Epilepsy in Nicolaides-Baraitser Syndrome: Review of Literature and Report of 25 Patients Focusing on Treatment Aspects.

Nicolaides-Baraitser syndrome (NCBRS), caused by a mutation in the SMARCA2 gene, which goes along with intellectual disability, congenital malformations, especially of face and limbs, and often difficult-to-treat epilepsy, is surveyed focusing on epilepsy and its treatment. Patients were recruited via "Network Therapy of Rare Epilepsies (NETRE)" and an international NCBRS parent support group. Inclusion criterion is NCBRS-defining SMARCA2 mutation. Clinical findings including epilepsy classification, anticonvulsive treatment, electroencephalogram (EEG) findings, and neurodevelopmental outcome were collected with an electronic questionnaire. Inclusion of 25 NCBRS patients with epilepsy in 23 of 25. Overall, 85% of the participants (17/20) reported generalized seizures, the semiology varied widely. EEG showed generalized epileptogenic abnormalities in 53% (9/17), cranial magnetic resonance imaging (cMRI) was mainly inconspicuous. The five most frequently used anticonvulsive drugs were valproic acid (VPA [12/20]), levetiracetam (LEV [12/20]), phenobarbital (PB [8/20]), topiramate (TPM [5/20]), and carbamazepine (CBZ [5/20]). LEV (9/12), PB (6/8), TPM (4/5), and VPA (9/12) reduced the seizures' frequency in more than 50%. Temporary freedom of seizures (>6 months) was reached with LEV (4/12), PB (3/8), TPM (1/5, only combined with PB and nitrazepam [NZP]), and VPA (4/12). Seizures aggravation was observed under lamotrigine (LTG [2/4]), LEV (1/12), PB (1/8), and VPA (1/12). Ketogenic diet (KD) and vagal nerve stimulation (VNS) reduced seizures' frequency in one of two each. This first worldwide retrospective analysis of anticonvulsive therapy in NCBRS helps to treat epilepsy in NCBRS that mostly shows only initial response to anticonvulsive therapy, especially with LEV and VPA, but very rarely shows complete freedom of seizures in this, rather genetic than structural epilepsy.

Expanding the clinical and genetic spectrum of CAD deficiency: an epileptic encephalopathy treatable with uridine supplementation.

PURPOSE: Biallelic CAD variants underlie CAD deficiency (or early infantile epileptic encephalopathy-50, [EIEE-50]), an error of pyrimidine de novo biosynthesis amenable to treatment via the uridine salvage pathway. We further define the genotype and phenotype with a focus on treatment. METHODS: Retrospective case series of 20 patients. RESULTS: Our study confirms CAD deficiency as a progressive EIEE with recurrent status epilepticus, loss of skills, and dyserythropoietic anemia. We further refine the phenotype by reporting a movement disorder as a frequent feature, and add that milder courses with isolated developmental delay/intellectual disability can occur as well as onset with neonatal seizures. With no biomarker available, the diagnosis relies on genetic testing and functional validation in patient-derived fibroblasts. Underlying pathogenic variants are often rated as variants of unknown significance, which could lead to underrecognition of this treatable disorder. Supplementation with uridine, uridine monophosphate, or uridine triacetate in ten patients was safe and led to significant clinical improvement in most patients. CONCLUSION: We advise a trial with uridine (monophosphate) in all patients with developmental delay/intellectual disability, epilepsy, and anemia; all patients with status epilepticus; and all patients with neonatal seizures until (genetically) proven otherwise or proven unsuccessful after 6 months. CAD deficiency might represent a condition for genetic newborn screening.

Unresponsive Wakefulness Syndrome in Children after Near-Drowning: Long-Term Outcome and Impact on the Families.

