Home / Deep Research / Autosomal Dominant Non-Syndromic Intellectual Disability

Autosomal Dominant Non-Syndromic Intellectual Disability

Autosomal Dominant Non-Syndromic Intellectual Disability: Disease Characteristics Report

2026-07-31
Falcon MONDO:0015802 Model: Edison Scientific Literature 37 citations

Autosomal Dominant Non-Syndromic Intellectual Disability: Disease Characteristics Report

Executive summary and scope

Autosomal dominant non-syndromic intellectual disability (AD-NSID) is not one uniform disorder. It is an umbrella for genetically heterogeneous neurodevelopmental disorders in which a heterozygous pathogenic variant causes intellectual and adaptive-function impairment as the principal phenotype, without a consistently recognizable congenital-malformation or multisystem syndrome. The preferred umbrella identifier is MONDO:0015802. It should be kept distinct from broader autosomal dominant intellectual disability (MONDO:0100172) and from numbered, gene-specific OMIM/MONDO entities. “Non-syndromic,” “nonspecific,” “isolated,” and “autosomal dominant mental retardation” are historical or alternative terms; however, “non-syndromic” is provisional because deeper phenotyping often identifies speech, behavioral, epileptic, growth, or subtle dysmorphic features. Open Targets currently associates MONDO:0015802 with genes including TLK2, ASH1L, STAG1, CLTC, CAMK2A, CIC, NAA15, TRIP12, KMT5B, TRIO, SET, and DLG4. This is a representative—not exhaustive—list and changes as gene–disease validity is reassessed. (OpenTargets Search: autosomal dominant intellectual disability)

Most evidence is aggregated from disease databases, gene-discovery studies, and mixed DD/ID sequencing cohorts, not from a single disease-specific EHR registry. Consequently, epidemiologic and phenotype frequencies reported for general ID/DD must not be interpreted as exact frequencies for MONDO:0015802.

