptoms of postural and motor dysfunction caused by an insult to the developing central nervous system in a fetus or an infant. CP manifests early in life, often within the first two to three years of age. CP is associated with poor growth, that is the deviation from the normal growth parameters. The prevalence of CP ranges from 2.0 to 3.5 per 1000 live births in high-income countries which is comparable to the estimates from low-income countries. Antenatal and perinatal insults are among the most commonly reported causes of CP; however, a large number of cases do not have an identifiable etiology of CP. The current study aims to examine the relationship between malnutrition and gross motor function in children with CP. Materials and Methods This study was conducted at the Department of Pediatrics and Neonatology, Nehru Hospital, Baba Raghav Das (BRD) Medical College, Gorakhpur (UP) over a period of one year (August 2020 to July 2021) after obtaining ethical clearance from the College Research Council. Children of age 1-15 years with CP attending the pediatric outpatient and inpatient departments were enrolled as the study participants after obtaining informed consent from a legal guardian. Assessment of motor function was done using the gross motor function classification system (GMFCS). Associations of malnutrition across levels of gross motor function were tested using Chi-square or Fisher's exact test whichever was applicable. Statistical significance was set at p < 0.05 as significant. Data was analyzed using IBM SPSS Statistics for Windows, Version 21 (Released 2012; IBM Corp., Armonk, New York, United States). Result We analyzed 110 children with a diagnosis of CP (median age 6.5 years, interquartile range (IQR) 4.4-9.0 years). The majority (65/110; 59%) of the patients were male, and 68 (61.8%) delivered at term gestation. The most common presenting symptom among children with CP was seizures (79/110; 72.3%), the second most common being delayed milestones among 73 (66.8%), followed by difficulty in breathing among 63 (57.5%). The association between the anthropometric index of participants and GMFCS was found to be highly significant. Conclusion Most CP patients were facing gross motor disturbances. Spastic type of CP was most frequent, and more than half of the patients experienced feeding difficulty. A statistically significant association was found between gross motor functioning and the prevalence of malnutrition and stunting.

Resting-State Functional Magnetic Resonance Imaging Network Association With Mortality, Epilepsy, Cognition, and Motor Two-Year Outcomes in Suspected Severe Neonatal Acute Brain Injury

BACKGROUND AND OBJECTIVES

In acute brain injury of neonates, resting-state functional magnetic resonance imaging (MRI) (RS) showed incremental association with consciousness, mortality, cognitive and motor development, and epilepsy, with correction for multiple comparisons, at six months postgestation in neonates with suspected acute brain injury (ABI). However, there are relatively few developmental milestones at six months to benchmark against, thus, we extended this cohort study to evaluate two-year outcomes.

METHODS

In 40 consecutive neonates with ABI and RS, ordinal scores of resting-state networks; MRI, magnetic resonance spectroscopy, and electroencephalography; and up to 42-month outcomes of mortality, general and motor development, Pediatric Cerebral Performance Category Scale (PCPC), and epilepsy informed associations between tests and outcomes.

RESULTS

Mean gestational age was 37.8 weeks, 68% were male, and 60% had hypoxic-ischemic encephalopathy. Three died in-hospital, four at six to 42 months, and five were lost to follow-up. Associations included basal ganglia network with PCPC (P = 0.0003), all-mortality (P = 0.005), and motor (P = 0.0004); language/frontoparietal network with developmental delay (P = 0.009), PCPC (P = 0.006), and all-mortality (P = 0.01); default mode network with developmental delay (P = 0.003), PCPC (P = 0.004), neonatal intensive care unit mortality (P = 0.01), and motor (P = 0.009); RS seizure onset zone with epilepsy (P = 0.01); and anatomic MRI with epilepsy (P = 0.01).

CONCLUSION

For the first time, at any age, resting state functional MRI in ABI is associated with long-term epilepsy and RSNs predicted mortality in neonates. Severity of RSN abnormality was associated with incrementally worsened neurodevelopment including cognition, language, and motor function over two years.

Causation in cerebral palsy: Parental beliefs and associated emotions

AIM

To better understand parents' beliefs about causation in cerebral palsy (CP) and the emotions related to those beliefs.

METHOD

We surveyed 226 parents of children with CP aged 1 to 18 years, recruited from the Victorian Cerebral Palsy Register, to evaluate their beliefs about the causes of CP, including genetic causes, causes specific to their own child, and their attitudes and emotions in relation to these.

RESULTS

Although 92% of participants reported that understanding the causes of their child's CP was important, uncertainty about the cause was expressed by 13%. The most frequently endorsed causal factors, in general and in their own child respectively, were intrapartum hypoxia (81%, 36%) or brain damage (69%, 22%), brain damage during pregnancy (73%, 28%), and preterm birth (66%, 28%). Genetic causes were deemed relevant by 13% of participants and hospital or professional error by 16%. Parents shared related feelings of anger (59%), sadness (80%), guilt (61%), and confusion (53%); parental anger was more likely when their child's CP was attributed to intrapartum events.

INTERPRETATION

Substantial parental interest in understanding the causes of CP, together with uncertainty about the causes, parents' causal attributions, and significant emotional sequelae, highlight a strong need for provision of information and support for families of children recently diagnosed with CP.

WHAT THIS PAPER ADDS

Understanding the causes of their child's cerebral palsy (CP) was important to parents. Parents most often endorsed intrapartum factors as a cause of CP. Parents reported experiencing strong emotions about the causes of their child's CP.

Emerging Subspecialties: Pediatric Movement Disorders Neurology

Pediatric movement disorders (PMD) neurologists care for infants, children, and adolescents with conditions that disrupt typical movement; serving as important subspecialist child neurologists in both academic and private practice settings. In contrast to adult movement disorders neurologists whose "bread and butter" is hypokinetic Parkinson disease, PMD subspecialty practice is often dominated by hyperkinetic movement disorders including tics, dystonia, chorea, tremor, and myoclonus. PMD neurology practice intersects with a variety of subspecialties, including neonatology, developmental pediatrics, rehabilitation medicine, epilepsy, child & adolescent psychiatry, psychology, orthopedics, genetics & metabolism, and neurosurgery. Over the past several decades, significant advancements in the PMD field have included operationalizing definitions for distinct movement disorders, recognizing the spectrum of clinical phenotypes, expanding research on genetic and neuroimmunologic causes of movement disorders, and advancing available treatments. Subspecialty training in PMD provides trainees with advanced clinical, diagnostic, procedural, and management skills that reflect the complexities of contemporary practice. The child neurologist who is fascinated by the intricacies of child motor development, appreciates the power of observation skills coupled with a thoughtful physical examination, and is excited by the challenge of the unknown may be well-suited to a career as a PMD specialist.

