Epileptic dyskinetic encephalopathy in KBG syndrome: Expansion of the phenotype.

KBG syndrome is characterised by developmental delay, dental (macrodontia of upper central incisors), craniofacial and skeletal anomalies. Since the identification of variants in the gene (ANKRD11) responsible for KBG syndrome, wider phenotypes are emerging. While there is phenotypic variability within many features of KBG syndrome, epilepsy is not usually markedly severe and movement disorders largely undocumented. Here we describe a novel early onset phenotype of dyskinetic epileptic encephalopathy in a male, who presented during infancy with a florid hyperkinetic movement disorder and developmental regression. Initially he had epileptic spasms and tonic seizures, and EEGs revealed a modified hypsarrhythmia. The epilepsy phenotype evolved to Lennox-Gastaut syndrome with seizures resistant to multiple anti-seizure therapies and the movement disorder evolved to choreoathetosis of limbs and head with oro-lingual dyskinesias. Previous extensive neurometabolic and imaging investigations, including panel-based exome sequencing were unremarkable. Later trio exome sequencing identified a de novo pathogenic heterozygous frameshift deletion of ANKRD11 (c.6792delC; p.Ala2265Profs*72). Review of the literature did not identify any individuals with such a hyperkinetic movement disorder presentation in combination with early-onset epileptic encephalopathy. This report expands the phenotype of ANKRD11-related KBG syndrome to include epileptic dyskinetic encephalopathy.

Increased rates of invasive bacterial disease in late 2022.

Invasive bacterial disease is associated with significant morbidity and mortality. In winter 2022, there was an apparent increased rate of invasive bacterial disease compared to preceding years. Cross-site retrospective analysis of the three Children's Health Ireland (CHI) hospitals looking at children admitted between 1st October 2022-31st December 2022 (Q4) with community-acquired invasive bacterial disease, defined as an abscess in a normally sterile site in the head, neck and chest or isolation or PCR detection of Streptococcus pneumoniae, Neisseria meningitidis, Streptococcus pyogenes (Group A streptococcus) or Haemophilus influenzae from a normally sterile site. Case numbers were compared to Q4 in each of 2018-2021. Eighty-two children met the case definition in Q4 2022 vs 97 (Q4 2018-2021). In 2022, 42/82 (51%) were female, median age 3.75 years (1.5-8.25 years). Only 2 (2%) were immunosuppressed and 2 others (2%) had underlying neurodisability. Fifty (61%) were admitted on second or subsequent presentation to a healthcare setting. Fifty-six (68%) had an abscess in a sterile site. Bloodstream infection (positive blood culture or PCR: 24 (29%)) was the most common site of infection, followed by neck 22 (27%) and intracranial 12 (15%). Group A streptococcus (GAS) 27 (33%) was the most common organism isolated. Seven cases (9%) died in 2022 compared to 2 patients (2%) from 2018 to 2021 (p < 0.05). More children had Paediatric Overall Performance Category (POPC) scores > 1 in 2022 than 2018-2021 (p = 0.003).  Conclusion: Invasive bacterial diseases increased in Q4 2022 with higher morbidity and mortality than in the preceding 4 years. Group A streptococcal infection was the most significant organism in 2022. What is known: • Invasive bacterial disease is the leading cause of childhood mortality globally. • There was an increase in cases of invasive Group A streptococcus infections reported in many countries (including Ireland) during the winter of 2022/23. What is new: • Head, neck and chest abscesses increased in Q4 of 2022 compared to the previous 4 years combined. • Invasive bacterial infections in Q4 of 2022 were associated with higher rates of mortality (9%), paediatric intensive care unit (PICU) admission (24%) and requirement for surgical drainage or intervention (67%) than in the preceding years.

Relationship Between Electroencephalography and Seizure Outcome in Typical Absence Seizures in Children.

