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Intellectual disability, neuroregression and adult-onset progressive dystonia due to a DLG4 pathogenic variant.

We report a 34-year-old male with childhood developmental delay, severe intellectual disability in adulthood, episodes of agitation with a previous diagnosis of schizoaffective disorder and adult-onset cognitive regression who developed progressive generalised dystonia due to a de novo DLG4 pathogenic loss-of-function variant. This case expands the phenotypic spectrum of recognised movement disorder manifestations associated with DLG4-related synaptopathy.

Humans

Deleterious, protein-altering variants in GSPT2 are putatively associated with an X-linked neurodevelopmental disorder with intellectual disability, language impairment, autism, and epilepsy.

PURPOSE: Approximately 6% of individuals with neurodevelopmental disorders are predicted to be X-linked, and the GSPT2 gene, located at Xp11.22, has not yet been associated with any Mendelian disease. METHODS: To establish genotype-phenotype associations between GSPT2 and neurodevelopmental disorders, clinical investigations were performed in unrelated individuals, genomic and functional studies were conducted on the participants' blood and heterologous cell system. RESULTS: We described 6 individuals from 6 unrelated families carrying hemizygous variants in GSPT2 with intellectual disability, delayed speech and language development, autism spectrum disorder, epilepsy, or abnormal fetal neurodevelopment. Structural molecular modeling revealed significant deleterious effects of the identified variants. GSPT2 is preferentially enriched in the brain and cerebellum compared with other tissues. GSPT2-deficient H4 neuroglioma cells slow down the proliferation and downregulate the expression of cell-cycle-related genes. Transcriptomics revealed that GABAergic and calcium-signaling-related genes were significantly downregulated in GSPT2-deficient cells. Consistent with the transcriptomic data, RT-PCR analysis verified the marked downregulation of critical genes (CACNA1B, etc) in GSPT2-knockout cells and further confirmed these findings with proteomic profiling. CONCLUSION: Our data suggest a putative GSPT2-related X-linked neurodevelopmental disorders through dysregulation of cell-cycle progression and calcium/GABAergic signaling pathways.

Humans

Osteogenesis imperfecta, intellectual disability and recurrent infections in a male with a pathogenic SASH3 variant.

Src Homology 3 Domain-containing Adaptor Protein 3 (SASH3) deficiency is an X-linked immune disorder. Here we identified a male case with a pathogenic SASH3 variant (c.1039C>T [p.Arg347Cys]) who presented with osteogenesis imperfecta, intellectual disability and recurrent infections. While immunological features in this case were characterized, further studies are needed to determine the association between the SASH3 variant and the skeletal or neurological manifestations.

Journal Article

Pregnancy and birth risk factors for intellectual disability in South Australia.

It is generally accepted that developmental handicaps can often be minimized through early detection and intervention. For this reason, it is normal practice in many hospitals to follow-up and screen infants who present at birth with established risk factors. Clinical judgement will always be important when selecting children for follow-up. However, as hospital data systems improve, automated systems could be developed for listing children potentially "at risk". Where initial clinical decisions not to follow-up individual children prove to be at odds with this automated output, the individual child could be re-assessed clinically. This process could increase the level of quality control. An initial risk-factor model for intellectual disability has been developed, based on the South Australian Perinatal Statistics Collection, for use in this context.

Australia

[Are we pushing the disabled intellectually into a ghetto? (AUTHOR'S TRANSL)].

Disabled people not only encounter barriers in their physical environment (in the form of steps which social rehabilitation is making efforts to level, remove or overcome through ramps) but also in the intellectual and emotional fields (in the life and thinking habits of our society, in expressions, song texts, etc.) i.e. basic expressions which seem to be applicable to the lives of the non-disabled but which prevent the disabled's access to life in the community. The examples given are: "What you are depends on what you have", "the world is beautiful", "everything will turn out all right". These expressions are, at least, as detrimental to full integration as the steps at the entrance to the post-office. The elimination of these sayings would not be beneficial to the disabled alone, but to all people: our life would become more honest and less strained. Phrases of the Biblical Message serve as the example for a thinking model which could give the impetus to a common learning process of tension release. Efforts to lessen the restraint (that is to correct the cited expressions) are called "weltanschauliche Rehabilitation", but whether this should rather be understood as a part of social rehabilitation or its parallel is a question which still remains unanswered.

