Objective:To analyze the clinical phenotypes and genetic features of a child with developmental and epileptic encephalopathy due to compound heterozygous variants in the ALG14 gene, and to improve clinicians′ understanding of the ALG14 gene and its associated disorders. Methods:Clinical data of a child with developmental and epileptic encephalopathy caused by ALG14 gene variants, who visited Linyi People′s Hospital on September 9, 2019, were collected and followed up. Whole exome sequencing (WES) and Sanger sequencing were applied to genetically detect the child and her parents, SWISS-MODEL software was used to perform 3D modeling of proteins for the screened ALG14 gene variants, and the literature was reviewed to summarize the clinical phenotypes and genetic characteristics of patients associated with ALG14 gene. Results:The proband, a 17-year-old female, presented with focal seizures and generalized tonic-clonic seizures, generalized developmental delay, cranial magnetic resonance imaging showing no significant abnormalities, and video-electroencephalogram showing widespread low-amplitude fast rhythms. The WES results showed that the affected child carried compound heterozygous variants c.243A>G (p.Ile81Met) and c.103delG(p.Glu35SerfsTer7) (NM_144988) in the ALG14 gene, and Sanger sequencing validation showed that they were derived from her father and mother with normal clinical phenotype, respectively, and the above loci had not been reported domestically or internationally. 3D modeling revealed that the p.Ile81Met variant resulted in a change in the coding amino acid at position 81, and alteration of the stability and hydrophobicity of the protein, which may affect the protein function; the p.Glu35SerfsTer7 variant resulted in early truncation of the peptide chain, loss of a large number of amino acid fragments, and significant alteration of the protein structure. According to the American College of Medical Genetics and Genomics and the Association for Molecular Pathology, p.Ile81Met was a variant of undetermined clinical significance (PM2+PM3+PP3), and p.Glu35SerfsTer7 was a likely pathogenic variant (PVS1+PM2+PP3). A total of 5 papers were retrieved reporting 13 cases related to ALG14 gene variants (including the present case), 4 cases with pure heterozygous variants, 9 with compound heterozygous variants, involving 11 variant types, all inherited from the parents, of which 9 being missense variants, 1 being shifted code variant, and 1 being intronic deletion variant. The main clinical phenotypes included epileptic seizure (11/13), hypotonia (10/13), craniofacial malformations (8/13), growth disorders (3/13), and behavioral abnormalities (2/13). Conclusions:This article reports the first case of ALG14 gene related developmental and epileptic encephalopathy in a child at home and abroad, characterized by focal seizures, generalized tonic-clonic seizures, and global developmental delay. The compound heterozygous variants c.243A>G (p.Ile81Met) and c.103delG(p.Glu35SerfsTer7) may be the genetic cause of this child, enriching the clinical phenotype and variation spectrum related to this gene.

Objective:To analyze the clinical phenotypes and genetic characteristics of pediatric patients with neurofibromatosis type 1 (NF1).Methods:A cross-sectional study was adopted. Clinical and imaging data of 25 pediatric patients diagnosed as having NF1 in Department of Pediatric Neurology, Linyi People's Hospital Affiliated to Shandong Second Medical University from January 2024 to July 2025 were collected. Whole exome sequencing and Sanger sequencing were used to conduct genetic testing on the pediatric patients and his/her parents. Protein 3D modeling of the domestic and foreign unreported variations was conducted using SWISS-MODEL software.Results:Among the 25 pediatric patients with NF1, 14 were male (56%) and 11 were female (44%), with age ranging from 8 months to 18 years. All pediatric patients exhibited café-au-lait macules, and 7 (28%) presented with plexiform neurofibromas. Genetic test identified 4 types of NF1 variants: nonsense variant ( n=11, 44%), frameshift variant ( n=9, 36%), missense variant ( n=3, 12%), and splice-site variant ( n=2, 8%). Importantly, 5 novel NF1 variants were discovered, including c.3455T>A, c.3709dupG, c.2665_2684del, c.7092_7095delinsTA, and c.3260del. Three pediatric patients inherited NF1 variant from their parents, while the remaining 22 harbored de novo mutation. Conclusion:NF1 exhibits a broad clinical spectrum, primarily affecting the skin and nervous system; this study identifies 5 previously unreported variants, expanding the genetic profile of NF1.

