ZFHX3 variants cause childhood partial epilepsy and infantile spasms with favourable outcomes.

BACKGROUND: The ZFHX3 gene plays vital roles in embryonic development, cell proliferation, neuronal differentiation and neuronal death. This study aims to explore the relationship between ZFHX3 variants and epilepsy. METHODS: Whole-exome sequencing was performed in a cohort of 378 patients with partial (focal) epilepsy. A Drosophila Zfh2 knockdown model was used to validate the association between ZFHX3 and epilepsy. RESULTS: Compound heterozygous ZFHX3 variants were identified in eight unrelated cases. The burden of ZFHX3 variants was significantly higher in the case cohort, shown by multiple/specific statistical analyses. In Zfh2 knockdown flies, the incidence and duration of seizure-like behaviour were significantly greater than those in the controls. The Zfh2 knockdown flies exhibited more firing in excitatory neurons. All patients presented partial seizures. The five patients with variants in the C-terminus/N-terminus presented mild partial epilepsy. The other three patients included one who experienced frequent non-convulsive status epilepticus and two who had early spasms. These three patients had also neurodevelopmental abnormalities and were diagnosed as developmental epileptic encephalopathy (DEE), but achieved seizure-free after antiepileptic-drug treatment without adrenocorticotropic-hormone/steroids. The analyses of temporal expression (genetic dependent stages) indicated that ZFHX3 orthologous were highly expressed in the embryonic stage and decreased dramatically after birth. CONCLUSION: ZFHX3 is a novel causative gene of childhood partial epilepsy and DEE. The patients of infantile spasms achieved seizure-free after treatment without adrenocorticotropic-hormone/steroids implies a significance of genetic diagnosis in precise treatment. The genetic dependent stage provided an insight into the underlying mechanism of the evolutional course of illness.

Both epilepsy and anti-seizure medications affect bone metabolism in children with self-limited epilepsy with centrotemporal spikes.

OBJECTIVE: Bone metabolism can be influenced by a range of factors. We selected children with self-limited epilepsy with centrotemporal spikes (SeLECTS) and lifestyles similar to those of healthy children to control for the confounding factors that may influence bone metabolism. We aimed to identify the specific effects of epilepsy and/or anti-seizure medications (ASMs) on bone metabolism. METHODS: Patients with SeLECTS were divided into an untreated group and a monotherapy group, and the third group was a healthy control group. We determined the levels of various biochemical markers of bone metabolism, including procollagen type I nitrogenous propeptide (PINP), alkaline phosphatase (ALP), osteocalcin (OC), collagen type I cross-linked C-telopeptide (CTX), calcium, magnesium, phosphorus, parathyroid hormone (PTH), and vitamin D3 (VD3 ). RESULTS: A total of 1487 patients (from 19 centers) were diagnosed with SeLECTS; 1032 were analyzed, including 117 patients who did not receive any ASMs (untreated group), 643 patients who received only one ASM (monotherapy group), and 272 children in the healthy control group. Except for VD3 , other bone metabolism of the three groups were different (p < .001). Bone metabolism was significantly lower in the untreated group than the healthy control group (p < .05). There were significant differences between the monotherapy and healthy control group in the level of many markers. However, when comparing the monotherapy and untreated groups, the results were different; oxcarbazepine, levetiracetam, and topiramate had no significant effect on bone metabolism. Phosphorus and magnesium were significantly lower in the valproic acid group than the untreated group (adjusted p < .05, Cliff's delta .282-.768). CTX was significantly higher in the lamotrigine group than in the untreated group (adjusted p = .012, Cliff's delta = .316). SIGNIFICANCE: Epilepsy can affect many aspects of bone metabolism. After controlling epilepsy and other confounders that affect bone metabolism, we found that the effects of ASMs on bone metabolism differed. Oxcarbazepine, levetiracetam, and topiramate did not affect bone metabolism, and lamotrigine corrected some of the abnormal markers of bone metabolism in patients with epilepsy.