A Call for Early Detection of Cerebral Palsy

Cerebral palsy (CP) is the most common physical disability across the lifespan, but historically, CP has not been diagnosed before the age of 2 years. Barriers to early diagnosis ranged from lack of available biomarkers, absence of curative treatments, perceived stigma associated with a lifelong diagnosis, and a desire to rule out other diagnoses first. Most importantly, the fundamental question that remained was whether children would benefit from earlier detection and intervention given the paucity of research. However, evidence-based guidelines published in 2017 demonstrated that the General Movements Assessment, the Hammersmith Infant Neurological Examination, and neuroimaging can be combined with other elements such as a clinical history and standardized motor assessments to provide the highest predictive value for diagnosing CP as early as age 3 months in high-risk newborns. Implementation of these guidelines has been successful in decreasing the age at CP diagnosis, particularly in high-risk infant follow-up clinics with expertise in performing these assessments. Early detection of CP allows for clinical and research opportunities investigating earlier interventions during a critical period of neuroplasticity, with the goal of improving developmental trajectories for children and their families. New guidelines and research are now being developed with a focus on early, targeted interventions that continue to be studied, along with global detection initiatives.

A Next-Generation Sequencing Study in a Cohort of Sicilian Patients with Parkinson's Disease

Parkinson's disease (PD) is a multisystem and multifactorial disorder and, therefore, the application of modern genetic techniques may assist in unraveling its complex pathophysiology. We conducted a clinical-demographic evaluation of 126 patients with PD, all of whom were Caucasian and of Sicilian ancestry. DNA was extracted from the peripheral blood for each patient, followed by sequencing using a Next-Generation Sequencing system. This system was based on a custom gene panel comprising 162 genes. The sample underwent further filtering, taking into account the allele frequencies of genetic variants, their presence in the Human Gene Mutation Database, and their association in the literature with PD or other movement/neurodegenerative disorders. The largest number of variants was identified in the leucine-rich repeat kinase 2 (LRRK2) gene. However, variants in other genes, such as acid beta-glucosidase (GBA), DNA polymerase gamma catalytic subunit (POLG), and parkin RBR E3 ubiquitin protein ligase (PRKN), were also discovered. Interestingly, some of these variants had not been previously associated with PD. Enhancing our understanding of the genetic basis of PD and identifying new variants possibly linked to the disease will contribute to improved diagnostic accuracy, therapeutic developments, and prognostic insights for affected individuals.

Mutation of key signaling regulators of cerebrovascular development in vein of Galen malformations

To elucidate the pathogenesis of vein of Galen malformations (VOGMs), the most common and most severe of congenital brain arteriovenous malformations, we performed an integrated analysis of 310 VOGM proband-family exomes and 336,326 human cerebrovasculature single-cell transcriptomes. We found the Ras suppressor p120 RasGAP (RASA1) harbored a genome-wide significant burden of loss-of-function de novo variants (2042.5-fold, p = 4.79 x 10-7). Rare, damaging transmitted variants were enriched in Ephrin receptor-B4 (EPHB4) (17.5-fold, p = 1.22 x 10-5), which cooperates with p120 RasGAP to regulate vascular development. Additional probands had damaging variants in ACVRL1, NOTCH1, ITGB1, and PTPN11. ACVRL1 variants were also identified in a multi-generational VOGM pedigree. Integrative genomic analysis defined developing endothelial cells as a likely spatio-temporal locus of VOGM pathophysiology. Mice expressing a VOGM-specific EPHB4 kinase-domain missense variant (Phe867Leu) exhibited disrupted developmental angiogenesis and impaired hierarchical development of arterial-capillary-venous networks, but only in the presence of a "second-hit" allele. These results illuminate human arterio-venous development and VOGM pathobiology and have implications for patients and their families.

PPA1 Deficiency Causes a Deranged Galactose Metabolism Recognizable in Neonatal Screening

Two siblings showed increased galactose and galactose-related metabolites in neonatal screening. Diagnostic workup did not reveal abnormalities in any of the known disease-causing enzymes involved in galactose metabolism. Using whole-exome sequencing, we identified a homozygous missense variant in PPA1 encoding the cytosolic pyrophosphatase 1 (PPA1), c.557C>T (p.Thr186Ile). The enzyme activity of PPA1 was determined using a colorimetric assay, and the protein content was visualized via western blotting in skin fibroblasts from one of the affected individuals. The galactolytic activity of the affected fibroblasts was determined by measuring extracellular acidification with a Seahorse XFe96 analyzer. PPA1 activity decreased to 22% of that of controls in the cytosolic fraction of homogenates from patient fibroblasts. PPA1 protein content decreased by 50% according to western blot analysis, indicating a reduced stability of the variant protein. The extracellular acidification rate was reduced in patient fibroblasts when galactose was used as a substrate. Untargeted metabolomics of blood samples revealed an elevation of other metabolites related to pyrophosphate metabolism. Besides hyperbilirubinemia in the neonatal period in one child, both children were clinically unremarkable at the ages of 3 and 14 years, respectively. We hypothesize that the observed metabolic derangement is a possible mild manifestation of PPA1 deficiency. Unresolved abnormalities in galactosemia screening might result in the identification of more individuals with PPA1 deficiency, a newly discovered inborn metabolic disorder (IMD).

Analysis of Traditional Chinese Medicine Symptoms in Children with Spastic Cerebral Palsy, a Protocol for Data Mining

Background

Cerebral palsy (CP) is characterized by abnormal pronunciation, posture, and movement. Clinically, CP can be categorized into various motor syndromes, including spastic hemiplegia, diplegia, quadriplegia, involuntary movement, ataxia, and mixed types. Among these, spastic CP represents over 70-80% of all CP cases. The primary objective of our study is to identify the top and core Traditional Chinese Medicine (TCM) symptoms and analysis their association rules in children with spastic cerebral palsy, thereby enhancing the theoretical foundations of TCM treatment on spastic CP.

