Search

BackgroundThe 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.MethodsTrios-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.ResultsDLG3 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.SignificanceThis 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.

Abstract 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.

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. [ABSTRACT FROM AUTHOR]

PurposeTo identify novel genetic causes of febrile seizures (FS) and epilepsy with febrile seizures plus (EFS+).MethodsWe 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.ResultsWe 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.ConclusionThis 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.

ObjectiveThe LAMA5 gene encodes the laminin subunit α5, the most abundant laminin α subunit in the human brain. It forms heterotrimers with the subunit β1/β2 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.MethodsTrios-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.ResultsSix 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.ConclusionRecessive 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.

Purpose: To identify novel genetic causes of febrile seizures (FS) and epilepsy with febrile seizures plus (EFSC). Methods: We performed whole-exome sequencing in a cohort of 32 families, in which at least two individuals were affected by FS or EFSC. 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 EFSC. 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 EFSC. 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. [ABSTRACT FROM AUTHOR]

Abstract Purpose The aim of this was to discover disease‐causing gene mutations linked to genetic epilepsy with febrile seizures plus (GEFS+) in a family in the Southern Chinese Han population. Of a three‐generation pedigree of 18 members in this family, 4 were affected with GEFS+. Method Blood samples of 7 family members—3 affected and 4 unaffected individuals—were collected. Whole‐exome sequencing was performed to assess for genetic mutations in two of the affected individuals and two of the unaffected individuals. Results Fourteen potentially consequential mutations were found in the two affected individuals and were validated with the Sanger sequencing method. Blood DNA tested in polymerase chain reaction with KCNAB3 primers revealed that one novel missense mutation, c.773A>G (p.H258R) in the KCNAB3 gene, which encoded the potassium voltage‐gated channel subfamily A regulatory β subunit 3 (KCNAB3), was shared by all three affected and one unaffected family member. However, this mutation did not appear in 300 unrelated control subjects. According to the bioinformatics tools SIFT and PROVEAN, p.H258R was thought to affect protein function. Functional verification showed that the KCNAB3 mutation could accelerate the inactivation of potassium channels, thus inhibiting potassium current, increasing neuronal excitability, and promoting epileptic convulsion. Conclusions These results reveal that mutations in the KCNAB3 gene may be associated with GEFS+.

To explore the phenotype spectrum of DEPDC5 variants and the possible mechanisms underlying phenotypical variation, we performed targeted next-generation sequencing in 305 patients with focal epilepsies and 91 patients with generalized epilepsies. Protein modeling was performed to predict the effects of missense mutations. All previously reported epilepsy-related DEPDC5 variants were reviewed. The genotype–phenotype correlations with molecular sub-regional implications were analyzed. We identified a homozygous DEPDC5 mutation (p.Pro1031His) in a case with focal cortical dysplasia and eight heterozygous mutations in 11 families with mild focal epilepsies, including 13 patients in eight families with focal epilepsy with febrile seizures plus/febrile seizures (FEFS + /FS). The mutations included one termination codon mutation (p.Ser1601_Ter1604del_ext133), three truncating mutations (p.Val151Serfs∗27, p.Arg239∗, and p.Arg838∗), and four missense mutations (p.Tyr7Cys, p.Tyr836Cys, p.Pro1031His, and p.Gly1545Ser) that were predicted to affect hydrogen bonds and protein stability. Analysis on epilepsy-related DEPDC5 variants revealed that malformations of cortical development (MCDs) had a tendency of higher frequency of null mutations than those without MCD. MCD-associated heterozygous missense mutations were clustered in structural axis for binding arrangement (SABA) domain and close to the binding sites to NPRL2/NPRL3 complex, whereas those associated with FEFS + /FS were a distance away from the binding sites. Evidence from four aspects and one possible evidence from sub-regional implication suggested MCD and FEFS + /FS as phenotypes of DEPDC5 variants. This study suggested that the phenotypes of DEPDC5 variants vary from mild FEFS + /FS to severe MCD. Heterozygous DEPDC5 mutations are generally less pathogenic and commonly associated with mild phenotypes. Bi-allelic mutations and second hit of somatic mutations, together with the genotype–phenotype correlation and sub-regional implication of DEPDC5 variants, explain severe phenotypes.

