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Mappings

MONDO

MONDO:0030918 intellectual disability, autosomal dominant 52

MONDO:0030918 is the MRD52 concept, xrefed to OMIM:617796 and carrying the RO:0004003 causal-gene relationship to HGNC:19088 (ASH1L).

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Inheritance

1

Autosomal dominant inheritance HP:0000006

Affected individuals are heterozygous for a loss-of-function ASH1L variant, most often de novo. The disease mechanism is haploinsufficiency rather than a dominant-negative effect.

Autosomal dominant inheritance Penetrance: UNKNOWN Expressivity: VARIABLE

Show evidence (2 references)

PMID:38674358 SUPPORT Human Clinical

"Heterozygous pathogenic variants in ASHL1 have been implicated in an autosomal dominant neurodevelopmental disorder (NDD)."

States the autosomal dominant, heterozygous inheritance mode. The gene symbol is misspelled "ASHL1" in the source sentence and is quoted as printed.

PMID:38674358 SUPPORT Human Clinical

"haploinsufficiency is believed to be at least one disease mechanism"

Identifies haploinsufficiency as the dominant mechanism, which is what `expressivity: VARIABLE` with `penetrance: UNKNOWN` is recording - no penetrance estimate has been published, and the reported phenotypes range from average measured cognition to moderate intellectual disability.

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Discussions and Knowledge Gaps

3

Which histone mark deposited by ASH1L - H3K36 or H3K4 - is the one whose loss causes the neurodevelopmental phenotype?

KNOWLEDGE GAP OPEN gap_mrd52_which_histone_mark_carries_the_disease

Attached to

pathophysiology#Reduced ASH1L Histone Methyltransferase Activity pathophysiology#Loss of Activating Chromatin Marks at Neurodevelopmental Gene Promoters

The clinical literature routinely describes ASH1L as an H3K36 methyltransferase, and the only human variant-interpretation paper to reason about mechanism attributes the defect to reduced H3K36 methylation. But the one study that actually measured chromatin in brain reports reduced H3K4me3 - in autism postmortem prefrontal cortex, and at the promoters of the downregulated genes in the mouse knockdown. Both marks are curated on the enzyme node because the sources support both, but they imply different downstream biology: H3K36 methylation is deposited across gene bodies of transcribed genes, whereas H3K4me3 is a promoter mark. Nothing in the published work resolves whether the H3K4me3 change is a direct catalytic product of ASH1L or an indirect consequence.

Proposed experiments

Separation-of-function ASH1L alleles in neurons

exp_mrd52_separation_of_function_ash1l_alleles

Compare catalytically dead ASH1L, and alleles selectively impaired for one mark, in the same neuronal system, measuring H3K36 and H3K4 methylation genome-wide alongside expression of the affected risk-gene set, to determine which mark's loss is sufficient for the transcriptional phenotype.

Show evidence (2 references)

PMID:34782621 SUPPORT Model Organism

"These downregulated genes are enriched in excitatory and inhibitory synaptic function and have decreased H3K4me3 occupancy at their promoters."

The measurement that puts H3K4me3, not H3K36 methylation, at the affected promoters.

PMID:38674358 SUPPORT Other

"ASH1L, located at chromosomal band 1q22, encodes a histone methyltransferase that catalyzes histone H3K36 methylation"

The clinical literature's H3K36 characterization, which is the other side of the discrepancy.

Are ASH1L missense variants genuinely associated with a more severe and more autism-weighted phenotype than truncating variants, and if so does that mean they act by something other than simple haploinsufficiency?

KNOWLEDGE GAP OPEN gap_mrd52_missense_versus_truncating_severity

Attached to

pathophysiology#Heterozygous ASH1L Loss of Function pathophysiology#Reduced ASH1L Histone Methyltransferase Activity

A 2021 review of published cases reported that missense-variant patients had more severe phenotypes and more autism than truncating-variant patients. If real, that is mechanistically important: a missense allele more damaging than a null implies a dominant-negative or gain-of-function effect rather than haploinsufficiency, which is the mechanism the field otherwise assumes. But the 2024 Brain Gene Registry review takes the opposite editorial position, treating the reported missense alleles as still requiring functional work and excluding the registry's own missense-variant participants from its phenotype tabulation on those grounds. No functional assay has been published for any human missense allele.

Proposed experiments

Functional assay of reported ASH1L missense alleles

exp_mrd52_missense_allele_functional_assay

Express reported missense alleles alongside wild type and null in a neuronal system, and test both catalytic output and whether the missense protein interferes with the wild-type allele, to distinguish haploinsufficiency from a dominant-negative effect.

