The doublecortin (DCX) gene encodes DCX, a microtubule-associated protein that plays a crucial role in brain development. DCX variants can disrupt microtubule binding and stabilization, interfere with intracellular transport, and affect post-translational modifications. A correlation exists between variant types and clinical severity. Animal models and induced pluripotent stem cell (iPSC) models simulating DCX deficiency revealed the dynamic progression of the disease, which has provided a powerful tool for investigating disease mechanisms and screening therapeutic agents. Currently there is no cure for DCX variants, with treatment primarily relying on anti-epileptic drugs and symptom management. Basic research is now offering new avenues for future therapeutic approaches. This article has summarized the potential pathogenic mechanisms and therapeutic strategies for the DCX variants, with an aim to provide insights for clinical treatment.
Humans ; Doublecortin Protein ; Doublecortin Domain Proteins ; Animals ; Neuropeptides/metabolism* ; Microtubule-Associated Proteins/metabolism* ; Mutation

OBJECTIVE: To analyze the clinical characteristics, treatment, and prognosis of seven pediatric patients with Acute myeloid leukemia (AML) positive for the t(16;21)(p11;q22) FUS::ERG fusion gene. METHODS: A retrospective analysis was carried out on the clinical data, treatment, and prognosis of seven AML patients with t(16;21)(p11;q22) FUS::ERG fusion gene admitted to Henan Children's Hospital between June 2015 and November 2024. Relevant literature was also reviewed. This study was approved by the Medical Ethics Committee of the Hospital (Ethics No.: 2024-102-001). RESULTS: Among 297 pediatric patients with AML, 7 cases (2.36%) were positive for the t(16;21)(p11;q22) FUS::ERG fusion gene, including 3 males and 4 females, with a median age of 11 years (range: 3 ~ 12 years). According to the FAB classification, these included 1 case of M2, 3 cases of M5, and 3 cases of AML-not otherwise specified (non-M3). All 7 patients were found to harbor the t(16;21)(p11;q22) translocation, with 3 cases showing additional chromosomal abnormalities. Immunophenotyping revealed universal expression of CD13, CD33, CD34, and CD117, with partial expression of CD56, CD4, CD64, CD123, CD15, CD38, CD11b, HLA-DR, cMPO, and CD16. One patient achieved complete remission (CR) after the first course of DAE (cytarabine + daunorubicin + etoposide) induction chemotherapy but relapsed and discontinued the treatment. Six patients received DAH (cytarabine + daunorubicin + homoharringtonine) induction therapy, of whom 2 achieved CR after two courses and underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT), resulting in an overall CR rate of 42.86%. Five children did not receive allo-HSCT and had a median overall survival of 9 months (range: 6 ~ 18 months). Two children who underwent transplantation achieved bone marrow morphological and molecular biological relapse at 6 and 9 months post-transplantation, respectively. After receiving combined chemotherapy and donor lymphocyte infusion, one child failed to achieve remission and died at 22 months post-transplantation, while the other has been followed up to date with positive fusion gene status. Their overall survival was 25 months and 30 months, respectively. CONCLUSION The t(16;21)(p11;q22) FUS::ERG fusion gene is rare in pediatric AML and associated with poor prognosis. Allo-HSCT may mitigate the adverse prognostic impact of the FUS::ERG fusion gene and contribute to prolonged survival.
Humans ; Male ; Child ; Female ; Leukemia, Myeloid, Acute/drug therapy* ; Oncogene Proteins, Fusion/genetics* ; Translocation, Genetic ; Retrospective Studies ; RNA-Binding Protein FUS/genetics* ; Chromosomes, Human, Pair 16/genetics* ; Adolescent ; Child, Preschool ; Chromosomes, Human, Pair 21/genetics* ; Prognosis ; Treatment Outcome

