Here, we report a previously unrecognized syndromic neurodevelopmental disorder associated with biallelic loss-of-function variants in the RBM42 gene. The patient is a 2-year-old female with severe central nervous system (CNS) abnormalities, hypotonia, hearing loss, congenital heart defects, and dysmorphic facial features. Familial whole-exome sequencing (WES) reveals that the patient has two compound heterozygous variants, c.304C>T (p.R102*) and c.1312G>A (p.A438T), in the RBM42 gene which encodes an integral component of splicing complex in the RNA-binding motif protein family. The p.A438T variant is in the RRM domain which impairs RBM42 protein stability in vivo. Additionally, p.A438T disrupts the interaction of RBM42 with hnRNP K, which is the causative gene for Au-Kline syndrome with overlapping disease characteristics seen in the index patient. The human R102* or A438T mutant protein failed to fully rescue the growth defects of RBM42 ortholog knockout ΔFgRbp1 in Fusarium while it was rescued by the wild-type (WT) human RBM42. A mouse model carrying Rbm42 compound heterozygous variants, c.280C>T (p.Q94*) and c.1306_1308delinsACA (p.A436T), demonstrated gross fetal developmental defects and most of the double mutant animals died by E13.5. RNA-seq data confirmed that Rbm42 was involved in neurological and myocardial functions with an essential role in alternative splicing (AS). Overall, we present clinical, genetic, and functional data to demonstrate that defects in RBM42 constitute the underlying etiology of a new neurodevelopmental disease which links the dysregulation of global AS to abnormal embryonic development.
Female ; Animals ; Mice ; Humans ; Child, Preschool ; Intellectual Disability/genetics* ; Heart Defects, Congenital/genetics* ; Facies ; Cleft Palate ; Muscle Hypotonia

Objective: To investigate the clinical features and gene variation characteristics of children with dynein cytoplasmic 1 heavy chain 1 (DYNC1H1) gene associated spinal muscular atrophy with lower extremity predominant (SMALED) 1. Methods: The clinical data of 4 SMALED1 children admitted to Peking University First Hospital from December 2018 to May 2021, who were found to have pathogenic variation of DYNC1H1 gene through genetic testing, except for other genes known to be related to motor retardation, were retrospectively summarized to analyze the phenotype and genotype characteristics. Results: There were 3 males and 1 female. The age of onset was 1 year, 1 day, 1 day and 4 months, respectively. The age of diagnosis was 4 years and 10 months, 9 months, 5 years and 9 months, and 3 years and 1 month, respectively. The clinical manifestations were muscle weakness and muscular atrophy of lower limbs, 2 cases with foot deformity, 1 case with early non progressive joint contracture, 1 case with hip dislocation and 1 case with mental retardation. De novo heterozygous missense variations in DYNC1H1 gene were found in all 4 children. According to the rating of American College of medical genetics and genomics, they were all possible pathogenic and pathogenic variations, with p.R598C, p.P776L, p.Y1109D variations had been reported, and p.I1086R variation had not been reported. Conclusions: For those with unexplained lower limb muscle weakness, muscle atrophy, joint contracture and foot deformity, upper limb motor ability related retention, with or without mental retardation, as well as the motor ability progresses slowly, it is necessary to consider the possibility of SMALED1 and the detection of DYNC1H1 gene when necessary.
Female ; Male ; Humans ; Intellectual Disability ; Retrospective Studies ; Muscular Atrophy, Spinal/genetics* ; Lower Extremity ; Muscle Weakness ; Muscular Atrophy ; Contracture ; Cytoplasmic Dyneins/genetics*

OBJECTIVE: To explore the clinical and genetic characteristics of three children with KBG syndrome. METHODS: Clinical data of the three children from two families who have presented at the First Affiliated Hospital of Zhengzhou University between October 2019 and September 2020 and their family members were collected. Trio-whole exome sequencing (trio-WES) and Sanger sequencing were carried out. RESULTS: All children had feeding difficulties, congenital heart defects and facial dysmorphism. The sib- pair from family 1 was found to harbor a novel de novo heterozygous c.6270delT (p.Q2091Rfs*84) variant of the ANKRD11 gene, whilst the child from family 2 was found to harbor a novel heterozygous c.6858delC (p.D2286Efs*51) variant of the ANKRD11 gene, which was inherited from his mother who had a mild clinical phenotype. CONCLUSION The heterozygous frameshift variants of the ANKRD11 gene probably underlay the disease in the three children. Above findings have enriched the spectrum of the ANKRD11 gene variants.
Female ; Child ; Humans ; Abnormalities, Multiple/genetics* ; Intellectual Disability/genetics* ; Bone Diseases, Developmental/genetics* ; Tooth Abnormalities/genetics* ; Facies ; Repressor Proteins/genetics* ; Mothers ; Mutation

