Are SCN2A-related BFNISs also responsible for seizures in adulthood? A case report opens new scenarios.

Large cohort studies and variant-specific electrophysiology have enabled the delineation of different SCN2A-epilepsy phenotypes, phenotype-genotype correlations, prediction of pharmacosensitivity to sodium channel blockers, and long-term prognostication for clinicians and families. One of the most common clinical presentations of SCN2A pathological variants is benign familial neonatal-infantile seizures (BFNIS), which are characterized by seizure onset between the first day of life and 23 months of age and typically resolve, either spontaneously or with the aid of sodium channel blockers, within the first 2 years of life. In 2004, Berkovic et al. reported the case of a young boy affected by SCN2A-related BFNIS whose mother, who carried the same pathological variant, had also presented with BFNIS in infancy. Our case report focuses on the aforementioned woman who, more than 40 years later, presented two additional seizures, therefore opening the possibility of a role for SCN2A-related seizures in adulthood.

Frequency of SCN2A-related disorder in the regional epilepsy centre of brescia between 2002 and 2021.

OBJECTIVE: SCN2A gene pathogenic variants are associated with a wide phenotypic spectrum, encompassing epilepsy, developmental delay, and autism spectrum disorder. Researches conducted in Denmark have revealed a disease frequency of approximately 1/78,608 (0.0012%) live births in this population. We estimated the frequency of SCN2A-related disorder in the birth cohort of Brescia and its province between 2002 and 2021. METHODS: Frequency was calculated by ratio between patients with SCN2A pathogenic variant and the total number of live births at the Regional Epilepsy Center of Brescia, between 2002 and 2021. The number of births in Brescia and province was obtained from the Italian National Institute of Statistics (ISTAT). RESULTS: A frequency of 11/23,2678 births (0.0047%) was found. In comparison with Danish data, we noticed a higher frequency of the pathogenic variant in our population, even considering the same time frame (0.0035% of subjects born between 2006 and 2014). CONCLUSION: The frequency of SCN2A pathogenic variant among live births in Brescia and its Province between 2006 and 2014 was about three times that of Danish population; this difference was about four times if we consider the period from 2002 to 2021. More studies are needed to further delineate the frequency of SCN2A pathogenic variant in Italian population.

[The coincidence of benign non-familial infantile seizures type 2 with osteogenesis imperfecta type 1]. / Sochetanie dobrokachestvennykh nesemeinykh infantil'nykh pristupov 2-go tipa s nesovershennym osteogenezom 1-go tipa.

A clinical case of a patient with neonatal epilepsy at the age of 5 months, with impaired bone formation, early osteoporosis and frequent limb fractures is described. Panel sequencing confirmed by Sanger sequencing revealed two independent hereditary diseases - osteogenesis imperfect type 1, associated with a mutation in the COL1A1 gene (c.2010delT) and benign non-familial infantile seizures associated with a mutation in the PRRT2 gene (c.649dupC). A unique clinical case of a combination of these diseases is presented.

Novel mutations in TRPM6 gene associated with primary hypomagnesemia with secondary hypocalcemia. Case report.

BACKGROUND: Primary hypomagnesemia with secondary hypocalcemia (HSH) is a rare genetic disorder. Dysfunctional transient receptor potential melastatin 6 causes impaired intestinal absorption of magnesium, leading to low serum levels accompanied by hypocalcemia. Typical signs at initial manifestation are generalized seizures, tetany, and/or muscle spasms. CASE REPORT: We present a 5 w/o female manifesting tonic-clonic seizures. Laboratory tests detected severe hypomagnesemia and hypocalcemia. The molecular genetic analysis revealed two novel mutations within the TRPM6 gene c.3308dupC (p.Pro1104Thrfs*28) (p.P1104Tfs*28) and c.3958C>T (p.Gln1302*) (p.Q1302*) and the patient was successfully treated with Mg supplementation. CONCLUSION: Ion disbalance should be taken into account in the differential diagnosis of infantile seizures. Accurate diagnosis of HSH together with appropriate treatment are crucial to prevent irreversible neurological outcomes.

The Spectrum of PRRT2-Associated Disorders: Update on Clinical Features and Pathophysiology.