Methods

The study will be conducted on children aged 4 to 14 years with spastic CP who are undergoing treatment at Xi'an Encephalopathy Hospital Affiliated to Shaanxi University of Chinese Medicine. Basic information about the patients and their TCM symptoms will be collected on the first day of admission. This information will include age, gender, birth history, family history, disease classification, and TCM symptoms (including symptoms, tongue, and pulse). Once the data is collected, it will be exported from the electronic medical record system for further analysis. Descriptive statistics will be performed using Excel 2019, while exploratory factor analysis and cluster analysis will be conducted using SPSS Statistics 22. Additionally, association rule analysis will be carried out using SPSS Modeler 18.

Results

This study will investigate the most top TCM symptoms in children with spastic CP and explore the association rules between these symptoms, mapping the presentation of spastic CP onto symptoms identified within TCM.

Conclusion

Our findings will provide the distinctive characteristics of TCM symptoms in children with spastic CP, furnishing evidence-based support to clinicians and patients in making well-informed decisions collaboratively.

Clinical actionability of genetic findings in cerebral palsy

Background and objectives

Single gene mutations are increasingly recognized as causes of cerebral palsy (CP) phenotypes, yet there is currently no standardized framework for measuring their clinical impact. We evaluated Pathogenic/Likely Pathogenic (P/LP) variants identified in individuals with CP to determine how frequently genetic testing results would prompt changes in care.

Methods

We analyzed published P/LP variants in OMIM genes identified in clinical (n = 1,345 individuals) or research (n = 496) cohorts using exome sequencing of CP patients. We established a working group of clinical and research geneticists, developmental pediatricians, genetic counselors, and neurologists and performed a systematic review of existing literature for evidence of clinical management approaches linked to genetic disorders. Scoring rubrics were adapted, and a modified Delphi approach was used to build consensus and establish the anticipated impact on patient care. Overall clinical utility was calculated from metrics assessing outcome severity if left untreated, safety/practicality of the intervention, and anticipated intervention efficacy .

Results

We found 140/1,841 (8%) of individuals in published CP cohorts had a genetic diagnosis classified as actionable , defined as prompting a change in clinical management based on knowledge related to the genetic etiology. 58/243 genes with P/LP variants were classified as actionable; 16 had treatment options targeting the primary disease mechanism , 16 had specific prevention strategies , and 26 had specific symptom management recommendations. The level of evidence was also graded according to ClinGen criteria; 44.6% of interventions had evidence class "D" or below. The potential interventions have clinical utility with 97% of outcomes being moderate-high severity if left untreated and 62% of interventions predicted to be of moderate-high efficacy . Most interventions (71%) were considered moderate-high safety/practicality .

Discussion

Our findings indicate that actionable genetic findings occur in 8% of individuals referred for genetic testing with CP. Evaluation of potential efficacy , outcome severity , and intervention safety / practicality indicates moderate-high clinical utility of these genetic findings. Thus, genetic sequencing to identify these individuals for precision medicine interventions could improve outcomes and provide clinical benefit to individuals with CP. The relatively limited evidence base for most interventions underscores the need for additional research.

Anterior segment indices in mentally retarded children

To compare the anterior segment indices between mentally retarded and normal children. The current study was conducted as a cohort. In this study, 73 mentally retarded and 76 normal children were selected from normal school and special schools for mentally retarded children using random cluster sampling method. Mental retardation in children was confirmed by a psychologist. Optometry examinations including visual acuity and refraction were performed for all participants, and ultimately, corneal imaging measurements were taken by Pentacam. The mean age of mentally retarded and normal children was of 13.30 ± 1.83 and 13.05 ± 1.82 years, respectively (P = 0.180). A multiple generalized estimating equations model demonstrated that there is a significant association between central corneal thickness (CCT) (coef = 1.011, P < 0.001), corneal diameter (CD) (coef = 0.444, P = 0.046), anterior chamber depth (ACD) (coef = 0.23), P < 0.001) and index of vertical asymmetry (IVA) (coef = 0.12, P < 0.001) and mental retardation. Cerebral palsy children had higher keratoconus index (KI), central keratoconus index (CKI), index of height asymmetry(IHA), and index of height decentration (IHD) compared to those without cerebral palsy (P < 0.05). Children with moderate mental retardation had higher index of surface variance (ISV), IVA, IHA, and IHD than those with mild mental retardation (P < 0.05). The mean and standard deviation of CCT, CD, ACD and IVA index in mentally retarded children were 535.3 ± 46.68 micron, 11.87 ± 0.42 mm, 3.29 ± 0.24 mm and 0.25 ± 0.18 mm, respectively. These indices in the normal group were 525.53 ± 47.52 micron, 11.84 ± 0.38 mm, 3.15 ± 0.28 mm and 0.17 ± 0.05 mm, respectively. The findings of this study showed that some anterior segment indices were different in mentally retarded compared to normal children. Moreover, some keratoconus indicators were worse in cerebral palsy children and children with higher grade mental retardation. So, it is important to consider keratoconus screening in these children.

AGAP1-associated endolysosomal trafficking abnormalities link gene-environment interactions in neurodevelopmental disorders

AGAP1 is an Arf1 GTPase-activating protein that regulates endolysosomal trafficking. Damaging variants have been linked to cerebral palsy and autism. We report three new cases in which individuals had microdeletion variants in AGAP1. The affected individuals had intellectual disability (3/3), autism (3/3), dystonia with axial hypotonia (1/3), abnormalities of brain maturation (1/3), growth impairment (2/3) and facial dysmorphism (2/3). We investigated mechanisms potentially underlying AGAP1 variant-mediated neurodevelopmental impairments using the Drosophila ortholog CenG1a. We discovered reduced axon terminal size, increased neuronal endosome abundance and elevated autophagy compared to those in controls. Given potential incomplete penetrance, we assessed gene-environment interactions. We found basal elevation in the phosphorylation of the integrated stress-response protein eIF2α (or eIF2A) and inability to further increase eIF2α phosphorylation with subsequent cytotoxic stressors. CenG1a-mutant flies had increased lethality from exposure to environmental insults. We propose a model wherein disruption of AGAP1 function impairs endolysosomal trafficking, chronically activating the integrated stress response and leaving AGAP1-deficient cells susceptible to a variety of second-hit cytotoxic stressors. This model may have broader applicability beyond AGAP1 in instances where both genetic and environmental insults co-occur in individuals with neurodevelopmental disorders.

