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PubMed2026

Clinical Application of Long-Read Sequencing for FMR1 Gene Mutation Detection in Populations From Shandong, China.

BACKGROUND: Fragile X syndrome (FXS) is a common inherited intellectual disability. In this study, long-read sequencing was used for the FMR1 gene detection. METHODS: Men with familial inherited intellectual disability and women with indications for FXS screening were defined as high-risk populations and were included in this study along with non-high-risk reproductive-aged women. PCR-capillary electrophoresis was used for preliminary screening of non-high-risk reproductive-aged women, and long-read sequencing was performed on abnormal samples and samples from high-risk populations. Prenatal diagnosis using long-read sequencing was performed for pregnant women in need. RESULTS: The prevalence of mutation in high-risk females was 3.10% (7/226). 3 mutations were detected in male samples, with a mutation ratio of approximately 8.3% (3/36). The three most common CGG repeats were 29, 30, and 36, respectively. Analysis of AGG interruption pattern in 242 samples identified 908 AGG interruptions, involving 67 different patterns. The most frequent AGG interruption pattern was (CGG)9AGG(CGG)9AGG(CGG)9. Furthermore, long-read sequencing was successfully applied for prenatal diagnosis in two pregnant women, and dynamic mutation of CGG repeat was detected within one family. CONCLUSION: Long-read sequencing-based assay cannot only accurately detect CGG repeat and AGG interruption, but also simultaneously identify other abnormalities of the FMR1 gene. Long-read sequencing offers a broader detection scope and better characterization of FXS-related genetic features.

Humans↗

PubMed1992

Communication abilities and Rett syndrome.

Investigated 6 girls with Rett syndrome (RS), ages between 2 and 13 years, to provide comprehensive descriptions of their communicative behaviors. Previous studies have not focused on communicative competence nor on the intentionality of the language used by children with RS. This study concluded that all members of the group investigated were at a preintentional level of communication. Intentional communication has previously been reported to develop in normally developing and intellectually disabled children attaining Piagetian Sensorimotor Stage V in Means-End behavior. The present study also investigated the cognitive performance of the group. We concluded that the preintentional level of communication noted was consistent with the subjects' profound intellectual disability. No Means-End (i.e., purposeful) behavior beyond Piagetian Sensorimotor Stage III could be elicited from the 6 girls. The relevance of this study for therapeutic intervention is discussed.

Adolescent↗

PubMed2025

A novel frameshift variant leads to familial osteopetrosis with variable phenotypes in a Chinese Han consanguineous family.

Osteopetrosis, a group of highly heterogeneous genetic bone disorders, is characterized by deafness, increased bone density, hepatosplenomegaly, pancytopenia and intellectual disability. Osteopetrosis can be divided into three subtypes: autosomal recessive osteopetrosis (ARO), intermediate autosomal recessive osteopetrosis (IARO), and autosomal dominant osteopetrosis (ADO). CLCN7 has been reported to be the most common gene responsible for the ADO-II subtype. In this study, a novel variant, c.175dupA (p.Met59Asnfs*8), of CLCN7 was identified in a Chinese Han consanguineous family with suspected ADO-II. The proband was homozygous for the p.Met59Asnfs*8 variant and exhibited multiple severe phenotypes, including deafness, short stature, brittle bones, optic atrophy, hepatosplenomegaly, intellectual disability, cleft palate and recurrent infection. However, except for the mother of the proband, who presented a series of clinical phenotypes caused by bone marrow failure, all the other family members who were heterozygous had no obvious abnormal phenotypes. Our study suggested that the novel variant p.Met59Asnfs*8 in CLCN7 was very likely pathogenic factor in our suspected ADO-II family. The phenotypes of heterozygous carriers may be affected by incomplete penetrance. Loss of function of CLCN7 caused by nonsense-mediated mRNA decay (NMD) due to the frameshift variant was likely the underlying pathogenic mechanism. This study broadened the mutation spectrum of CLCN7, provided a foundation for timely and effective clinical intervention for related diseases, and demonstrates the importance of genetic counselling.