Bible

A report on voluntary sterilisation with special reference to minors and women who are intellectually disabled.

There are no specific legislative provisions regulating sterilisation in any State or Territory in Australia and there is a dearth of general case law on the subject. To determine the law relating to sterilisation, we need to consider both criminal and civil liability. In the absence of specific statutory provisions, it is necessary to examine the common law and the possible application of non-specific statutory provisions in both areas.

Adolescent

Recurrent ATP1A1 variant Gly903Arg causes developmental delay, intellectual disability, and autism.

ATP1A1 encodes a sodium-potassium ATPase that has been linked to several neurological diseases. Using exome and genome sequencing, we identified the heterozygous ATP1A1 variant NM_000701.8: c.2707G>A;p.(Gly903Arg) in two unrelated children presenting with delayed motor and speech development and autism. While absent in controls, the variant occurred de novo in one proband and co-segregated in two affected half-siblings, with mosaicism in the healthy mother. Using a specific ouabain resistance assay in mutant transfected HEK cells, we found significantly reduced cell viability. Demonstrating loss of ATPase function, we conclude that this novel variant is pathogenic, expanding the phenotype spectrum of ATP1A1.

Child

Two iPSC lines with frameshift mutations in FTSJ1 as models for X-linked non-syndromic intellectual disability.

CRISPR/Cas9 was used to introduce two different FTSJ1 frameshift mutations into an existing human male iPSC line (UMGWi004-B). No additional genomic or chromosomal changes were detected. The modified iPSC express different stem cell markers and can be induced to differentiate into cells from all three germ layers. FTSJ1 is ubiquitously expressed and mutations in this X-chromosomal gene are involved in an intellectual developmental disorder (OMIM: #309549). These cells can be used to model the disease at the cellular and organoid level in their original state or after differentiation into cell types of interest.

Journal Article

An analysis of WISC-R factors for gifted students with learning disabilities.

Intellectual patterns of gifted students with learning disabilities were studied to determine cognitive factors characterizing these children. Twenty-four gifted children with learning disabilities (LD) and a control group of nondisabled gifted children were administered the Wechsler Intelligence Scale for Children-Revised (WISC-R) (Wechsler, 1974). While differences between the two groups on individual subtests were examined, a comparison of broader factors was emphasized in discovering cognitive patterns that might suggest effective intervention. Experimental and control performances were compared on 14 factor scores, using cognitive classification systems of Bannatyne (1971), Kaufman (1975), Rapaport, Gill, and Schafer (1946), and Wechsler (1974). Gifted students with LD were more reliant on verbal conceptualization and reasoning than the control students. They also demonstrated deficiencies in short-term auditory memory and sound discrimination. The gifted group with LD exhibited the Organic Brain Syndrome factor (Wechsler, 1974) to a significantly greater extent than did the control group.

Achievement

RORA-neurodevelopmental disorder: A unique triad of developmental disabilities, cerebellar anomalies, and myoclonic seizures.

PURPOSE: RORA encodes the RAR-related orphan receptor-α, playing a pivotal role in cerebellar maturation and function. Here, we report the largest series of individuals with RORA-related-neurodevelopmental disorder. METHODS: Forty individuals (30 unrelated; 10 siblings from 4 families) carrying RORA pathogenic/likely pathogenic variants were collected through an international collaboration. RESULTS: The 33 variants (29 de novo, 4 inherited, and 1 shared), identified by genome/exome sequencing (n = 21), chromosomal microarray analysis (n = 7), or gene panels (n = 4), included frameshift (n = 18/33), missense (n = 9/33), and stop codon (n = 6/33). Developmental disability (n = 32/37), intellectual disability (n = 22/32), and cerebellar signs (n = 25/34) were the most striking clinical features. Cerebellar symptoms were divided into early-onset, late-onset, and progressive subgroups. Cerebellar hypoplasia, atrophy, or both (n = 16/25) were more frequent in individuals with missense variants in the DNA-binding domain. Epilepsy (n = 18/38), with prominent myoclonic seizure types (n = 11/18), was classified in (1) genetic generalized epilepsy (n = 10/18) with a syndromic diagnosis identifiable for 6: epilepsy with eyelid myoclonia (n = 5/6) and epilepsy with myoclonic absence (n = 1/6); (2) developmental and epileptic encephalopathy (n = 5/18); and (3) unclassified (n = 3/18). A participant with rapid deterioration of visual acuity and cone/rod dystrophy was reported. CONCLUSION: Missense variants in DNA-binding domain correlate to a more severe cerebellar phenotype. The RORA-related-neurodevelopmental disorder triad comprises developmental disability, cerebellar features, and a spectrum of myoclonic epilepsy.

