Mutations in the cyclin-dependent kinase-like 5 gene (CDKL5) cause a severe neurodevelopmental disorder, yet the impact of truncating mutations remains unclear. Here, we introduce the Cdkl5^492stop mouse model, mimicking C-terminal truncating mutations in patients. 492stop/Y mice exhibit altered dendritic spine morphology and spontaneous seizure-like behaviors, alongside other behavioral deficits. After creating cell lines with various Cdkl5 truncating mutations, we found that these mutations are regulated by the nonsense-mediated RNA decay pathway. Most truncating mutations result in CDKL5 protein loss, leading to multiple disease phenotypes, and offering new insights into the pathogenesis of CDKL5 disorder.
Animals ; Disease Models, Animal ; Mice ; Protein Serine-Threonine Kinases/deficiency* ; Mutation/genetics* ; Epileptic Syndromes/genetics* ; Humans ; Dendritic Spines/pathology* ; Spasms, Infantile/genetics* ; Male ; Seizures/genetics* ; Mice, Inbred C57BL

Epilepsy is a chronic neurological disorder affecting ~65 million individuals worldwide. Abnormal synaptic plasticity is one of the most important pathological features of this condition. We investigated how ubiquitin-specific peptidase 47 (USP47) influences synaptic plasticity and its link to epilepsy. We found that USP47 enhanced excitatory postsynaptic transmission and increased the density of total dendritic spines and the proportion of mature dendritic spines. Furthermore, USP47 inhibited the degradation of the ubiquitinated α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) subunit glutamate receptor 1 (GluR1), which is associated with synaptic plasticity. In addition, elevated levels of USP47 were found in epileptic mice, and USP47 knockdown reduced the frequency and duration of seizure-like events and alleviated epileptic seizures. To summarize, we present a new mechanism whereby USP47 regulates excitatory postsynaptic plasticity through the inhibition of ubiquitinated GluR1 degradation. Modulating USP47 may offer a potential approach for controlling seizures and modifying disease progression in future therapeutic strategies.
Animals ; Receptors, AMPA/metabolism* ; Neuronal Plasticity/physiology* ; Seizures/physiopathology* ; Disease Models, Animal ; Mice, Inbred C57BL ; Mice ; Ubiquitin Thiolesterase/genetics* ; Male ; Excitatory Postsynaptic Potentials/physiology* ; Ubiquitination ; Dendritic Spines/metabolism* ; Hippocampus/metabolism*

The patient is a 10-month and 21-day-old girl who began to show developmental delays at 3 months of age, with severe language developmental disorders, stereotyped movements, and easily provoked laughter. Physical examination revealed fair skin and a flattened occiput. At 10 months of age, a video electroencephalogram suggested atypical absence seizures, with migrating slow-wave activity observed during the interictal period. Whole exome sequencing of three family members indicated a novel mutation in the AP2M1 gene, c.508C>T (p.R170W), in the patient. A total of six cases of autosomal dominant intellectual developmental disorder 60 with seizures associated with mutations in the AP2M1 gene have been reported both domestically and internationally (including this study). The main clinical features included developmental delays (6 cases), language developmental disorders (5 cases), stereotyped movements (3 cases), a tendency to smile (1 case), and atypical absence seizures (4 cases). Interictal electroencephalograms showed widespread spike waves and spike-slow wave discharges (5 cases), and migrating slow-wave activity (1 case). The c.508C>T (p.R170W) mutation may be a hotspot for mutations in the AP2M1 gene, and its clinical features are similar to those of Angelman syndrome.
Humans ; Female ; Seizures/genetics* ; Infant ; Mutation ; Intellectual Disability/genetics* ; Electroencephalography ; Developmental Disabilities/genetics*

Objective: To discuss the clinical and genetic features of intellectual developmental disorder with behavioral abnormalities and craniofacial dysmorphism with or without seizures (IDDBCS). Methods: The clinical and genetic records of a patient who was diagnosed with IDDBCS caused by PHF21A gene variation at Children's Hospital Capital Institute of Pediatrics in 2021 were collected retrospectively. Using " PHF21A gene" as the keyword, relevant articles were searched at CNKI, Wanfang Data and PubMed from establishment of databases to February 2023. Clinical and genetic features of IDDBCS were summarized in the combination of this case. Results: An 8 months of age boy showed overgrowth (height, weight and head circumference were all higher than the 97^th percentile of children of the same age and sex) and language and motor developmental delay after birth, and gradually showed autism-like symptoms like stereotyped behavior and poor eye contact. At 8 months of age, he began to show epileptic seizures, which were in the form of a series of spastic seizures with no reaction to adrenocorticotropic hormone but a good response to vigabatrin. Physical examination showed special craniofacial appearances including a prominent high forehead, sparse eyebrows, broad nasal bridge, and downturned mouth with a tent-shaped upper lip. The patient also manifested hypotonia. Whole exome sequencing showed a de novo heterogeneous variant, PHF21A (NM_001101802.1): c.54+1G>A, and IDDBCS was diagnosed. A total of 6 articles (all English articles) were collected, involving this case and other 14 patients of IDDBCS caused by PHF21A gene variation. Clinical manifestations were intellectual disability or developmental delay (15 patients), craniofacial anomalies (15 patients), behavioral abnormalities (12 patients), seizures (9 patients), and overgrowth (8 patients). The main pathogenic variations were frameshift variations (8 patients). Conclusions: IDDBCS should be considered when patients show nervous developmental abnormalities, craniofacial anomalies, seizures and overgrowth. PHF21A gene variation detection helps to make a definite diagnosis.
Male ; Humans ; Child ; Intellectual Disability/genetics* ; Developmental Disabilities/genetics* ; Retrospective Studies ; Seizures/genetics* ; Craniofacial Abnormalities/genetics* ; Histone Deacetylases/genetics*