Table (click to expand)
Domain Current evidence Suggested ontology/identifier
Scope / definition Autosomal dominant non-syndromic intellectual disability is best treated as a heterogeneous umbrella disorder rather than a single uniform entity. Open Targets maps autosomal dominant non-syndromic intellectual disability to MONDO:0015802 and lists representative associated genes including TLK2, ASH1L, STAG1, CLTC, CAMK2A, CIC, NAA15, TRIP12, KMT5B, TRIO, SET, DLG4; broader autosomal dominant ID is separated as MONDO:0100172. NSID denotes ID as the principal/isolated phenotype, though many reported “non-syndromic” cases may later accrue additional neurodevelopmental features (OpenTargets Search: autosomal dominant intellectual disability, maia2021intellectualdisabilitygenomics pages 1-2). MONDO:0015802; related umbrella: MONDO:0100172
Disease level vs patient level evidence Available evidence is mainly aggregated from disease/gene discovery studies, sequencing cohorts, and reviews; this is not primarily an EHR-derived single-disease registry. Most current knowledge comes from heterogeneous DD/ID/NDD cohorts in which AD de novo etiologies are overrepresented (li2024triowholeexomesequencing pages 1-2, ko2023genomewidesequencingmodalities pages 2-4, maia2021intellectualdisabilitygenomics pages 1-2). Evidence type: aggregated disease/gene-level resource
Cardinal phenotype: intellectual disability ID is defined by impaired intellectual functioning and adaptive behavior; overall ID prevalence is commonly cited at 1–3% worldwide, with GDD/ID together affecting nearly 2% of the pediatric population. Severity can range mild to profound; severe/profound forms are more often monogenic (maia2021intellectualdisabilitygenomics pages 1-2, ko2023genomewidesequencingmodalities pages 1-2, liaci2021neuronalcytoskeletonin pages 1-2). HPO: Intellectual disability HP:0001249; Global developmental delay HP:0001263
Common associated neurodevelopmental phenotypes Across DD/ID cohorts and mechanism reviews, common co-phenotypes include developmental delay, speech/language delay, seizures/epilepsy, autism/behavioral abnormalities, microcephaly, and dysmorphic features; these often increase diagnostic yield even when the target label is “non-syndromic” (li2024triowholeexomesequencing pages 1-2, ko2023genomewidesequencingmodalities pages 2-4, wayhelova2024exomesequencingimproves pages 1-2, kim2024diagnosticyieldof pages 1-2). HPO: Developmental delay HP:0001263; Speech delay HP:0000750; Seizure HP:0001250; Autism HP:0000717; Behavioral abnormality HP:0000708; Microcephaly HP:0000252; Facial dysmorphism HP:0001999
Representative causal genes: synaptic / excitability Representative AD genes linked in umbrella resources or cohort literature include GRIN1, DLG4, CAMK2A, TRIO, NRXN1, STXBP1, DYRK1A, KIF1A, GNB1; these converge on synapse formation/function, neuronal signaling, and plasticity (OpenTargets Search: autosomal dominant intellectual disability, vas2023regulatorydenovo pages 1-2, ford2023dendriticspineand pages 1-2). HGNC gene symbols; GO: synapse organization GO:0050808; regulation of synaptic plasticity GO:0048167
Representative causal genes: chromatin / transcription / cohesin Representative AD genes include ASH1L, KMT5B, STAG1, CIC, TLK2, ARID1B, KANSL1, WDR5 and related chromatin modifiers highlighted as strong ASD/ID susceptibility factors affecting dendritic spine and synapse biology (OpenTargets Search: autosomal dominant intellectual disability, vas2023regulatorydenovo pages 1-2, ford2023dendriticspineand pages 1-2). HGNC gene symbols; GO: chromatin organization GO:0006325; regulation of transcription by RNA polymerase II GO:0006357
Representative causal genes: cytoskeleton / trafficking / neuronal morphogenesis Reviews emphasize convergence of many ID genes on cytoskeleton dynamics and Rho GTPase-regulated neuronal migration, neuritogenesis, and synaptic plasticity; examples include TRIO, KIF1A, CLTC and Rho-pathway-related genes in broader ID biology (liaci2021neuronalcytoskeletonin pages 1-2). GO: actin cytoskeleton organization GO:0030036; microtubule cytoskeleton organization GO:0000226; neuron projection development GO:0031175
Variant classes / molecular lesion types Relevant pathogenic mechanisms include coding missense, nonsense, frameshift, splice, CNVs, small structural variants, and increasingly regulatory de novo mutations in fetal-brain enhancers. Vas et al. showed regulatory DNMs enriched in fetal brain-specific enhancers, with recurrent enhancer clusters linked to CSMD1, OLFM1, POU3F3 (vas2023regulatorydenovo pages 1-2, kim2024diagnosticyieldof pages 1-2). Variant classes per ACMG/AMP; regulatory regions / enhancers
Inheritance / de novo contribution AD ID is often caused by de novo variants, especially in moderate/severe disease. In a Finnish ID cohort, 75% of variants in known ID genes were de novo/suspected de novo, including 64% autosomal dominant and 11% X-linked; only 25% were inherited (jarvela2021exomesequencingreveals pages 1-2). Trio-WES in unexplained DD/ID also concluded that de novo variants in AD genes are major contributors, especially in non-consanguineous families (li2024triowholeexomesequencing pages 1-2). Inheritance: autosomal dominant; de novo germline origin
Mosaicism / recurrence risk Apparent de novo AD findings do not guarantee negligible recurrence risk. In a trio genome-wide study of 500 families, 12 cases of apparent mosaicism were identified, including 9 parental and 3 proband mosaic cases; empirical recurrence for a child with a de novo dominant condition is often cited as ~1%, but parental gonadal mosaicism can raise risk substantially (cook2021somaticmosaicismdetected pages 1-2). Counseling concept: parental/gonadal mosaicism; somatic mosaicism
Anatomy / organ systems Primary affected organ/system is the central nervous system, especially cortical and hippocampal circuits supporting cognition, learning, and adaptive behavior. Reviews also note involvement of excitation/inhibition balance and, in some genetic subgroups, broader multisystem findings despite a nominally nonsyndromic label (liaci2021neuronalcytoskeletonin pages 1-2, ford2023dendriticspineand pages 1-2). UBERON: brain UBERON:0000955; cerebral cortex UBERON:0000956; hippocampus UBERON:0002421
Cells / subcellular processes Mechanistic evidence highlights neurons, especially pyramidal neurons, dendrites, dendritic spines, and synapses; abnormal neuronal migration, neuritogenesis, and synaptic plasticity are recurrent themes. Subcellular emphasis includes chromatin, actin/microtubule cytoskeleton, and synaptic compartments (liaci2021neuronalcytoskeletonin pages 1-2, ford2023dendriticspineand pages 1-2). CL: neuron CL:0000540; pyramidal neuron CL:0000598; GO CC: dendrite GO:0030425; dendritic spine GO:0043197; synapse GO:0045202; nucleus GO:0005634
Pathophysiology / causal chain Upstream lesions include de novo coding or regulatory variants affecting chromatin regulation, transcription, enhancer activity, cytoskeleton dynamics, trafficking, and synaptic proteins. Downstream consequences include altered neuronal migration/neuritogenesis, abnormal dendritic spine and synapse morphogenesis, impaired network formation, excitation/inhibition imbalance, and finally impaired cognition/adaptive behavior (liaci2021neuronalcytoskeletonin pages 1-2, vas2023regulatorydenovo pages 1-2, ford2023dendriticspineand pages 1-2). GO: neuron migration GO:0001764; axonogenesis GO:0007409; dendrite morphogenesis GO:0048813; learning or memory GO:0007611
Diagnostic workflow Current evidence supports trio exome sequencing as first-tier for unexplained DD/ID/NDD, with genome sequencing used early or after nondiagnostic CMA/exome, particularly where structural, intronic, or regulatory variants are suspected. Standard pre-genomic workup often includes history/exam, CMA, Fragile X or targeted testing when indicated, and phenotype-guided metabolic testing (ko2023genomewidesequencingmodalities pages 1-2, wayhelova2024exomesequencingimproves pages 1-2, wigby2024evidencereviewand pages 1-2, kim2024diagnosticyieldof pages 1-2). ACMG-aligned genome-wide testing strategy
Recent diagnostic yield data (2023–2024 priority) Recent cohorts report: trio-WES 49.7% (86/173) in unexplained DD/ID; syndromic 57.8% vs non-syndromic 47.2% (li2024triowholeexomesequencing pages 1-2). Trio-ES in severe pediatric NDDs 48.9% (44/90), with 53.2% of causative variants novel (wayhelova2024exomesequencingimproves pages 1-2). Singleton WES in undiagnosed rare pediatric disease 43% (25/58) and clinical utility/actionability 76% (slaba2024diagnosticefficacyand pages 1-2). Trio-WGS after prior chromosome analysis/CMA/CES gave an additional 19.2% (10/52) diagnoses, 8/10 due to AD de novo variants (kim2024diagnosticyieldof pages 1-2). First-line GS review found mean diagnostic yield 45% for first-line GS and management changes 24–100% depending on cohort (wigby2024evidencereviewand pages 1-2). Diagnostic modalities: WES, WGS, CMA
Real-world implementation Real-world implementation now centers on clinical genetics and pediatric neurology pathways using trio-based ES/GS, ACMG-guided variant classification, and phenotype-driven reanalysis. ES/GS findings influence surveillance, reproductive counseling, and personalized management even when no disease-specific drug exists (wayhelova2024exomesequencingimproves pages 1-2, wigby2024evidencereviewand pages 1-2, slaba2024diagnosticefficacyand pages 1-2). ACMG/AMP variant classification framework
Management / treatment There is no single disease-specific pharmacotherapy for the umbrella disorder. Care is supportive and phenotype-directed: developmental therapies, speech/language therapy, educational support, behavioral management, seizure treatment when present, surveillance based on the molecular diagnosis, and genetic counseling. Reviews note that no pharmacological therapies are currently available for ID broadly, although pathway-based therapeutic opportunities are being explored (liaci2021neuronalcytoskeletonin pages 1-2, slaba2024diagnosticefficacyand pages 1-2). MAXO: genetic counseling; developmental therapy; speech therapy; educational intervention; seizure management
Prevention / family planning Primary prevention is generally not available for de novo monogenic disease; practical prevention focuses on genetic counseling, discussion of recurrence including mosaicism, and reproductive options after molecular diagnosis. Earlier genomic diagnosis can shorten the diagnostic odyssey and inform family planning (kim2024diagnosticyieldof pages 1-2, slaba2024diagnosticefficacyand pages 1-2, cook2021somaticmosaicismdetected pages 1-2). MAXO: genetic counseling; reproductive counseling
Model systems / mechanistic platforms Evidence includes animal and neuronal model studies summarized in reviews, especially mouse models of chromatin modifiers (ARID1B, KANSL1, WDR5, ZMIZ1) and systems-biology approaches emphasizing convergent neuronal network defects. These models are useful for studying dendritic spine, synapse, and developmental circuitry abnormalities (liaci2021neuronalcytoskeletonin pages 1-2, ford2023dendriticspineand pages 1-2). Model categories: mouse models; neuronal cultures; systems biology
Evidence limitations Disease boundaries are porous: “non-syndromic” cases may later show additional features; many data come from mixed DD/ID/NDD cohorts rather than pure MONDO:0015802 cohorts; gene lists change rapidly; penetrance/expressivity are often incompletely quantified; and few disorder-specific natural history or treatment trials exist (maia2021intellectualdisabilitygenomics pages 1-2, wayhelova2024exomesequencingimproves pages 1-2, slaba2024diagnosticefficacyand pages 1-2). Curation note: maintain umbrella-vs-gene-specific distinction