Efficacy and safety of switching from brand-name to domestic generic levetiracetam in children with epilepsy. / å·¦ä¹™æ‹‰è¥¿å¦çš„å›½äº§ä»¿åˆ¶è¯æ›¿æ¢æ²»ç–—å„¿ç«¥ç™«ç—«çš„ç–—æ•ˆåŠå®‰å ¨æ€§ç ”ç©¶.

OBJECTIVES: To study the efficacy and safety of domestic generic levetiracetam in replacement of brand-name levetiracetam in the treatment of children with epilepsy. METHODS: A retrospective analysis was performed on the medical data of 154 children with epilepsy who received domestic generic levetiracetam in the inpatient or outpatient service of Guangdong Provincial People's Hospital from May 2019 to December 2020. Domestic generic levetiracetam and brand-name levetiracetam were compared in terms of efficacy and safety. RESULTS: For these 154 children, the epilepsy control rate was 77.3% (119/154) at baseline. At 6 months after switching to domestic generic levetiracetam, the epilepsy control rate reached 83.8% (129/154), which showed a significant increase (P<0.05). There was no significant change in the frequency of seizures from baseline to 6 months after switching (P>0.05). The incidence of refractory epilepsy in children with no response after switching treatment was significantly higher than that in children with response (P<0.05). Before switching, only 1 child (0.6%) experienced somnolence, while after switching, 3 children (1.9%) experienced mild adverse drug reactions, including dizziness, somnolence, irritability, and bad temper. CONCLUSIONS: Switching from brand-name to generic levetiracetam is safe and effective and holds promise for clinical application, but more prospective randomized controlled trials are required in future.

[Effect of Ilepcimide Combined Western Drugs on Serum Level of Neuron Specific Enolase in Treating Epilepsy Children Patients].

Objective To observe changes of serum neuron specific enolase (NSE) level in children patients with epilepsy by additional use of ilepcimide (piperine derivative). Methods Totally 107 epilepsy children patients were assigned to the test group (77 cases) and the control group (30 cases) ac- cording to random digit table. Children patients in the control group received anti-epileptic Western drugs only. Those in the test group additionally took ilepcimide, 5 mg/kg per day as initial dose, taken in two times. The dose was gradually added to those without control of epilepsy attack. Added dose within a week should not exceed 10 mg/kg per day. The therapeutic course for all was one year. Electoencephalo- gram (EEG) was performed before treatment, half a year after treatment, and one year after treatment, respectively. Serum NSE level was detected using electrochemiluminescence. Efficacy was assessed after 1-year treatment. Results The total effective rate was 65. 0% (50177) in the test group, with statistical difference as compared with that in the control group [30. 0% (9/30), P <0. 01 ]. Compared with before treatment, serum NES-level obviously decreased in the test group after 0. 5-year treatment and 1- year treatment respectively (P <0. 05, P <0. 01). Besides, serum NES level was lower after 1-year treatment than after 0. 5-year treatment (P <0. 05, P <0. 01). There was no statistical difference in serum NES level between the test group and the control group at each time point (P >0. 05). Results of EEG were obviously superior in the test group (3 with normal range EEG, 5 critically abnormal EEG, 69 abnormal EEG) to the control group (2 with normal range EEG and 75 abnormal EEG) after 1-year treatment, with statistical difference (Z= -2. 33, P <0. 05). There was no statistical difference in EEG results of the control group between before treatment (all abnormal EEG) and after 1-year treatment (3 critically abnormal EEG and 27 abnormal EEG) (Z = -1. 732, P > 0. 05). Conclusion Adding ilepcimide (piperine derivative) for epilepsy children patients could lower serum NSE level and the frequency of seizures, and improve results of EEG.

[Clinical analysis of 15 pediatric patients with tuberous sclerosis complex complicated by cardiac rhabdomyomas].