BACKGROUND: Typical absence seizures (TAS) are seen in idiopathic generalized epilepsy. Electroencephalography (EEG) contributes to syndrome characterization and counseling in an area where genetics does not currently play a significant role. Prominent interictal EEG findings are seen in juvenile absence epilepsy (JAE) and are thus thought to be associated with less favorable outcome in any TAS case despite lack of evidence. Our study evaluates EEG findings and their association with seizure outcomes in children with TAS. METHODS: Retrospective cohort study of 123 children over 10 years with extensive EEG analysis and medical record review. Phone interviews ascertained longer-term outcomes. EEG reviewers were unaware of outcomes. RESULTS: Total cohort included 123 children with phone review completed in 98. Median follow-up was 5 years 9 months. Seizure freedom was seen in 59% off antiseizure medicines (ASMs). Interictal findings included focal discharges in 29%, fragments of spike-wave (SW) discharges in 82.1%, and generalized interictal discharges in 63.4%. Interictal SW was more likely in those who slept (100%, 18 of 18) versus those who did not (57%, 60 of 105) (P < 0.001). Outcome analysis found no associations between focal or generalized interictal findings and seizure freedom, relapse off ASM, occurrence of other seizure types, or response to first ASM. CONCLUSION: Focal and generalized interictal EEG discharges are common in children with TAS and are not associated with poorer outcomes. These interictal findings were traditionally associated with JAE rather than childhood absence epilepsy and were thus believed to be associated with potentially poorer outcome, which is probably not the case.

Everolimus precision therapy for the GATOR1-related epilepsies: A case series.

BACKGROUND: Pathogenic variants in the GAP activity towards RAGs 1 (GATOR1) complex genes (DEPDC5, NPRL2, NPRL3) cause focal epilepsy through hyperactivation of the mechanistic target of rapamycin pathway. We report our experience using everolimus in patients with refractory GATOR1-related epilepsy. METHODS: We performed an open-label observational study of everolimus for drug-resistant epilepsy caused by variants in DEPDC5, NPRL2 and NPRL3. Everolimus was titrated to a target serum concentration (5-15 ng/mL). The primary outcome measure was change in mean monthly seizure frequency compared with baseline. RESULTS: Five patients were treated with everolimus. All had highly active (median baseline seizure frequency, 18/month) and refractory focal epilepsy (failed 5-16 prior anti-seizure medications). Four had DEPDC5 variants (three loss-of-function, one missense) and one had a NPRL3 splice-site variant. All patients with DEPDC5 loss-of-function variants had significantly reduced seizures (74.3%-86.1%), although one stopped everolimus after 12 months due to psychiatric symptoms. Everolimus was less effective in the patient with a DEPDC5 missense variant (43.9% seizure frequency reduction). The patient with NPRL3-related epilepsy had seizure worsening. The most common adverse event was stomatitis. CONCLUSIONS: Our study provides the first human data on the potential benefit of everolimus precision therapy for epilepsy caused by DEPDC5 loss-of-function variants. Further studies are needed to support our findings.

Heterozygous and homozygous variants in STX1A cause a neurodevelopmental disorder with or without epilepsy.

The neuronal SNARE complex drives synaptic vesicle exocytosis. Therefore, one of its core proteins syntaxin 1A (STX1A) has long been suspected to play a role in neurodevelopmental disorders. We assembled eight individuals harboring ultra rare variants in STX1A who present with a spectrum of intellectual disability, autism and epilepsy. Causative variants comprise a homozygous splice variant, three de novo missense variants and two inframe deletions of a single amino acid. We observed a phenotype mainly driven by epilepsy in the individuals with missense variants in contrast to intellectual disability and autistic behavior in individuals with single amino acid deletions and the splicing variant. In silico modeling of missense variants and single amino acid deletions show different impaired protein-protein interactions. We hypothesize the two phenotypic courses of affected individuals to be dependent on two different pathogenic mechanisms: (1) a weakened inhibitory STX1A-STXBP1 interaction due to missense variants results in an STX1A-related developmental epileptic encephalopathy and (2) a hampered SNARE complex formation due to inframe deletions causes an STX1A-related intellectual disability and autism phenotype. Our description of a STX1A-related neurodevelopmental disorder with or without epilepsy thus expands the group of rare diseases called SNAREopathies.

Neurodevelopmental and Epilepsy Phenotypes in Individuals With Missense Variants in the Voltage-Sensing and Pore Domains of KCNH5.