Table: This table compacts the most actionable current evidence for autosomal dominant non-syndromic intellectual disability into a knowledge-base-ready format. It emphasizes scope, representative mechanisms and genes, ontology suggestions, modern diagnostic practice, and key evidence limitations.

1. Disease information

ID is defined by significant limitations in both intellectual functioning and adaptive behavior—conceptual, social, and practical skills—with onset during the developmental period. Global developmental delay (GDD) is used in young children, generally under five years, when standardized intellectual assessment is not yet reliable. The older IQ-only definition is insufficient; adaptive impairment is essential. ID overall affects approximately 1–3% of the population, while GDD/ID together affect nearly 2% of children. These figures cover all etiologies, not specifically AD-NSID. Mild ID represents approximately 85% of ID, moderate 10%, severe 3.5%, and profound 1.5% in commonly cited aggregate classifications. (maia2021intellectualdisabilitygenomics pages 1-2, ko2023genomewidesequencingmodalities pages 1-2, liaci2021neuronalcytoskeletonin pages 1-2)

Key identifiers and terminology

  • MONDO: MONDO:0015802, autosomal dominant non-syndromic intellectual disability.
  • Related MONDO: MONDO:0100172, intellectual disability, autosomal dominant.
  • MeSH: Intellectual Disability is the applicable broad concept; there is no uniquely specific MeSH descriptor for the AD-NSID umbrella.
  • ICD-10: F70–F79 classify intellectual disabilities by severity; they do not encode AD-NSID etiology.
  • ICD-11: 6A00, disorders of intellectual development, with severity extensions; again, inheritance is not encoded.
  • OMIM/Orphanet: individual gene-defined disorders generally have separate entries; no single OMIM number adequately represents the full umbrella.
  • Synonyms: autosomal dominant nonsyndromic ID; autosomal dominant non-syndromic mental retardation; isolated autosomal dominant intellectual disability; nonspecific autosomal dominant ID.

2. Etiology, risk, protection, and gene–environment interaction

Genetic causes

The defining cause is a germline heterozygous pathogenic variant. Moderate-to-severe cases are frequently de novo; familial transmission is more readily observed in mild disease because affected adults may reproduce. A 2024 review estimated that more than 400 genes have been associated with autosomal-dominant ID, while broader ID databases contain well over 1,500 established genes. (hou2024a10yearreview pages 5-7, wayhelova2024exomesequencingimproves pages 1-2)

Variant classes include missense, nonsense, frameshift, splice-altering and in-frame variants; exon-level or larger CNVs; balanced/complex structural rearrangements; and regulatory variants. Mechanisms differ by gene and allele: haploinsufficiency/loss of function, dominant-negative effects, and gain of function are all possible. Therefore, a gene cannot be assigned one universal molecular mechanism without allele-specific evidence.

The Finnish exome study of 39 ID families found pathogenic/likely pathogenic variants in 25/39 (64%). Among variants in known ID genes, 75% were de novo or suspected de novo—64% autosomal dominant and 11% X-linked—whereas 25% were inherited. This mixed syndromic/non-syndromic cohort supports the dominant de novo contribution but is not a prevalence study of AD-NSID. The abstract states: “de novo variants were the most common variants underlying ID in the studied Finnish population.” Published March 12, 2021; DOI: https://doi.org/10.1007/s00439-021-02268-1. (jarvela2021exomesequencingreveals pages 1-2)