OBJECTIVE: To explore the genetic basis for a Chinese pedigree affected with Hereditary spastic paraplegia type 3A (SPG3A) and the genotype-phenotype correlation. METHODS: A three-generation pedigree presented at Huantai Maternal and Child Health Care Hospital in March 2021 was selected as the study subject. Whole-exome sequencing (WES) and pedigree analysis was carried out. Candidate variant was validated by Sanger sequencing of the members from the pedigree. Haplotype analysis was used to trace the origin of the variant, and pathogenicity was rated based on the guidelines from the American College of Medical Genetics and Genomics (ACMG). This study was approved by the Medical Ethics Committee of the Hospital (Ethics No.: 2025-12). RESULTS: A c.1024C>T (p.Pro342Ser) variant of the ATL1 was identified in the four affected members, including the proband, but none of the three unaffected relatives. Haplotype analysis suggested that the variant was derived from the proband's mother and has co-segregated with the disease phenotype. Based on the guidelines of the ACMG, it was classified as likely pathogenic. CONCLUSION The ATL1 c.1024C>T (p.Pro342Ser) variant probably underlay the pathogenesis in this pedigree. Above finding has enriched the mutational spectrum of ATL1 and phenotypic spectrum of SPG3A in the Chinese population, and enabled genetic counseling for this pedigree.
Humans ; Pedigree ; Spastic Paraplegia, Hereditary/genetics* ; Male ; Female ; Asian People/genetics* ; Adult ; Haplotypes ; Membrane Proteins/genetics* ; Exome Sequencing ; GTP-Binding Proteins/genetics* ; Mutation ; Middle Aged ; China ; Genetic Association Studies ; East Asian People

OBJECTIVE: To delineate the clinical and genetic features of a Chinese girl harboring a rare de novo variant of SYNGAP1 associated with Mental retardation, autosomal dominant 5 (MRD5), and to conduct a comprehensive genotype-phenotype correlation analysis within the Chinese population through an extensive literature review. METHODS: A 5-year-old girl presenting with seizures without an obvious cause was enrolled in September 2020. Genomic DNA was extracted from the patient and her parents. Whole exome sequencing (WES) was performed on the proband to identify suspected pathogenic variants based on her clinical phenotype. Sanger sequencing was used for validation, followed by bioinformatic analysis of the variant. Additionally, data from 54 previously reported Chinese cases with SYNGAP1 variants were integrated to summarize the distribution of variant types and clinical characteristics. Ethical approval was obtained from the Ethics Committee of Kunming Children's Hospital (Ethics No.: 2021-03-055-K01). RESULTS: WES identified a heterozygous nonsense variant, SYNGAP1 c.725G>A (p.Trp242*), in the proband. Sanger sequencing confirmed it was a de novo variant. According to the ACMG guidelines, this variant was classified as pathogenic (PVS1+PS2). Based on the clinical manifestations, the patient was diagnosed with MRD5. Bioinformatic analysis suggested that this variant introduces a premature stop codon at tryptophan 242, disrupting the PH domain and leading to the loss of the C2, Ras-GAP, and C-terminal domains. The pooled analysis of Chinese cases revealed that nonsense (38.2%) and frameshift (36.4%) variants were the predominant types. Intellectual disability/developmental delay was present in 100.0% of patients, epilepsy in 83.6%, and autism spectrum disorder in 41.3%. The incidence of epilepsy differed significantly among variant types (P = 0.045). Exons 8 and 15 were identified as mutation hotspots. CONCLUSION This study has identified a SYNGAP1 c.725G>A variant in the Chinese population and confirmed it as a potential cause of MRD5, which expanded the mutational spectrum of this disorder.
Humans ; Female ; Child, Preschool ; Intellectual Disability/genetics* ; ras GTPase-Activating Proteins/genetics* ; Phenotype ; Exome Sequencing ; Genetic Association Studies