Objective:To analyze the clinical phenotypes and genetic features of a child with developmental and epileptic encephalopathy due to compound heterozygous variants in the ALG14 gene, and to improve clinicians′ understanding of the ALG14 gene and its associated disorders. Methods:Clinical data of a child with developmental and epileptic encephalopathy caused by ALG14 gene variants, who visited Linyi People′s Hospital on September 9, 2019, were collected and followed up. Whole exome sequencing (WES) and Sanger sequencing were applied to genetically detect the child and her parents, SWISS-MODEL software was used to perform 3D modeling of proteins for the screened ALG14 gene variants, and the literature was reviewed to summarize the clinical phenotypes and genetic characteristics of patients associated with ALG14 gene. Results:The proband, a 17-year-old female, presented with focal seizures and generalized tonic-clonic seizures, generalized developmental delay, cranial magnetic resonance imaging showing no significant abnormalities, and video-electroencephalogram showing widespread low-amplitude fast rhythms. The WES results showed that the affected child carried compound heterozygous variants c.243A>G (p.Ile81Met) and c.103delG(p.Glu35SerfsTer7) (NM_144988) in the ALG14 gene, and Sanger sequencing validation showed that they were derived from her father and mother with normal clinical phenotype, respectively, and the above loci had not been reported domestically or internationally. 3D modeling revealed that the p.Ile81Met variant resulted in a change in the coding amino acid at position 81, and alteration of the stability and hydrophobicity of the protein, which may affect the protein function; the p.Glu35SerfsTer7 variant resulted in early truncation of the peptide chain, loss of a large number of amino acid fragments, and significant alteration of the protein structure. According to the American College of Medical Genetics and Genomics and the Association for Molecular Pathology, p.Ile81Met was a variant of undetermined clinical significance (PM2+PM3+PP3), and p.Glu35SerfsTer7 was a likely pathogenic variant (PVS1+PM2+PP3). A total of 5 papers were retrieved reporting 13 cases related to ALG14 gene variants (including the present case), 4 cases with pure heterozygous variants, 9 with compound heterozygous variants, involving 11 variant types, all inherited from the parents, of which 9 being missense variants, 1 being shifted code variant, and 1 being intronic deletion variant. The main clinical phenotypes included epileptic seizure (11/13), hypotonia (10/13), craniofacial malformations (8/13), growth disorders (3/13), and behavioral abnormalities (2/13). Conclusions:This article reports the first case of ALG14 gene related developmental and epileptic encephalopathy in a child at home and abroad, characterized by focal seizures, generalized tonic-clonic seizures, and global developmental delay. The compound heterozygous variants c.243A>G (p.Ile81Met) and c.103delG(p.Glu35SerfsTer7) may be the genetic cause of this child, enriching the clinical phenotype and variation spectrum related to this gene.

Objective:To analyze the clinical phenotypes and genetic characteristics of pediatric patients with neurofibromatosis type 1 (NF1).Methods:A cross-sectional study was adopted. Clinical and imaging data of 25 pediatric patients diagnosed as having NF1 in Department of Pediatric Neurology, Linyi People's Hospital Affiliated to Shandong Second Medical University from January 2024 to July 2025 were collected. Whole exome sequencing and Sanger sequencing were used to conduct genetic testing on the pediatric patients and his/her parents. Protein 3D modeling of the domestic and foreign unreported variations was conducted using SWISS-MODEL software.Results:Among the 25 pediatric patients with NF1, 14 were male (56%) and 11 were female (44%), with age ranging from 8 months to 18 years. All pediatric patients exhibited café-au-lait macules, and 7 (28%) presented with plexiform neurofibromas. Genetic test identified 4 types of NF1 variants: nonsense variant ( n=11, 44%), frameshift variant ( n=9, 36%), missense variant ( n=3, 12%), and splice-site variant ( n=2, 8%). Importantly, 5 novel NF1 variants were discovered, including c.3455T>A, c.3709dupG, c.2665_2684del, c.7092_7095delinsTA, and c.3260del. Three pediatric patients inherited NF1 variant from their parents, while the remaining 22 harbored de novo mutation. Conclusion:NF1 exhibits a broad clinical spectrum, primarily affecting the skin and nervous system; this study identifies 5 previously unreported variants, expanding the genetic profile of NF1.