Show evidence (2 references)

PMID:34373061 SUPPORT Human Clinical

"We found that patients with missense mutations in ASH1L appeared to present with more severe phenotypes and a higher likelihood of ASD than those with truncating mutations."

States the genotype-phenotype claim this gap is about.

PMID:38674358 SUPPORT Human Clinical

"haploinsufficiency is believed to be at least one disease mechanism"

The hedged wording - "at least one" mechanism - is the counterweight: the 2024 review holds the missense mechanism open rather than accepting the severity claim.

Do the Ash1l mouse models inform human ASH1L-related epilepsy, given that the strongest excitation-inhibition data come from a severe knockdown rather than haploinsufficiency, and the haploinsufficient model's spontaneous seizures are absence-like rather than the focal and myoclonic types reported in patients?

HUMAN MODEL MISMATCH OPEN mismatch_mrd52_model_genotype_and_seizure_semiology

Attached to

pathophysiology#Cortical Excitation-Inhibition Imbalance pathophysiology#Seizures

Two different manipulations underlie the excitability story and they are not interchangeable. The mechanistic detail - which genes lose H3K4me3, which synaptic currents change, that diazepam plus chemogenetic silencing rescues seizures - comes from a prefrontal knockdown described by its own authors as severe deficiency, causing early mortality that human patients do not have. The genotype-matched heterozygous gene-trap model reproduces hyperexcitability but its spontaneous seizures are absence-like, and convulsive seizures appear only on pentylenetetrazole challenge, whereas reported patients have febrile, focal motor and myoclonic seizures. Reading the knockdown's rescue result as a therapeutic lead for patients therefore crosses two gaps at once: dose and semiology.

Proposed experiments

Longitudinal seizure phenotyping of genotype-matched Ash1l heterozygotes

exp_mrd52_heterozygous_model_seizure_characterization

Perform long-term video-EEG across development in heterozygous Ash1l mice on more than one genetic background, classifying seizure types against the human semiologies, and test whether the GABA-enhancing rescue that works in the severe knockdown also works at heterozygous dose.

Show evidence (2 references)

PMID:34782621 SUPPORT Model Organism

"Chemogenetic inhibition of PFC pyramidal neuronal activity, combined with the administration of GABA enhancer diazepam, rescues PFC synaptic imbalance and seizures, but not autistic social deficits or anxiety-like behaviors."

The rescue result, and its own limit - the same intervention does not touch the social or anxiety phenotype, so even within the model it addresses one arm only.

PMID:39766886 SUPPORT Model Organism

"Epileptiform discharges were found on electroencephalograms (EEGs) of Ash1l+/GT mice, indicating absence-like seizures."

Establishes the semiology of the genotype-matched model, which is the half of the mismatch that dose-matching does not fix.

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Pathophysiology

12

Heterozygous ASH1L Loss of Function

A heterozygous loss-of-function variant in ASH1L - nonsense, frameshift or whole-gene deletion - is the initiating lesion. This node captures the single concept of the genetic lesion.

ASH1L hgnc:19088

Downstream

Reduced ASH1L Histone Methyltransferase Activity One functional allele does not supply enough enzyme; ASH1L is among the most loss-of-function intolerant genes in the genome.

Show evidence (2 references)

PMID:38674358 SUPPORT Human Clinical

"Heterozygous pathogenic variants in ASHL1 have been implicated in an autosomal dominant neurodevelopmental disorder (NDD)."

Establishes heterozygous ASH1L variants as the cause. The gene symbol is misspelled in the source sentence and is quoted as printed.

PMID:28191889 SUPPORT Human Clinical

"Clinical follow-up for NAA15, KMT5B, and ASH1L highlighted new syndromic and nonsyndromic forms of disease."

The large targeted-sequencing study that delineated ASH1L as a neurodevelopmental-disorder gene with a syndromic presentation.

Reduced ASH1L Histone Methyltransferase Activity

ASH1L is the human Trithorax-group homolog of Drosophila Ash1 and deposits activating histone methylation. Sources differ on which mark carries the disease: the gene is most often described as an H3K36 methyltransferase, while the study that measured chromatin in brain reports H3K4 methylation as the affected mark. Both are recorded and the discrepancy is carried as an open gap. This node captures the single concept of reduced methyltransferase activity.

histone H3K36 methyltransferase activity GO:0046975 ↓ DECREASED histone H3K4 methyltransferase activity GO:0042800 ↓ DECREASED

Downstream

Loss of Activating Chromatin Marks at Neurodevelopmental Gene Promoters Reduced enzyme activity leaves promoters of ASH1L-dependent genes with less activating methylation.