Mutations in the PRRT2 (proline-rich transmembrane protein 2) gene have been identified as the main cause of an expanding spectrum of disorders, including paroxysmal kinesigenic dyskinesia and benign familial infantile epilepsy, which places this gene at the border between epilepsy and movement disorders. The clinical spectrum has largely expanded to include episodic ataxia, hemiplegic migraine, and complex neurodevelopmental disorders in cases with biallelic mutations. Prior to the discovery of PRRT2 as the causative gene for this spectrum of disorders, the sensitivity of paroxysmal kinesigenic dyskinesia to anticonvulsant drugs regulating ion channel function as well as the co-occurrence of epilepsy in some patients or families fostered the hypothesis this could represent a channelopathy. However, recent evidence implicates PRRT2 in synapse functioning, which disproves the "channel hypothesis" (although PRRT2 modulates ion channels at the presynaptic level), and justifies the classification of these conditions as synaptopathies, an emerging rubric of brain disorders. This review aims to provide an update of the clinical and pathophysiologic features of PRRT2-associated disorders.

The clinical and genetic spectrum in infants with (an) unprovoked cluster(s) of focal seizures.

BACKGROUND: Self-limited (familial) infantile epilepsy (S(F)IE), formerly known as benign (familial) infantile convulsions (B(F)IC), is an infantile cluster epilepsy with in rule a complete recovery. This form of epilepsy is most often caused by variations in the PRRT2 gene (OMIM #605751). AIM: To describe the clinical and genetic spectrum of sudden onset clusters of focal seizures in infancy. METHODS: We retrospectively reviewed all individuals, who presented with unprovoked infantile seizures and selected all infants who had unprovoked clustered focal seizures between 1 and 20 months of age. We described the clinical and genetic spectrum of this cohort. RESULTS: The data of 23 patients from 21 families were collected. All had an initial diagnosis of S(F)IE which was adjusted in 5 individuals. In 12 individuals a pathogenic variation in PRRT2 gene or complete deletion was identified. Pathogenic variants in PCDH19 and KCNQ2 were found in respectively 3 and 1 individuals. One individual had a non-pathogenic variant in ATP1A3 and in 6 others no variants were identified. The mean cluster duration was 2.9 days (range 1-13) (see Table 1). Twelve infants had only one cluster. All patients had focal motor or non-motor seizures, in 12 (52%) followed by bilateral (tonic)clonic seizures. Positive family history was present in 74% of individuals. In 11/12 (92%) tested families, ≥1 family member carried the pathogenic PRRT2 variant. Age of seizure onset (ASO) averaged 6.2 months (range 2-20 months). Age of latest seizure averaged 16 months (range 2-92). In several interictal EEG (electroencephalogram) recordings multifocal spikes or spike-wave abnormalities were detected. Ictal EEG recordings detected primary focal abnormalities. CONCLUSION: We described 23 individuals with unprovoked cluster(s) of focal seizures at infancy. It appears to be a heterogeneous group. Half of them had a pathogenic variation in PRRT2 gene. Most had only one cluster of seizures. When clusters reoccur frequently, when seizures are more therapy-resistant and when seizures persist beyond the age of 2 years, another diagnosis or causative gene is likely.

A PRRT2 variant in a Chinese family with paroxysmal kinesigenic dyskinesia and benign familial infantile seizures results in loss of interaction with STX1B.

