Yuehua Zhang

Association between genetic variation of CACNA1H and childhood absence epilepsy

Direct sequencing of exons 3 to 35 and the exon–intron boundaries of the CACNA1H gene was conducted in 118 childhood absence epilepsy patients of Han ethnicity recruited from North China. Sixty‐eight variations have been detected in the CACNA1H gene, and, among the variations identified, 12 were missense mutations and only found in 14 of the 118 patients in a heterozygous state, but not in any of 230 unrelated controls. The identified missense mutations occurred in the highly conserved residues of the T‐type calcium channel gene. Our results suggest that CACNA1H might be an important susceptibility gene involved in the pathogenesis of childhood absence epilepsy. Ann Neurol 2003

ILAE classification of the epilepsies: Position paper of the ILAE Commission for Classification and Terminology

The International League Against Epilepsy (ILAE) Classification of the Epilepsies has been updated to reflect our gain in understanding of the epilepsies and their underlying mechanisms following the major scientific advances that have taken place since the last ratified classification in 1989. As a critical tool for the practicing clinician, epilepsy classification must be relevant and dynamic to changes in thinking, yet robust and translatable to all areas of the globe. Its primary purpose is for diagnosis of patients, but it is also critical for epilepsy research, development of antiepileptic therapies, and communication around the world. The new classification originates from a draft document submitted for public comments in 2013, which was revised to incorporate extensive feedback from the international epilepsy community over several rounds of consultation. It presents three levels, starting with seizure type, where it assumes that the patient is having epileptic seizures as defined by the new 2017 ILAE Seizure Classification. After diagnosis of the seizure type, the next step is diagnosis of epilepsy type, including focal epilepsy, generalized epilepsy, combined generalized, and focal epilepsy, and also an unknown epilepsy group. The third level is that of epilepsy syndrome, where a specific syndromic diagnosis can be made. The new classification incorporates etiology along each stage, emphasizing the need to consider etiology at each step of diagnosis, as it often carries significant treatment implications. Etiology is broken into six subgroups, selected because of their potential therapeutic consequences. New terminology is introduced such as developmental and epileptic encephalopathy. The term benign is replaced by the terms self‐limited and pharmacoresponsive, to be used where appropriate. It is hoped that this new framework will assist in improving epilepsy care and research in the 21st century.

Dravet syndrome or genetic (generalized) epilepsy with febrile seizures plus

Dravet syndrome and genetic epilepsy with febrile seizures plus (GEFS+) can both arise due to mutations of SCN1A, the gene encoding the alpha 1 pore-forming subunit of the sodium channel. GEFS+ refers to a familial epilepsy syndrome where at least two family members have phenotypes that fit within the GEFS+ spectrum. The GEFS+ spectrum comprises a range of mild to severe phenotypes varying from classical febrile seizures to Dravet syndrome. Dravet syndrome is a severe infantile onset epilepsy syndrome with multiple seizure types, developmental slowing and poor outcome. More than 70% of patients with Dravet syndrome have mutations of SCN1A; these include both truncation and missense mutations. In contrast, only 10% of GEFS+ families have SCN1A mutations and these comprise missense mutations. GEFS+ has also been associated with mutations of genes encoding the sodium channel beta 1 subunit, SCN1B, and the GABA(A) receptor gamma 2 subunit, GABRG2. The phenotypic heterogeneity that is characteristic of GEFS+ families is likely to be due to modifier genes. Interpretation of the significance of a SCN1A missense mutation requires a thorough understanding of the phenotypes in the GEFS+ spectrum whereas a de novo truncation mutation is likely to be associated with a severe phenotype. Early recognition of Dravet syndrome is important as aggressive control of seizures may improve developmental outcome.

Genetic analysis of first-trimester miscarriages with a combination of cytogenetic karyotyping, microsatellite genotyping and arrayCGH

Miscarriage is the spontaneous loss of an embryo or fetus before the 20th week of pregnancy. Most miscarriages occur before the end of the first trimester (<13 weeks). Although many risk factors relate to this occurrence, genetic factors play the most important role. Chromosomal abnormalities, including both numerical and structural anomalies, underlie the majority of miscarriages. In this study, we employed a comprehensive approach using cytogenetic karyotyping, polymerase chain reaction (PCR)‐based genotyping, and microarray‐based comparative genomic hybridization (arrayCGH) in combination to analyze chromosomal profiles of 115 first‐trimester miscarriages of Chinese women. Seventy cases (61%) were found to have chromosomal anomalies, of which 90% were numerical and 10% were structural. Cytogenetic karyotyping identified 78.6% (55/70), PCR assays 2.9% (2 triploids), and arrayCGH 18.6% (13/70) of the anomalies. In this study, a microdeletion of 108 kb and four microduplications sizing from 300 to 1460 kb were observed. An advantage of using this combination approach is that microsatellite genotyping and arrayCGH can be accomplished in spite of culture failure and maternal cell contamination. In addition, arrayCGH can detect submicroscopic chromosomal anomalies and gene dosage alterations.

New variants in the CACNA1H gene identified in childhood absence epilepsy.

Childhood absence epilepsy (CAE) is a common form of idiopathic generalized epilepsy with polygenic inheritance. In our previous studies, relatively high frequent variants in the T-type calcium channel gene, CACNA1H, were identified in the Chinese Han population, most of which are located in exons 6-12. The goal of this study was to identify additional variants in this region of the CACNA1H gene. To this end, exons 6-12 were sequenced in 100 newly recruited CAE trios and 191 normal controls. Thirty-nine variants were identified in CAE trios or controls, 14 of which were found only in CAE patients, including two nonsynonymous variants that were newly found. Thirteen of the 39 variants were found in both CAE patients and controls, 11 were found only in parents of CAE trios, and one was found only in controls. Twenty-eight of these variants had not been previously reported. Both permutation test and transmission/disequilibrium test (TDT) indicated that a SNP-52037C>T in intron11 was significant in association with CAE. In conclusion, these data further support the hypothesis that CACNA1H is an important susceptibility gene for CAE in the Chinese Han population.