Regulatory and chromosomal causes

De Vas et al. sequenced 21 ID trios and analyzed another 30 exome-negative probands. Regulatory de novo variants were enriched in fetal-brain-specific enhancers, including recurrent enhancer clusters linked to CSMD1, OLFM1, and POU3F3. Luciferase assays showed allele-specific activity for most tested variants, and CRISPR mutation/epigenome editing altered putative target-gene expression. Their exact conclusion was that these results “provide new evidence to indicate that DNMs in fetal brain-specific enhancers play an essential role in the aetiology of ID.” This is primary genomic, in-vitro reporter, and CRISPR functional evidence, but the small cohort does not establish clinical penetrance for each regulatory variant. Published February 28, 2023; DOI: https://doi.org/10.26508/lsa.202201843. (vas2023regulatorydenovo pages 1-2)

Large CNVs explain approximately 10–14% of ID overall, mostly de novo, but many produce syndromic phenotypes and should not automatically be labeled AD-NSID. (maia2021intellectualdisabilitygenomics pages 1-2)

Environmental, infectious, and lifestyle factors

No toxin, pathogen, diet, exercise pattern, smoking exposure, or occupational factor is established as a cause of a genetically confirmed AD-NSID disorder. Prenatal infection, hypoxic–ischemic injury, prematurity complications, neonatal meningitis, toxins, severe malnutrition, and other acquired insults are important alternative or additive causes of DD/ID, not causes of Mendelian inheritance. They may worsen developmental outcome in an affected child, but quantitative AD-NSID-specific gene–environment interaction data are unavailable. (liaci2021neuronalcytoskeletonin pages 1-2)

No validated genetic or environmental protective factor prevents expression after a highly penetrant pathogenic variant. Favorable modifiers may exist, but none is sufficiently validated for clinical annotation. Early enriched education, communication support, and rehabilitation improve function rather than biologically preventing the genotype.

3. Phenotypes and quality-of-life effects

The cardinal phenotype is developmental-onset impairment of cognition and adaptive functioning. Severity ranges from mild learning disability to profound dependence. Onset is congenital/developmental but recognition usually occurs in infancy or childhood through delayed milestones, speech delay, school difficulty, or impaired adaptive skills. The disorder is generally chronic and lifelong, not relapsing-remitting. Skills may continue to develop slowly; true neurodegeneration or loss of milestones should trigger evaluation for a different or additional diagnosis.

Table (click to expand)
Phenotype Typical characteristics Suggested HPO term
Intellectual disability Universal by definition; mild to profound; lifelong HP:0001249
Global developmental delay Common presenting label in children under five HP:0001263
Delayed speech/language Frequent across AD-ID genes; severity variable HP:0000750
Motor developmental delay Variable; often less severe than language/cognitive delay HP:0001270
Impaired adaptive functioning Conceptual, social, and practical limitations HP:0011446, Abnormality of higher mental function, plus domain-specific terms
Behavioral abnormality Autism, attention problems, anxiety, aggression, or stereotypy may occur but are not defining HP:0000708; HP:0000717 for autism
Seizures/epilepsy Gene-dependent rather than universal; may shift classification toward a syndromic/developmental epileptic encephalopathy HP:0001250
Hypotonia Variable, often early childhood HP:0001252
Microcephaly or macrocephaly Gene-dependent; not required HP:0000252 / HP:0000256
Subtle facial dysmorphism May emerge with systematic examination and challenges a strict “non-syndromic” designation HP:0001999

Quality-of-life impact is dominated by communication limitations, educational needs, reduced independence, social participation barriers, caregiver burden, and need for lifelong support. Gene-specific QoL, EQ-5D, SF-36, survival, and phenotype-frequency datasets are generally absent. A 2024 consensus analysis found that phenotype descriptions in novel Mendelian disorder reports were superficial or deficient in more than 87% of publications across prioritized domains, illustrating why exact frequencies, adulthood outcomes, sleep, pain, and QoL remain uncertain.

4. Genetic and molecular information

Representative gene architecture

The following mechanistic groups are useful for curation; they are not an exhaustive diagnostic panel:

  • Chromatin, transcription, and cohesin: ASH1L, KMT5B, STAG1, CIC, SET, TLK2, NAA15, TRIP12; broader AD-ID genes include ARID1B and other chromatin regulators.
  • Synapse and excitability: CAMK2A, DLG4, GRIN1, GNB1 and gene-specific disorders involving STXBP1 or NRXN1.
  • Rho-GTPase/cytoskeletal development: TRIO and related neuronal morphogenesis pathways.
  • Vesicle trafficking/transport: CLTC, KIF1A, DYNC1H1.

Open Targets supports the association of the first set with MONDO:0015802 but does not, by itself, establish allele-level pathogenicity. Each variant requires ClinGen/ClinVar review, ACMG/AMP classification, segregation analysis, population frequency evaluation, and mechanism compatibility. (OpenTargets Search: autosomal dominant intellectual disability)

Pathogenic variants and classification

Pathogenic/likely pathogenic variants are ordinarily absent or extremely rare in population databases such as gnomAD, although gene-specific reduced penetrance can complicate interpretation. A 2024 trio-WES study filtered variants at minor allele frequency ≤0.01, but the threshold for a severe de novo dominant disorder is usually much lower and should be set using disease prevalence, penetrance, and allelic heterogeneity. A VUS does not establish diagnosis and must not guide predictive testing or irreversible reproductive decisions. (li2024triowholeexomesequencing pages 2-3)

Most causal variants are constitutional germline variants. Postzygotic mosaicism in the proband can attenuate severity; parental somatic/gonadal mosaicism can make an apparently de novo variant recurrent. In 500 genome-wide-sequenced families, Cook et al. identified 12 apparent mosaic cases: nine parental and three proband; six were not recognized as mosaic by Sanger sequencing. The authors concluded that genome-wide detection “can permit more accurate genetic counseling.” Published 2021; DOI: https://doi.org/10.1101/mcs.a006125. (cook2021somaticmosaicismdetected pages 1-2)

No consistently validated modifier gene, protective allele, or umbrella-specific episignature exists. Some individual chromatin disorders have blood DNA-methylation signatures, but those results should be recorded under the specific gene-defined disorder rather than generalized to AD-NSID.