Show evidence (2 references)

PMID:34782621 SUPPORT Other

"is a histone methyltransferase catalyzing H3K4 and H3K36 methylation, which plays an important role in chromatin modification and gene transcription"

Assigns both marks to ASH1L. Evidence source is OTHER because this is the paper's introductory characterization of the enzyme rather than its own measurement.

PMID:38674358 SUPPORT Other

"ASH1L, located at chromosomal band 1q22, encodes a histone methyltransferase that catalyzes histone H3K36 methylation"

Names H3K36 as the catalysed mark. Support is PARTIAL because this source names only H3K36 while the brain chromatin study measures H3K4; that disagreement is the subject of a curated knowledge gap.

Loss of Activating Chromatin Marks at Neurodevelopmental Gene Promoters

Genes that depend on ASH1L lose activating histone methylation at their promoters. In prefrontal cortex the affected set is enriched for genes with synaptic function and is dominated by established risk genes for autism, intellectual disability and epilepsy - so the epigenetic lesion is not diffuse but falls on the same gene set that other neurodevelopmental disorders converge on. This node captures the single concept of the promoter chromatin defect.

neuron CL:0000540

Downstream

Downregulation of Synaptic and Neurodevelopmental Gene Programs Loss of activating marks translates into reduced transcription of the affected genes.

Show evidence (1 reference)

PMID:34782621 SUPPORT Model Organism

"These downregulated genes are enriched in excitatory and inhibitory synaptic function and have decreased H3K4me3 occupancy at their promoters."

Directly links reduced promoter H3K4me3 occupancy to the downregulated synaptic gene set, in mouse prefrontal cortex.

Downregulation of Synaptic and Neurodevelopmental Gene Programs

Transcription of ASH1L-dependent synaptic and neurodevelopmental genes falls. This node is the branch point of the disorder: from here the phenotype separates into a synaptic-pruning arm, an excitability arm, and a cortical-patterning arm. This node captures the single concept of the transcriptional deficit.

neuron CL:0000540

regulation of transcription by RNA polymerase II GO:0006357 ↓ DECREASED

Downstream

Synaptic Pruning Failure In haploinsufficient mice the route runs through silencing of the Eph receptor A7 gene by EZH2-deposited H3K27me3.

Cortical Excitation-Inhibition Imbalance The downregulated gene set is enriched for both excitatory and inhibitory synaptic function, and the net measured effect is loss of inhibition with enhanced excitation.

Disrupted Cortical Neuron Specification and Lamination The same transcriptional dependence operates during corticogenesis, when ASH1L is required to specify upper-layer projection neuron identity.

Extraneural Developmental Anomalies ASH1L is required for gene expression across organ systems, but the transcriptional programmes linking its loss to the genital, skeletal and craniofacial findings have not been identified.

Show evidence (2 references)

PMID:34782621 SUPPORT Model Organism

"Knockdown of Ash1L in PFC of juvenile mice induces the downregulation of risk genes associated with ASD, intellectual disability (ID) and epilepsy."

Establishes that the transcriptional consequence of ASH1L loss falls specifically on autism, intellectual-disability and epilepsy risk genes.

PMID:34145365 SUPPORT Model Organism

"Gene expression analyses uncover critical roles of ASH1L in regulating gene expression during neural cell development."

Independent model-organism support for ASH1L acting through transcriptional regulation during neural development.

Synaptic Pruning Failure

Developmental synapse elimination fails and excess synapses persist. In haploinsufficient mice this is traced to loss of Eph receptor A7 expression through EZH2-mediated H3K27me3 accumulation in its gene body, and restoring EphA7 signalling with its ligand ephrin-A5 restores pruning. This node captures the single concept of the pruning deficit.

neuron CL:0000540

synapse pruning GO:0098883 ↓ DECREASED

Animal models

Ash1l heterozygous knockout mouse (EphA7 pruning model) Mouse recapitulates Excess synapses persist because developmental pruning fails, and the responsible gene, Eph receptor A7, is identified together with the repressive-mark mechanism silencing it.

Downstream

Autistic and Behavioral Phenotype Persisting excess synapses are proposed as the substrate of the autistic phenotype; the steps from altered connectivity to behaviour are not established.

Show evidence (2 references)

PMID:35081333 SUPPORT Model Organism

"Mechanistically, deletion of Ash1l in neurons induces excessive synapses due to the synapse pruning deficits, especially during the post-learning period."

Establishes failed synapse pruning as the cellular mechanism in Ash1l-deficient neurons.

PMID:35081333 SUPPORT Model Organism

"Specifically, Eph receptor A7 is downregulated in Ash1l+/- mice through accumulating EZH2-mediated H3K27me3 in its gene body."