SCN1A, SCN1B, and GABRG2 gene mutation analysis in Chinese families with generalized epilepsy with febrile seizures plus.

AbstractGeneralized epilepsy with febrile seizures plus (GEFS+; MIM#604233) is a familial epilepsy syndrome characterized by phenotypic and genetic heterogeneity. It was associated with mutations in the neuronal voltage-gated sodium channel subunit gene (SCN1A, SCN2A, SCN1B) and ligand-gated gamma aminobutyric acid receptors genes (GABRG2, GABRD). We investigated the roles of SCN1A, SCN1B, and GABRG2 mutations in the etiology of Chinese GEFS+ families. Genomic deoxyribonucleic acid (DNA) was extracted from peripheral blood lymphocytes of 23 probands and their family members. The sequences of SCN1A, SCN1B, and GABRG2 genes were analyzed by polymerase chain reaction (PCR) and direct sequencing. The major phenotypes of affected members in the 23 GEFS+ families exhibited FS and FS+, whereas rare phenotypes afebrile generalized tonic-clonic seizures (AGTCS), myoclonic-astatic epilepsy (MAE), and partial seizures were also observed. A novel SCN1A mutation, p.N935H, was identified in one family and another novel mutation in GABRG2, p.W390X, in another family. However, no SCN1B mutation was identified. The combined frequency of SCN1A, SCN1B, and GABRG2 mutations was 8.7% (2/23), extending the distribution of SCN1A and GABRG2 mutations to Chinese GEFS+ families. There were still unidentified genes contributing to the pathogenesis of GEFS+.

Clinical study and PLA2G6 mutation screening analysis in Chinese patients with infantile neuroaxonal dystrophy

Background and purpose:  Infantile neuroaxonal dystrophy (INAD) is a rare autosomal recessive neurodegenerative disorder. The most typical neuropathological finding of this disease is axonal swelling. Before the identification of associated mutations in PLA2G6‐encoding iPLA2‐VIA (cytosolic Ca2+‐independent phospholipids A2, group VIA) in 2006, neuropathological evidence was critical for definitive diagnosis. Only five genetic studies in INAD patients have been published worldwide, wherein 44 mutations were reported. To define the clinical and genetic characteristics of Chinese patients with INAD, 10 cases were analyzed.

Anti-endothelial cell antibodies (AECA) in patients with propylthiouracil (PTU)-induced ANCA positive vasculitis are associated with disease activity.

Increasing evidence has demonstrated that propylthiouracil (PTU) could induce ANCA positive vasculitis. However, our previous work has suggested that only one‐fifth of the PTU‐induced ANCA positive patients had clinical vasculitis and so the mechanism is not clear. Anti‐endothelial cell antibodies (AECA) have been implicated in the pathogenesis of various vasculitides, including primary ANCA positive systemic vasculitis. The purpose of this study is to investigate the prevalence of AECA and their possible role in the pathogenesis of patients with PTU‐induced ANCA positive vasculitis. Sera from 11 patients with PTU‐induced ANCA positive vasculitis at both active and quiescent phases, and sera from 10 patients with PTU‐induced ANCA but without clinical vasculitis, were studied. Sera from 30 healthy blood donors were collected as normal controls. Soluble proteins from 1% Triton‐100 extracted in vitro cultured human umbilical vein endothelial cells were used as antigens and an immunoblotting technique was performed to determine the presence of AECA, and their specific target antigens were identified. In patients with PTU‐induced ANCA positive vasculitis, 10 of the 11 patients in an active phase of disease were serum IgG‐AECA positive and six protein bands of endothelial antigens could be blotted (61 kD, 69 kD, 77 kD, 85 kD, 91 kD and 97 kD). However, in the quiescent phase, seven of the 10 positive sera turned negative. None of the ANCA positive but vasculitis negative patients or normal controls were AECA positive. In conclusion, AECA could be found in sera from patients with PTU‐induced ANCA positive vasculitis and were associated more closely with vasculitic disease activity.

SCN8A mutations in Chinese children with early onset epilepsy and intellectual disability.

Mutations in SCN8A, a voltage‐gated sodium‐channel type VIII alpha subunit gene, have recently been recognized as one of the pathogenic mechanisms leading to epilepsy and intellectual/developmental disabilities (IDDs). The aim of this study was to detect SCN8A mutations in Chinese patients with epilepsy of unknown etiology and ID/DD.

T-type calcium channel gene alpha (1G) is not associated with childhood absence epilepsy in the Chinese Han population.

We investigated whether the T-type calcium channel gene alpha (1G) is associated with childhood absence epilepsy (CAE), a form of idiopathic generalized epilepsy. We carried out direct sequencing of exons 1-37 and the exon-intron boundaries of the alpha (1G) gene in 48 Han Chinese patients with CAE and 48 normal controls. We found no mutation in the exons of alpha (1G). However, we did identify six single nucleotide polymorphisms (SNPs). Using two of these as markers, we carried out a case-control study in 192 patients with CAE and 192 normal controls. The allele and genotype distributions of all the SNPs studied were not significantly different between cases and control groups, thus the alpha (1G) gene is not an important susceptibility gene for CAE, at least in the Chinese population.