BACKGROUND AND OBJECTIVES: KCNH5 encodes the voltage-gated potassium channel EAG2/Kv10.2. We aimed to delineate the neurodevelopmental and epilepsy phenotypic spectrum associated with de novo KCNH5 variants. METHODS: We screened 893 individuals with developmental and epileptic encephalopathies for KCNH5 variants using targeted or exome sequencing. Additional individuals with KCNH5 variants were identified through an international collaboration. Clinical history, EEG, and imaging data were analyzed; seizure types and epilepsy syndromes were classified. We included 3 previously published individuals including additional phenotypic details. RESULTS: We report a cohort of 17 patients, including 9 with a recurrent de novo missense variant p.Arg327His, 4 with a recurrent missense variant p.Arg333His, and 4 additional novel missense variants. All variants were located in or near the functionally critical voltage-sensing or pore domains, absent in the general population, and classified as pathogenic or likely pathogenic using the American College of Medical Genetics and Genomics criteria. All individuals presented with epilepsy with a median seizure onset at 6 months. They had a wide range of seizure types, including focal and generalized seizures. Cognitive outcomes ranged from normal intellect to profound impairment. Individuals with the recurrent p.Arg333His variant had a self-limited drug-responsive focal or generalized epilepsy and normal intellect, whereas the recurrent p.Arg327His variant was associated with infantile-onset DEE. Two individuals with variants in the pore domain were more severely affected, with a neonatal-onset movement disorder, early-infantile DEE, profound disability, and childhood death. DISCUSSION: We describe a cohort of 17 individuals with pathogenic or likely pathogenic missense variants in the voltage-sensing and pore domains of Kv10.2, including 14 previously unreported individuals. We present evidence for a putative emerging genotype-phenotype correlation with a spectrum of epilepsy and cognitive outcomes. Overall, we expand the role of EAG proteins in human disease and establish KCNH5 as implicated in a spectrum of neurodevelopmental disorders and epilepsy.

Transitional care models in adolescent kidney transplant recipients-a systematic review.

BACKGROUND: Adolescence is a time of significant change for patients, guardians and clinicians. The paediatrician must ensure patients develop the necessary skills and knowledge required to transition and to function as an independent entity, with autonomy over their own care. The transfer from paediatric to adult care carries an increased risk of graft-related complications attributable to a multitude of reasons, particularly non-adherence to immunosuppressive medicines and poor attendance at scheduled appointments. This systematic review was conducted to ascertain the transitional care models available to clinicians caring for kidney transplant recipients and to compare the approach in each respective case. METHODS: A systematic review was performed, in a methodology outlined by the PRISMA guidelines. OVID MEDLINE and EMBASE databases were searched for studies that outlined valid, replicable models pertaining to transitional care of paediatric kidney transplant recipients between 1946 and Quarter 3 of 2021. The reference lists of selected articles were also perused for further eligible studies and experts in the field were consulted for further eligible articles. Two investigators assessed all studies for eligibility and independently performed data extraction. Any discrepancies were settled by consensus. RESULTS: A total of 1121 abstracts were identified, which was reduced to 1029 upon removal of duplicates. A total of 51 articles were deemed appropriate for full-text review and critical appraisal. A total of 12 articles that described models for transition pertaining to kidney transplant patients were included in qualitative synthesis. Every paper utilized a different transition model. All but one model included a physician and nurse at minimum in the transition process. The involvement of adult nephrologists, medical social work, psychology and psychiatry was variable. The mean age for the initiation of transition was 13.4 years (range: 10-17.5 years). The mean age at transfer to adult services was 18.3 years (range: 16-20.5 years). CONCLUSIONS: Despite the well-established need for good transitional care for paediatric solid-organ transplant recipients, models tailored specifically for kidney transplant recipients are lacking. Further research and validation studies are required to ascertain the best method of providing effective transitional care to these patients. Transitional care should become a standardized process for adolescents and young adults with kidney transplants.

MED27, SLC6A7, and MPPE1 Variants in a Complex Neurodevelopmental Disorder with Severe Dystonia.