Identifies the specific gene, and the repressive-mark mechanism, connecting ASH1L haploinsufficiency to the pruning deficit.

Cortical Excitation-Inhibition Imbalance

Loss of the ASH1L-dependent synaptic gene programme leaves cortical circuits with diminished GABAergic inhibition and enhanced glutamatergic transmission. This node captures the single concept of the excitation-inhibition imbalance and conforms to the shared epilepsy final common pathway.

GABAergic neuron CL:0000617

gamma-aminobutyric acid signaling pathway GO:0007214 ↓ DECREASED

Downstream

Pyramidal Neuron Hyperexcitability The imbalance raises the intrinsic and synaptic excitability of cortical pyramidal neurons.

Show evidence (1 reference)

PMID:34782621 SUPPORT Model Organism

"Furthermore, Ash1L deficiency in PFC causes the diminished GABAergic inhibition, enhanced glutamatergic transmission, and elevated PFC pyramidal neuronal excitability, which is associated with severe seizures and early mortality."

Direct electrophysiological demonstration of the imbalance and its link to seizures, in a prefrontal knockdown model.

Pyramidal Neuron Hyperexcitability

Cortical pyramidal neurons become hyperexcitable through altered intrinsic properties as well as the synaptic shift. This node captures the single concept of network hyperexcitability and conforms to the shared epilepsy final common pathway.

pyramidal neuron CL:0000598

action potential GO:0001508 ↑ INCREASED

Animal models

Ash1l gene-trap haploinsufficient mouse Mouse recapitulates Whole-cell recording in prefrontal cortex demonstrates increased pyramidal excitability arising from intrinsic property changes plus enhanced glutamatergic and diminished GABAergic transmission, in a heterozygous animal matching the human genotype.

Downstream

Seizures Hyperexcitable cortical networks generate epileptiform discharge and clinical seizures.

Show evidence (1 reference)

PMID:39766886 SUPPORT Model Organism

"Whole-cell patch-clamp recordings showed that Ash1l haploinsufficiency increased the excitability of pyramidal neurons in the PFC by altering intrinsic neuronal properties, enhancing glutamatergic synaptic transmission, and diminishing GABAergic synaptic inhibition."

Establishes pyramidal hyperexcitability in the model that matches the human heterozygous genotype, and separates the intrinsic from the synaptic contribution.

Seizures

Seizures occur in roughly half of reported patients and span febrile, focal motor, absence and myoclonic semiologies; at least one reported proband's epilepsy was drug-resistant. This node captures the single concept of the clinical seizure endpoint and conforms to the shared epilepsy final common pathway.

neuron CL:0000540

Animal models

Ash1l gene-trap haploinsufficient mouse Mouse partially recapitulates The model has an electrographic seizure phenotype and increased susceptibility to provoked convulsive seizures.

Show evidence (2 references)

PMID:38674358 SUPPORT Human Clinical

"ID/DD is the most frequent phenotype (15/16, 94%), with other common phenotypes being ADHD or hyperactivity (6/7, 86%), obsessive behaviors (4/5, 80%), gastrointestinal disturbances (6/8, 75%), facial dysmorphisms (9/13, 69%), sleep disorders (6/9, 67%), ASD (6/10, 60%), ocular problems (6/10,..."

Gives the proportion of reported probands with seizures, with its denominator.

PMID:34373061 SUPPORT Human Clinical

"Here, we present twin sisters exhibiting mild intellectual disability and seizures."

An independent report of seizures alongside intellectual disability in ASH1L-mutant patients.

Disrupted Cortical Neuron Specification and Lamination

ASH1L is required during corticogenesis to specify projection neuron identity and place neurons in the correct layer. In its absence, SATB2-expressing neurons increase in number, are distributed through the cortical plate instead of being confined to upper layers, and follow an altered differentiation trajectory. This node captures the single concept of the cortical patterning defect.

cortical projection neuron CL:0000598

cerebral cortex neuron differentiation GO:0021895 ⚠ ABNORMAL

Animal models

Cortex-specific Ash1l conditional knockout mouse Mouse recapitulates Cortical Ash1l deletion produces excess and ectopically placed SATB2-expressing projection neurons with an altered differentiation trajectory, establishing a requirement for ASH1L in projection neuron specification.

Downstream

Intellectual Disability and Developmental Delay Miswired cortex is the presumed structural substrate of the cognitive phenotype; no human neuropathological correlate has been reported.

Show evidence (1 reference)

PMID:38943682 SUPPORT Model Organism

"Birthdating revealed generation of ectopically placed deep layer neurons that express SATB2"

Demonstrates misspecified, ectopically positioned cortical projection neurons after cortical Ash1l deletion.