Among 131 children admitted to our institution for early phase rehabilitation after freshwater near-drowning (ND) between the year 1986 and 2000, 87 were in unresponsive wakefulness syndrome (UWS) for at least 4 weeks after the accidents. An anonymous questionnaire was sent to the families after 0.5 to 15.0 years (median: 4.6) and 48 mothers and 51 fathers of 55 of these 87 children were interviewed after 6.6 to 23.8 years (median: 13.8) of ND. At the time of the interviews, 8/55 children were able to perform daily living activities independently, 36/55 children were not able to do so (many of them suffered from chronic medical conditions like spasticity or disorders of swallowing), and 11/55 children had died. Health-related quality of life (HRQoL) was, however, similar to the normal population for mothers, and even higher for fathers. Furthermore, the ND accident had apparently not lead to a higher rate of separations of parents but had increased their likelihood to have further children. Feelings of guilt were highly prevalent (23/47 mothers, 20/47 fathers), and correlated with lower HRQoL of the respective parent. We found correlations between duty of supervision and feelings of guilt and between outcome and HRQoL for only the fathers. In conclusion, we found that after 4 weeks in UWS, the long-term neurological outcome of pediatric ND victims is often but not always poor. Despite often severe disabilities or death of the child during long-term care, parents surprisingly report little impact on their HRQoL, on the stability of their partnership or on their wish to have further children. Our findings may help parents and physicians to choose the best treatment for a child in UWS due to different etiologies striking the balance between rehabilitation and palliative care.

CAD mutations and uridine-responsive epileptic encephalopathy.

Unexplained global developmental delay and epilepsy in childhood pose a major socioeconomic burden. Progress in defining the molecular bases does not often translate into effective treatment. Notable exceptions include certain inborn errors of metabolism amenable to dietary intervention. CAD encodes a multifunctional enzyme involved in de novo pyrimidine biosynthesis. Alternatively, pyrimidines can be recycled from uridine. Exome sequencing in three families identified biallelic CAD mutations in four children with global developmental delay, epileptic encephalopathy, and anaemia with anisopoikilocytosis. Two died aged 4 and 5 years after a neurodegenerative disease course. Supplementation of the two surviving children with oral uridine led to immediate cessation of seizures in both. A 4-year-old female, previously in a minimally conscious state, began to communicate and walk with assistance after 9 weeks of treatment. A 3-year-old female likewise showed developmental progress. Blood smears normalized and anaemia resolved. We establish CAD as a gene confidently implicated in this neurometabolic disorder, characterized by co-occurrence of global developmental delay, dyserythropoietic anaemia and seizures. While the natural disease course can be lethal in early childhood, our findings support the efficacy of uridine supplementation, rendering CAD deficiency a treatable neurometabolic disorder and therefore a potential condition for future (genetic) newborn screening.

Clinical and electrophysiological features of SCN8A variants causing episodic or chronic ataxia.

BACKGROUND: Variants in SCN8A are associated with a spectrum of epilepsies and neurodevelopmental disorders. Ataxia as a predominant symptom of SCN8A variation has not been well studied. We set out to investigate disease mechanisms and genotype-phenotype correlations of SCN8A-related ataxia. METHODS: We collected genetic and electro-clinical data of ten individuals from nine unrelated families carrying novel SCN8A variants associated with chronic progressive or episodic ataxia. Electrophysiological characterizations of these variants were performed in ND7/23 cells and cultured neurons. FINDINGS: Variants associated with chronic progressive ataxia either decreased Na+ current densities and shifted activation curves towards more depolarized potentials (p.Asn995Asp, p.Lys1498Glu and p.Trp1266Cys) or resulted in a premature stop codon (p.Trp937Ter). Three variants (p.Arg847Gln and biallelic p.Arg191Trp/p.Asp1525Tyr) were associated with episodic ataxia causing loss-of-function by decreasing Na+ current densities or a hyperpolarizing shift of the inactivation curve. Two additional episodic ataxia-associated variants caused mixed gain- and loss-of function effects in ND7/23 cells and were further examined in primary murine hippocampal neuronal cultures. Neuronal firing in excitatory neurons was increased by p.Arg1629His, but decreased by p.Glu1201Lys. Neuronal firing in inhibitory neurons was decreased for both variants. No functional effect was observed for p.Arg1913Trp. In four individuals, treatment with sodium channel blockers exacerbated symptoms. INTERPRETATION: We identified episodic or chronic ataxia as predominant phenotypes caused by variants in SCN8A. Genotype-phenotype correlations revealed a more pronounced loss-of-function effect for variants causing chronic ataxia. Sodium channel blockers should be avoided under these conditions. FUNDING: BMBF, DFG, the Italian Ministry of Health, University of Tuebingen.

Homoplasmy of the Mitochondrial DNA Mutation m.616T>C Leads to Mitochondrial Tubulointerstitial Kidney Disease and Encephalopathia.