Objective:To explore the clinical phenotype and genetic characteristics of children with childhood absence epilepsy caused by KMT2E gene variants. Methods:The clinical data of 1 case of KMT2E gene variant-associated childhood absence epilepsy admitted to the Department of Pediatric Neurology of Linyi People′s Hospital in January 2023 were collected and followed up, and the child and her family were genetically examined by using whole-exome sequencing and Sanger sequencing, and the pathogenicity of mutation loci was analyzed. The Online Mendelian Inheritance in Man, Human Gene Mutation Database, PubMed database, China National Knowledge Infrastructure, and Wanfang database were consulted with the search term " KMT2E" to summarize the clinical phenotype and genetics of the children with epilepsy associated with KMT2E gene variant. Results:The child is a female, presented with typical absence seizures at the age of 3 years and 8 months, with normal development, video electroencephalogram showing widespread spikes and slow waves around 3 Hz accompanied by typical absence seizures. Seizures decreased after valproic acid was applied at full dosage, and were controlled after combination with lamotrigine. Her clinical diagnosis of childhood absence epilepsy was made. The results of whole-exome sequencing showed that the child had a de novo frameshift variant c.2404dup (p.Arg802Lysfs *8) in the KMT2E gene (NM_182931.3), which had not yet been reported domestically or internationally. The c.2404dup variant was interpreted as a pathogenic variant (PVS1+PS2_Supporting+PM2_Supporting) according to the American Society of Medical Genetics and Genomics variant classification criteria and guidelines. Her parents, older brother and younger sister did not carry the variant and had a normal clinical phenotype. A total of 22 patients with epilepsy associated with KMT2E gene variants were retrieved (including this case, a total of 23 cases), including 10 females and 13 males. All of them were autosomal dominant inheritance, with 20 minor variations, including 8 frameshift variants, 7 missense variants, 2 splicing variants, 2 nonsense variants, 1 synonymous variant, and the remaining 3 cases had large fragment deletions (including 2 cases of the whole gene). Clinical manifestations mainly included epileptic seizures (5 cases of absence seizures, 7 cases of focal seizures with or without secondary tonic-clonic seizures, 9 cases of tonic-clonic seizures, 1 case of spasm seizures, 1 case of myoclonic seizures, tonic seizures, and atonic seizures, 3 cases of epileptic status, and 5 cases of refractory epilepsy, with the onset age of epilepsy ranging from neonatal to adolescence), mental retardation (21/23 cases, 4 mild, 5 moderate, and 5 severe), peculiar facial features (11/23), and autism (3/23), etc. Conclusion:KMT2E gene variant-associated epilepsy is an autosomal dominant disorder with a wide spectrum of clinical phenotypes, and the novel variant c.2404dup in the KMT2E gene identified in the present study can lead to childhood absence epilepsy, which enriches the spectrum of mutations and clinical phenotype of the KMT2E gene.