OBJECTIVE: To analyze the clinical characteristics of patients with 11q23 rearrangement acute lymphoblastic leukemia (ALL) with non-KMT2A::AFF1 fusion genes. METHODS: The clinical data of 10 patients with KMT2A fusion gene positive and partner gene non-AFF1 ALL admitted to Henan Cancer Hospital from December 2016 to December 2024 were retrospectively summarized. The immunophenotype, molecular genetic characteristics, clinical manifestations and disease prognosis of these patients were analyzed. This research has been approved by the Medical Ethics Committee of Henan Cancer Hospital (Ethics No.: 2019342). RESULTS: Among the 10 patients, the fusion genes were KMT2A::MLLT1 in 7 cases, KMT2A::MLLT4, KMT2A::MLLT3 and KMT2A::MLLT10 in 1 case each. The European Group for the Immunological Classification of Leukemias (EGIL) classification included 6 cases of T-ALL, 2 cases of pro-B-ALL, 1 case of Common-B-ALL and 1 case of pre-B-ALL. 4 cases of B-ALL all expressed CD19, cCD79a, CD38 and HLA-DR, and some expressed CD34 and CD22, without expression or weak expression of CD10, without expression of CD20. One case was accompanied by myeloid marker CD15 expression. 6 cases of T-ALL all expressed CD34, CD7, most expressed CD38, and some expressed CD3, CD5, CD2, CD4 and CD8, and 1 case expressed CD4 and CD8 together. Chromosomal abnormalities were detected in 3 cases, 5 cases were positive for WT1 fusion gene, and 6 cases had gene alterations. 9 patients achieved the first complete remission (CR1) during chemotherapy, and 1 patient relapsed within 6 months after CR1. At the last follow up, 1 patient (the fusion gene was KMT2A::MLLT4) remained unrelieved. There were 2 cases of KMT2A rearrangement (KMT2A-r) persistent positive (+/+) and 8 cases of KMT2A-r negative (+/-). The overall survival (OS) rate and leukemia-free survival (LFS) rate of patients with KMT2A-r persistent positive were significantly lower than those of patients with negative change, and the differences were statistically significant (P values were all < 0.05). Among the 3 patients who received chemotherapy+allogeneic hematopoietic stem cell transplantation (allo-HSCT), no relapse was observed until the follow up day. The OS rate and LFS rate of patients with KMT2A::MLLT1 and chemotherapy+allo-HSCT were higher than those of non-KMT2A::MLLT1 and single chemotherapy patients, and the differences were not statistically significant (P values were all ≥ 0.05). There was no significant difference in OS rate and LFS rate between T-ALL and B-ALL patients (P values were all ≥ 0.05). The median LFS time of the 10 patients was 32 (0 ~ 100) months, and the median OS time was 36 (1 ~ 101) months. CONCLUSION The 11q23 rearrangement ALL with non-KMT2A::AFF1 transcript is mainly KMT2A::MLLT1, T-ALL is more common, and the rate of chromosomal karyotype detection is relatively low. Persistent positive KMT2A-r is unfavorable for patient survival, and allo-HSCT during the CR1 period may improve patient survival.
Humans ; Precursor Cell Lymphoblastic Leukemia-Lymphoma/genetics* ; Female ; Male ; Myeloid-Lymphoid Leukemia Protein/genetics* ; Histone-Lysine N-Methyltransferase/genetics* ; Adult ; Adolescent ; Chromosomes, Human, Pair 11/genetics* ; Child ; Transcriptional Elongation Factors/genetics* ; Gene Rearrangement ; Oncogene Proteins, Fusion/genetics* ; Retrospective Studies ; Young Adult ; Middle Aged ; Prognosis ; Child, Preschool ; DNA-Binding Proteins/genetics*

OBJECTIVE: To explore the clinical features and genetic characteristics of three patients with Infantile liver failure syndrome type 2 (ILFS2). METHODS: Three children who were diagnosed with ILFS2 at the Children's Hospital Affiliated to Zhengzhou University from February 2023 to February 2024 were selected as the study subjects. Clinical data of the children were collected. Peripheral blood samples of the children and their parents were collected and subjected to whole exome sequencing (WES). Candidate variants of the NBAS gene were verified by Sanger sequencing. This study was approved by the Ethics Committee of the Children's Hospital Affiliated to Zhengzhou University (Ethics No. 2024-k-069). RESULTS: The three children had presented with fever-triggered recurrent acute liver failure. All of them were found to harbor compound heterozygous variants of the NBAS gene, including c.3596G>A and c.1181A>T in child 1, c.2617C>T and c.2T>C in child 2, and c.3596G>A and c.2817_2818insT in child 3. Among these, the c.1181A>T and c.2817_2818insT variants were unreported previously. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), they were respectively classified as variants of uncertain significance (PM2_Supporting+PM3+PP3) and pathogenic (PVS1+PM2_Supporting+PM3). CONCLUSION Combined with the patient's clinical phenotype, the compound heterozygous variants of the NBAS gene probably underlay the pathogenesis of ILFS2 in the three children. For children with fever-related acute liver failure of unknown causes, the possibility of this disease should be suspected, and genetic testing may facilitate the diagnosis. Early diagnosis and timely intervention can significantly improve the prognosis. Discoveries of the c.1181A>T and c.2817_2818insT variants have enriched the mutational spectrum of the NBAS gene.
Humans ; Exome Sequencing ; Genetic Testing/methods* ; Liver Failure, Acute/etiology* ; Mutation ; Child ; Adult ; Neoplasm Proteins