OBJECTIVE: To explore the genetic basis for two patients from a family with BCL11A-related intellectual disability (BCL11A-ID). METHODS: Clinical data of the proband and her family members was analyzed. Chromosomal karyotyping analysis, trio-whole exome sequencing (trio-WES) and copy number variation sequencing (CNV-seq) were carried out. For the suspected genetic variants, Sanger sequencing was used to verify, and pathogenicity assessment was conducted. RESULTS: The proband and her mother both had intellectual and language impairment, and their fetal hemoglobin (HbF) was significantly elevated. A heterozygous c.1327_c.1328delTC (p.Ser443Hisfs*128) variant was found in exon 4 of the BCL11A gene by WES, which has resulted in truncated expression of the encoded protein, and Sanger sequencing has verified that the variant was inherited from the mother. The variant was not found in related databases. The variant was predicted as pathogenic according to the guidelines from the American College of Medical Genetics and Genomics (ACMG) (PVS1+PM2+PP1). No karyotypic abnormality was found in the proband, her parents and brother, and no pathogenic CNVs was found in the proband and her parents. CONCLUSION The c.1327_c.1328delTC (p.Ser443Hisfs*128) variant may underlay the BCL11A-ID in the proband and her mother. This de novo variant has expanded the mutational spectrum of the BCL11A gene.
Humans ; Male ; Female ; Intellectual Disability/genetics* ; DNA Copy Number Variations ; Pedigree ; Mutation ; Transcription Factors/genetics* ; Mothers ; Repressor Proteins/genetics*

OBJECTIVE: To explore the clinical and genetic features of a child with autosomal dominant mental retardation type 40 (MRD40) due to variant of the CHAMP1 gene. METHODS: Clinical characteristics of the child were analyzed. Genetic testing was carried out by low-depth high-throughput and whole genome copy number variant sequencing (CNV-seq) and whole exome sequencing (WES). A literature review was also carried out for the clinical phenotype and genetic characteristics of patients with MRD40 due to CHAMP1 gene variants. RESULTS: The child, a 11-month-old girl, has presented with intellectual and motor developmental delay. CNV-seq revealed no definite pathogenic variants. WES has detected the presence of a heterozygous c.1908C>G (p.Y636*) variant in the CHAMP1 gene, which was carried by neither parent and predicted to be pathogenic. Literature review has identified 33 additional children from 12 previous reports. All children had presented with developmental delay and mental retardation, and most had dystonia (94.1%), delayed speech and/or walking (85.2%, 82.4%) and ocular abnormalities (79.4%). In total 26 variants of the CHAMP1 gene were detected, with all nonsense variants being of loss-of-function type, located in exon 3, and de novo in origin. CONCLUSION The heterozygous c.1908C>G (p.Y636*) variant of the CHAMP1 gene probably underlay the WRD40 in this child. Genetic testing should be considered for children featuring global developmental delay, mental retardation, hypertonia and facial dysmorphism.
Humans ; Intellectual Disability/genetics* ; Genetic Testing ; Phenotype ; Exome Sequencing ; Heterozygote ; Mutation ; Chromosomal Proteins, Non-Histone/genetics* ; Phosphoproteins/genetics*

OBJECTIVE: To explore the genetic basis for a child with mental retardation. METHODS: Whole exome sequencing was carried out for the child. Candidate variant was screened based on his clinical features and verified by Sanger sequencing. RESULTS: The child was found to harbor a c.995_1002delAGACAAAA(p.Asp332AlafsTer84) frameshift variant in the SYNGAP1 gene. Bioinformatic analysis suggested it to be pathogenic. The same variant was not detected in either parent. CONCLUSION The c.995_1002delAGACAAAA(p.Asp332AlafsTer84) frameshift variant of the SYNGAP1 gene probably underlay the mental retardation in this child. Above finding has expanded the spectrum of SYNGAP1 gene variants and provided a basis for the diagnosis and treatment for this child.
Child ; Humans ; Intellectual Disability/genetics* ; Frameshift Mutation ; High-Throughput Nucleotide Sequencing ; Computational Biology ; Heterozygote ; Mutation ; ras GTPase-Activating Proteins/genetics*

OBJECTIVE: To explore the genetic etiology for a child featuring mental retardation, language delay and autism. METHODS: G-banding chromosomal karyotyping and single nucleotide polymorphism array (SNP-array) were carried out for the child and her parents. RESULTS: The child was found to have a 46,XX,dup(8p?) karyotype, for which both of her parents were normal. SNP-array revealed that the child has harbored a 6.8 Mb deletion in 8p23.3p23.1 and a 21.8 Mb duplication in 8p23.1p12, both of which were verified as de novo pathogenic copy number variants. CONCLUSION The clinical features of the child may be attributed to the 8p deletion and duplication. SNP-array can facilitate genetic diagnosis for children featuring mental retardation in conjunct with other developmental anomalies.
Humans ; Child ; Pregnancy ; Female ; Intellectual Disability/genetics* ; Prenatal Diagnosis ; Karyotyping ; Chromosome Banding ; Chromosome Deletion

