A Heterozygous Variant of FGF13 Caused X-Linked Developmental and Epileptic Encephalopathy 90 in a Chinese Family.

Developmental and epileptic encephalopathy (DEE) refers to a group of severe epilepsy encephalopathy and development disorders, and its typical clinical features include seizures, drug resistance, and developmental delay or regression. To date, limited studies have reported DEEs driven by FGF13. Here, we reported a girl with developmental and epileptic encephalopathy 90 caused by variant of FGF13. Her electroencephalogram (EEG) showed discontinuous hypsarrhythmia, and a heterozygous nonsynonymous variant in FGF13 [NM_004114.4: c.5C>G, p.(Ala2Gly)] was identified from the proband. The variant was not reported in public databases such as gnomAD and Exome Aggregation Consortium (ExAC), and was predicted to be damaging to proteins and classified as likely pathogenic according to the ACMG guidelines. The seizure was finally controlled by a combination of ACTH + zonisamide (10 mg/kg.d) + levetiracetam (52 mg/kg.d) + clonazepam (0.7 mg/kg.d).

Giant axonal neuropathy (GAN) in an 8-year-old girl caused by a homozygous pathogenic splicing variant in GAN gene.

Giant axonal neuropathy (GAN) is a progressive disease that involves the peripheral and central nervous systems. This neurodegenerative disease is caused by variants in the GAN gene encoding gigaxonin, and is inherited in an autosomal recessive manner. Herein, we performed whole-exome sequencing on a 8-year-old child with dense, curly hair, weakness in both lower limbs, and abnormal MRI. The child was born to consanguineous parents. Our results revealed that the child carried the c.1373+1G>A homozygous pathogenic variant of the GAN gene, while both parents were heterozygous carriers. According to the validation at the cDNA levels, the splicing variant led to the skipping of exon 8 and affected the Kelch domain's formation. Unlike the previously reported cases of GAN, the child's clinical manifestations revealed peripheral nervous system involvement, no vertebral signs, cerebellar signs, and spasticity, but only MRI abnormalities. These results suggested that the patient's central nervous system was mildly involved, which may be related to the genotype. In order to further clarify the correlation between GAN genotype and phenotype, combined with this patient, 54 cases of reported homozygous variants of the GAN gene were merged for the analysis of genotype and phenotype. The results revealed a certain correlation between the GAN gene variant domain and the patient's clinical phenotype, such as central nervous system involvement and age of onset.

Genotype and phenotype analysis using an epilepsy-associated gene panel in Chinese pediatric epilepsy patients.

Epilepsy is a common and genetically heterogeneous disorder among children. Advances in next-generation sequencing have revealed that numerous epilepsy genes, helped us improve the understanding of mechanisms underlying epileptogenesis, and guided the development of treatments. We identified 39 candidate variants in 21 genes, including 37 that were pathogenic or likely pathogenic variants according to the American College of Medical Genetics and Genomics scoring system and two variants of uncertain significance that were considered causative after they were associated with clinical characteristics. Thirty were de novo variants (76.9%), and 20 variants had not previously been reported (51.3%). We obtained a diagnosis in 39 of the 141 probands (27.7%). The most frequently mutated gene was SCN1A; KCNQ2, KCNT1, PCDH19, STXBP1, SCN2A, TSC2, and PRRT2 were mutated in more than one individual; ANKRD11, CDKL5, DCX, DEPDC5, GABRB3, GRIN2A, IQSEC2, KCNA2, KCNB1, KCNJ6, TSC1, SCN9A, and SCN1B were mutated in a single individual. In addition, we detected a nonsense variant in a candidate gene KCND1 and considered it as a new candidate epilepsy gene, which needed further functional study. Consequently, large number of unreported variants were detected, diverse phenotypes were associated with known epilepsy genes. Changes in clinical management beyond genetic counseling were suggested.

Hemizygous splicing variant in CNKSR2 results in X-linked intellectual developmental disorder.