OBJECTIVE: To investigate the clinical features in children with tuberous sclerosis complex (TSC)-associated cardiac rhabdomyomas (CRM). METHODS: The clinical data of 15 children with TSC complicated by CRM were collected. The clinical features of the patients were analyzed, and TSC gene mutations were detected. RESULTS: Eleven cases (73%) developed multiple CRM. The majority of the tumors were located in the left and right ventricles. Most tumors presented as a round-like hyperechogenic mass with a clear margin on echocardiography. Arrhythmias occurred in 3 patients and 2 patients experienced heart failure. Gene mutation tests were performed in 2 patients, and pathogenic mutations were detected in both patients, which were TSC1 mutation and TSC2 mutation, respectively. Three patients were followed up for 6 to 38 months, and their CRM shrank or regressed spontaneously. CONCLUSIONS: TSC-associated CRM is generally multiple. Heart failure and arrhythmias may occur in some patients. Echocardiography is important for diagnosis of CRM. TSC-associated CRM has an inclination to spontaneous regression. TSC can be diagnosed at a molecular genetic level by TSC gene mutation detection.

CABP4 mutation in mice shows alteration in protein expression level and neuron discharge frequency.

Background: The calcium-binding protein 4 (CABP4) gene is a newly identified epilepsy-related gene that might be associated with a rare type of genetic focal epilepsy; that is, autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE). In vitro, mutant CABP4 causes an increased inward flow voltage of calcium ions and a significant increase in the electrical signal discharge in hippocampus neurons; however, the role of CABP4 in epilepsy has not yet been specifically described, and there is not yet a CABP4 mutant animal model recapitulating the epilepsy phenotype. Methods: We introduced a human CABP4 missense mutation into the C57BL/6J mouse genome and generated a knock-in strain carrying a glycine-to-aspartic acid mutation in the gene. Quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot were performed to evaluate the CABP4 expression level. Slice patch-clamp recording was carried out on pyramidal cells of prefrontal cortex layers II and III. Results: The CABP4G155D/+ mutant mice were viable and born at an expected Mendelian ratio. Surprisingly, the heterozygous (HE) mice did not display either an abnormal appearance or an overt seizure phenotype, and there was no statistically significant difference between the HE and wild-type (WT) mice in terms of overall messenger RNA (mRNA) and protein expression. However, the HE mutant mice showed an imbalance in the amount of protein expressed in the brain regions. Additionally, the patch-clamp recordings from the HE mouse layer II/III cortical pyramidal cells revealed an increase in the frequency of micro-excitatory post-synaptic currents (mEPSCs) but no change in the amplitude was observed. Conclusions: The findings of this study suggest that the CABP4 p.G155D mutation might be one of the mechanisms underlying seizure onset.

MED12 variants associated with X-linked recessive partial epilepsy without intellectual disability.

OBJECTIVES: The MED12 gene encodes mediator complex subunit 12, which is a component of the mediator complex involved in the transcriptional regulation of nearly all RNA polymerase II-dependent genes. MED12 variants have previously been associated with developmental disorders with or without nonspecific intellectual disability. This study aims to explore the association between MED12 variants and epilepsy. MATERIALS AND METHODS: Trios-based whole-exome sequencing was performed in a cohort of 349 unrelated cases with partial (focal) epilepsy without acquired causes. The genotype-phenotype correlations of MED12 variants were analyzed. RESULTS: Five hemizygous missense MED12 variants, including c.958A>G/p.Ile320Val, c.1757G>A/p.Ser586Asn, c.2138C>T/p.Pro713Leu, c.3379T>C/p.Ser1127Pro, and c.4219A>C/p.Met1407Leu were identified in five unrelated males with partial epilepsy. All patients showed infrequent focal seizures and achieved seizure free without developmental abnormalities or intellectual disability. All the hemizygous variants were inherited from asymptomatic mothers (consistent with the X-linked recessive inheritance pattern) and were absent in the general population. The two variants with damaging hydrogen bonds were associated with early-onset seizures. Further genotype-phenotype analysis revealed that congenital anomaly disorder (Hardikar syndrome) was associated with (de novo) destructive variants in an X-linked dominant inheritance pattern, whereas epilepsy was associated with missense variants in an X-linked recessive inheritance pattern. Phenotypic features of intellectual disability appeared as the intermediate phenotype in terms of both genotype and inheritance. Epilepsy-related variants were located at the MED12-LCEWAV domain and the regions between MED12-LCEWAV and MED12-POL. CONCLUSION: MED12 is a potentially causative gene for X-linked recessive partial epilepsy without developmental or intellectual abnormalities. The genotype-phenotype correlation of MED12 variants explains the phenotypic variations and can help the genetic diagnosis.