Autistic and Behavioral Phenotype

Autism, ADHD or hyperactivity, compulsive behaviours, anxiety and mood disorder make up the behavioural component of the syndrome and are as consistent a feature as the cognitive impairment. This node captures the single concept of the behavioural endpoint.

Show evidence (2 references)

PMID:38674358 SUPPORT Human Clinical

"ID/DD is the most frequent phenotype (15/16, 94%), with other common phenotypes being ADHD or hyperactivity (6/7, 86%), obsessive behaviors (4/5, 80%), gastrointestinal disturbances (6/8, 75%), facial dysmorphisms (9/13, 69%), sleep disorders (6/9, 67%), ASD (6/10, 60%), ocular problems (6/10,..."

Quantifies the behavioural component with its denominators.

PMID:35081333 SUPPORT Model Organism

"We find haploinsufficiency of Ash1l causally induces anxiety and autistic-like behavior, including repetitive behavior, and alters social behavior."

Model-organism evidence that the same heterozygous lesion is sufficient to produce the behavioural phenotype.

Intellectual Disability and Developmental Delay

Intellectual disability or developmental delay is the most consistent feature, present in fifteen of sixteen reported probands. Severity ranges widely - one proband tested in the average range on standardized cognitive assessment while still meeting criteria for the syndrome, which is what makes the "intellectual disability" name of the OMIM entry an incomplete description. This node captures the single concept of the cognitive endpoint.

Show evidence (1 reference)

PMID:38674358 SUPPORT Human Clinical

"ID/DD is the most frequent phenotype (15/16, 94%)"

Gives the proportion of reported probands with intellectual disability or developmental delay, with its denominator.

Extraneural Developmental Anomalies

Beyond the nervous system, reported probands have genital malformations (penile torsion, cryptorchidism), musculoskeletal findings (pectus carinatum or excavatum, scoliosis, cervical spinal fusion) and variable facial dysmorphism with no recognizable gestalt. The mouse null adds craniofacial evidence - shortened nasal bones and perinatal lethality. This node captures the single concept of the extraneural developmental phenotype.

Animal models

Cortex-specific Ash1l conditional knockout mouse Mouse partially recapitulates The germline null dies perinatally and has shortened nasal bones, demonstrating a requirement for Ash1l in craniofacial development outside the brain.

Show evidence (2 references)

PMID:38674358 SUPPORT Human Clinical

"ID/DD is the most frequent phenotype (15/16, 94%), with other common phenotypes being ADHD or hyperactivity (6/7, 86%), obsessive behaviors (4/5, 80%), gastrointestinal disturbances (6/8, 75%), facial dysmorphisms (9/13, 69%), sleep disorders (6/9, 67%), ASD (6/10, 60%), ocular problems (6/10,..."

Gives the proportion of reported probands with genital malformations, with its denominator.

PMID:38943682 SUPPORT Model Organism

"This study underscores the essential role of Ash1l in postnatal survival and normal craniofacial development."

Model-organism evidence that Ash1l loss affects craniofacial development outside the nervous system.

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Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.

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Phenotypes

19

Digestive 2

Gastrointestinal Disturbance FREQUENT Abnormality of the gastrointestinal tract HP:0011024

Show evidence (1 reference)

PMID:38674358 SUPPORT Human Clinical

"ID/DD is the most frequent phenotype (15/16, 94%), with other common phenotypes being ADHD or hyperactivity (6/7, 86%), obsessive behaviors (4/5, 80%), gastrointestinal disturbances (6/8, 75%), facial dysmorphisms (9/13, 69%), sleep disorders (6/9, 67%), ASD (6/10, 60%), ocular problems (6/10,..."

6/8 = 75% maps to the FREQUENT band (30-79%), on a denominator of eight.

Feeding Difficulties FREQUENT HP:0011968

Show evidence (1 reference)

PMID:38674358 SUPPORT Human Clinical

"ID/DD is the most frequent phenotype (15/16, 94%), with other common phenotypes being ADHD or hyperactivity (6/7, 86%), obsessive behaviors (4/5, 80%), gastrointestinal disturbances (6/8, 75%), facial dysmorphisms (9/13, 69%), sleep disorders (6/9, 67%), ASD (6/10, 60%), ocular problems (6/10,..."

4/8 = 50% maps to the FREQUENT band (30-79%), on a denominator of eight.

Ear 1

Sensorineural Hearing Impairment FREQUENT HP:0000407

Show evidence (1 reference)

PMID:38674358 SUPPORT Human Clinical

"other less common phenotypes include hearing impairments (4/9, 44%), pectus carinatum/excavatum (2/7, 29%), and scoliosis (2/7, 29%)"

4/9 = 44% maps to the FREQUENT band (30-79%), on a denominator of nine.