Adult↗

PubMed1992

Assessment and training of functional conversation behaviour.

Measures for the assessment of initial, dyadic conversations are critically reviewed, and an alternative approach is described. The Verbal Interaction Analysis System is illustrated by two case studies featuring mildly to moderately intellectually disabled adults. These studies show how the VIAS provides an index of competence and assists in the development of specific treatment strategies. Social validity is examined in each case, and suggestions are made for improvements to the VIAS.

Adult↗

PubMed2025

KLHL13 functional defects cause neurodevelopmental disorder in humans that can be rescued via inhibition of AURKB in cellular and animal models.

PURPOSE: Neurodevelopmental disorders (NDDs) are characterized by limitations in brain development. This study aims to determine the genetic causes of NDD in humans. METHODS: Exome sequencing was used to detect genetic variants of KLHL13, which encodes Kelch like protein 13 (KLHL13), in four families segregating in an X-linked pattern. In silico protein modeling and overexpression in heterologous cells were used to determine the variant's impact. klhl13 loss of function was modeled in zebrafish, followed by rescue studies using human KLHL13 messenger RNA (mRNA) and an Aurora Kinase B (AURKB) inhibitor. RESULTS: We found one frameshift and three missense hemizygous variants of KLHL13 in individuals exhibiting NDD characteristics, such as intellectual disability (ID) and macrocephaly. Three-dimensional protein modeling simulation predicted the alteration of the KLHL13 protein folding for missense variants. Overexpression of NDD-associated variants in HEK293T cells revealed a significant impact on KLHL13-mediated cell-cycle regulation during mitosis, leading to genomic instability. Knocking down klhl13 in zebrafish resulted in developmental deficits, which were rescued by coinjection of human KLHL13WT messenger RNA but not by transcript encoding NDD variants. Treatment with AURKB selective inhibitor AZD1152-HQPA rescued genomic stability in heterologous cells and neurobehavioral deficits in zebrafish. CONCLUSION: Our results implicate KLHL13-mediated AURKB regulation as a significant contributor to NDD in humans. Inhibiting AURKB activity could serve as a potential therapeutic approach to improve brain development and cognitive function.

Humans↗

PubMed2023

De novo variants in MRTFB have gain-of-function activity in Drosophila and are associated with a novel neurodevelopmental phenotype with dysmorphic features.

PURPOSE: Myocardin-related transcription factor B (MRTFB) is an important transcriptional regulator, which promotes the activity of an estimated 300 genes but is not known to underlie a Mendelian disorder. METHODS: Probands were identified through the efforts of the Undiagnosed Disease Network. Because the MRTFB protein is highly conserved between vertebrate and invertebrate model organisms, we generated a humanized Drosophila model expressing the human MRTFB protein in the same spatial and temporal pattern as the fly gene. Actin binding assays were used to validate the effect of the variants on MRTFB. RESULTS: Here, we report 2 pediatric probands with de novo variants in MRTFB (p.R104G and p.A91P) and mild dysmorphic features, intellectual disability, global developmental delays, speech apraxia, and impulse control issues. Expression of the variants within wing tissues of a fruit fly model resulted in changes in wing morphology. The MRTFBR104G and MRTFBA91P variants also display a decreased level of actin binding within critical RPEL domains, resulting in increased transcriptional activity and changes in the organization of the actin cytoskeleton. CONCLUSION: The MRTFBR104G and MRTFBA91P variants affect the regulation of the protein and underlie a novel neurodevelopmental disorder. Overall, our data suggest that these variants act as a gain of function.

Animals↗

PubMed1992

The intensive mothercraft program--a report.

A report on the Intensive Mothercraft Program (IMP) developed at The Queen Elizabeth Hospital (TEQH) Adelaide. This program was developed in 1987 mainly in response to needs demonstrated by parents, who were physically and/or intellectually disabled.

Persons with Disabilities↗

PubMed2023

De novo missense variants in ZBTB47 are associated with developmental delays, hypotonia, seizures, gait abnormalities, and variable movement abnormalities.