Autosomal-dominant tubulointerstitial kidney disease -(ADTKD) describes tubulointerstitial kidney disease with autosomal-dominant inheritance. In 2017, the term mitochondrial tubulointerstitial kidney disease (MITKD) was introduced for tubulointerstitial kidney disease caused by mitochondrial DNA (mtDNA) mutations. To date, there are few mutations described in literature causing MITKD, one of them is m.616T>C. A 5-year-old girl presented with chronic renal insufficiency and epilepsia. At the age of 3 years, status epileptic occurred and evolved into epilepsia partialis continua. At the age of 5 years, chronic renal failure (CKD II-III) was diagnosed due to tubulointerstitial kidney disease. Urine analysis showed elevated fractional excretions of sodium and chloride. Kidneys were enlarged and hyperechogenic. Blood pressure was elevated. The family history was unremarkable for renal and/or neurological disorders. Genetic testing was performed and revealed homoplasmy of the substitution m.616T>C in our patient's mtDNA. This mutation has been shown to cause chronic tubulointerstitial kidney disease leading to end-stage renal disease (ESRD) and epilepsia formerly. MITKD is a rare mitochondrial disease leading to ESRD and should be suggested in patients with epilepsia and renal insufficiency.

Clinical features and blood iron metabolism markers in children with beta-propeller protein associated neurodegeneration.

BACKGROUND: Neurodegeneration with brain iron accumulation constitutes a group of rare progressive movement disorders sharing intellectual disability and neuroimaging findings as common denominators. Beta-propeller protein-associated neurodegeneration (BPAN) represents approximately 7% of the cases, and its first signs are typically epilepsy and developmental delay. We aimed to describe in detail the phenotype of BPAN with a special focus on iron metabolism. MATERIAL AND METHODS: We present a cohort of paediatric patients with pathogenic variants of WD-Repeat Domain 45 gene (WDR45). The diagnosis was established by targeted panel sequencing of genes associated with epileptic encephalopathies (n = 9) or by Sanger sequencing of WDR45 (n = 1). Data on clinical characteristics, molecular-genetic findings and other performed investigations were gathered from all participating centres. Markers of iron metabolism were analysed in 6 patients. RESULTS: Ten children (3 males, 7 females, median age 8.4 years) from five centres (Prague, Berlin, Vogtareuth, Tubingen and Cologne) were enrolled in the study. All patients manifested first symptoms (e.g. epilepsy, developmental delay) between 2 and 31 months (median 16 months). Seven patients were seizure-free (6 on antiepileptic medication, one drug-free) at the time of data collection. Neurological findings were non-specific with deep tendon hyperreflexia (n = 4) and orofacial dystonia (n = 3) being the most common. Soluble transferrin receptor/log ferritin ratio was elevated in 5/6 examined subjects; other parameters of iron metabolism were normal. CONCLUSION: Severity of epilepsy often gradually decreases in BPAN patients. Elevation of soluble transferrin receptor/log ferritin ratio could be another biochemical marker of the disease and should be explored by further studies.

Mutations in GABRB3: From febrile seizures to epileptic encephalopathies.

OBJECTIVE: To examine the role of mutations in GABRB3 encoding the ß3 subunit of the GABAA receptor in individual patients with epilepsy with regard to causality, the spectrum of genetic variants, their pathophysiology, and associated phenotypes. METHODS: We performed massive parallel sequencing of GABRB3 in 416 patients with a range of epileptic encephalopathies and childhood-onset epilepsies and recruited additional patients with epilepsy with GABRB3 mutations from other research and diagnostic programs. RESULTS: We identified 22 patients with heterozygous mutations in GABRB3, including 3 probands from multiplex families. The phenotypic spectrum of the mutation carriers ranged from simple febrile seizures, genetic epilepsies with febrile seizures plus, and epilepsy with myoclonic-atonic seizures to West syndrome and other types of severe, early-onset epileptic encephalopathies. Electrophysiologic analysis of 7 mutations in Xenopus laevis oocytes, using coexpression of wild-type or mutant ß3, together with α5 and γ2s subunits and an automated 2-microelectrode voltage-clamp system, revealed reduced GABA-induced current amplitudes or GABA sensitivity for 5 of 7 mutations. CONCLUSIONS: Our results indicate that GABRB3 mutations are associated with a broad phenotypic spectrum of epilepsies and that reduced receptor function causing GABAergic disinhibition represents the relevant disease mechanism.