Redefining cerebral palsies as a diverse group of neurodevelopmental disorders with genetic aetiology

Cerebral palsy is a clinical descriptor covering a diverse group of permanent, non-degenerative disorders of motor function. Around one-third of cases have now been shown to have an underlying genetic aetiology, with the genetic landscape overlapping with those of neurodevelopmental disorders including intellectual disability, epilepsy, speech and language disorders and autism. Here we review the current state of genomic testing in cerebral palsy, highlighting the benefits for personalized medicine and the imperative to consider aetiology during clinical diagnosis. With earlier clinical diagnosis now possible, we emphasize the opportunity for comprehensive and early genomic testing as a crucial component of the routine diagnostic work-up in people with cerebral palsy.

Abnormal changes of bone metabolism markers with age in children with cerebral palsy

Cerebral palsy (CP) is a broad range of diseases with permanent and nonprogressive motor impairments, carrying a high cost for both the individual and the society. The characteristics of low bone mineral density and high risk of fractures suggest that bone metabolism disorders are present in CP. This study aims to investigate the association between indicators of bone metabolism and children with CP. A total of 139 children (75 children with CP and 64 healthy controls) were included in this cross-sectional study. Participants were divided into three age groups (0-2 years, 2.1-4 years, and 4.1-7 years). All children with CP were diagnosed according to clinical criteria and furtherly divided into clinical subtypes. The levels of total procollagen type I N-terminal propeptide (TPINP), N-MID osteocalcin (OC), beta-crosslaps (β-CTX), 25-hydroxyvitamin D (25-OHD) and parathyroid hormone (PTH) in the serum were measured with corresponding detection kits according to the manufacturer's instructions. Serum levels of TPINP and 25-OHD were lower with older age, whereas β-CTX and PTH were higher with older age. In the CP group, TPINP (age 0-2 years and 2.1-4 years) and OC (age 2.1-4 years) levels were higher, while β-CTX (age 2.1-4 years and 4.1-7 years) and PTH (age 2.1-4 years) values were lower than the control group. In addition, there were no statistically significant differences in the levels of these indicators among the CP subgroups with different clinical characteristics. Our study shows that bone turnover markers, indicators of bone metabolism, in children with CP differ significantly from healthy controls. The indicators we studied changed with age, and they did not correlate with disease severity.

Uncertainties regarding cerebral palsy diagnosis: opportunities to operationalize the consensus definition

Background and Objectives

Cerebral palsy (CP), the most common motor disability of childhood, is variably diagnosed. We hypothesized that child neurologists and neurodevelopmentalists, often on the frontlines of CP diagnosis in North America, harbor uncertainties regarding the practical application of the most recent CP consensus definition from 2006.

Methods

We conducted a cross-sectional survey of child neurologists and neurodevelopmentalists at the 2022 Child Neurology Society Annual Meeting. Attendees were provided the 2006 CP consensus definition and asked whether they had any uncertainties about the practical application of the definition across four hypothetical clinical vignettes.

Results

Of 230 attendees, 164 responded to the closing survey questions (71%). 145/164 (88%) expressed at least one uncertainty regarding the clinical application of the 2006 definition. Overwhelmingly, these areas of uncertainty focused on: 1) Age, both with regards to the minimum age of diagnosis and the maximum age of brain disturbance or motor symptom onset, (67/164, 41%), and 2) Interpretation of the term "non-progressive" (48/164, 29%). The vast majority of respondents (157/164, 96%) answered 'Yes' to the question: Do you think we should revise the 2006 consensus definition of CP?

Discussion

We propose that the uncertainties we identified could be addressed by operationalizing the 2006 consensus definition to support a more uniform CP diagnosis. To address the most common CP diagnostic uncertainties we identified, we propose 3 points of clarification based on the available literature: 1) Motor symptoms/signs should be present by 2 years old; 2) CP can and should be diagnosed as early as possible, even if activity limitation is not yet present, if motor symptoms/signs can be reasonably predicted to yield activity limitation (e.g. by using standardized examination instruments, Brain MRI, and a suggestive clinical history); and 3) The clinical motor disability phenotype should be non-progressive through 5 years old. We anticipate that operationalizing the 2006 definition of CP in this manner could clarify the uncertainties we identified among child neurologists and neurodevelopmentalists and reduce the diagnostic variability that currently exists.

CTNNB1-related neurodevelopmental disorder mimics cerebral palsy: case report

While somatic gain-of-function mutations in the CTNNB1 gene cause diverse malignancies, germline loss-of-function mutations cause neurodevelopmental disorders or familial exudative vitreoretinopathy. In particular, CTNNB1-related neurodevelopmental disorders have various phenotypes, and a genotype-phenotype relationship has not been established. We report two patients with CTNNB1-related neurodevelopmental disorder whose clinical features were similar to those of cerebral palsy, hindering diagnosis.

Diagnostic Yield of Exome Sequencing in Cerebral Palsy and Implications for Genetic Testing Guidelines: A Systematic Review and Meta-analysis

Importance

Exome sequencing is a first-tier diagnostic test for individuals with neurodevelopmental disorders, including intellectual disability/developmental delay and autism spectrum disorder; however, this recommendation does not include cerebral palsy.

Objective

To evaluate if the diagnostic yield of exome or genome sequencing in cerebral palsy is similar to that of other neurodevelopmental disorders.

Data Sources

The study team searched PubMed for studies published between 2013 and 2022 using cerebral palsy and genetic testing terms. Data were analyzed during March 2022.