5. Environmental information

Environmental exposures, lifestyle factors, and infectious agents are not primary etiologies once a causal AD variant is established. Their clinical relevance is principally differential diagnosis, prevention of additional brain injury, and optimization of general health. There is no AD-NSID-specific evidence that smoking, alcohol use by the affected person, diet, or exercise changes penetrance. Prenatal alcohol or teratogen exposure may create a blended phenotype. Routine immunization is appropriate but does not prevent the genetic disorder.

6. Mechanism and pathophysiology

Integrated causal chain

  1. Upstream genetic lesion: a coding, splice, CNV, structural, or fetal-brain regulatory variant alters dosage or function of an AD-ID gene.
  2. Molecular dysregulation: disturbed chromatin remodeling/transcription, enhancer activity, RNA/protein regulation, Rho-GTPase signaling, microtubule/actin dynamics, vesicle transport, glutamatergic signaling, or postsynaptic scaffolding.
  3. Cellular effects: altered neural progenitor programs, neuronal migration, neurite extension, dendritic arborization, spine morphogenesis, synapse formation and plasticity.
  4. Circuit effects: inefficient cortical/hippocampal connectivity and, in some genes, excitation–inhibition imbalance.
  5. Clinical manifestation: impaired learning, memory, language, executive function, and adaptive behavior.

The cytoskeleton review describes this hierarchy from molecular defect to “cell compartment and functions, circuits, cognition, and behavior.” It identifies cytoskeletal disruption affecting neuronal migration, neuritogenesis, and synaptic plasticity, and notes convergence on Rho-GTPase signaling. Published June 7, 2021; DOI: https://doi.org/10.3390/ijms22116167. (liaci2021neuronalcytoskeletonin pages 1-2)

Chromatin modifiers can also act upstream of synaptic pathology. Animal models and human postmortem evidence show abnormal dendritic-spine/synapse morphogenesis and plasticity; ARID1B, KANSL1, and WDR5 are highlighted examples. This evidence is mechanistically informative but is not specific to every MONDO:0015802 gene. Published January 19, 2023; DOI: https://doi.org/10.3389/fnmol.2022.1048713. (ford2023dendriticspineand pages 1-2)

Suggested GO biological-process terms: chromatin organization (GO:0006325); regulation of transcription by RNA polymerase II (GO:0006357); nervous system development (GO:0007399); neuron migration (GO:0001764); neuron projection development (GO:0031175); axonogenesis (GO:0007409); dendrite morphogenesis (GO:0048813); synapse organization (GO:0050808); regulation of synaptic plasticity (GO:0048167); actin cytoskeleton organization (GO:0030036); learning or memory (GO:0007611).

Suggested cell types: neuron (CL:0000540), pyramidal neuron (CL:0000598), excitatory neuron and inhibitory interneuron where gene-specific evidence exists, neural stem/progenitor cell for prenatal chromatin/enhancer mechanisms. No immune-cell or inflammatory mechanism is consistently implicated in the umbrella disorder.

No reproducible umbrella-level metabolomic, lipidomic, proteomic, or circulating biomarker signature exists. WGS plus regulatory epigenomics and functional CRISPR assays represent the most relevant recent multi-omic advance. (vas2023regulatorydenovo pages 1-2)

7. Anatomical structures affected

The central nervous system is primary, especially cerebral cortex and hippocampal networks involved in cognition and memory. Cerebellar involvement may occur in individual genotypes. Peripheral organs are not obligatorily involved; consistent congenital or multisystem abnormalities should prompt a gene-specific syndromic diagnosis.

Suggested annotations are brain (UBERON:0000955), cerebral cortex (UBERON:0000956), hippocampus (UBERON:0002421), nervous tissue, neuron (CL:0000540), pyramidal neuron (CL:0000598), nucleus (GO:0005634), chromatin, cytoskeleton, dendrite (GO:0030425), dendritic spine (GO:0043197), and synapse (GO:0045202). Effects are bilateral and network-level; there is no characteristic lateralization. (liaci2021neuronalcytoskeletonin pages 1-2, ford2023dendriticspineand pages 1-2)

8. Temporal development

The biological lesion is present from conception or arises early postzygotically. Vulnerability is greatest during prenatal neurogenesis, neuronal migration, circuit assembly, and early-childhood synaptic maturation. Clinical onset is insidious and developmental rather than acute. The course is usually stable/nondegenerative but lifelong; developmental gains occur at a slower rate and may plateau. There are no validated early/intermediate/end-stage categories and no expected remission. Early childhood is the principal intervention window because communication systems, adaptive skills, and educational supports can be introduced during maximal developmental plasticity.

9. Inheritance and population

Inheritance is autosomal dominant. An affected heterozygous parent generally has a 50% transmission probability per pregnancy, although expression may vary. Many moderate/severe cases are de novo, so family history is often negative. In the 2024 trio-WES cohort, 95.4% had no family history of epilepsy or DD/ID, emphasizing that a negative pedigree does not exclude dominant disease. (li2024triowholeexomesequencing pages 2-3)

Penetrance is high for many severe de novo loss-of-function disorders but gene- and allele-specific. Expressivity can vary widely. Anticipation is not a general feature; repeat-expansion disorders belong in the differential rather than the core AD-NSID category. Consanguinity is not a risk factor for AD-NSID, though it raises the probability of an alternative recessive diagnosis. Founder effects and carrier frequencies are variant-specific; there is no meaningful aggregate carrier frequency because affected heterozygotes are not asymptomatic “carriers.”