The collection of known genetic etiologies of neurodevelopmental disorders continues to increase, including several syndromes associated with defects in zinc finger protein transcription factors (ZNFs) that vary in clinical severity from mild learning disabilities and developmental delay to refractory seizures and severe autism spectrum disorder. Here we describe a new neurodevelopmental disorder associated with variants in ZBTB47 (also known as ZNF651), which encodes zinc finger and BTB domain-containing protein 47. Exome sequencing (ES) was performed for five unrelated patients with neurodevelopmental disorders. All five patients are heterozygous for a de novo missense variant in ZBTB47, with p.(Glu680Gly) (c.2039A>G) detected in one patient and p.(Glu477Lys) (c.1429G>A) identified in the other four patients. Both variants impact conserved amino acid residues. Bioinformatic analysis of each variant is consistent with pathogenicity. We present five unrelated patients with de novo missense variants in ZBTB47 and a phenotype characterized by developmental delay with intellectual disability, seizures, hypotonia, gait abnormalities, and variable movement abnormalities. We propose that these variants in ZBTB47 are the basis of a new neurodevelopmental disorder.

Child↗

PubMed2026

The Homozygous p.(Arg215Ter) Variant in XRCC2 Is Associated With Atypical Fanconi Anemia Without Major Hematological Abnormalities in Childhood.

Fanconi Anemia (FA) is the most frequent inherited bone marrow failure syndrome. A role for the XRCC2 gene in FA was suspected in 2012 and confirmed in 2016, but only two affected individuals have been described thus far, and no long-term follow-up is available. Here we present two young related adults born to consanguineous parents, in whom we identified the homozygous p.(Arg215Ter) variant in XRCC2. Both patients presented with mild intellectual disability, microcephaly, distinctive facial features, short stature, thumb abnormalities, and abnormal skin pigmentation. Unlike in FA, DEB test resulted negative in peripheral blood during childhood and no cytopenia, clonal evolution, or other hematological complications were detected until the age of 19 and 20 years, respectively. Our report suggests that the homozygous p.(Arg215Ter) variant in XRRC2 causes a distinctive FA-like disorder, characterized by the typical physical characteristics seen in FA, but a lack of major hematological manifestations in childhood, and the presence of a more pronounced neurodevelopmental phenotype than that seen in FA.

Humans↗

PubMed2022

Biallelic variants in ZNF142 lead to a syndromic neurodevelopmental disorder.

Biallelic variants of the gene encoding for the zinc-finger protein 142 (ZNF142) have recently been associated with intellectual disability (ID), speech impairment, seizures, and movement disorders in nine individuals from five families. In this study, we obtained phenotype and genotype information of 26 further individuals from 16 families. Among the 27 different ZNF142 variants identified in the total of 35 individuals only four were missense. Missense variants may give a milder phenotype by changing the local structure of ZF motifs as suggested by protein modeling; but this correlation should be validated in larger cohorts and pathogenicity of the missense variants should be investigated with functional studies. Clinical features of the 35 individuals suggest that biallelic ZNF142 variants lead to a syndromic neurodevelopmental disorder with mild to moderate ID, varying degrees of delay in language and gross motor development, early onset seizures, hypotonia, behavioral features, movement disorders, and facial dysmorphism. The differences in symptom frequencies observed in the unpublished individuals compared to those of published, and recognition of previously underemphasized facial features are likely to be due to the small sizes of the previous cohorts, which underlines the importance of larger cohorts for the phenotype descriptions of rare genetic disorders.

Humans↗

PubMed2026

Bi-allelic loss-of-function variants in JKAMP cause a neurodevelopmental syndrome associated with dysregulation of GPR37 trafficking.