DYNC1H1 variants associated with infant-onset epilepsy without neurodevelopmental disorders.

OBJECTIVES: The DYNC1H1 variants are associated with abnormal brain morphology and neuromuscular disorders that are accompanied by epilepsy. This study aimed to explore the relationship between DYNC1H1 variants and epilepsy. MATERIALS AND METHODS: Trios-based whole-exome sequencing was performed on patients with epilepsy. Previously reported epilepsy-related DYNC1H1 variants were systematically reviewed to analyse genotype-phenotype correlation. RESULTS: The DYNC1H1 variants were identified in four unrelated cases of infant-onset epilepsy, including two de novo and two biallelic variants. Two patients harbouring de novo missense variants located in the stem and stalk domains presented with refractory epilepsies, whereas two patients harbouring biallelic variants located in the regions between functional domains had mild epilepsy with infrequent focal seizures and favourable outcomes. One patient presented with pachygyria and neurodevelopmental abnormalities, and the other three patients presented with normal development. These variants have no or low frequencies in the Genome Aggregation Database. All the missense variants were predicted to be damaging using silico tools. Previously reported epilepsy-related variants were monoallelic variants, mainly de novo missense variants, and all the patients presented with severe epileptic phenotypes or developmental delay and malformations of cortical development. Epilepsy-related variants were clustered in the dimerization and stalk domains, and generalized epilepsy-associated variants were distributed in the stem domain. CONCLUSION: This study suggested that DYNC1H1 variants are potentially associated with infant-onset epilepsy without neurodevelopmental disorders, expanding the phenotypic spectrum of DYNC1H1. The genotype-phenotype correlation helps to understand the underlying mechanisms of phenotypic variation.

Corrigendum: ATP6V0C is associated with febrile seizures and epilepsy with febrile seizures plus.

[This corrects the article DOI: 10.3389/fnmol.2022.889534.].

Reprint of: Recessive APC2 missense variants associated with epilepsies without neurodevelopmental disorders.

OBJECTIVES: The APC2 gene, encoding adenomatous polyposis coli protein-2, is involved in cytoskeletal regulation in neurons responding to endogenous extracellular signals and plays an important role in brain development. Previously, the APC2 variants have been reported to be associated with cortical dysplasia and intellectual disability. This study aims to explore the association between APC2 variants and epilepsy. METHODS: Whole-exome sequencing (WES) was performed in cases (trios) with epilepsies of unknown causes. The damaging effects of variants were predicted by protein modeling and in silico tools. Previously reported APC2 variants were reviewed to analyze the genotype-phenotype correlations. RESULTS: Four pairs of compound heterozygous missense variants were identified in four unrelated patients with epilepsy without brain malformation/intellectual disability. All variants presented no or low allele frequencies in the controls. The missense variants were predicted to be damaging by silico tools, and affect hydrogen bonding with surrounding amino acids or decreased protein stability. Patients with variants that resulted in significant changes in protein stability exhibited more severe and intractable epilepsy, whereas patients with variants that had minor effect on protein stability exhibited relatively mild phenotypes. The previously reported APC2 variants in patients with complex cortical dysplasia with other brain malformations-10 (CDCBM10; MIM: 618677) were all truncating variants; in contrast, the variants identified in epilepsy in this study were all missense variants, suggesting a potential genotype-phenotype correlation. SIGNIFICANCE: This study suggests that APC2 is potentially associated with epilepsy without brain malformation/intellectual disability. The genotype-phenotype correlation helps to understand the underlying mechanisms of phenotypic heterogeneity.

CCDC22 variants caused X-linked focal epilepsy and focal cortical dysplasia.