Study Selection

Studies performing exome or genome sequencing in at least 10 participants with cerebral palsy were included. Studies with fewer than 10 individuals and studies reporting variants detected by other genetic tests were excluded. Consensus review was performed. The initial search identified 148 studies, of which 13 met inclusion criteria.

Data Extraction and Synthesis

Data were extracted by 2 investigators and pooled using a random-effects meta-analysis. Incidence rates with corresponding 95% CIs and prediction intervals were calculated. Publication bias was evaluated by the Egger test. Variability between included studies was assessed via heterogeneity tests using the I2 statistic.

Main Outcomes and Measures

The primary outcome was the pooled diagnostic yield (rate of pathogenic/likely pathogenic variants) across studies. Subgroup analyses were performed based on population age and on the use of exclusion criteria for patient selection.

Results

Thirteen studies were included consisting of 2612 individuals with cerebral palsy. The overall diagnostic yield was 31.1% (95% CI, 24.2%-38.6%; I2 = 91%). The yield was higher in pediatric populations (34.8%; 95% CI, 28.3%-41.5%) than adult populations (26.9%; 95% CI, 1.2%-68.8%) and higher among studies that used exclusion criteria for patient selection (42.1%; 95% CI, 36.0%-48.2%) than those that did not (20.7%; 95% CI, 12.3%-30.5%).

Conclusions and Relevance

In this systematic review and meta-analysis, the genetic diagnostic yield in cerebral palsy was similar to that of other neurodevelopmental disorders for which exome sequencing is recommended as standard of care. Data from this meta-analysis provide evidence to support the inclusion of cerebral palsy in the current recommendation of exome sequencing in the diagnostic evaluation of individuals with neurodevelopmental disorders.

Neurodevelopmental disorders, like cancer, are connected to impaired chromatin remodelers, PI3K/mTOR, and PAK1-regulated MAPK

Neurodevelopmental disorders (NDDs) and cancer share proteins, pathways, and mutations. Their clinical symptoms are different. However, individuals with NDDs have higher probabilities of eventually developing cancer. Here, we review the literature and ask how the shared features can lead to different medical conditions and why having an NDD first can increase the chances of malignancy. To explore these vital questions, we focus on dysregulated PI3K/mTOR, a major brain cell growth pathway in differentiation, and MAPK, a critical pathway in proliferation, a hallmark of cancer. Differentiation is governed by chromatin organization, making aberrant chromatin remodelers highly likely agents in NDDs. Dysregulated chromatin organization and accessibility influence the lineage of specific cell brain types at specific embryonic development stages. PAK1, with pivotal roles in brain development and in cancer, also regulates MAPK. We review, clarify, and connect dysregulated pathways with dysregulated proliferation and differentiation in cancer and NDDs and highlight PAK1 role in brain development and MAPK regulation. Exactly how PAK1 activation controls brain development, and why specific chromatin remodeler components, e.g., BAF170 encoded by SMARCC2 in autism, await clarification.

Genetic dysregulation of an endothelial Ras signaling network in vein of Galen malformations

To elucidate the pathogenesis of vein of Galen malformations (VOGMs), the most common and severe congenital brain arteriovenous malformation, we performed an integrated analysis of 310 VOGM proband-family exomes and 336,326 human cerebrovasculature single-cell transcriptomes. We found the Ras suppressor p120 RasGAP ( RASA1 ) harbored a genome-wide significant burden of loss-of-function de novo variants (p=4.79×10 ^-7 ). Rare, damaging transmitted variants were enriched in Ephrin receptor-B4 ( EPHB4 ) (p=1.22×10 ^-5 ), which cooperates with p120 RasGAP to limit Ras activation. Other probands had pathogenic variants in ACVRL1 , NOTCH1 , ITGB1 , and PTPN11 . ACVRL1 variants were also identified in a multi-generational VOGM pedigree. Integrative genomics defined developing endothelial cells as a key spatio-temporal locus of VOGM pathophysiology. Mice expressing a VOGM-specific EPHB4 kinase-domain missense variant exhibited constitutive endothelial Ras/ERK/MAPK activation and impaired hierarchical development of angiogenesis-regulated arterial-capillary-venous networks, but only when carrying a "second-hit" allele. These results illuminate human arterio-venous development and VOGM pathobiology and have clinical implications.

Familial and syndromic forms of arachnoid cyst implicate genetic factors in disease pathogenesis

Arachnoid cysts (ACs) are the most common space-occupying lesions in the human brain and present significant challenges for clinical management. While most cases of ACs are sporadic, nearly 40 familial forms have been reported. Moreover, ACs are seen with increased frequency in multiple Mendelian syndromes, including Chudley-McCullough syndrome, acrocallosal syndrome, and autosomal recessive primary ciliary dyskinesia. These findings suggest that genetic factors contribute to AC pathogenesis. However, traditional linkage and segregation approaches have been limited in their ability to identify causative genes for ACs because the disease is genetically heterogeneous and often presents asymptomatically and sporadically. Here, we comprehensively review theories of AC pathogenesis, the genetic evidence for AC formation, and discuss a different approach to AC genomics that could help elucidate this perplexing lesion and shed light on the associated neurodevelopmental phenotypes seen in a significant subset of these patients.