OBJECTIVE: To investigate the clinical features and genetic variants associated with Multiple mitochondrial dysfunction syndrome (MMDS) type 3 in two children. METHODS: Two children diagnosed with MMDS type 3 at Zhuhai Maternal and Child Health Care Hospital in January 2021 were selected for this study. A retrospective analysis of their clinical data was carried out. Whole exome sequencing was conducted on the two children and their parents, followed by Sanger sequencing for candidate variants and bioinformatic analysis. Both children received comprehensive rehabilitative therapy and were followed up for 3 years. This study was approved by the Ethics Committee of Zhuhai Maternal and Child Health Hospital (Ethics No. 202380). RESULTS: The two MMDS type 3 children were monozygotic twin girls, aged 9 months, presenting with developmental regression, pyramidal signs, and other clinical manifestations. Cranial MRI revealed widespread abnormal signals and vacuolar changes in the white matter. Whole exome sequencing revealed that both children had harbored compound heterozygous variants of the IBA57 gene, namely c.286T>C (p.Tyr96His) and c.307C>T (p.Gln103Ter). Sanger sequencing confirmed that these variants were inherited from their father and mother, respectively. According to the American College of Medical Genetics and Genomics (ACMG) guidelines, both variants were classified as pathogenic (PM2_Supporting+PM3_Very Strong+PP3_Moderate; PVS1+PM2_Supporting+PM3). After treatment with vitamins, levocarnitine, ATP, coenzyme Q10, and other drugs, both children showed partial recovery of neurodevelopmental regression, with improvement in feeding and sleep. Over the 3-year follow-up, there was slow but progressive improvement in motor, language, and cognitive development. CONCLUSION The compound heterozygous variants c.286T>C (p.Tyr96His) and c.307C>T (p.Gln103Ter) of the IBA57 gene probably underlay the MMDS type 3 in the twin pair. Clinicians should be vigilant about the possibility of MMDS type 3 in children with neurodevelopmental regression and early cranial MRI findings indicating widespread white matter abnormalities with vacuolar changes, as these may be indicative of IBA57 gene variants.
Female ; Humans ; Infant ; Calcium-Binding Proteins/genetics* ; Exome Sequencing ; Genetic Testing/methods* ; Microfilament Proteins/genetics* ; Mitochondrial Diseases/genetics* ; Mutation ; Retrospective Studies ; Carrier Proteins

OBJECTIVE: To explore the genotype-phenotype correlation in a Charcot-Marie-Tooth type 2A2A (CMT2A2A) pedigree and to provide genetic counseling for its subsequent pregnancies. METHODS: A Chinese pedigree presenting with "lower limb muscle atrophy and movement disorders" at the Prenatal Diagnosis Center of Xuzhou Central Hospital between January and August 2024 was selected as the study subject. Relevant clinical data were collected from the pedigree members. Peripheral blood samples from affected individuals, and amniotic fluid and/or chorionic villus samples were obtained for DNA extraction. Whole exome sequencing (WES) was carried out. Candidate variants were verified by Sanger sequencing. Pathogenicity assessment and bioinformatic analysis were conducted. This study was approved by the Medical Ethics Committee of Xuzhou Central Hospital (Ethics No. XZXY-LK-20240111-0019). RESULTS: All affected individuals in this pedigree were females, whom included the proband, her mother, and her first daughter. Earlier age of onset was associated with more severe lower limb atrophy. A heterozygous missense variant of the MFN2 gene, namely c.314C>T (p.Thr105Met), was identified in the proband, her mother, daughter, and the third fetus from a re-marriage. The same variant was absent in her elder brother, current husband, and her fourth fetus. Based on the guidelines from American College of Medical Genetics and Genomics (ACMG) and recommendations from Clinical Genome Resources (ClinGen), the variant was classified as pathogenic (PP1_Strong+PM1+PS3+PS4_Moderate+PP3_Moderate+PM2_Supporting). Analyses with PROVEAN and Mutation Taster had categorized the variant as "deleterious" and "disease-causing", respectively. Analysis with Uniprot and Jalview showed that the affected amino acid residue is conserved across multiple species. ChEBI software predicted that the variant may alter the polarity of the 105th amino acid residue. CONCLUSION The c.314C>T (p.Thr105Met) missense variant of the MFN2 gene probably underlie the CMT2A2A in this pedigree. Above finding has enabled prenatal diagnosis and genetic counseling for its subsequent pregnancies.
Adult ; Female ; Humans ; Male ; Charcot-Marie-Tooth Disease/genetics* ; East Asian People/genetics* ; Exome Sequencing ; Genetic Testing/methods* ; GTP Phosphohydrolases/genetics* ; Mitochondrial Proteins/genetics* ; Mutation, Missense ; Pedigree