BACKGROUND: Despite advances in next generation sequencing technologies, the identification of variants of uncertain significance (VUS) can often hinder definitive diagnosis in patients with complex neurodevelopmental disorders. OBJECTIVE: The objective of this study was to identify and characterize the underlying cause of disease in a family with two children with severe developmental delay associated with generalized dystonia and episodic status dystonicus, chorea, epilepsy, and cataracts. METHODS: Candidate genes identified by autozygosity mapping and whole-exome sequencing were characterized using cellular and vertebrate model systems. RESULTS: Homozygous variants were found in three candidate genes: MED27, SLC6A7, and MPPE1. Although the patients had features of MED27-related disorder, the SLC6A7 and MPPE1 variants were functionally investigated. SLC6A7 variant in vitro overexpression caused decreased proline transport as a result of reduced cell-surface expression, and zebrafish knockdown of slc6a7 exhibited developmental delay and fragile motor neuron morphology that could not be rescued by L-proline transporter-G396S RNA. Lastly, patient fibroblasts displayed reduced cell-surface expression of glycophosphatidylinositol-anchored proteins linked to MPPE1 dysfunction. CONCLUSIONS: We report a family harboring a homozygous MED27 variant with additional loss-of-function SLC6A7 and MPPE1 gene variants, which potentially contribute to a blended phenotype caused by multilocus pathogenic variants. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Response to treatment and outcomes of infantile spasms in Down syndrome.

AIM: To estimate the prevalence, and evaluate presentation, treatment response, treatment side effects, and long-term seizure outcomes in all known cases of children with Down syndrome and infantile spasms on the island of Ireland. METHOD: This was a 10-year retrospective multicentre review of clinical records and investigations, focusing on treatment response, side effects, and long-term outcomes. RESULTS: The prevalence of infantile spasms in Down syndrome was 3.0% during the study period. Fifty-four infants were identified with median age of spasm onset at 201 days (interquartile range [IQR] 156-242). Spasm cessation was achieved in 88% (n=46) at a median of 110 days (IQR 5-66). The most common first-line medications were prednisolone (n=20, 37%), vigabatrin (n=18, 33.3%), and sodium valproate (n=9, 16.7%). At follow-up (median age 23.7mo; IQR 13.4-40.6), 25% had ongoing seizures and 85% had developmental concerns. Treatment within 60 days did not correlate with spasm cessation. Seventeen children (31%) experienced medication side effects, with vigabatrin accounting for 52%. INTERPRETATION: Prednisolone is an effective and well-tolerated medication for treating infantile spasms in Down syndrome. Despite the high percentage of spasm cessation, developmental concerns and ongoing seizures were common.

Neurological involvement in children with hemolytic uremic syndrome.

Our objective was to establish the rate of neurological involvement in Shiga toxin-producing Escherichia coli-hemolytic uremic syndrome (STEC-HUS) and describe the clinical presentation, management and outcome. A retrospective chart review of children aged ≤ 16 years with STEC-HUS in Children's Health Ireland from 2005 to 2018 was conducted. Laboratory confirmation of STEC infection was required for inclusion. Neurological involvement was defined as encephalopathy, focal neurological deficit, and/or seizure activity. Data on clinical presentation, management, and outcome were collected. We identified 240 children with HUS; 202 had confirmed STEC infection. Neurological involvement occurred in 22 (11%). The most common presentation was seizures (73%). In the neurological group, 19 (86%) were treated with plasma exchange and/or eculizumab. Of the 21 surviving children with neurological involvement, 19 (91%) achieved a complete neurological recovery. A higher proportion of children in the neurological group had renal sequelae (27% vs. 12%, P = .031). One patient died from multi-organ failure.Conclusion: We have identified the rate of neurological involvement in a large cohort of children with STEC-HUS as 11%. Neurological involvement in STEC-HUS is associated with good long-term outcome (complete neurological recovery in 91%) and a low case-fatality rate (4.5%) in our cohort. What is Known: • HUS is associated with neurological involvement in up to 30% of cases. • Neurological involvement has been reported as predictor of poor outcome, with associated increased morbidity and mortality. What is New: • The incidence of neurological involvement in STEC-HUS is 11%. • Neurological involvement is associated with predominantly good long-term outcome (90%) and a reduced case-fatality rate (4.5%) compared to older reports.

Persistent sodium currents in SCN1A developmental and degenerative epileptic dyskinetic encephalopathy.