BACKGROUND: Intellectual disability (ID) refers to a childhood-onset neurodevelopmental disorder with a prevalence of approximately 1%-3%. METHODS: We performed whole exome sequencing for the patient with ID. And the splicing variant we found was validated by minigene assay. RESULTS: Here, we report a boy with ID caused by a variant of CNKSR2. His neurological examination revealed hypsarrhythmia via electroencephalography and a right temporal polar arachnoid cyst via brain magnetic resonance imaging. A novel splicing variant in the CNKSR2 gene (NM_014927.5, c.1657+1G>A) was discovered by exome sequencing. The variant caused a 166 bp intron retention between exons 14 and 15, which was validated by a minigene assay. The variant was not reported in public databases such as gnomAD and the Exome Aggregation Consortium. CONCLUSIONS: The variant was predicted to be damaging to correct the translation of the CNKRS2 protein and was classified as likely pathogenic according to the ACMG guidelines.

Generation of a human iPSC line (ZJSHDPi001-A) from peripheral blood mononuclear cells of a patient with Developmental epileptic encephalopathy-47 carrying FGF12 gene mutation (c.334G > A).

Developmental epileptic encephalopathy-47 (DEE47) is a nervous system disease characterized by the onset of intractable seizures that appear the first days or weeks after birth. FGF12 is the disease-causing gene of DEE47 that encodes a small cytoplasm protein, which is a member of the fibroblast growth factor homologous factor (FGF) family. The FGF12-encoded protein interacts with the cytoplasmic tail of voltage-gated sodium channels to enhance the voltage dependence of rapid inactivation of sodium channels in neurons. This study used non-insertion Sendai virus transfection to establish the induced pluripotent stem cells(iPSCs)line with FGF12 mutation. The cell line was obtained from a 3-year-old boy carrying the c.334G > A heterozygous mutation in the FGF12 gene. This iPSC line could facilitate the investigations of pathogeneses of complex nervous system diseases such as developmental epileptic encephalopathy.

Establishment of an induced pluripotent stem cell line (ZJSHi001-A) from a patient with epileptic encephalopathy carrying KCNB1 Glu330Asp mutation.

Early infantile epileptic encephalopathy 26 (EE26) is a form of epileptic encephalopathy, a heterogeneous group of severe childhood-onset epilepsies characterized by refractory seizures, neurodevelopmental impairment, and poor prognosis. A recent study has shown that the KCNB1 gene mutation is associated with EE26; yet, the exact mechanism remains unclear. In this study, we produced an induced pluripotent stem cell line (iPSC) with a heterozygous variant of the KCNB1 gene (c.990G > T, p.Glu330Asp). Induced iPSCs were generated from peripheral blood mononuclear cells (PBMCs) obtained from a female child aged 6 with KCNB1 gene c. 990G > T and p.Glu330Asp heterozygous mutation.

Glucose Metabolic Profile by Visual Assessment Combined with Statistical Parametric Mapping Analysis in Pediatric Patients with Epilepsy.

PET with 18F-FDG has been used for presurgical localization of epileptogenic foci; however, in nonsurgical patients, the correlation between cerebral glucose metabolism and clinical severity has not been fully understood. The aim of this study was to evaluate the glucose metabolic profile using 18F-FDG PET/CT imaging in patients with epilepsy. Methods: One hundred pediatric epilepsy patients who underwent 18F-FDG PET/CT, MRI, and electroencephalography examinations were included. Fifteen age-matched controls were also included. 18F-FDG PET images were analyzed by visual assessment combined with statistical parametric mapping (SPM) analysis. The absolute asymmetry index (|AI|) was calculated in patients with regional abnormal glucose metabolism. Results: Visual assessment combined with SPM analysis of 18F-FDG PET images detected more patients with abnormal glucose metabolism than visual assessment only. The |AI| significantly positively correlated with seizure frequency (P < 0.01) but negatively correlated with the time since last seizure (P < 0.01) in patients with abnormal glucose metabolism. The only significant contributing variable to the |AI| was the time since last seizure, in patients both with hypometabolism (P = 0.001) and with hypermetabolism (P = 0.005). For patients with either hypometabolism (P < 0.01) or hypermetabolism (P = 0.209), higher |AI| values were found in those with drug resistance than with seizure remission. In the post-1-y follow-up PET studies, a significant change of |AI| (%) was found in patients with clinical improvement compared with those with persistence or progression (P < 0.01). Conclusion:18F-FDG PET imaging with visual assessment combined with SPM analysis could provide cerebral glucose metabolic profiles in nonsurgical epilepsy patients. |AI| might be used for evaluation of clinical severity and progress in these patients. Patients with a prolonged period of seizure freedom may have more subtle (or no) metabolic abnormalities on PET. The clinical value of PET might be enhanced by timing the scan closer to clinical seizures.