OBJECTIVE: To explore the genetic basis for a girl with primary microcephaly and growth retardation. METHODS: A girl who was admitted to Guangdong Maternal and Child Health Care Hospital in was selected as the study subject. Peripheral blood samples were collected from the child and her parents. Trio whole exome sequencing was carried out, and candidate variants were verified by Sanger sequencing and bioinformatic analysis. This study was approved by the Medical Ethnics Committee of Guangdong Maternal and Child Health Care Hospital (Ethics No. 202201278). RESULTS: DNA sequencing revealed that the child has harbored compound heterozygous variants of the WDR62 gene, including a frameshifting c.2963delC (p.Pro988Argfs*80) variant in exon 24 which was inherited from the unaffected father, and a nonsense c.3163G>T (p.Glu1055*) variant in exon 26, which was inherited from her unaffected mother. Both variants were predicted to affect the reading frame of the WDR62 gene. CONCLUSION Based on the clinical manifestations, results of genetic testing and pedigree analysis, the compound heterozygous variants were predicted to underlay the pathogenesis of microcephaly and growth retardation in this child. Above discovery has expanded the mutational spectrum for WDR62-associated Primary microcephaly type 2, and facilitated genetic counseling for the family.
Female ; Humans ; Cell Cycle Proteins ; Heterozygote ; Microcephaly/genetics* ; Mutation ; Nerve Tissue Proteins/genetics* ; Pedigree

OBJECTIVE: To explore the mechanism of BNIP3-mediated mitophagy in m.3635G>A related Leber's hereditary optic neuropathy (LHON). METHODS: A trans-mitochondrial cybrid cell line derived from a Chinese LHON patient carrying the m.3635G>A, diagnosed at the Eye Hospital of Wenzhou Medical University in September 2013, was selected as the study subject. A trans-mitochondrial cybrid cell line from a healthy control with an identical mitochondrial background was included as a control. Immunofluorescence, real-time quantitative PCR (RT-qPCR), and Western blotting were employed to assess the expression of autophagy-related proteins, aiming to explore the role of BNIP3-mediated mitophagy in m.3635G>A related LHON. This study was approved by the Medical Ethics Committee of the Eye Hospital of Wenzhou Medical University (Ethics No. 2023-J-096). RESULTS: Compared with the control group, the protein expression levels of autophagy-related markers LC3 (LC3-II/LC3-I) and LAMP1 were significantly reduced in the variant group (P < 0.05). Additionally, the protein levels of macroautophagy-related proteins ATG12, ATG7, and ATG5 were also significantly decreased (P < 0.05). Compared with the control cells, the mRNA and protein expression levels of mitophagy-associated protein BNIP3 were significantly reduced in the cells of the variant group (P < 0.05). Compared with the control group, both mRNA and protein expression levels of the mitophagy-related protein BNIP3 were significantly reduced in the variant group (P < 0.05). CONCLUSION The m.3635G>A inhibits BNIP3-mediated mitophagy, thereby contributing to the pathogenesis of LHON.
Humans ; Proto-Oncogene Proteins/metabolism* ; Mitophagy/genetics* ; Membrane Proteins/metabolism* ; Optic Atrophy, Hereditary, Leber/metabolism* ; Mitochondria/metabolism* ; Cell Line ; Male