Pathogenic variants in the voltage-gated sodium channel gene (SCN1A) are amongst the most common genetic causes of childhood epilepsies. There is considerable heterogeneity in both the types of causative variants and associated phenotypes; a recent expansion of the phenotypic spectrum of SCN1A associated epilepsies now includes an early onset severe developmental and epileptic encephalopathy with regression and a hyperkinetic movement disorder. Herein, we report a female with a developmental and degenerative epileptic-dyskinetic encephalopathy, distinct and more severe than classic Dravet syndrome. Clinical diagnostics indicated a paternally inherited c.5053G>T; p. A1685S variant of uncertain significance in SCN1A. Whole-exome sequencing detected a second de novo mosaic (18%) c.2345G>A; p. T782I likely pathogenic variant in SCN1A (maternal allele). Biophysical characterization of both mutant channels in a heterologous expression system identified gain-of-function effects in both, with a milder shift in fast inactivation of the p. A1685S channels; and a more severe persistent sodium current in the p. T782I. Using computational models, we show that large persistent sodium currents induce hyper-excitability in individual cortical neurons, thus relating the severe phenotype to the empirically quantified sodium channel dysfunction. These findings further broaden the phenotypic spectrum of SCN1A associated epilepsies and highlight the importance of testing for mosaicism in epileptic encephalopathies. Detailed biophysical evaluation and computational modelling further highlight the role of gain-of-function variants in the pathophysiology of the most severe phenotypes associated with SCN1A.

4-Aminopyridine is a promising treatment option for patients with gain-of-function KCNA2-encephalopathy.

Developmental and epileptic encephalopathies are devastating disorders characterized by epilepsy, intellectual disability, and other neuropsychiatric symptoms, for which available treatments are largely ineffective. Following a precision medicine approach, we show for KCNA2-encephalopathy that the K+ channel blocker 4-aminopyridine can antagonize gain-of-function defects caused by variants in the KV1.2 subunit in vitro, by reducing current amplitudes and negative shifts of steady-state activation and increasing the firing rate of transfected neurons. In n-of-1 trials carried out in nine different centers, 9 of 11 patients carrying such variants benefitted from treatment with 4-aminopyridine. All six patients experiencing daily absence, myoclonic, or atonic seizures became seizure-free (except some remaining provoked seizures). Two of six patients experiencing generalized tonic-clonic seizures showed marked improvement, three showed no effect, and one worsening. Nine patients showed improved gait, ataxia, alertness, cognition, or speech. 4-Aminopyridine was well tolerated up to 2.6 mg/kg per day. We suggest 4-aminopyridine as a promising tailored treatment in KCNA2-(gain-of-function)­encephalopathy and provide an online tool assisting physicians to select patients with gain-of-function mutations suited to this treatment.

Paroxysmal Movement Disorders.

Paroxysmal movement disorders (PxMDs) are a clinical and genetically heterogeneous group of movement disorders characterized by episodic involuntary movements (dystonia, dyskinesia, chorea and/or ataxia). Historically, PxMDs were classified clinically (triggers and characteristics of the movements) and this directed single-gene testing. With the advent of next-generation sequencing (NGS), how we classify and investigate PxMDs has been transformed. Next-generation sequencing has enabled new gene discovery (RHOBTB2, TBC1D24), expansion of phenotypes in known PxMDs genes and a better understanding of disease mechanisms. However, PxMDs exhibit phenotypic pleiotropy and genetic heterogeneity, making it challenging to predict genotype based on the clinical phenotype. For example, paroxysmal kinesigenic dyskinesia is most commonly associated with variants in PRRT2 but also variants identified in PNKD, SCN8A, and SCL2A1. There are no radiological or biochemical biomarkers to differentiate genetic causes. Even with NGS, diagnosis rates are variable, ranging from 11 to 51% depending on the cohort studied and technology employed. Thus, a large proportion of patients remain undiagnosed compared to other neurological disorders such as epilepsy, highlighting the need for further genomic research in PxMDs. Whole-genome sequencing, deep-sequencing, copy number variant analysis, detection of deep-intronic variants, mosaicism and repeat expansions, will improve diagnostic rates. Identifying the underlying genetic cause has a significant impact on patient care, modification of treatment, long-term prognostication and genetic counseling. This paper provides an update on the genetics of PxMDs, description of PxMDs classified according to causative gene rather than clinical phenotype, highlighting key clinical features and providing an algorithm for genetic testing of PxMDs.