BACKGROUND: The CCDC22 gene plays vital roles in regulating the NF-κB pathway, an essential pathway for neuroinflammation, neurodevelopment, and epileptogenesis. Previously, variants in CCDC22 were reported to be associated with intellectual disability. This study aimed to explore the association between CCDC22 and epilepsy. METHODS: Trios-based whole-exome sequencing (WES) was performed in a cohort of patients with epilepsy of unknown cause recruited from the China Epilepsy Gene 1.0 Project. Damaging effects of variants were analysed using protein modelling. RESULTS: Hemizygous missense CCDC22 variants were identified in three unrelated cases. These variants had no hemizygous frequencies in controls. All missense variants identified in this study were predicted to be "damaging" by multiple in silico tools and to alter the hydrogen bonds with surrounding residues and/or protein stability. The three patients presented with focal epilepsy of varying severity, including one with refractory seizures and focal cortical dysplasia (FCD) and two with seizures responding to antiseizure medicine. Notably, the variant associated with the severe phenotype was located in the coiled-coil domain and predicted to alter hydrogen bonding and protein stability, whereas the two variants associated with mild epilepsy were located outside functional domains and had moderate molecular alterations. Analysis of spatiotemporal expression indicated that CCDC22 was expressed in brain subregions with three peaks in the fetal stage, infancy, and early adulthood, especially in the fetal stage, explaining the occurrence of developmental abnormities. SIGNIFICANCE: CCDC22 variants are potentially associated with X-linked focal epilepsy and FCD. The molecular subregional effects supported the occurrence of FCD.

[Clinical features and mutation analysis of CHRNA4 gene for families and sporadic cases affected with autosomal dominant nocturnal frontal lobe epilepsy].

OBJECTIVE: To investigate mutations of CHRNA4 gene in Chinese patients with autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE). METHODS: Two hundred and fifty-seven patients (including 215 sporadic and 42 familial cases) were analyzed. Mutational screening was performed by sequencing all of the 6 exons of the CHRNA4 gene including the donor and acceptor splice sites. RESULTS: The results have excluded the involvement of any known mutations of the CHRNA4 gene. A novel synonymous mutation c.570C>T(D190D) and 6 single nucleotide polymorphisms (SNPs) of the CHRNA4 gene were detected in 6 sporadic cases, including c.639T/C, c.678T/C, c.1209G/T, c.1227T/C, c.1659G/A, and c.1629C/T. The SNP D190D was hererozygous and absent in 200 healthy controls. CONCLUSION: This results suggested that mutations of the CHRNA4 gene may be rare in southern Chinese population with ADNFLE. The synonymous mutation D190D has not been reported previously. Its impact on the pathogenesis of ADNFLE warrant further study.

Recessive APC2 missense variants associated with epilepsies without neurodevelopmental disorders.

OBJECTIVES: The APC2 gene, encoding adenomatous polyposis coli protein-2, is involved in cytoskeletal regulation in neurons responding to endogenous extracellular signals and plays an important role in brain development. Previously, the APC2 variants have been reported to be associated with cortical dysplasia and intellectual disability. This study aims to explore the association between APC2 variants and epilepsy. METHODS: Whole-exome sequencing (WES) was performed in cases (trios) with epilepsies of unknown causes. The damaging effects of variants were predicted by protein modeling and in silico tools. Previously reported APC2 variants were reviewed to analyze the genotype-phenotype correlations. RESULTS: Four pairs of compound heterozygous missense variants were identified in four unrelated patients with epilepsy without brain malformation/intellectual disability. All variants presented no or low allele frequencies in the controls. The missense variants were predicted to be damaging by silico tools, and affect hydrogen bonding with surrounding amino acids or decreased protein stability. Patients with variants that resulted in significant changes in protein stability exhibited more severe and intractable epilepsy, whereas patients with variants that had minor effect on protein stability exhibited relatively mild phenotypes. The previously reported APC2 variants in patients with complex cortical dysplasia with other brain malformations-10 (CDCBM10; MIM: 618677) were all truncating variants; in contrast, the variants identified in epilepsy in this study were all missense variants, suggesting a potential genotype-phenotype correlation. SIGNIFICANCE: This study suggests that APC2 is potentially associated with epilepsy without brain malformation/intellectual disability. The genotype-phenotype correlation helps to understand the underlying mechanisms of phenotypic heterogeneity.