Epilepsy syndromes in cerebral palsy: varied, evolving and mostly self-limited

Seizures occur in approximately one-third of children with cerebral palsy. This study aimed to determine epilepsy syndromes in children with seizures and cerebral palsy due to vascular injury, anticipating that this would inform treatment and prognosis. We studied a population-based cohort of children with cerebral palsy due to prenatal or perinatal vascular injuries, born 1999-2006. Each child's MRI was reviewed to characterize patterns of grey and white matter injury. Children with syndromic or likely genetic causes of cerebral palsy were excluded, given their inherent association with epilepsy and our aim to study a homogeneous cohort of classical cerebral palsy. Chart review, parent interview and EEGs were used to determine epilepsy syndromes and seizure outcomes. Of 256 children, 93 (36%) had one or more febrile or afebrile seizures beyond the neonatal period and 87 (34%) had epilepsy. Children with seizures were more likely to have had neonatal seizures, have spastic quadriplegic cerebral palsy and function within Gross Motor Function Classification System level IV or V. Fifty-six (60%) children with seizures had electroclinical features of a self-limited focal epilepsy of childhood; we diagnosed these children with a self-limited focal epilepsy-variant given the current International League Against Epilepsy classification precludes a diagnosis of self-limited focal epilepsy in children with a brain lesion. Other epilepsy syndromes were focal epilepsy-not otherwise specified in 28, infantile spasms syndrome in 11, Lennox-Gastaut syndrome in three, genetic generalized epilepsies in two and febrile seizures in nine. No epilepsy syndrome could be assigned in seven children with no EEG. Twenty-one changed syndrome classification during childhood. Self-limited focal epilepsy-variant usually manifested with a mix of autonomic and brachio-facial motor features, and occipital and/or centro-temporal spikes on EEG. Of those with self-limited focal epilepsy-variant, 42/56 (75%) had not had a seizure for >2 years. Favourable seizure outcomes were also seen in some children with infantile spasms syndrome and focal epilepsy-not otherwise specified. Of the 93 children with seizures, at last follow-up (mean age 15 years), 61/91 (67%) had not had a seizure in >2 years. Children with cerebral palsy and seizures can be assigned specific epilepsy syndrome diagnoses typically reserved for normally developing children, those syndromes commonly being age-dependent and self-limited. Compared to typically developing children with epilepsy, self-limited focal epilepsy-variant occurs much more commonly in children with cerebral palsy and epilepsy. These findings have important implications for treatment and prognosis of epilepsy in cerebral palsy, and research into pathogenesis of self-limited focal epilepsy.

AGAP1-associated endolysosomal trafficking abnormalities link gene-environment interactions in a neurodevelopmental disorder

AGAP1 is an Arf1 GAP that regulates endolysosomal trafficking. Damaging variants have been linked to cerebral palsy and autism. We report 3 new individuals with microdeletion variants in AGAP1 . Affected individuals have intellectual disability (3/3), autism (3/3), dystonia with axial hypotonia (1/3), abnormalities of brain maturation (1/3), growth impairment (2/3) and facial dysmorphism (2/3). We investigated mechanisms potentially underlying AGAP1 neurodevelopmental impairments using the Drosophila ortholog, CenG1a . We discovered reduced axon terminal size, increased neuronal endosome abundance, and elevated autophagy at baseline. Given potential incomplete penetrance, we assessed gene-environment interactions. We found basal elevation in phosphorylation of the integrated stress-response protein eIF2α and inability to further increase eIF2α-P with subsequent cytotoxic stressors. CenG1a -mutant flies have increased lethality from exposure to environmental insults. We propose a model wherein disruption of AGAP1 function impairs endolysosomal trafficking, chronically activating the integrated stress response, and leaving AGAP1-deficient cells susceptible to a variety of second hit cytotoxic stressors. This model may have broader applicability beyond AGAP1 in instances where both genetic and environmental insults co-occur in individuals with neurodevelopmental disorders.

Summary statement

We describe 3 additional patients with heterozygous AGAP1 deletion variants and use a loss of function Drosophila model to identify defects in synaptic morphology with increased endosomal sequestration, chronic autophagy induction, basal activation of eIF2α-P, and sensitivity to environmental stressors.

Key role of Rho GTPases in motor disorders associated with neurodevelopmental pathologies

Growing evidence suggests that Rho GTPases and molecules involved in their signaling pathways play a major role in the development of the central nervous system (CNS). Whole exome sequencing (WES) and de novo examination of mutations, including SNP (Single Nucleotide Polymorphism) in genes coding for the molecules of their signaling cascade, has allowed the recent discovery of dominant autosomic mutations and duplication or deletion of candidates in the field of neurodevelopmental diseases (NDD). Epidemiological studies show that the co-occurrence of several of these neurological pathologies may indeed be the rule. The regulators of Rho GTPases have often been considered for cognitive diseases such as intellectual disability (ID) and autism. But, in a remarkable way, mild to severe motor symptoms are now reported in autism and other cognitive NDD. Although a more abundant litterature reports the involvement of Rho GTPases and signaling partners in cognitive development, molecular investigations on their roles in central nervous system (CNS) development or degenerative CNS pathologies also reveal their role in embryonic and perinatal motor wiring through axon guidance and later in synaptic plasticity. Thus, Rho family small GTPases have been revealed to play a key role in brain functions including learning and memory but their precise role in motor development and associated symptoms in NDD has been poorly scoped so far, despite increasing clinical data highlighting the links between cognition and motor development. Indeed, early impairements in fine or gross motor performance is often an associated feature of NDDs, which then impact social communication, cognition, emotion, and behavior. We review here recent insights derived from clinical developmental neurobiology in the field of Rho GTPases and NDD (autism spectrum related disorder (ASD), ID, schizophrenia, hypotonia, spastic paraplegia, bipolar disorder and dyslexia), with a specific focus on genetic alterations affecting Rho GTPases that are involved in motor circuit development.

Integrative Multi-Omics Research in Cerebral Palsy: Current Progress and Future Prospects

Cerebral palsy (CP) describes a heterogeneous group of non-progressive neurodevelopmental disorders affecting movement and posture. The etiology and diagnostic biomarkers of CP are a hot topic in clinical research. Recent advances in omics techniques, including genomics, epigenomics, transcriptomics, metabolomics and proteomics, have offered new insights to further understand the pathophysiology of CP and have allowed for identification of diagnostic biomarkers of CP. In present study, we reviewed the latest multi-omics investigations of CP and provided an in-depth summary of current research progress in CP. This review will offer the basis and recommendations for future fundamental research on the pathogenesis of CP, identification of diagnostic biomarkers, and prevention strategies for CP.

Genetic counseling considerations in cerebral palsy

Genome-wide sequencing (exome and whole genome) has transformed our ability to diagnose patients with suspected genetic disorders. Cerebral palsy (CP), although historically thought to be due to birth injury (perinatal hypoxia), represents a clinical spectrum of disorders, many of which have been attributed to a genetic cause. GWS has elucidated the underlying single gene cause for many patients with CP and has important implications for the customization of treatment, management, and genetic counseling. International guidelines recommend genetic counseling for all families considering genome-wide sequencing. Genetic counselors educate and support families and help them to make testing decisions based on their values. They can help families adapt to, and understand the implications of a genomic diagnosis. Here, we review advances in sequencing for CP, clinical features suggestive of a genetic etiology of CP, practice guidelines for GWS, and a practical approach to the genetic counseling of these families. This includes: the content to be addressed in pre-test and post-test genetic counseling sessions, the benefits of a establishing a genetic cause and importantly, the need for ongoing support.