Head and Neck 1

Facial Dysmorphism FREQUENT Abnormal facial shape HP:0001999

Show evidence (1 reference)

PMID:38674358 SUPPORT Human Clinical

"ID/DD is the most frequent phenotype (15/16, 94%), with other common phenotypes being ADHD or hyperactivity (6/7, 86%), obsessive behaviors (4/5, 80%), gastrointestinal disturbances (6/8, 75%), facial dysmorphisms (9/13, 69%), sleep disorders (6/9, 67%), ASD (6/10, 60%), ocular problems (6/10,..."

9/13 = 69% maps to the FREQUENT band (30-79%). The same paper notes that in most published probands it is unclear whether dysmorphology was assessed and negative or simply not assessed, so this figure is likely inflated.

Musculoskeletal 3

Hypotonia FREQUENT HP:0001252

Show evidence (1 reference)

PMID:38674358 SUPPORT Human Clinical

"ID/DD is the most frequent phenotype (15/16, 94%), with other common phenotypes being ADHD or hyperactivity (6/7, 86%), obsessive behaviors (4/5, 80%), gastrointestinal disturbances (6/8, 75%), facial dysmorphisms (9/13, 69%), sleep disorders (6/9, 67%), ASD (6/10, 60%), ocular problems (6/10,..."

4/7 = 57% maps to the FREQUENT band (30-79%), on a denominator of seven.

Scoliosis OCCASIONAL HP:0002650

Show evidence (1 reference)

PMID:38674358 SUPPORT Human Clinical

"other less common phenotypes include hearing impairments (4/9, 44%), pectus carinatum/excavatum (2/7, 29%), and scoliosis (2/7, 29%)"

2/7 = 29% maps to the OCCASIONAL band (5-29%), on a denominator of seven.

Pectus Deformity OCCASIONAL Pectus carinatum HP:0000768

Show evidence (1 reference)

PMID:38674358 SUPPORT Human Clinical

"other less common phenotypes include hearing impairments (4/9, 44%), pectus carinatum/excavatum (2/7, 29%), and scoliosis (2/7, 29%)"

2/7 = 29% maps to the OCCASIONAL band (5-29%), on a denominator of seven. The source counts carinatum and excavatum together; this entry binds the carinatum term and names both in the description rather than splitting an undivided count.

Nervous System 10

Intellectual Disability or Developmental Delay VERY_FREQUENT HP:0001249

Show evidence (1 reference)

PMID:38674358 SUPPORT Human Clinical

"ID/DD is the most frequent phenotype (15/16, 94%)"

15/16 = 94% maps to the VERY_FREQUENT band (80-99%). The denominator is small and drawn from published reports plus a registry, so the estimate is ascertainment-biased.

Attention Deficit Hyperactivity Disorder VERY_FREQUENT HP:0007018

Show evidence (1 reference)

PMID:38674358 SUPPORT Human Clinical

"ID/DD is the most frequent phenotype (15/16, 94%), with other common phenotypes being ADHD or hyperactivity (6/7, 86%), obsessive behaviors (4/5, 80%), gastrointestinal disturbances (6/8, 75%), facial dysmorphisms (9/13, 69%), sleep disorders (6/9, 67%), ASD (6/10, 60%), ocular problems (6/10,..."

6/7 = 86% maps to the VERY_FREQUENT band (80-99%), on a denominator of seven assessed probands.

Compulsive Behaviors VERY_FREQUENT HP:0000722

Show evidence (1 reference)

PMID:38674358 SUPPORT Human Clinical

"ID/DD is the most frequent phenotype (15/16, 94%), with other common phenotypes being ADHD or hyperactivity (6/7, 86%), obsessive behaviors (4/5, 80%), gastrointestinal disturbances (6/8, 75%), facial dysmorphisms (9/13, 69%), sleep disorders (6/9, 67%), ASD (6/10, 60%), ocular problems (6/10,..."

4/5 = 80% falls at the lower edge of the VERY_FREQUENT band (80-99%), on a denominator of only five assessed probands.

Autism FREQUENT HP:0000717

Show evidence (1 reference)

PMID:38674358 SUPPORT Human Clinical

"ID/DD is the most frequent phenotype (15/16, 94%), with other common phenotypes being ADHD or hyperactivity (6/7, 86%), obsessive behaviors (4/5, 80%), gastrointestinal disturbances (6/8, 75%), facial dysmorphisms (9/13, 69%), sleep disorders (6/9, 67%), ASD (6/10, 60%), ocular problems (6/10,..."

6/10 = 60% maps to the FREQUENT band (30-79%), on a denominator of ten assessed probands.