Humans

Unraveling a Diagnostic Enigma: A TECPR2 Case Solved Through Multi-Omic Genomics.

TECPR2 is a key regulator of autophagy, encoded by the TECPR2 gene. Pathogenic variants in this gene have been linked to a rare hereditary sensory and autonomic neuropathy with intellectual disability (HSAN9). We report a teenage female with a syndromic intellectual disability disorder associated with neuromuscular abnormalities. Multi-omics analysis including genomics, transcriptomics, and proteomics, together with muscle biopsy from the affected individual, were used in this clinical case. Through trio exome sequencing we identified two heterozygous variants in the TECPR2 gene, NM_014844.4: c.480G>A; p.(Gln160=) and c.2846C>A; p.(Ala949Glu). Both were classified as variants of uncertain significance due to the lack of supporting evidence for pathogenicity. Subsequent long-read sequencing phased the variants and confirmed they were in trans. Additional functional studies using RNAseq and proteomics analyses verified the pathogenicity of the variants. This case study demonstrated the value of a multi-omics assisted analysis, which complemented the traditional phenotype-first approach in reaching a definitive clinical diagnosis.

Humans

INPP5K-related muscular dystrophy caused by a novel synonymous splicing variant in a Chinese patient: a case report.

Congenital muscular dystrophies (CMDs) are a genetically heterogeneous group of disorders. Variants in the INPP5K gene, which encodes a phosphoinositide phosphatase, are a rare cause of CMD. The condition is commonly associated with muscle weakness, early-onset cataracts, and intellectual disability, and prior reports have primarily identified missense, frameshift, or deletion variants. We describe the first Chinese case of INPP5K-related muscular dystrophy in a 28-year-old male with a mild phenotype, notably lacking intellectual disability. His presentation included bilateral cataracts at age 5 and adolescent onset limb girdle weakness. Muscle magnetic resonance imaging (MRI) revealed a characteristic pattern of selective fatty infiltration, with severe involvement of gluteal and thigh muscles and striking sparing of the rectus femoris, sartorius, and gracilis. Genetic analysis identified compound heterozygous novel INPP5K variants: a missense c.274C>T, p.(Arg92Cys) and a synonymous c.261G>A, p.(Lys87=) change. Functional studies confirmed the synonymous variant causes aberrant splicing (exon 3 skipping), leading to a frameshift and premature termination p.(Leu52SerfsTer49). According to American College of Medical Genetics and Genomics guidelines, the c.274C>T and c.261G>A variants were classified as likely pathogenic and pathogenic, respectively. This first report of a Chinese patient with INPP5K-related muscular dystrophy broadens both the genetic and clinical spectrum of the disorder. We identify the first disease-causing synonymous variant (via aberrant splicing) and a novel hypomorphic missense variant p.(Arg92Cys), the combination of which explains the attenuated phenotype lacking intellectual disability. Our case highlights the critical role of RNA analysis in diagnosing non-canonical variants and confirms the universal diagnostic relevance of the characteristic muscle MRI pattern.

Adult

Biallelic ABCA13 Loss-of-Function Variants in a Child With Neurodevelopmental Delay: A Case Report.

ABCA13 encodes ATP-binding cassette subfamily A member 13, one of the largest members of the ABC transporter family. Rare ABCA13 variants have been reported in neuropsychiatric and neurodevelopmental phenotypes, including schizophrenia, bipolar disorder, autism spectrum disorder, intellectual disability, and developmental delay; however, the mode of inheritance remains uncertain, and most published cases have focused on heterozygous variants in the context of a possible dominant or susceptibility model. We report a 5-year-old boy with neurodevelopmental delay, skeletal foot deformities, nonspecific dysmorphic features, convergent strabismus, and behavioral abnormalities. Initial genome sequencing analysis was nondiagnostic. Reanalysis after 6 months identified two rare predicted loss-of-function variants in ABCA13 in trans: c.2510del, p.(Leu837TyrfsTer21), a frameshift variant, and c.12064C>T, p.(Arg4022Ter), a nonsense variant previously reported in a patient with unexplained intellectual disability. The identification of compound heterozygous predicted loss-of-function variants supports the possibility that biallelic disruption of ABCA13 may contribute to neurodevelopmental disease, whereas previously reported heterozygous variants may represent incompletely penetrant risk alleles, susceptibility factors, or candidate findings rather than fully penetrant dominant causes. This case expands the emerging clinical and genetic spectrum associated with ABCA13 and supports further evaluation of a recessive model in patients with intellectual disability and neurodevelopmental delay.