Objective:To investigate the clinical phenotype and genetic characteristics of developmental epileptic encephalopathy 18 (DEE18) caused by SZT2 gene variants. Methods:Clinical data of 2 children with SZT2 related DEE18 who visited the Department of Pediatric Neurology, Linyi People′s Hospital in March 2020 and July 2023 were collected. The whole exome sequencing (WES) and Sanger sequencing were applied to verify the child and their parents. SWISS-MODEL software was used to perform protein 3D modeling for the selected SZT2 gene variants. Results:Both of the 2 cases showed severe global developmental delay, epileptic seizures, autism, megacephaly, facial deformity, hypotonia, corpus callosum malformation, persistent cavum septum pellucidum, and slow background activity and focal discharge in video electroencephalography. Case 1 was easy to startle and thin in stature; case 2 had immune deficiency and clustered seizures. WES results showed that case 1 carried a compound heterozygous variant of c.5811G>A (p.W1937X) (paternal) and c.9269delG (p.S3090Ifs *94) (maternal), while case 2 carried a compound heterozygous variant of c.6302A>C(p.H2101P) (paternal) and c.7584dupA (p.E2529Rfs *20) (maternal), the parents of both patients with normal clinical phenotypes. The 4 mutations mentioned above were novel variations that had not yet been reported domestically or internationally. According to the American College of Medical Genetics and Genomics variant classification criteria and guidelines, the p.S3090Ifs *94 variant was interpreted as pathogenic; p.W1937X variant was interpreted as pathogenic; p.E2529Rfs *20 variant was interpreted as likely pathogenic; p.H2101P variant was interpreted as uncertain significance. 3D modeling showed that the variant of p.H2101P resulted in a significant change in the hydrogen bond around the 2 101st amino acid encoded, leading to a decrease in protein stability. The other 3 variants led to early truncation of peptide chain and obvious changes in protein structure. Conclusions:DEE18 caused by SZT2 gene mutation is mainly an autosome recessive genetic disease, and its clinical manifestations include global developmental delay, epileptic seizures, autism, craniofacial malformation, hypotonia, epileptic discharge, corpus callosum malformation, persistent cavum septum pellucidum, shock, small and thin stature, and immune deficiency. Four novel variants related to the SZT2 gene may be the genetic etiology of DEE18 patients in this study.

Objective:To analyze the clinical phenotypes and TSC1/TSC2 gene variations in 52 children with tuberous sclerosis complex. Methods:The clinical data of 59 children with tuberous sclerosis complex hospitalized in Linyi People′s Hospital between January 2017 and October 2022 were collected. The analysis of TSC1 and TSC2 gene variations on main family members was performed, and then bioinformatics analysis followed. The positive children were divided into TSC1 gene group and TSC2 gene group, and the difference of clinical characteristics between the two groups was analyzed. Results:Among 59 children, 52 cases were detected TSC1/ TSC2 gene variations (17 cases in the TSC1 gene group and 35 cases in the TSC2 gene group). Of the 52 children, 28 (53.8%) were male, 24 were female (46.2%); 17 (32.7%) were familial cases (10 with TSC1 gene variations and 7 with TSC2 gene variations), 35 (67.3%) were sporadic cases; 46 (88.5%) had hypomelanotic macules, 13 (25.0%) had facial angiofibromas, 5 (9.6%) had shagreen patches, 49 (94.2%) had subependymal nodules/calcifications, 47 (90.4%) had cortical nodules, 2 (3.8%) had subependymal giant cell astrocytomas, 39 (75.0%) had intellectual/developmental disabilities, 49 (94.2%) had epileptic seizures, 8 (15.4%) had cardiac rhabdomyomas, 9 (17.3%) had renal angiomyolipomas, and 4 (7.7%) had retinal hamartomas. Of the 52 children, 49 variations were detected, including 4 large fragment deletion/duplication variations, and 45 point variations; 41 pathogenic variations, 7 likely pathogenic variations, and 1 variation of uncertain significance. In this study, 16 point mutations and 1 large fragment duplication mutation which had not been reported at home and abroad, and 3 high-frequency mutation sites (p.Arg692 *, p.Arg228 *, and p.Arg1200Try) were found. There was a statistically significant difference in the proportion of familial cases [10/17 vs 7/35(20%), χ2=7.838, P=0.005], median onset age of epilepsy [38.0(0.5-134.0) months vs 8.0(0.1-63.0) months, Z=3.506 , P<0.001] and the incidence of developmental retardation/intellectual impairment [8/17 vs 31/35(88.6%), χadj2=8.423, P=0.004] between the TSC1 gene and TSC2 gene groups. Conclusions:Tuberous sclerosis compiex has widespread phenotypes, can affect every body system, especially the skin and nervous system. The pathogenic gene is TSC1/ TSC2. The TSC1 gene group has more familial cases. The TSC2 gene group has an earlier onset age of epilepsy and a higher incidence of developmental retardation/intellectual impairment. In this study, 16 novel point mutations, 1 novel large fragment duplication mutation, and 3 hotspot mutations were identified, expanding the gene variation spectrum of tuberous sclerosis complex.