OBJECTIVE: To explore the genetic etiology of a child with Hypomagnesemia, epilepsy and mental retardation syndrome (HSMR). METHODS: A child who was admitted to the Children's Hospital of Shandong University on July 9, 2021 due to repeated convulsions for 2 months was selected as the study subject. Clinical data of the child was collected. Peripheral blood samples of the child and his pedigree members were collected for the extraction of genomic DNA. Whole exome sequencing was carried out, and candidate variant was verified by Sanger sequencing and bioinformatic analysis. RESULTS: The child, a 1-year-and-7-month-old male, had presented with epilepsy and global developmental delay. Serological testing revealed that he has low serum magnesium. Genetic testing showed that the child has harbored a heterozygous c.1448delT (p.Val483GlyfsTer29) variant of the CNNM2 gene, which was de novo in origin. The variant has caused substitution of the Valine at position 483 by Glycine and formation of a termination codon after 29 amino acids at downstream. As predicted by Swiss-Model online software, the variant may alter the protein structure, resulting in a truncation. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), the c.1448delT (p.Val483GlyfsTer29) was predicted as a pathogenic variant (PVS1+PS2+PM2_Supporting+PP4). CONCLUSION The heterozygous c.1448delT variant of the CNNM2 gene probably underlay the HSMR in this child. Above finding has enriched the phenotype-genotype spectrum of the CNNM2 gene.
Humans ; Male ; Cation Transport Proteins ; Computational Biology ; Ethnicity ; Intellectual Disability/genetics* ; Magnesium ; Mutation ; Seizures/genetics* ; Infant

OBJECTIVE: To explore the clinical phenotype and genetic characteristics of a child with Intellectual developmental disorder with behavioral abnormalities and craniofacial malformations without epilepsy (IDDBCS). METHODS: A child who had visited the Lianyungang Maternal and Child Health Care Hospital in April 2021 was selected as the study subject. Clinical data of the child were collected. Genomic DNA was extracted from peripheral blood samples of the child and his parents and subjected to whole exome sequencing (WES). Candidate variants were verified by Sanger sequencing of his family members. RESULTS: The child, a 3-year-and-4-month-old male, had presented with global developmental delay and cranial malformation. Genetic testing revealed that he has harbored a heterozygous c.1703delA (p.K568Sfs9) variant of the PHF21A gene, for which both of his parents were of the wild type. This low-frequency variant may alter the structure and function of the protein product. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), it was classified as a pathogenic variant (PVS1+PS2+PM2_Supporting). CONCLUSION The heterozygous c.1703delA (p.K568Sfs9) variant of the PHF21A gene probably underlay the IDDBCS in this patient.
Child ; Male ; Humans ; Infant ; Developmental Disabilities/genetics* ; Craniofacial Abnormalities/genetics* ; Seizures/genetics* ; Intellectual Disability/genetics* ; Problem Behavior ; Mutation

A boy, aged 6 years, attended the hospital due to global developmental delay for 6 years and recurrent fever and convulsions for 5 years. The boy was found to have delayed mental and motor development at the age of 3 months and experienced recurrent fever and convulsions since the age of 1 year, with intermittent canker sores and purulent tonsillitis. During the fever period, blood tests showed elevated white blood cell count, C-reactive protein, and erythrocyte sedimentation rate, which returned to normal after the fever subsides. Electroencephalography showed epilepsy, and genetic testing showed compound heterozygous mutations in the GPAA1 gene. The boy was finally diagnosed with glycosylphosphatidylinositol biosynthesis deficiency 15 (GPIBD15) and periodic fever. The patient did not respond well to antiepileptic treatment, but showed successful fever control with glucocorticoid therapy. This article reports the first case of GPIBD15 caused by GPAA1 gene mutation in China and summarizes the genetic features, clinical features, diagnosis, and treatment of this disease, which provides a reference for the early diagnosis and treatment of GPIBD15.
Humans ; Male ; Fever ; Glycosylphosphatidylinositols/genetics* ; Membrane Glycoproteins/genetics* ; Mutation ; Rare Diseases ; Seizures ; Child