ABCA13

Effect of the OPHN1 novel variant c.1025+1 G>A on RNA splicing: insights from a minigene assay.

This research analyzes the clinical data, whole-exome sequencing results, and in vitro minigene functional experiments of a child with developmental delay and intellectual disability. The male patient, aged 4, began experiencing epileptic seizures at 3 months post-birth and has shown developmental delay. Rehabilitation training was administered between the ages of one and two. There were no other significant family medical histories. Through comprehensive family exome genetic testing, a hemizygous variant in the 11th exon of the OPHN1 gene was identified in the affected child: c.1025 + 1G > A. Family segregation analysis confirmed the presence of this variant in the patient's mother, which had not been previously reported. According to the ACMG guidelines, this variant was classified as a likely pathogenic variant. In response to this variant, an in vitro minigene functional experiment was designed and conducted, confirming that the mutation affects the normal splicing of the gene's mRNA, resulting in a 56 bp retention on the left side of Intron 11. It was confirmed that OPHN1: c.1025 + 1G > A is the pathogenic cause of X-linked intellectual disabilities in the child, with clinical phenotypes including developmental delay and seizures.

Humans

De Novo 2.2 Mb 19q13.42-q13.43 Microdeletion Encompassing U2AF2: Support for a Haploinsufficiency Model.

U2 small nuclear RNA auxiliary factor 2 (U2AF2) is an essential pre-mRNA splicing factor involved in the early stages of pre-mRNA splicing. To date, multiple individuals have been reported with predominantly heterozygous missense variants presenting intellectual disability, speech and motor delays, seizures, hypotonia, and thin or hypoplastic corpus callosum. Here, we describe a patient with a de novo 2.2 Mb interstitial deletion involving chromosome 19q13.42-q13.43, encompassing U2AF2, presenting with intellectual disability, epilepsy, corpus callosum hypoplasia, dysmorphic features, and congenital heart disease. The patient's clinical features overlap substantially with those reported in individuals harboring heterozygous U2AF2 variants, supporting haploinsufficiency as a plausible disease mechanism. To our knowledge, this represents the first postnatal report of complete U2AF2 gene deletion. In addition, this is the first detailed phenotypic characterization of a distal 19q chromosomal interstitial deletion, further delineating the clinical spectrum associated with this genomic region.

Humans

Increasing histone acetylation improves sociability and restores learning and memory in KAT6B-haploinsufficient mice.

Mutations in genes encoding chromatin modifiers are enriched among mutations causing intellectual disability. The continuing development of the brain postnatally, coupled with the inherent reversibility of chromatin modifications, may afford an opportunity for therapeutic intervention following a genetic diagnosis. Development of treatments requires an understanding of protein function and models of the disease. Here, we provide a mouse model of Say-Barber-Biesecker-Young-Simpson syndrome (SBBYSS) (OMIM 603736) and demonstrate proof-of-principle efficacy of postnatal treatment. SBBYSS results from heterozygous mutations in the KAT6B (MYST4/MORF/QFK) gene and is characterized by intellectual disability and autism-like behaviors. Using human cells carrying SBBYSS-specific KAT6B mutations and Kat6b heterozygous mice (Kat6b+/-), we showed that KAT6B deficiency caused a reduction in histone H3 lysine 9 acetylation. Kat6b+/- mice displayed learning, memory, and social deficits, mirroring SBBYSS individuals. Treatment with a histone deacetylase inhibitor, valproic acid, or an acetyl donor, acetyl-carnitine (ALCAR), elevated histone acetylation levels in the human cells with SBBYSS mutations and in brain and blood cells of Kat6b+/- mice and partially reversed gene expression changes in Kat6b+/- cortical neurons. Both compounds improved sociability in Kat6b+/- mice, and ALCAR treatment restored learning and memory. These data suggest that a subset of SBBYSS individuals may benefit from postnatal therapeutic interventions.

Animals