Objective:To explore the clinical and genetic characteristics of five children with epilepsies due to variants of SCN8A gene. Methods:Clinical data of five children (four males and one female) admitted to Linyi People′s Hospital due to hereditary epilepsies between August 2015 and August 2022 were collected. Whole exome sequencing was carried out for these children, and candidate variants were verified by Sanger sequencing.Results:All of the five children were found to harbor variants of the SCN8A gene. Case 1, who had benign familial infantile epilepsy, inherited a known pathogenic c. 4840A>G variant from his father with similar symptoms. Cases 2 to 4 had presented with intermediate epilepsy. Among these, case 2 has harbored a de novo c. 3967G>A variant which was rated as pathogenic (PS1+ PS2+ PM1+ PM2_Supporting+ PP3) based on the guidelines from the American College of Medical Genetics and Genomics. Cases 3 and 4 were found to respectively harbor a de novo c. 415A>T and a c. 4697C>T variant, which were both rated as likely pathogenic (PS2+ PM1+ PM2_Supporting+ PP3). Case 5, who had early-onset infantile epileptic encephalopathy transformed into Lennox Gastaut-like syndrome, has harbored a de novo c. 5615G>A variant, which was known to be pathogenic. The children had their age of onset ranging from 2 to 14 months, and all had focal seizures and generalized tonic clonic seizures. Four children (cases 1, 2, 3 and 5) had cluster seizures, four (cases 1 to 4) had become seizure-free after single or dual treatment and showed normal growth and development, whilst case 5 was drug-resistant and showed severe developmental retardation. Conclusion:The five children had new features such as cluster seizures, occasional benign seizures in adulthood, and intermediate epilepsy which are prone to relapse after discontinuation of medication, which may be attributed to the pathogenic variants of the SCN8A gene.

Objective:To explore the clinical manifestations and pathogenic variant in a family with epilepsy, developmental delay and brain deformity.Methods:Clinical data of the child and his family members who had visited the Department of Pediatrics, Linyi People's Hospital on July 2, 2022 were collected. The child, his sister and parents were subjected to high-throughput sequencing, and the result was verified by Sanger sequencing.Results:The child was a 6-year-old boy with developmentally delay and had epileptic seizures with fever sensitivity for four years. Cranial imaging showed brain dysplasia, while the video electroencephalogram showed abnormal discharge. High-throughput sequencing showed the child has harbored a heterozygous c. 5G>T (p.Arg2Leu) variant of TUBB2A gene, which was unreported previously. His sister also carried the variant and had similar clinical manifestations, whilst his parents were of the wild-type and had normal clinical phenotypes. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), the variant was classified as pathogenic (PS2+ PM2_Supporting+ PM5+ PP1+ PP2+ PP3). Conclusion:The heterozygous c. 5G>T (p.Arg2Leu) variant of the TUBB2A gene, in the form of gonadal mosaicism, probably underlay the disorders in this family.

Objective:To explore the clinical features and genetic etiology of a child with Baraitser-Winter syndrome (BWS).Methods:A BWS child who had sought medical attention at the Linyi People′s Hospital on April 8, 2022 was selected as the study subject. Clinical data of the child was collected, and peripheral blood samples were obtained from the child and his parents. Whole exome sequencing (WES) was carried out, and candidate variant was verified by Sanger sequencing and bioinformatic analysis.Results:The child, a 5-year-and-6-month-old male, had typical clinical features of BWS including congenital non-myogenic ptosis, arched eyebrows, wide philtrum, and pointed chin. Neurological symptoms included microcephaly, developmental delay, epilepsy, and deafness. Cranial MRI revealed enlarged frontal lobes, decreased white matter, and hydrocephalus. WES has identified a heterozygous c. 430G>A (p.Asn144Tyr) missense variant in the ACTG1 gene. Sanger sequencing confirmed that neither of his parents has carried the same variant. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), the variant was classified as likely pathogenic (PS2+ PM2_Supporting+ PP3_Moderate+ PP4). Conclusion:The heterozygous c. 430G>A (p.Asn144Tyr) missense variant of the ACTG1 gene probably underlay the pathogenesis of BWS in this child. Above finding has enriched the mutation spectrum of BWS-related genes and provided a basis for clinical diagnosis and genetic counseling.