Objective To summarize the clinical features of tuberous sclerosis complex (TSC), the distribution and description of TSC gene, and to probe into the correlation of genotype with phenotype. Methods According to the 1998 International Tuberous Sclerosis Complex Diagnostic Criteria, a total of 163 TSC patients with pathogenic mutation in TSC gene (3 cases were detected in our hospital, and the other 160 cases were collected from other institutions in China) were enrolled, and their gene detection results and clinical data were analyzed. Results Among 163 cases, TSC1 mutation (31 cases) accounted for 19.02% [32.26% (10/31) in exon 15, 16.13% (5/31) in exon 21, 12.90% (4/31) in exon 18], and TSC2 mutation (132 cases) accounted for 80.98% [9.85% (13/132) in exon 37, 7.58% (10/132) in exon 40, 6.82%(9/132) in exon 33]. The proportion of base replacement in TSC1 was 41.94% (13/31), and 52.27% (69/132) in TSC2. Male patients exhibited significantly more subependymal nodules or calcifications than thefemale patients (χ2 = 8.016, P = 0.005). Sporadic patients exhibited significantly more cortical tubers than familial patients (χ2 = 6.273, P = 0.012). Patients with TSC2 mutations had significantly higher frequencies of hypomelanotic macules than patients with TSC1 mutations (χ2 = 6.756, P = 0.009). Patients with missense mutations were more likely to have facial angiofibromas compared with patients with other mutations (χ2 = 4.438, P = 0.035). Conclusions Exon 15, 21 and 18 of TSC1 and exon 37, 40 and 33 of TSC2 accounted for higher percentage of mutations. Correlating genotypes with phenotypes should facilitate the individualized treatment and prognostic assessment of tuberous sclerosis complex. DOI: 10.3969/j.issn.1672-6731.2015.04.013

Etiological and clinical analyses of 220 children with cerebrovascular diseases were retrospectively analyzed. One hundred and forty-nine cases (67.73%) were male, and 71 cases (32.27%) were female. There were 186 cases (84.55%) of patients to be found with clear causes, most of which were arteriovenous malformation (80/220, 36.36%), traumatic brain injury (38/220, 17.27%), intracranial infection (15/220, 6.82% ), intracranial aneurysm (13/220, 5.91% ), delayed vitamin K deficiency (12/220, 5.45% ), congenital heart disease (9/220, 4.09%) and cavernous malformation (7/220, 3.18%). The etiological and clinical features of children cerebrovascular diseases are distinct, and timely diagnosis and treatment will help to improve patients' prognosis. doi: 10.3969/j.issn.1672-6731.2014.03.017

Objective To explore the relevance between the level changes of serum neuron⁃specific enolase (NSE) and neuronal damage in various seizure types of children with epilepsy. Methods According to the classification criteria of seizure types formulated by International League Against Epilepsy (ILAE) in 1981, 190 children with epilepsy were enrolled including tonic⁃clonic seizure group (41 cases), tonic seizure group (34 cases), clonic seizure group (22 cases), myoclonic seizure group (12 cases), atonic seizure group (17 cases), absence seizure group (22 cases), simple partial seizure group (21 cases) and complex partial seizure group (21 cases), and 64 healthy children were enrolled as control group. The long⁃ range vedio⁃electroencephalogram (VEEG) was operated and the blood samples were collected from these cases within 72 h after their seizures. Results The serum NSE levels of epileptic children were significantly higher than control group (P = 0.000). Among these seizure groups, serum NSE in myoclonic seizure group [(32.42 ± 6.62) ng/ml] was significantly higher than the other types, except for tonic⁃clonic seizure group (P = 0.062). There was no significant difference among the other types (P > 0.05, for all). According to rank correlation analysis, there was positive corrlation between serum NSE levels and VEEG abnormal intensity (rs = 0.613, P = 0.000). Conclusion The serum NSE were markedly increased in children with epilepsy after seizures, suggesting that a certain degree of neuronal damage may result from seizures; the higher NSE levels were, the more serious neuronal damage caused by epileptiform discharges was. The serum NSE levels in myoclonic seizure group and tonic⁃clonic seizure group were significantly higher than other seizure types, indicating the two kinds of seizures may result in greater neuronal damage. DOI：10.3969/j.issn.1672⁃6731.2012.05.013