DLG3 variants caused X-linked epilepsy with/without neurodevelopmental disorders and the genotype-phenotype correlation.

Background: The DLG3 gene encodes disks large membrane-associated guanylate kinase scaffold protein 3, which plays essential roles in the clustering of N-methyl-D-aspartate receptors (NMDARs) at excitatory synapses. Previously, DLG3 has been identified as the causative gene of X-linked intellectual developmental disorder-90 (XLID-90; OMIM# 300850). This study aims to explore the phenotypic spectrum of DLG3 and the genotype-phenotype correlation. Methods: Trios-based whole-exome sequencing was performed in patients with epilepsy of unknown causes. To analyze the genotype-phenotype correlations, previously reported DLG3 variants were systematically reviewed. Results: DLG3 variants were identified in seven unrelated cases with epilepsy. These variants had no hemizygous frequencies in controls. All variants were predicted to be damaging by silico tools and alter the hydrogen bonds with surrounding residues and/or protein stability. Four cases mainly presented with generalized seizures, including generalized tonic-clonic and myoclonic seizures, and the other three cases exhibited secondary generalized tonic-clonic seizures and focal seizures. Multifocal discharges were recorded in all cases during electroencephalography monitoring, including the four cases with generalized discharges initially but multifocal discharges after drug treating. Protein-protein interaction network analysis revealed that DLG3 interacts with 52 genes with high confidence, in which the majority of disease-causing genes were associated with a wide spectrum of neurodevelopmental disorder (NDD) and epilepsy. Three patients with variants locating outside functional domains all achieved seizure-free, while the four patients with variants locating in functional domains presented poor control of seizures. Analysis of previously reported cases revealed that patients with non-null variants presented higher percentages of epilepsy than those with null variants, suggesting a genotype-phenotype correlation. Significance: This study suggested that DLG3 variants were associated with epilepsy with/without NDD, expanding the phenotypic spectrum of DLG3. The observed genotype-phenotype correlation potentially contributes to the understanding of the underlying mechanisms driving phenotypic variation.

HCFC1 variants in the proteolysis domain are associated with X-linked idiopathic partial epilepsy: Exploring the underlying mechanism.

BACKGROUND: HCFC1 encodes transcriptional co-regulator HCF-1, which undergoes an unusual proteolytic maturation at a centrally located proteolysis domain. HCFC1 variants were associated with X-linked cobalamin metabolism disorders and mental retardation-3. This study aimed to explore the role of HCFC1 variants in common epilepsy and the mechanism underlying phenotype heterogeneity. METHODS: Whole-exome sequencing was performed in a cohort of 313 patients with idiopathic partial (focal) epilepsy. Functional studies determined the effects of the variants on the proteolytic maturation of HCF-1, cell proliferation and MMACHC expression. The role of HCFC1 variants in partial epilepsy was validated in another cohort from multiple centers. RESULTS: We identified seven hemizygous HCFC1 variants in 11 cases and confirmed the finding in the validation cohort with additional 13 cases and six more hemizygous variants. All patients showed partial epilepsies with favorable outcome. None of them had cobalamin disorders. Functional studies demonstrated that the variants in the proteolysis domain impaired the maturation by disrupting the cleavage process with loss of inhibition of cell growth but did not affect MMACHC expression that was associated with cobalamin disorder. The degree of functional impairment was correlated with the severity of phenotype. Further analysis demonstrated that variants within the proteolysis domain were associated with common and mild partial epilepsy, whereas those in the kelch domain were associated with cobalamin disorder featured by severe and even fatal epileptic encephalopathy, and those in the basic and acidic domains were associated with mainly intellectual disability. CONCLUSION: HCFC1 is potentially a candidate gene for common partial epilepsy with distinct underlying mechanism of proteolysis dysfunction. The HCF-1 domains played distinct functional roles and were associated with different clinical phenotypes, suggesting a sub-molecular effect. The distinct difference between cobalamin disorders and idiopathic partial epilepsy in phenotype and pathogenic mechanism, implied a clinical significance in early diagnosis and management.