OBJECTIVE: To identify the causative gene of autosomal dominant paroxysmal kinesigenic dyskinesia and benign familial infantile seizures (PKD/BFIS) in a large Chinese family and explore the potential pathogenic mechanism of a PRRT2 (proline-rich transmembrane protein 2) variant. METHODS: Genetic testing was performed via whole exome sequencing. Western blotting and immunofluorescence were used to analyze the protein expression level and subcellular localization of the PRRT2 mutant in HeLa cells and N2A cells. Coimmunoprecipitation was conducted to investigate the interaction of the PRRT2 mutant with syntaxin 1B (STX1B). RESULTS: In a large Chinese family with autosomal dominant PKD/BFIS showing wide phenotypic heterogeneity, including patients suffering from PKD, BFIS, or epilepsy and asymptomatic variant carriers, a c.621dupA variant in PRRT2 was identified in the proband and was shown to cosegregate with the phenotype in this family. This variant results in premature termination at codon 224, producing a truncated protein (p.Ser208Ilefs*17) in which the two conserved hydrophobic segments and the cytoplasmic loop are missing. Both the expression and subcellular localization of PRRT2 are strongly affected by the c.621dupA variant. In addition, we found that PRRT2 directly interacts with STX1B, a SNARE protein critical for neurotransmitter release, whereas the truncated variant p.Ser208Ilefs*17 lacking the helix-loop-helix domain fails to bind to STX1B. SIGNIFICANCE: Our findings identified a PRRT2 variant in a family with PKD/BFIS and confirmed STX1B as a new binding partner of PRRT2, which suggested that the loss of the interaction between PRRT2 and STX1B may contribute to the pathogenesis of PKD/BFIS.

Whole gene duplication of SCN2A and SCN3A is associated with neonatal seizures and a normal intellectual development.

Duplications at 2q24.3 encompassing the voltage-gated sodium channel gene cluster are associated with early onset epilepsy. All cases described in the literature have presented in addition with different degrees of intellectual disability, and have involved neighbouring genes in addition to the sodium channel gene cluster. Here, we report eight new cases with overlapping duplications at 2q24 ranging from 0.05 to 7.63 Mb in size. Taken together with the previously reported cases, our study suggests that having an extra copy of SCN2A has an effect on epilepsy pathogenesis, causing benign familial infantile seizures which eventually disappear at the age of 1-2 years. However, the number of copies of SCN2A does not appear to have an effect on cognitive outcome.

Difficulty of Early Diagnosis and Requirement of Long-Term Follow-Up in Benign Infantile Seizures.

PURPOSE: We investigated whether benign infantile seizures can be diagnosed in the acute phase. METHODS: We retrospectively analyzed the medical records of 44 patients initially diagnosed with acute phase benign infantile seizures. All patients were followed for more than 12 months, and we reviewed patients' psychomotor development and presence or absence of seizure recurrence at the last visit. Patients were divided into the following three groups according to the final diagnosis: benign infantile seizures, benign infantile seizures associated with mild gastroenteritis, and non-benign infantile seizures. We defined benign infantile seizures associated with mild gastroenteritis and benign infantile seizures as those associated with normal psychomotor development and no seizure recurrence 3 months after onset of the first seizure, whereas non-benign infantile seizures were associated with delayed psychomotor development and/or seizure recurrence after 3 months of onset of the first seizure. We analyzed the clinical features in the acute phase and compared them between the groups. RESULTS: The median age of seizure onset was 7.6 months. A final diagnosis of benign infantile seizures associated with mild gastroenteritis was made in three patients. In the remaining 41 patients, the final diagnosis was benign infantile seizures in 30 (73.2%) and non-benign infantile seizures in 11 (26.8%). In the non-benign infantile seizure group, intellectual disability was diagnosed in eight patients and seizure recurrence in six. There were no significant differences in clinical features between the groups in the acute phase, such as seizure type or seizure duration. CONCLUSION: About 30% of patients initially diagnosed as having benign infantile seizures did not experience a benign clinical course. Our findings suggest that clinical features in the acute phase are not helpful for predicting benign outcomes in benign infantile seizures and that only long-term follow-up can discriminate benign infantile seizures from non-benign infantile seizures.

Treatment of infants with epilepsy: Common practices around the world.