The endoplasmic reticulum (ER) serves as a key hub for protein homeostasis, maintaining a strict quality-control system that ensures only properly folded proteins reach their destinations, while misfolded proteins are degraded via ER-associated degradation (ERAD) or selective ER-phagy. JKAMP, which encodes an ER-resident transmembrane protein involved in ERAD, has not previously been associated with human disease. Here, we report bi-allelic loss-of-function variants in JKAMP in 14 affected individuals from 10 unrelated families presenting with a neurodevelopmental syndrome characterized by intellectual disability, developmental delay, seizures, hypotonia, microcephaly, and dysmorphic features. An in vivo zebrafish model lacking jkamp recapitulated key aspects of the human disorder, including developmental abnormalities and impaired myelin production, further corroborating its pathogenic role. Mechanistic studies identified GPR37, a brain-enriched orphan G protein-coupled receptor (GPCR) and known JKAMP interactor, as a critical downstream effector. GPR37 plays essential roles in dopaminergic signaling, inflammatory pain regulation, neuroprotection, and myelination. Loss of JKAMP resulted in defective folding and degradation of GPR37, leading to its accumulation within the ER and impaired trafficking to the plasma membrane, likely due to impaired ER quality control. These findings establish JKAMP as a previously unrecognized contributor to human neurodevelopment and uncover a pathogenic mechanism linking ER protein quality control to GPCR regulation and neurological disease.

Humans↗

PubMed1991

Dental health of disabled children in Singapore.

The oral health status of the disabled has generally been poorer than the general population as the treatment and care afforded to them has been minimal. This paper examines the relationship of the various types of disabilities to dental health status. The dental status of a random sample of 322 disabled children aged between 6 and 18 years was assessed. The children had various disabilities: intellectual, hearing, visual, and musculo-skeletal. Most differences in the prevalence and severity of the dental conditions assessed among the children in the various disability groups were not significant. However, in comparison with normal schoolchildren aged 6 to 18, the disabled children had higher levels of disease and received less dental attention.

Adolescent↗

PubMed2026

Novel splice-site and recurrent p.Arg729* CNKSR2 variants in ESES/CSWS: insights into sex-dependent expression.

PURPOSE: Pathogenic variants in CNKSR2 (Xp22.12) cause an X-linked neurodevelopmental disorder with intellectual disability, language impairment, and a distinctive epilepsy phenotype, including encephalopathy with status epilepticus during slow-wave sleep (ESES/CSWS). Hemizygous males are typically severely affected, whereas symptomatic females remain rare and incompletely characterized. We describe two unrelated patients with de novo CNKSR2 variants to expand the mutational and sex-dependent phenotypic spectrum of this disorder. METHODS: Both patients underwent clinical, electroencephalographic, and neuroimaging evaluation. CNKSR2 variants were identified by whole exome sequencing with parental segregation, and the splice-site variant was assessed in silico (SpliceAI, MaxEntScan, Human Splicing Finder). RESULTS: Patient 1, a 17-year-old female, harbored a novel canonical splice-site variant (c.64+1G>A) in the N-terminal region and presented with a relatively mild phenotype. In silico analysis supported abolition of the canonical donor splice site. Patient 2, an 8-year-old male, carried a de novo nonsense variant (c.2185C>T, p.Arg729*) and exhibited drug-resistant ESES, autism, and severe language impairment. p.Arg729* had previously been reported in one independent male. Our case represents its second independent occurrence, a CGA>TGA transition at a CpG dinucleotide consistent with a mutational hotspot. CONCLUSION: Together, these cases expand the mutational spectrum and provide further evidence for sex-dependent phenotypic variability in CNKSR2-related epilepsy. Our observations support the hypothesis that X-chromosome inactivation may contribute to phenotypic variability in females, although XCI was not assessed here, and support inclusion of CNKSR2 in epilepsy gene panels regardless of sex.

Humans↗

PubMedDate not supplied

A regional survey of the housing circumstances of families with children experiencing intellectual and motor disabilities.

Housing is an important aspect in promoting the home care of disabled children, but also one which is too often forgotten by professionals. The purpose of this study was to evaluate the housing conditions and the need for modifications, of 204 families with disabled children using technical aids. The housing condition of the families was good compared to average Finnish families with children. One hundred and sixty families had made no housing modifications, but 48 families had need for them, most often to bathrooms and toilets. The need increased with the severity of the children's motor and intellectual disabilities and the need to provide care in line with the number of technical aids in use. It is concluded that families with disabled children need more information on the possibilities for carrying out housing modifications, and that home visits by a case manager are important to evaluate environmental factors affecting the care.