Sleep Disturbance FREQUENT HP:0002360

Show evidence (1 reference)

PMID:38674358 SUPPORT Human Clinical

"ID/DD is the most frequent phenotype (15/16, 94%), with other common phenotypes being ADHD or hyperactivity (6/7, 86%), obsessive behaviors (4/5, 80%), gastrointestinal disturbances (6/8, 75%), facial dysmorphisms (9/13, 69%), sleep disorders (6/9, 67%), ASD (6/10, 60%), ocular problems (6/10,..."

6/9 = 67% maps to the FREQUENT band (30-79%), on a denominator of nine.

Speech Delay FREQUENT Delayed speech and language development HP:0000750

Show evidence (1 reference)

PMID:38674358 SUPPORT Human Clinical

"ID/DD is the most frequent phenotype (15/16, 94%), with other common phenotypes being ADHD or hyperactivity (6/7, 86%), obsessive behaviors (4/5, 80%), gastrointestinal disturbances (6/8, 75%), facial dysmorphisms (9/13, 69%), sleep disorders (6/9, 67%), ASD (6/10, 60%), ocular problems (6/10,..."

6/10 = 60% maps to the FREQUENT band (30-79%), on a denominator of ten.

Seizures FREQUENT HP:0001250

Show evidence (1 reference)

PMID:38674358 SUPPORT Human Clinical

"ID/DD is the most frequent phenotype (15/16, 94%), with other common phenotypes being ADHD or hyperactivity (6/7, 86%), obsessive behaviors (4/5, 80%), gastrointestinal disturbances (6/8, 75%), facial dysmorphisms (9/13, 69%), sleep disorders (6/9, 67%), ASD (6/10, 60%), ocular problems (6/10,..."

6/11 = 55% maps to the FREQUENT band (30-79%), on a denominator of eleven.

Motor Delay FREQUENT HP:0001270

Show evidence (1 reference)

PMID:38674358 SUPPORT Human Clinical

"ID/DD is the most frequent phenotype (15/16, 94%), with other common phenotypes being ADHD or hyperactivity (6/7, 86%), obsessive behaviors (4/5, 80%), gastrointestinal disturbances (6/8, 75%), facial dysmorphisms (9/13, 69%), sleep disorders (6/9, 67%), ASD (6/10, 60%), ocular problems (6/10,..."

6/12 = 50% maps to the FREQUENT band (30-79%), on a denominator of twelve.

Gait Disturbance FREQUENT HP:0001288

Show evidence (1 reference)

PMID:38674358 SUPPORT Human Clinical

"and abnormal gait (2/4, 50%)"

2/4 = 50% maps to the FREQUENT band (30-79%), but on a denominator of only four probands - the weakest estimate in this set.

Depression FREQUENT HP:0000716

Show evidence (1 reference)

PMID:38674358 SUPPORT Human Clinical

"ID/DD is the most frequent phenotype (15/16, 94%), with other common phenotypes being ADHD or hyperactivity (6/7, 86%), obsessive behaviors (4/5, 80%), gastrointestinal disturbances (6/8, 75%), facial dysmorphisms (9/13, 69%), sleep disorders (6/9, 67%), ASD (6/10, 60%), ocular problems (6/10,..."

2/4 = 50% maps to the FREQUENT band (30-79%), on a denominator of only four probands.

Other 2

Ocular Abnormality FREQUENT Abnormality of the eye HP:0000478

Show evidence (1 reference)

PMID:38674358 SUPPORT Human Clinical

"ID/DD is the most frequent phenotype (15/16, 94%), with other common phenotypes being ADHD or hyperactivity (6/7, 86%), obsessive behaviors (4/5, 80%), gastrointestinal disturbances (6/8, 75%), facial dysmorphisms (9/13, 69%), sleep disorders (6/9, 67%), ASD (6/10, 60%), ocular problems (6/10,..."

6/10 = 60% maps to the FREQUENT band (30-79%), on a denominator of ten.

Genital Malformation FREQUENT Abnormality of the genital system HP:0000078

Show evidence (1 reference)

PMID:38674358 SUPPORT Human Clinical

"ID/DD is the most frequent phenotype (15/16, 94%), with other common phenotypes being ADHD or hyperactivity (6/7, 86%), obsessive behaviors (4/5, 80%), gastrointestinal disturbances (6/8, 75%), facial dysmorphisms (9/13, 69%), sleep disorders (6/9, 67%), ASD (6/10, 60%), ocular problems (6/10,..."

5/9 = 56% maps to the FREQUENT band (30-79%), on a denominator of nine.