OBJECTIVES: High quality data to guide recommendations for infants with epilepsy are lacking. This study aimed to develop an understanding of common practice and regional variations in the treatment interventions of infants with epilepsy, and also to identify areas for further study and to highlight where common practice occurs without sound evidence. METHOD: A survey addressed clinical treatment practice for infants with epilepsy. Alternative interventions were included. RESULTS: The survey found that most regions had similar practice for first-line interventions, except for North America, where more levetiracetam was prescribed. There was a preference for valproate as first-line therapy for generalized seizures, myoclonic seizures, and Dravet syndrome; only Oceania differed for generalized and myoclonic seizures. Phenobarbital was used for generalized and focal seizures in resource-poor and resource-equipped regions. Carbamazepine and oxcarbazepine were the preferred agents for focal seizures from all regions except North America, which uses more levetiracetam. For second- and third-line interventions, the range of choices was diverse, often with little correlation across regions. The ketogenic diet, vagus nerve stimulation, and epilepsy surgery were considered viable choices in most settings, but usually only once seizures were considered medically refractory. The survey highlighted the marked discrepancy in Africa, the one region that consistently confirmed a lack of access to these alternative interventions and to the newer antiepileptic drugs. SIGNIFICANCE: More randomized controlled trials in infants with seizures are needed to permit useful recommendations. The survey identified widespread use of levetiracetam in North America, which may be the result of effective marketing or based on good clinical practice. The widespread use of valproate may have safety implications. The lack of access to care in the African region highlighted the need for more sustained resources. Although the survey was not evidence based, the findings could be useful to support additional well-designed studies.

Evaluation of clinical course and neurocognition in children with self-limited infantile epilepsy in a Turkish cohort study.

The outcome of children with self-limited infantile epilepsy was reported to be normal psychosocial and cognitive development as a characteristic criterion. We aimed to investigate the clinical course and neurocognitive outcome in children with self-limited infantile epilepsy in a Turkish cohort. The clinical course, electroencephalographic (EEG) characteristics, neuroimaging, treatment, and outcome of children with self-limited infantile epilepsy were retrospectively analyzed. All infants were reevaluated with the Denver Developmental Screening Test in addition to neurologic examination. Of 44 patients, self-limited familial infantile epilepsy was diagnosed in 8 infants (18.2%) and self-limited nonfamilial infantile epilepsy in 28 (63.6%). Interictal EEGs and neurologic examinations were normal in all cases. Fine motor and gross motor skills, language, adaptive personal/social skills were near-normal in all patients with self-limited familial infantile epilepsy. Delay in language parameters was observed in 2 infants with self-limited nonfamilial infantile epilepsy. Language skills should be thoroughly evaluated with detailed neurocognitive screening tests in patients with self-limited infantile epilepsy.

Abnormal cerebrospinal fluid biochemistry in biotinidase deficiency causing diagnostic conundrum.

Biotinidase deficiency is a treatable cause of infantile epilepsy and the presentation can be nonspecific. The seizures are difficult to differentiate from other causes of epileptic encephalopathy, which generally have a poor prognosis. We report 2 infants who presented with seizures, and whose low cerebrospinal fluid glucose and high cerebrospinal lactate caused a diagnostic dilemma. Subsequent urine organic acids pointed to the correct diagnosis and avoided invasive investigation. The children had a good clinical outcome with resolution of their seizures on biotin treatment.

Mutation analysis of PRRT2 in two Chinese BFIS families and nomenclature of PRRT2 related paroxysmal diseases.

Benign familial infantile seizure (BFIS) and paroxysmal kinesigenic dyskinesia (PKD) are autosomal-dominant inherited self-limited neurological disorders. BFIS is characterized by clusters of epileptic seizures in infancy while, in some cases, infantile seizures and adolescent-onset paroxysmal kinesigenic choreoathetosis co-occurred, which is called infantile convulsions and choreoathetosis (ICCA) syndrome. We and other researchers have reported the proline-rich transmembrane protein 2 (PRRT2) as the causative gene of PKD. We and our collaborators also identified PRRT2 mutations in ICCA and other phenotypes. Here we collected two BFIS families of Chinese Han origin. The linkage analysis has mapped the BFIS-causing locus to 16p12.1-q12.2, where PRRT2 is located. We then performed mutation analysis of PRRT2 by direct sequencing and identified c.649-650insC mutation in all BFIS patients. We also noticed that paroxysmal diseases (such as BFIS, PKD and ICCA) with PRRT2 mutations, instead of other forms, share some characteristics like being responded well to anti-epiletic treatment, we thus suggest to name them as PRRT2-related paroxysmal diseases (PRPDs) in order to assist clinical diagnosis and treatment.

An SCN2A mutation in a family with infantile seizures from Madagascar reveals an increased subthreshold Na(+) current.