Genomics in Cerebral Palsy phenotype across the lifespan: Comparison of diagnostic yield between children and adult population

PURPOSE

The presentation and underlying etiology of Cerebral Palsy (CP) in general are heterogenous. Clinical features present differently in pediatric versus adult patient populations. Many metabolic and genetic conditions present with clinical symptoms suggestive of CP. Precision medicine practices are currently a standard of care, and Next-Generation-Sequencing (NGS) tools are used for the purpose of diagnosis and management. We describe the diagnostic yield and impact on management of NGS comparing a cohort of 102 children and 37 adults with CP, referred to two tertiary care centres between 2015 and 2020 (adult cohort) and 2017-2020 (pediatric cohort) respectively.

PRINCIPAL RESULTS

In the adult cohort, 28 patients had a positive genetic diagnosis, giving a yield of 75.6%. Their age varied between 18 and 59 years, with a median of 28 years. Out of the positive diagnoses, 12 were consistent with an inborn error of metabolism and in 9 patients (32.1%) some form of treatment or management guideline was recommended. In the pediatric cohort 21 patients had a positive genetic diagnosis and 22 results are still pending, giving a yield of 32.8%. Age at diagnosis ranged between 18 months and 12 years. In 15 patients (71.4%) there was some form of management recommendation. All families benefited from genetic counseling.

MAJOR CONCLUSIONS

Given the combined high yield of positive genetic diagnosis in pediatric and adult cases presenting with symptoms of Cerebral Palsy, and the more readily available Next Generation Sequencing testing in major academic centres, we recommend that either a referral to a pediatric or adult neurometabolic centre to be made, or genetic testing to be initiated where this is available.

Molecular Diagnostic Yield of Exome Sequencing and Chromosomal Microarray in Cerebral Palsy: A Systematic Review and Meta-analysis

Importance

There are many known acquired risk factors for cerebral palsy (CP), but in some cases, CP is evident without risk factors (cryptogenic CP). Early CP cohort studies report a wide range of diagnostic yields for sequence variants assessed by exome sequencing (ES) and copy number variants (CNVs) assessed by chromosomal microarray (CMA).

Objective

To synthesize the emerging CP genetics literature and address the question of what percentage of individuals with CP have a genetic disorder via ES and CMA.

Data Sources

Searched articles were indexed by PubMed with relevant queries pertaining to CP and ES/CMA (query date, March 15, 2022).

Study Selection

Inclusion criteria were as follows: primary research study, case series with 10 or more nonrelated individuals, CP diagnosis, and ES and/or CMA data used for genetic evaluation. Nonblinded review was performed.

Data Extraction and Synthesis

Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines were used for assessing data quality and validity. Data were extracted by a single observer.

Main Outcomes and Measures

A separate meta-analysis was performed for each modality (ES, CMA). The primary outcome was proportion/molecular diagnostic yield (number of patients with a discovered genetic disorder divided by the total number of patients in the cohort), evaluated via meta-analysis of single proportions using random-effects logistic regression. A subgroup meta-analysis was conducted, using risk factor classification as a subgroup. A forest plot was used to display diagnostic yields of individual studies.

Results

In the meta-analysis of ES yield in CP, the overall diagnostic yield of ES among the cohorts (15 study cohorts comprising 2419 individuals from 11 articles) was 23% (95% CI, 15%-34%). The diagnostic yield across cryptogenic CP cohorts was 35% (95% CI, 27%-45%), compared with 7% (95% CI, 4%-12%) across cohorts with known risk factors (noncryptogenic CP). In the meta-analysis of CMA yield in CP, the diagnostic yield of CMA among the cohorts (5 study cohorts comprising 294 individuals from 5 articles) was 5% (95% CI, 2%-12%).

Conclusions and Relevance

Results of this systematic review and meta-analysis suggest that for individuals with cryptogenic CP, ES followed by CMA to identify molecular disorders may be warranted.

Cerebral palsy and related neuromotor disorders: Overview of genetic and genomic studies

Cerebral palsy (CP) is a debilitating condition characterized by abnormal movement or posture, beginning early in development. Early family and twin studies and more recent genomic investigations clearly demonstrate that genetic factors of major effect contribute to the etiology of CP. Most copy number variants and small alterations of nucleotide sequence that cause CP arise as a result of de novo mutations, so studies that estimate heritability on basis of recurrence frequency within families substantially underestimate genetic contributions to the etiology. At least 4% of patients with typical CP have disease-causing CNVs, and at least 14% have disease-causing single nucleotide variants or indels. The rate of pathogenic genomic lesions is probably more than twice as high among patients who have atypical CP, i.e., neuromotor dysfunction with additional neurodevelopmental abnormalities or malformations, or with MRI findings and medical history that are not characteristic of a perinatal insult. Mutations of many different genetic loci can produce a CP-like phenotype. The importance of genetic variants of minor effect and of epigenetic modifications in producing a multifactorial predisposition to CP is less clear. Recognizing the specific cause of CP in an affected individual is essential to providing optimal clinical management. An etiological diagnosis provides families an "enhanced compass" that improves overall well-being, facilitates access to educational and social services, permits accurate genetic counseling, and, for a subset of patients such as those with underlying inherited metabolic disorders, may make precision therapy that targets the pathophysiology available. Trio exome sequencing with assessment of copy number or trio genome sequencing with bioinformatics analysis for single nucleotide variants, indels, and copy number variants is clinically indicated in the initial workup of CP patients, especially those with additional malformations or neurodevelopmental abnormalities.