OBJECTIVE: To analyze the clinical manifestation and genetic basis for four children with delayed onset Ornithine transcarbamylase deficiency (OTCD). METHODS: Clinical data of four children with OTCD admitted to the Children's Hospital of the First Affiliated Hospital of Zhengzhou University from January 2020 to April 2021 were reviewed. Peripheral blood samples of the children and their parents were collected and subjected to whole exome sequencing (WES). Bioinformatic analysis and Sanger sequencing verification were carried out to verify the candidate variants. Impact of the candidate variants on the protein structure was also predicted. RESULTS: The clinical manifestations of the four children included vomiting, convulsion and disturbance of consciousness. WES revealed that the child 1 was heterozygous for a c.421C>T (p.R141X) variant in exon 5, children 2 and 3 were hemizygous for a c.119G>A (p.R40H) variant in exon 2, and child 4 was hemizygous for a c.607T>A (p.S203T) variant in exon 5 of the OTC gene. Among these, the c.607T>A variant was unreported previously and predicted to be pathogenic (PM1+PM2_Supporting+PP3+PP4). Bioinformatic analysis has predicted that the variant may result in breakage of hydrogen bonds and alter the protein structure and function. Sanger sequencing confirmed that the variants in children 2 to 4 have derived from their mothers. CONCLUSION The pathogenic variants of the OTC gene probably underlay the delayed OTCD in 4 children. The discovery of the c.607T>A variant has enriched the mutational spectrum of the OTC gene.
Child ; Humans ; Ornithine Carbamoyltransferase Deficiency Disease/genetics* ; Exons ; Seizures ; Computational Biology ; Heterozygote

OBJECTIVE: To explore the genetic etiology of a patient with epilepsy and provide genetic counseling. METHODS: A patient who had visited the Center for Reproductive Medicine of Shandong University on November 11, 2020 was selected as the study subject, and her clinic information was collected. Candidate variant was identified through whole exome sequencing (WES), and Sanger sequencing was used for validation. Possible transcriptional changes caused by the variant was detected by reverse transcription-PCR and Sanger sequencing. RESULTS: The patient was a 35-year-old female with no fever at the onset, loss of consciousness and abnormal firing in the temporal lobe, manifesting predominantly as convulsions and fainting. WES revealed that she had harbored a heterozygous c.2841+5G>A variant of the SCN9A gene, which was verified by Sanger sequencing. cDNA sequencing confirmed that 154 bases were inserted between exons 16 and 17 of the SCN9A gene, which probably produced a truncated protein and affected the normal function of the SCN9A protein. Based on the guidelines from the American College of Medical Genetics and Genomics, the c.2841+5G>A variant was classified as likely pathogenic (PVS1_Strong+PM2_Supporting). CONCLUSION The c.2841+5G>A variant of the SCN9A gene probably underlay the epilepsy in this patient. Above finding has enriched the variant spectrum of the SCN9A gene and provided a basis for the prenatal diagnosis and preimplantation genetic testing for this patient.
Humans ; Female ; Pregnancy ; Adult ; Epilepsy/genetics* ; Seizures ; Exons ; DNA, Complementary ; Genetic Counseling ; NAV1.7 Voltage-Gated Sodium Channel

OBJECTIVE: To explore the clinical characteristics and genetic etiology of three children with Menkes disease. METHODS: Three children who had presented at the Children's Medical Center, the Affiliated Hospital of Guangdong Medical University from January 2020 to July 2022 were selected as the study subjects. Clinical data of the children were reviewed. Genomic DNA was extracted from peripheral blood samples of the children, their parents and sister of child 1. Whole exome sequencing (WES) was carried out. Candidate variants were verified by Sanger sequencing, copy number variation sequencing (CNV-seq), and bioinformatic analysis. RESULTS: Child 1 was a 1-year-and-4-month male, and children 2 and 3 were monozygotic twin males aged 1-year-and-10-month. The clinical manifestations of the three children have included developmental delay and seizures. WES showed that child 1 has harbored a c.3294+1G>A variant of the ATP7A gene. Sanger sequencing confirmed that his parents and sister did not carry the same variant, suggesting that it was de novo. Children 2 and 3 had carried a c.77266650_77267178del copy number variation. CNV-seq results showed that their mother has carried the same variant. By searching the HGMD, OMIM and ClinVar databases, the c.3294+1G>A was known to be pathogenic. No carrier frequency has been recorded in the 1000 Genomes, ESP, ExAC and gnomAD databases. Based on the Standards and Guidelines for the Interpretation of Sequence Variants: A Joint Consensus Recommendation of the American College of Medical Genetics and Genomics (ACMG), the ATP7A gene c.3294+1G>A variant was predicted to be pathogenic. The c.77266650_77267178del variant has involved exons 8 to 9 of the ATP7A gene. ClinGen online system score for it was 1.8, which was also considered to be pathogenic. CONCLUSION The c.3294+1G>A and c.77266650_ 77267178del variants of the ATP7A gene probably underlay the Menkes disease in the three children. Above finding has enriched the mutational spectrum of Menkes disease and provided a basis for clinical diagnosis and genetic counseling.
Humans ; Male ; Computational Biology ; Copper-Transporting ATPases/genetics* ; DNA Copy Number Variations ; Exons ; Menkes Kinky Hair Syndrome/genetics* ; Mutation ; Peptide Fragments ; Seizures ; Infant