Missense mutations in SCN2A, encoding the brain sodium channel NaV 1.2, have been described in benign familial neonatal-infantile seizures (BFNIS), a self-limiting disorder, whereas several SCN2A de novo nonsense mutations have been found in patients with more severe phenotypes including epileptic encephalopathy. We report a family with BFNIS originating from Madagascar. Onset extended from 3 to 9 months of age. Interictal EEGs were normal. In two patients, ictal electroencephalography (EEG) studies showed partial seizure patterns with secondary generalization in one. Seizures remitted before 18 months of age, with or without medication. Intellectual development was normal. A novel missense mutation of SCN2A, c.4766A>G/p.Tyr1589Cys, was found in a highly conserved region of NaV 1.2 (D4/S2-S3). Functional studies using heterologous expression in tsA201 cells and whole-cell patch clamping revealed a depolarizing shift of steady-state inactivation, increased persistent Na(+) current, a slowing of fast inactivation and an acceleration of its recovery, thus a gain-of-function. Using an action potential waveform in a voltage-clamp experiment we indicated an increased inward Na(+) current at subthreshold voltages, which can explain a neuronal hyperexcitability. Our results suggest that this mutation induces neuronal hyperexcitability, resulting in infantile epilepsy with favorable outcome.

Síndrome de Sturge Weber: reporte de un caso y revisión de la literatura / Sturge-Weber syndrome: a case report and review of the literature

Introdución: El síndrome de Sturge-Weber (SSW) es una entidad neurocutánea congénita caracterizada por una malformación vascular facial (mancha en vino de Oporto) asociado a angiomatosis leptomeníngea. Su prevalencia es aproximadamente de uno por cada 50 000 nacidos vivos. Afecta por igual a ambos sexos. Las manifestaciones clínicas incluyen a las convulsiones, nevus vascular cutáneo unilateral en relación a la división oftálmica del nervio trigémino, glaucoma ipsilateral, hemiparesia contralateral, hemiatrofia, hemianopia y retraso psicomotor. La característica radiológica es la presencia de calcificaciones giriformes en los lóbulos occipital y parietal. Reporte de caso: Una paciente de 1 año 7 meses llegó a la emergencia presentando convulsiones generalizadas que cesaron con diazepan, y se inició tratamiento con ácido valproico. Mostraba una mancha congénita color vino de Oporto en la frente, además se evidenció un leve retraso psicomotor. La tomografia mostró una calcificación cortical en los lóbulos parietal y occipital izquierdos. En la resonancia magnética se evidenció un reforzamientoleptomeníngeo parietal izquierdo. Conclusiones: El SSW es una entidad rara y de curso progresivo, el diagnóstico no es difícil cuando las manifestaciones típicas están presentes. Una malformación cutánea facial y la presencia de retardo mental debería alertar a los médicos cuando se encuentran frente a niños con convulsiones focales o parciales complejas secundariamente generalizadas en el primer o segundo año de vida.

Introduction: Sturge- Weber syndrome (SWS) is a congenital neurocutaneous syndrome characterized by unilateral facial cutaneous vascular malformation (Port-wine stain) in association with ipsilateral leptomeningeal angiomatosis. Prevalence is approximately one per 50 000 live births. Males and females are equally affected. Clinical manifestations include seizures, unilateral cutaneous vascular nevus following the ophthalmic divisions of the trigeminal nerve, ipsilateral glaucoma, contralateral hemiparesis, hemiatrophy, hemianopia and psychomotor retardation. The radiographic hallmarks of SWS are gyriform calcifications usually involving the occipital and parietal lobes. Case report: A 1 year and 7 month-old girl carne to emergence department showing generalized seizures that resolved with diazepam and valproic acid was started. She had a facial Port-wine birthmark located on the forehead; a mild psychomotor retardation was evidenced. Head CT demonstrated a cortical calcification of the left parietal and occipital lobe. MRI showed a left parietal leptomeningeal enhancement. Conclusions: SWS is a rare and progressive entity, the diagnosis is not hard when typical manifestations are present. Mental retardation and facial cutaneous malfonnations should alert physician when they are in front of infants with focal or complex partial/secondarily generalized seizures in the first or second year of life.