RHOBTB2 Mutations Expand the Phenotypic Spectrum of Alternating Hemiplegia of Childhood.

OBJECTIVE: To explore the phenotypic spectrum of RHOBTB2-related disorders and specifically to determine whether patients fulfill criteria for alternating hemiplegia of childhood (AHC), we report the clinical features of 11 affected individuals. METHODS: Individuals with RHOBTB2-related disorders were identified through a movement disorder clinic at a specialist pediatric center, with additional cases identified through collaboration with other centers internationally. Clinical data were acquired through retrospective case-note review. RESULTS: Eleven affected patients were identified. All had heterozygous missense variants involving exon 9 of RHOBTB2, confirmed as de novo in 9 cases. All had a complex motor phenotype, including at least 2 different kinds of movement disorder, e.g., ataxia and dystonia. Many patients demonstrated several features fulfilling the criteria for AHC: 10 patients had a movement disorder including paroxysmal elements, and 8 experienced hemiplegic episodes. In contrast to classic AHC, commonly caused by mutations in ATP1A3, these events were reported later only in RHOBTB2 mutation-positive patients from 20 months of age. Seven patients had epilepsy, but of these, 4 patients achieved seizure freedom. All patients had intellectual disability, usually moderate to severe. Other features include episodes of marked skin color change and gastrointestinal symptoms, each in 4 patients. CONCLUSION: Although heterozygous RHOBTB2 mutations were originally described in early infantile epileptic encephalopathy type 64, our study confirms that they account for a more expansive clinical phenotype, including a complex polymorphic movement disorder with paroxysmal elements resembling AHC. RHOBTB2 testing should therefore be considered in patients with an AHC-like phenotype, particularly those negative for ATPA1A3 mutations.

Psychiatric comorbidity is common in dystonia and other movement disorders.

OBJECTIVE: To determine rates of psychiatric comorbidity in a clinical sample of childhood movement disorders (MDs). DESIGN: Cohort study. SETTING: Tertiary children's hospital MD clinics in Sydney, Australia and London, UK. PATIENTS: Cases were children with tic MDs (n=158) and non-tic MDs (n=102), including 66 children with dystonia. Comparison was made with emergency department controls (n=100), neurology controls with peripheral neuropathy or epilepsy (n=37), and community controls (n=10 438). INTERVENTIONS: On-line development and well-being assessment which was additionally clinically rated by experienced child psychiatrists. MAIN OUTCOME MEASURES: Diagnostic schedule and manual of mental disorders-5 criteria for psychiatric diagnoses. RESULTS: Psychiatric comorbidity in the non-tic MD cohort (39.2%) was comparable to the tic cohort (41.8%) (not significant). Psychiatric comorbidity in the non-tic MD cohort was greater than the emergency control group (18%, p<0.0001) and the community cohort (9.5%, p<0.00001), but not the neurology controls (29.7%, p=0.31). Almost half of the patients within the tic cohort with psychiatric comorbidity were receiving medical psychiatric treatment (45.5%) or psychology interventions (43.9%), compared with only 22.5% and 15.0%, respectively, of the non-tic MD cohort with psychiatric comorbidity. CONCLUSIONS: Psychiatric comorbidity is common in non-tic MDs such as dystonia. These psychiatric comorbidities appear to be under-recognised and undertreated.

Fifteen-minute consultation: Approach to investigation and management of childhood dystonia.

Dystonia is a hyperkinetic movement disorder characterised by sustained or intermittent muscle contractions causing abnormal movements, postures or both. Dystonia is a challenging condition to diagnose and treat. Dystonia is often under-recognised in children, particularly in cerebral palsy, and frequently coexists with spasticity. This guide aims to simplify the approach to diagnosis, investigation and treatment of childhood-onset dystonia. The principle of treatment is similar regardless of the underlying aetiology: identification of potential triggers and consideration of both pharmacological and surgical options.