Functional characterization of a KCNAB3 genetic epilepsy with febrile seizures plus adult mouse model.

Background: Genetic epilepsy with febrile seizures plus (GEFS+) is a type of epileptic syndrome closely related to heredity factors, which can be caused by gene mutations. However, it still remains unclear how these mutations result in seizures. Previously, we identified a new heterozygous missense mutation of the KCNAB3 gene, H258R, in the GEFS+ family; the electric currents of the human embryonic kidney 293 (HEK293) cells co-expressing Kvß3 (H258R) and Kv1.1 showed obvious inactivation. This study sought to examine the effects of this mutation on the potassium channels in the mammalian brain. Methods: Mutant mice were generated by introducing the human H258R missense mutation within exon 10 at an equivalent position in the mouse KCNAB3 gene via CRISPR/Cas9 and homologous recombination. A patch clamp was used to detect the potassium currents in the pyramidal cells of the hippocampal CA1 region of the mutant mice. The total potassium currents of the pyramidal cells in the hippocampal CA1 region of KCNAB3 [wild-type (WT)] and KCNAB3 (H258R) adult mice were recorded with increased voltage. Results: We found a decreased total potassium current in the H258R group but no significant differences at a maximum voltage (+80 mV; P>0.05). Conclusions: These results suggest that the KCNAB3 mutation reduced hippocampal potassium currents in this mouse model.

BCOR variants are associated with X-linked recessive partial epilepsy.

OBJECTIVE: BCOR gene, encoding a corepressor of BCL6, plays an important role in fetal development. BCOR mutations were previously associated with oculofaciocardiodental syndrome (OFCD or MCOPS2, OMIM# 300166). The BCOR protein is ubiquitously expressed in multiple areas, including the brain. However, the role of BCOR in neurological disorder remains elusive. METHODS: Trios-based whole-exome sequencing was performed in a cohort of 323 cases with partial epilepsy without acquired causes. RESULTS: Seven hemizygous missense BCOR variants, including c 0.103 G>C/p.Asp35His, c.1079 A>G/p.His360Arg, c 0.1097 C>T/p.Thr366Ile, c 0.3301 C>T/p.Pro1101Ser, c 0.3391 C>T/p.Arg1131Trp, c 0.4199 G>A/p.Arg1400Gln, and c 0.5254 G>A/p.Asp1752Asn, were identified in seven cases with partial epilepsy. Two patients presented partial seizures with generalized seizures and/or generalized discharges. One case showed cortical dysplasia in the right temporal-occipital area on MRI. Two cases presented mild developmental delay. However, all patients achieved seizure-free. The frequency of BCOR variants in the present cohort was significantly higher than that in the controls of healthy Chinese volunteers and all populations of Genome Aggregation Database (gnomAD). Computational modeling, including hydrogen bond and prediction of protein stability, implied that the variants lead to structural impairment. Previously, OFCD associated BCOR mutations were mostly destructive mutations in an X-linked dominant (XLD) pattern; in contrast, the BCOR variants identified in this study were all missense variants, which were associated with partial epilepsy in an X-linked recessive (XLR) pattern. The proportion of missense mutations in epilepsy was significantly higher than that in OFCD. CONCLUSIONS: BCOR was potentially a candidate pathogenic gene of partial epilepsy with or without developmental delay. The genotype-phenotype correlation helps understanding the mechanism underlying phenotypic variation.

ATP6V0C Is Associated With Febrile Seizures and Epilepsy With Febrile Seizures Plus.