For a confirmed de novo variant absent from parental blood, counseling commonly starts with an empirical recurrence risk near 1%, reflecting possible gonadal mosaicism. If a parent is mosaic, recurrence can be substantially higher and depends on germ-cell involvement; Cook et al. explain a theoretical range from approximately 1–2% to as high as 50%. Deep sequencing of multiple parental tissues or paternal sperm can refine risk in selected families. (cook2021somaticmosaicismdetected pages 1-2)

There is no reliable incidence or prevalence specifically for MONDO:0015802, no established ethnic concentration, geographic endemicity, or robust sex ratio. Autosomal inheritance predicts broadly similar biological risk in males and females; ascertainment may differ because males are more often referred for neurodevelopmental assessment.

10. Diagnostics

Clinical assessment

Assessment should include prenatal/perinatal and three-generation history; growth and dysmorphology examination; formal developmental, cognitive, language, and adaptive testing; hearing and vision evaluation; neurologic examination; and autism/behavioral screening. EEG is indicated for seizures or suspicious episodes, MRI for abnormal neurologic examination, regression, focal signs, abnormal head growth, or a genotype-specific indication. Routine biopsy is not useful. Metabolic testing should be phenotype-directed, particularly for regression, episodic decompensation, organomegaly, movement disorder, or unusual biochemical findings.

Current genetic-testing algorithm

  1. Trio ES or GS early/first tier, with CNV calling and ACMG/AMP interpretation.
  2. If ES is used, ensure adequate CNV detection; add CMA where platform/payer practice requires it or CNV sensitivity is insufficient.
  3. Use Fragile X testing, repeat-expansion assays, methylation testing, mitochondrial testing, or single-gene testing when clinically indicated because standard ES may miss these mechanisms.
  4. For nondiagnostic ES, perform periodic reanalysis, then GS to detect structural, deep-intronic, regulatory, repeat, low-level mosaic, or poorly covered variants.
  5. RNA sequencing or methylation studies may resolve splice variants or gene-specific episignatures, but are not universal diagnostic tests.

Recent implementation data are strong:

Differential diagnosis includes syndromic AD-ID, X-linked or recessive ID, chromosomal disorders, Fragile X, imprinting disorders, developmental epileptic encephalopathy, autism without ID, cerebral palsy/perinatal injury, fetal alcohol spectrum disorder, congenital infection, metabolic disease, hypothyroidism, hearing/vision impairment, and neurodegenerative disorders. Clinical phenotype alone often cannot reliably distinguish them.

Population newborn screening is not available. After finding a familial variant, cascade testing, prenatal diagnosis, and preimplantation genetic testing are technically possible. Predictive testing of asymptomatic minors requires careful consideration because onset is developmental and penetrance may be allele-specific.

11. Outcome and prognosis

No umbrella-specific 5-year survival, life expectancy, or disease-specific mortality rate is available. In genuinely non-syndromic ID without epilepsy, severe motor impairment, swallowing dysfunction, or organ disease, life expectancy may approach that of the general population, but this cannot be assumed for every genotype. Morbidity is chiefly lifelong cognitive, communication, adaptive, educational, vocational, and social disability.

Major prognostic factors are severity of early developmental impairment, language acquisition, epilepsy, autism/behavioral comorbidity, motor and feeding ability, access to communication and educational services, and the specific molecular diagnosis. There is no validated molecular prognostic biomarker across AD-NSID. Recovery to fully typical cognition is uncommon, but meaningful functional gains are expected with individualized support. Regression, new neurologic signs, or unexpectedly rapid deterioration warrants reassessment for seizures, medication effects, psychiatric illness, sleep disorder, or an alternative/blended diagnosis.

12. Treatment and current applications

There is no approved disease-modifying pharmacotherapy, gene therapy, RNA therapy, cell therapy, immunotherapy, or surgery for the MONDO:0015802 umbrella. The 2021 mechanistic review states that “no pharmacological therapies are currently available” for ID broadly. Molecular diagnosis nevertheless changes surveillance, avoids unnecessary testing, informs recurrence counseling, and occasionally identifies a genotype-specific comorbidity or treatment. (liaci2021neuronalcytoskeletonin pages 1-2, slaba2024diagnosticefficacyand pages 1-2)

Standard multidisciplinary management

  • Individualized early developmental intervention, special education, and behavioral supports.
  • Speech-language therapy and augmentative/alternative communication.
  • Occupational and physical therapy for adaptive, sensory, fine-motor, gross-motor, or hypotonia-related needs.
  • Standard evidence-based treatment for epilepsy, ADHD, anxiety, sleep disturbance, constipation, feeding problems, and other comorbidities.
  • Hearing, vision, dental, nutritional, sleep, and safeguarding assessment.
  • Transition planning, supported decision-making, vocational support, respite, and caregiver mental-health support.

Suggested MAXO annotations include genetic counseling, developmental assessment, neuropsychological assessment, speech-language therapy, occupational therapy, physical therapy, educational intervention, augmentative communication, EEG, brain MRI, genomic sequencing, and seizure management. Precise MAXO IDs should be verified against the current ontology release before database ingestion.

No clinical trial retrieved was a disease-modifying trial specifically for AD-NSID. Relevant ID-wide studies largely concern behavioral, communication, lifestyle, or comorbidity interventions—for example written-language intervention (NCT05851937) and metformin for antipsychotic-associated weight gain (NCT05744479)—and should not be represented as treatments for the underlying genetic disease.

Research directions include restoring gene dosage, allele-specific silencing for gain-of-function alleles, ASOs, CRISPR-based correction, and pathway modulation of chromatin, Rho-GTPase/cytoskeletal, or synaptic defects. These remain gene- and variant-specific, largely preclinical concepts; the same intervention could be harmful if applied across opposite loss- and gain-of-function mechanisms.

13. Prevention

Primary prevention by lifestyle change or vaccination is not applicable. Prevention is principally reproductive and complication-focused:

  • Preconception and postdiagnostic genetic counseling.
  • Parental testing with consideration of low-level mosaicism.
  • Prenatal testing by CVS/amniocentesis or PGT-M when a familial pathogenic variant is known.
  • Early developmental surveillance of at-risk children.
  • Prevention of secondary harm through seizure control, communication support, safe feeding, sleep care, sensory screening, vaccination, and avoidance of additional neurotoxic exposures.