Clinical and biochemical footprints of inherited metabolic disease. V. Cerebral palsy phenotypes

Cerebral palsy is the most common physical disability of childhood describing a heterogeneous group of neurodevelopmental disorders that cause activity limitation, but often are accompanied by disturbances of sensation, perception, cognition, communication and behavior, or by epilepsy. Inborn errors of metabolism have been reported in the literature as presenting with features of cerebral palsy. We reviewed and updated the list of metabolic disorders known to be associated with symptoms suggestive of cerebral palsy and found more than 150 relevant IEMs. This represents the fifth of a series of articles attempting to create and maintain a comprehensive list of clinical and metabolic differential diagnosis according to system involvement.

Treatment on patients with spastic cerebral palsy in the past 30 years: A systematic review and bibliometric analysis

BACKGROUND

Over the past 30 years, treatments from different disciplines have been applied to spastic cerebral palsy (SCP). However, few bibliometric studies have been conducted to date. This study explored the knowledge base, emerging hotspots, and future trends related to SCP treatment research using bibliometric analysis.

METHODS

Publications on SCP treatment included in the Web of Science Core Collection database between 1990 and 2020 were retrieved, and Medical Subject Headings terms were extracted from PubMed. Online bibliometric analysis website (http://bibliometric.com/), 2 pieces of software called "CiteSpace" and "VOSViewer" were used for quantitative analysis and knowledge map establishment.

RESULTS

A total of 1668 papers were retrieved from 1990 to 2020. The number of publications has increased annually. Developmental Medicine and Child Neurology is the most productive and the highest co-cited journal. The United States has been the largest contributor. Vrije Universiteit Amsterdam ranked first in the number of papers published among institutions that have conducted correlational research. Becher JG and Graham HK should be considered scholars who have made outstanding contributions. The knowledge base of the SCP treatment research field is thoughtfully constructed to promote understanding of the field.

CONCLUSION

This bibliometric study identified global achievements, research hotspots, and trends of SCP treatment. They provide insights into the research field and valuable information for future scientific research and clinical treatment.

Making waves: The changing tide of cerebral palsy

Cerebral palsy (CP) is a broad diagnosis unbound by aetiology and is based on a clinical examination demonstrating abnormalities of movement or posture. CP represents a static neurological condition, provided that neurodegenerative conditions, leukoencephalopathies and neuromuscular disorders are excluded. In paediatrics, the genetic conditions associated with CP are rapidly increasing, with primary and overlapping neurodevelopmental conditions perhaps better categorised by the predominant clinical feature such as CP, intellectual disability, autism spectrum disorder or epilepsy. Progress in molecular genetics may challenge what constitutes CP, but a genetic diagnosis does not negate the CP diagnosis. As clinicians working in the field, we discuss the changing tide of CP. Neuroimaging provides essential information through pattern recognition and demonstration of static brain changes. We present examples of children where a layered clinical diagnosis or dual aetiologies are appropriate. We also present examples of children with genetic causes of CP to highlight the challenges and limitations of neuroimaging to provide an aetiological diagnosis. In consultation with a geneticist, access to genomic testing (exome or genome sequencing) is now available in Australia under Medicare billing for children under the age of 10 with dysmorphic features, one or more major structural organ anomalies, (an evolving) intellectual disability or global developmental delay. We encourage the uptake of genomic testing in CP, because it can be difficult to tell whether a child has an environmental or genetic cause for CP. A specific genetic diagnosis may change patient management, reduce guilt and enable more distinctive research in the future to assist with understanding disease mechanisms.

Genomic and phenotypic characterization of 404 individuals with neurodevelopmental disorders caused by CTNNB1 variants

PURPOSE

Germline loss-of-function variants in CTNNB1 cause neurodevelopmental disorder with spastic diplegia and visual defects (NEDSDV; OMIM 615075) and are the most frequent, recurrent monogenic cause of cerebral palsy (CP). We investigated the range of clinical phenotypes owing to disruptions of CTNNB1 to determine the association between NEDSDV and CP.

METHODS

Genetic information from 404 individuals with collectively 392 pathogenic CTNNB1 variants were ascertained for the study. From these, detailed phenotypes for 52 previously unpublished individuals were collected and combined with 68 previously published individuals with comparable clinical information. The functional effects of selected CTNNB1 missense variants were assessed using TOPFlash assay.

RESULTS

The phenotypes associated with pathogenic CTNNB1 variants were similar. A diagnosis of CP was not significantly associated with any set of traits that defined a specific phenotypic subgroup, indicating that CP is not additional to NEDSDV. Two CTNNB1 missense variants were dominant negative regulators of WNT signaling, highlighting the utility of the TOPFlash assay to functionally assess variants.

CONCLUSION

NEDSDV is a clinically homogeneous disorder irrespective of initial clinical diagnoses, including CP, or entry points for genetic testing.

Impaired microtubule dynamics contribute to microthrombocytopenia in RhoB-deficient mice

Megakaryocytes are large cells in the bone marrow that give rise to blood platelets. Platelet biogenesis involves megakaryocyte maturation, the localization of the mature cells in close proximity to bone marrow sinusoids, and the formation of protrusions, which are elongated and shed within the circulation. Rho GTPases play important roles in platelet biogenesis and function. RhoA-deficient mice display macrothrombocytopenia and a striking mislocalization of megakaryocytes into bone marrow sinusoids and a specific defect in G-protein signaling in platelets. However, the role of the closely related protein RhoB in megakaryocytes or platelets remains unknown. In this study, we show that, in contrast to RhoA deficiency, genetic ablation of RhoB in mice results in microthrombocytopenia (decreased platelet count and size). RhoB-deficient platelets displayed mild functional defects predominantly upon induction of the collagen/glycoprotein VI pathway. Megakaryocyte maturation and localization within the bone marrow, as well as actin dynamics, were not affected in the absence of RhoB. However, in vitro-generated proplatelets revealed pronouncedly impaired microtubule organization. Furthermore, RhoB-deficient platelets and megakaryocytes displayed selective defects in microtubule dynamics/stability, correlating with reduced levels of acetylated α-tubulin. Our findings imply that the reduction of this tubulin posttranslational modification results in impaired microtubule dynamics, which might contribute to microthrombocytopenia in RhoB-deficient mice. Importantly, we demonstrate that RhoA and RhoB are localized differently and have selective, nonredundant functions in the megakaryocyte lineage.