Purpose: To identify novel genetic causes of febrile seizures (FS) and epilepsy with febrile seizures plus (EFS+). Methods: We performed whole-exome sequencing in a cohort of 32 families, in which at least two individuals were affected by FS or EFS+. The probands, their parents, and available family members were recruited to ascertain whether the genetic variants were co-segregation. Genes with repetitively identified variants with segregations were selected for further studies to define the gene-disease association. Results: We identified two heterozygous ATP6V0C mutations (c.64G > A/p.Ala22Thr and c.361_373del/p.Thr121Profs*7) in two unrelated families with six individuals affected by FS or EFS+. The missense mutation was located in the proteolipid c-ring that cooperated with a-subunit forming the hemichannel for proton transferring. It also affected the hydrogen bonds with surround residues and the protein stability, implying a damaging effect. The frameshift mutation resulted in a loss of function by yielding a premature termination of 28 residues at the C-terminus of the protein. The frequencies of ATP6V0C mutations identified in this cohort were significantly higher than that in the control populations. All the six affected individuals suffered from their first FS at the age of 7-8 months. The two probands later manifested afebrile seizures including myoclonic seizures that responded well to lamotrigine. They all displayed favorable outcomes without intellectual or developmental abnormalities, although afebrile seizures or frequent seizures occurred. Conclusion: This study suggests that ATP6V0C is potentially a candidate pathogenic gene of FS and EFS+. Screening for ATP6V0C mutations would help differentiating patients with Dravet syndrome caused by SCN1A mutations, which presented similar clinical manifestation but different responses to antiepileptic treatment.

Recessive LAMA5 Variants Associated With Partial Epilepsy and Spasms in Infancy.

Objective: The LAMA5 gene encodes the laminin subunit α5, the most abundant laminin α subunit in the human brain. It forms heterotrimers with the subunit ß1/ß2 and γ1/γ3 and regulates neurodevelopmental processes. Genes encoding subunits of the laminin heterotrimers containing subunit α5 have been reported to be associated with human diseases. Among LAMAs encoding the laminin α subunit, LAMA1-4 have also been reported to be associated with human disease. In this study, we investigated the association between LAMA5 and epilepsy. Methods: Trios-based whole-exome sequencing was performed in a cohort of 118 infants suffering from focal seizures with or without spasms. Protein modeling was used to assess the damaging effects of variations. The LAMAs expression was analyzed with data from the GTEX and VarCards databases. Results: Six pairs of compound heterozygous missense variants in LAMA5 were identified in six unrelated patients. All affected individuals suffered from focal seizures with mild developmental delay, and three patients presented also spasms. These variants had no or low allele frequencies in controls and presented statistically higher frequency in the case cohort than in controls. The recessive burden analysis showed that recessive LAMA5 variants identified in this cohort were significantly more than the expected number in the East Asian population. Protein modeling showed that at least one variant in each pair of biallelic variants affected hydrogen bonds with surrounding amino acids. Among the biallelic variants in cases with only focal seizures, two variants of each pair were located in different structural domains or domains/links, whereas in the cases with spasms, the biallelic variants were constituted by two variants in the identical functional domains or both with hydrogen bond changes. Conclusion: Recessive LAMA5 variants were potentially associated with infant epilepsy. The establishment of the association between LAMA5 and epilepsy will facilitate the genetic diagnosis and management in patients with infant epilepsy.

[Mutational analysis of CHRNB2 and CHRNA2 genes in southern Chinese population with autosomal dominant nocturnal frontal lobe epilepsy].

OBJECTIVE: To investigate the gene mutations of CHRNB2 and CHRNA2 in Chinese population with autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE). METHODS: One hundred and six Han nationality patients (74 sporadic and 32 familial) were recruited and studied. Mutational screening was performed by sequencing all the 6 coding exons of the CHRNB2 gene and exons 6 and 7 of the CHRNA2 gene including the donor and acceptor splice sites. RESULTS: The results excluded the involvement of all known published mutations of the CHRNB2 and CHRNA2 genes. However, a novel synonymous mutation c.483C>T (H161H) and a single nucleotide polymorphism (c.1407C>G) of CHRNB2 gene were detected in two ADNFLE sporadic patients respectively. The nucleotide variation H161H was heterozygous and absent in 200 healthy control samples. The mutation was also found in the proband's unaffected mother. CONCLUSION: Our study suggests that the mutations of CHRNB2 and CHRNA2 genes may be rare in Chinese ADNFLE population. The novel synonymous mutation of H161H has not been reported previously and its impact on the pathogenesis of ADNFLE needs to be further studied.