Adolescent↗

PubMed2026

Prominent Movement Disorders in RNU2-2-Related Spliceosomopathy.

Pediatric movement disorders often overlap with neurodevelopmental diseases, suggesting shared molecular mechanisms. Variants in small nuclear RNA (snRNA) genes encoding spliceosome components have recently been associated with neurodevelopmental disorders, termed "RNUopathies." We analyzed genome sequencing data from 14 patients with undiagnosed pediatric movement disorders for pathogenic variants in snRNA genes. We identified recurrent de novo RNU2-2 variants (n.35A > G and n.4G > A) in two patients with intellectual disability, epilepsy, and hyperkinetic movement disorders. RNA sequencing of fibroblasts in one patient showed no characteristic transcriptomic signature. Spliceosomopathies should be considered in neurodevelopmental disorders and developmental and epileptic encephalopathies with hyperkinetic features.

Humans↗

PubMed1992

The family v. the family court: sterilisation issues.

Parents as guardians of minor children have the right and duty to give and withhold consent to medical treatment when the treatment is neither routine nor urgent. Parental authority, however, is not absolute and dwindles as the child gradually matures. In general, teenagers can give consent to medical treatment if they understand the nature and consequences of the proposed treatment. The diminution of parental authority is based on the premise that the child will eventually become autonomous. In cases where a sterilisation or hysterectomy procedure is being considered for a severely intellectually disabled teenager the question of consent is most contentious. Should this power belong to parents or the state? This paper examines some recent Family Court cases concerning this issue and also addresses questions about human rights, medical autonomy and the role of the Family Court. Finally, a proposal for an alternative means of decision-making in these cases is briefly outlined.

Adolescent↗

PubMed1990

Interstitial deletion of the band 4p15.3 defined by sequential replication banding.

A 15-year-old boy with intellectual disability was found to have a de novo interstitial deletion in the short arm of chromosome 4. Using GTL banding and sequential replication banding the deleted band was found to be the more terminal of the two G dark sub-bands of 4p15, that is 4p15.3. The karyotype was defined as 46,XY,del(4)(p15.2p16.100). To our knowledge this specific deletion has not been previously described.

Abnormalities, Multiple↗

PubMed2025

Diagnostic and clinical utility of exome sequencing and chromosomal microarray in children with GDD/iD: a meta-analysis.

BACKGROUND: Global developmental delay/intellectual disability (GDD/ID) is among the most common neurodevelopmental disorders, with up to half of cases are attributed to genetic factors. Chromosome microarray (CMA) has traditionally been the primary genetic test for idiopathic GDD/ID. However, whole exome sequencing (WES) and whole genome sequencing (WGS) have recently emerged, substantially increasing diagnostic yields in these populations. METHODS: We conducted a comprehensive literature search of PubMed, Scopus, EMBASE, and the Cochrane Library from inception to April 29, 2025. Studies reporting the diagnostic utility of these tests in children with GDD/ID were included and analyzed. RESULTS: A total of 102 studies, comprising 55,752 children, were reviewed. The pooled diagnostic yield of WES was 0.37 (95% CI: 0.33-0.41; I2 = 93%), significantly higher than that of CMA at 0.19 (95% CI: 0.16-0.21; I2 = 95%). Subgroup analyses showed that WES yielded significantly higher diagnostic rates than CMA in both same-sample comparisons (OR = 2.27, 95% CI: 1.08-4.78) and different-sample comparisons (OR = 1.65, 95% CI: 1.15-2.37). Only one study evaluated WGS, reporting a diagnostic yield of 0.27. Meta-regression revealed a significant association between CMA diagnostic yield and the proportion of male participants (p < 0.01), but not with WES. No significant difference in diagnostic utility was observed between isolated GDD/ID and GDD/ID with comorbidities. CONCLUSION: In children with unexplained GDD/ID, WES demonstrates superior diagnostic and clinical utility compared to CMA. Incorporating WES as a first-line investigation in the diagnostic evaluation of GDD/ID may be warranted.

Humans↗