OBJECTIVE: To explore the prevalence and clinical manifestations of ring chromosomes among children featuring abnormal development. METHODS: From January 2015 to August 2021, 7574 children referred for abnormal development were selected, and their peripheral blood samples were subjected to G-banded chromosomal karyotyping analysis. RESULTS: Twelve cases of ring chromosomes were detected, which have yielded a prevalence of 0.16% and included 1 r(6), 2 r(9), 1 r(13), 1 r(14), 2 r(15), 1 r(21) and 3 r(X). The children had various clinical manifestations including growth and mental retardation, limb malformation, and congenital heart disease. For two children with r(9) and two with r(15) with similar breakpoints, one child with r(9) and one with r(15) only had growth retardation, whilst another with r(9) and another with r(15) also had peculiar facies and complex congenital heart disease. The r(X) has featured some manifestations of Turner syndrome. CONCLUSION Ring chromosomes are among the common causes for severe growth and mental retardation in children with diverse clinical phenotypes. Clinicians should pay attention to those with developmental anomalies and use chromosomal analysis to elucidate their genetic etiology.
Humans ; Ring Chromosomes ; Intellectual Disability/genetics* ; Turner Syndrome/genetics* ; Phenotype ; Heart Defects, Congenital/genetics*

OBJECTIVE: To explore the clinical features and genetic etiology of a child with Wiedemann-Steiner syndrome. METHODS: A child with WSS who was admitted to the Hematology Department of Tianjin Children's Hospital in May 2021 was selected as the subject. Clinical data of the child was collected. Peripheral blood samples were collected from the child and his parents for the extraction of genomic DNA. The child was subjected to whole exome sequencing, and candidate variant was verified by Sanger sequencing of the child and his parents. RESULTS: The main clinical features of the child have included pancytopenia, growth and mental retardation, and facial dysmorphism. Whole exome sequencing revealed that the child has harbored a heterozygous variant of the KMT2A gene, namely c.7804delA (p.M2602Cfs*39). Sanger sequencing verified the variant to be de novo in origin. The variant was unreported previously and predicted to be pathogenic based on the guidelines of American College of Medical Genetics and Genomics (PVS1+PS2+PM2). CONCLUSION The heterozygous c.7804delA (p.M2602Cfs*39) variant of the KMT2A gene probably underlay the WSS in this child. Above finding has enriched the mutational spectrum and clinical phenotypes of the KMT2A gene.
Humans ; Abnormalities, Multiple/genetics* ; Intellectual Disability/genetics* ; Mutation ; Syndrome

OBJECTIVE: To explore the clinical phenotype and genetic basis of a neonate with Au-Kline syndrome (AKS). METHODS: Clinical data and result of genetic testing of a neonate with AKS who was admitted to the Affiliated Provincial Children's Hospital of Anhui Medical University in January 2021 were retrospectively analyzed. Relevant literature was searched from the Wanfang Data Knowledge Service Platform, China National Knowledge Infrastructure and PubMed databases using key words "Au Kline syndrome", "Au-Kline syndrome", "HNRNPK" and "AKS". The research period was set as from January 1, 2000 to December 31, 2020. RESULTS: The male newborn has manifested feeding difficulties, hypotonia, absence of the upper jaw to the uvula and facial dysmorphism. Trio-whole exome sequencing revealed that he has harbored a frameshift c.478dupA (p.Ile160AsnfsTer7) variant of the HNRNPK gene, which was varified by Sanger sequencing to have a de novo origin. The variant has not been included in the databases. Based on the guidelines from the American College of Medical Genetics and Genomics, the variant was rated as pathogenic (PVS1+PS2+PM2_Supporting). Literature retrieval has identified 14 children with AKS and de novo mutations of the HNRNPK gene. Their clinical manifestations have included growth and motor retardation, various degree of mental retardation, facial dysmorphism and a high frequency of congenital heart malformations. CONCLUSION The AKS in this child may be attributed to the c478dupA frameshifting variant of the HNRNPK gene. Diagnosis of AKS should be suspected for children with mental retardation and multiple congenital malformation syndromes including Kabuki syndrome.
Humans ; Male ; Abnormalities, Multiple/genetics* ; Genetic Testing ; Heterogeneous-Nuclear Ribonucleoprotein K/genetics* ; Intellectual Disability/genetics* ; Mutation ; Retrospective Studies ; Infant, Newborn