Noninvasive prenatal screening does not comprehensively detect heterogeneous single-gene AD-NSID. Prenatal diagnosis should not be based on a VUS.

14. Other species and natural disease

There is no recognized naturally occurring veterinary disease that is directly equivalent to the heterogeneous human AD-NSID umbrella. Orthologous genes are widely conserved in mammals, zebrafish, Drosophila, and C. elegans, and variants may cause learning, behavior, synaptic, or developmental phenotypes. These are comparative models rather than zoonotic disease. There is no infectious transmission, cross-species transmission, or zoonotic potential. Gene-, species-, NCBI Taxon-, NCBI Gene-, and VBO-level entries should be curated separately for each causal gene/model.

15. Model organisms

Available systems include constitutive or conditional knockout/heterozygous mice, variant knock-in mice, zebrafish, Drosophila, cultured primary neurons, patient-derived iPSCs, induced neurons, and cerebral organoids. Chromatin-modifier models involving ARID1B, KANSL1, WDR5, and related genes reproduce aspects of dendritic arborization, spine morphology, synaptic signaling, learning, or behavior. Cytoskeletal models test neuronal migration, neuritogenesis, Rho-GTPase signaling, and network plasticity. Regulatory-variant studies combine human WGS with luciferase assays and CRISPR epigenome editing. (liaci2021neuronalcytoskeletonin pages 1-2, vas2023regulatorydenovo pages 1-2, ford2023dendriticspineand pages 1-2)

Model limitations are substantial: human adaptive behavior cannot be directly modeled; heterozygous null animals may not mimic a human dominant-negative or gain-of-function allele; developmental timing and cortical architecture differ across species; and behavioral assays have limited construct validity. The preferred model is therefore variant-specific and should demonstrate directionally correct molecular dysfunction before therapeutic testing.

Evidence-quality conclusions

The strongest current evidence concerns the high contribution of de novo AD variants, the diagnostic effectiveness of trio ES/GS, and convergence on prenatal gene regulation, cytoskeletal development, and synaptic function. The weakest areas are disease-specific epidemiology, phenotype frequencies, adult natural history, QoL, penetrance, modifier genes, and treatment outcomes. A knowledge base should consequently retain MONDO:0015802 as an umbrella, attach variants and mechanisms to the relevant gene-specific disease whenever possible, and label statistics derived from mixed DD/ID cohorts as indirect rather than AD-NSID-specific evidence.

References

  1. (OpenTargets Search: autosomal dominant intellectual disability): Open Targets Query (autosomal dominant intellectual disability, 32 results). Buniello, A. et al. (2025). Open Targets Platform: facilitating therapeutic hypotheses building in drug discovery. Nucleic Acids Research.

  2. (maia2021intellectualdisabilitygenomics pages 1-2): Nuno Maia, Maria João Nabais Sá, Manuel Melo-Pires, Arjan P. M. de Brouwer, and Paula Jorge. Intellectual disability genomics: current state, pitfalls and future challenges. BMC Genomics, Dec 2021. URL: https://doi.org/10.1186/s12864-021-08227-4, doi:10.1186/s12864-021-08227-4. This article has 125 citations and is from a peer-reviewed journal.

  3. (li2024triowholeexomesequencing pages 1-2): Chengyan Li, You Wang, Cizheng Zeng, Binglong Huang, Yinhui Chen, Chupeng Xue, Ling Liu, Shiwen Rong, and Yongwen Lin. Trio-whole exome sequencing reveals the importance of de novo variants in children with intellectual disability and developmental delay. Scientific Reports, Nov 2024. URL: https://doi.org/10.1038/s41598-024-79431-x, doi:10.1038/s41598-024-79431-x. This article has 22 citations and is from a peer-reviewed journal.

  4. (ko2023genomewidesequencingmodalities pages 2-4): Mary Hsin-Ju Ko and Hui-Ju Chen. Genome-wide sequencing modalities for children with unexplained global developmental delay and intellectual disabilities—a narrative review. Mar 2023. URL: https://doi.org/10.3390/children10030501, doi:10.3390/children10030501. This article has 14 citations.

  5. (ko2023genomewidesequencingmodalities pages 1-2): Mary Hsin-Ju Ko and Hui-Ju Chen. Genome-wide sequencing modalities for children with unexplained global developmental delay and intellectual disabilities—a narrative review. Mar 2023. URL: https://doi.org/10.3390/children10030501, doi:10.3390/children10030501. This article has 14 citations.

  6. (liaci2021neuronalcytoskeletonin pages 1-2): Carla Liaci, Mattia Camera, Giovanni Caslini, Simona Rando, Salvatore Contino, Valentino Romano, and G. Merlo. Neuronal cytoskeleton in intellectual disability: from systems biology and modeling to therapeutic opportunities. International Journal of Molecular Sciences, Jun 2021. URL: https://doi.org/10.3390/ijms22116167, doi:10.3390/ijms22116167. This article has 36 citations.

  7. (wayhelova2024exomesequencingimproves pages 1-2): Marketa Wayhelova, Vladimira Vallova, Petr Broz, Aneta Mikulasova, Jan Smetana, Hana Dynkova Filkova, Dominika Machackova, Kristina Handzusova, Renata Gaillyova, and Petr Kuglik. Exome sequencing improves the molecular diagnostics of paediatric unexplained neurodevelopmental disorders. Orphanet Journal of Rare Diseases, Feb 2024. URL: https://doi.org/10.1186/s13023-024-03056-6, doi:10.1186/s13023-024-03056-6. This article has 18 citations and is from a peer-reviewed journal.

  8. (kim2024diagnosticyieldof pages 1-2): Jaewon Kim, Jaewoong Lee, Myungshin Kim, and Dae-Hyun Jang. Diagnostic yield of trio whole-genome sequencing in children with undiagnosed developmental delay or congenital anomaly: a prospective cohort study. Diagnostics, 14:1680, Aug 2024. URL: https://doi.org/10.3390/diagnostics14151680, doi:10.3390/diagnostics14151680. This article has 6 citations.

  9. (vas2023regulatorydenovo pages 1-2): Matias G De Vas, Fanny Boulet, Shweta S Joshi, Myles G Garstang, Tahir N Khan, Goutham Atla, David Parry, David Moore, Inês Cebola, Shuchen Zhang, Wei Cui, Anne K Lampe, Wayne W Lam, Jorge Ferrer, Madapura M Pradeepa, and Santosh S Atanur. Regulatory de novo mutations underlying intellectual disability. Life Science Alliance, 6:e202201843, Feb 2023. URL: https://doi.org/10.26508/lsa.202201843, doi:10.26508/lsa.202201843. This article has 7 citations and is from a peer-reviewed journal.

  10. (ford2023dendriticspineand pages 1-2): Thomas James L. Ford, Byeong Tak Jeon, Hyunkyoung Lee, and Woo-Yang Kim. Dendritic spine and synapse pathology in chromatin modifier-associated autism spectrum disorders and intellectual disability. Frontiers in Molecular Neuroscience, Jan 2023. URL: https://doi.org/10.3389/fnmol.2022.1048713, doi:10.3389/fnmol.2022.1048713. This article has 30 citations.

  11. (jarvela2021exomesequencingreveals pages 1-2): Irma Järvelä, Tuomo Määttä, Anushree Acharya, Juha Leppälä, Shalini N. Jhangiani, Maria Arvio, Auli Siren, Minna Kankuri-Tammilehto, Hannaleena Kokkonen, Maarit Palomäki, Teppo Varilo, Mary Fang, Trevor D. Hadley, Angad Jolly, Tarja Linnankivi, Ritva Paetau, Anni Saarela, Reetta Kälviäinen, Jan Olme, Liz M. Nouel-Saied, Diana M. Cornejo-Sanchez, Lorida Llaci, James R. Lupski, Jennifer E. Posey, Suzanne M. Leal, and Isabelle Schrauwen. Exome sequencing reveals predominantly de novo variants in disorders with intellectual disability (id) in the founder population of finland. Human Genetics, 140:1011-1029, Mar 2021. URL: https://doi.org/10.1007/s00439-021-02268-1, doi:10.1007/s00439-021-02268-1. This article has 55 citations and is from a peer-reviewed journal.

  12. (cook2021somaticmosaicismdetected pages 1-2): Courtney B. Cook, Linlea Armstrong, Cornelius F. Boerkoel, Lorne A. Clarke, Christèle du Souich, Michelle K. Demos, William T. Gibson, Harinder Gill, Elena Lopez, Millan S. Patel, Kathryn Selby, Ziad Abu-Sharar, Alison M. Elliott, and Jan M. Friedman. Somatic mosaicism detected by genome-wide sequencing in 500 parent–child trios with suspected genetic disease: clinical and genetic counseling implications. Molecular Case Studies, 7:a006125, Oct 2021. URL: https://doi.org/10.1101/mcs.a006125, doi:10.1101/mcs.a006125. This article has 25 citations.

  13. (wigby2024evidencereviewand pages 1-2): Kristen M. Wigby, Deanna Brockman, Gregory Costain, Caitlin Hale, Stacie L. Taylor, John Belmont, David Bick, David Dimmock, Susan Fernbach, John Greally, Vaidehi Jobanputra, Shashikant Kulkarni, Elizabeth Spiteri, and Ryan J. Taft. Evidence review and considerations for use of first line genome sequencing to diagnose rare genetic disorders. npj Genomic Medicine, Feb 2024. URL: https://doi.org/10.1038/s41525-024-00396-x, doi:10.1038/s41525-024-00396-x. This article has 26 citations and is from a peer-reviewed journal.

  14. (slaba2024diagnosticefficacyand pages 1-2): Katerina Slaba, Petra Pokorna, Robin Jugas, Hana Palova, Dagmar Prochazkova, Stefania Aulicka, Klara Spanelova, Pavlina Danhofer, Ondrej Horak, Jana Tuckova, Petra Kleiblova, Renata Gaillyova, Matej Hrunka, Martin Jouza, Blanka Pinkova, Jan Papez, Petra Konecna, Jana Zidkova, Petr Stourac, Jaroslav Sterba, Regina Demlova, Eva Demlova, Petr Jabandziev, and Ondrej Slaby. Diagnostic efficacy and clinical utility of whole-exome sequencing in czech pediatric patients with rare and undiagnosed diseases. Scientific Reports, Nov 2024. URL: https://doi.org/10.1038/s41598-024-79872-4, doi:10.1038/s41598-024-79872-4. This article has 5 citations and is from a peer-reviewed journal.

  15. (hou2024a10yearreview pages 5-7): Kexin Hou and Xinyan Zheng. A 10-year review on advancements in identifying and treating intellectual disability caused by genetic variations. Genes, 15:1118, Aug 2024. URL: https://doi.org/10.3390/genes15091118, doi:10.3390/genes15091118. This article has 9 citations.

  16. (li2024triowholeexomesequencing pages 2-3): Chengyan Li, You Wang, Cizheng Zeng, Binglong Huang, Yinhui Chen, Chupeng Xue, Ling Liu, Shiwen Rong, and Yongwen Lin. Trio-whole exome sequencing reveals the importance of de novo variants in children with intellectual disability and developmental delay. Scientific Reports, Nov 2024. URL: https://doi.org/10.1038/s41598-024-79431-x, doi:10.1038/s41598-024-79431-x. This article has 22 citations and is from a peer-reviewed journal.

Artifacts