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Genetic Associations

1

ASH1L

Gene: ASH1L hgnc:19088 relationship_type: CAUSATIVE

Show evidence (2 references)

PMID:38674358 SUPPORT Human Clinical

"relationship to syndromic complex neurodevelopmental disorder was classified as Definitive."

Records the ClinGen Definitive gene-disease validity classification for ASH1L.

PMID:39902220 SUPPORT Human Clinical

"A review of reported ASH1L nonsense mutations to explore genotype-phenotype correlations suggested that these variants typically result in a loss of function."

Supports loss of function as the mechanism of the nonsense allele class.

💊

Medical Actions

2

Antiseizure Medication

Action: Pharmacotherapy NCIT:C15986

Seizures are managed with standard antiseizure medication. No agent has been shown to be preferentially effective in this disorder, and at least one reported proband's epilepsy was resistant to clonazepam, so treatment is empirical.

Show evidence (1 reference)

PMID:38674358 SUPPORT Human Clinical

"ASD, mild bilateral sensorineural hearing loss, and epilepsy (absence, focal motor, and myoclonic seizures); this proband"

Documents the epilepsy that requires treatment and, in the continuation of the same sentence, its drug resistance. Support is PARTIAL because no disease-specific efficacy data exist for any antiseizure medication here.

Developmental and Behavioral Support

Action: Rehabilitation NCIT:C15315

Management is otherwise supportive and multidisciplinary: developmental, speech and language, and behavioural intervention for the intellectual disability, autism, ADHD and compulsive behaviours, together with surveillance for the sleep, gastrointestinal, ocular, hearing and musculoskeletal features that make up the syndromic phenotype. This is standard neurodevelopmental care rather than a disease-specific protocol.

🔬

Diagnosis

1

Exome or Genome Sequencing

The diagnosis is molecular: identification of a heterozygous loss-of-function ASH1L variant, usually de novo, on trio exome or genome sequencing performed for developmental delay, autism or epilepsy. There is no biochemical or imaging marker. Interpretation is complicated in practice by the frequency with which additional variants of uncertain significance are found alongside the ASH1L variant.

Show evidence (1 reference)

PMID:38674358 SUPPORT Human Clinical

"ASH1L variants were first implicated in human disease in 2012 through a large sequencing study in persons with severe ID."

Establishes sequencing as the route by which the disorder is identified.

📊

Prevalence

1

Worldwide

Cases In Literature Ultra Rare

Only sixteen probands had been reported with detailed phenotyping at the time of the 2024 review, although over a hundred loss-of-function ASH1L variants have been catalogued in autism sequencing cohorts without individual clinical description. No population rate has been estimated, and the gap between the two counts is itself the reason a rate cannot be inferred.

Show evidence (2 references)

PMID:38674358 SUPPORT Human Clinical

"ID/DD is the most frequent phenotype (15/16, 94%)"

The denominator of sixteen is the deeply phenotyped literature cohort; no normalized population rate is asserted.

PMID:34782621 SUPPORT Other

"Over 100 loss-of-function (LOF) mutations in the coding regions of ASH1L have been discovered"

Establishes the much larger variant count from sequencing cohorts, against which the small clinically described cohort should be read. Evidence source is OTHER because this is the paper's summary of the genetic literature.

🐁

Animal Models

3

Ash1l gene-trap haploinsufficient mouse

A heterozygous gene-trap knockout, and the model whose genotype most closely matches human patients. It shows social deficits, increased self-grooming and cognitive impairment, absence-like epileptiform discharge on EEG, increased susceptibility to chemically provoked convulsive seizures, and prefrontal pyramidal hyperexcitability.

Species

Mouse

Genotype

Ash1l+/GT (targeted gene-trap knockout, heterozygous)

Publication

PMID:39766886

Pathograph links

Pyramidal Neuron Hyperexcitability recapitulates fidelity: moderate Whole-cell recording in prefrontal cortex demonstrates increased pyramidal excitability arising from intrinsic property changes plus enhanced glutamatergic and diminished GABAergic transmission, in a heterozygous animal matching the human genotype.

Limitations: Measured only in prefrontal cortex; the human seizure semiologies include focal motor and myoclonic seizures whose generators are not necessarily prefrontal, and no human electrophysiological or tissue correlate exists.

Readouts

Prefrontal pyramidal neuron excitability

Whole-cell patch-clamp recording of prefrontal pyramidal neurons in Ash1l+/GT versus wild-type mice.

Direction: INCREASED

Interpretation: Increased excitability with the excitatory-inhibitory shift is the direct electrophysiological correlate of this node.

Show evidence (1 reference)

PMID:39766886 SUPPORT Model Organism

"Whole-cell patch-clamp recordings showed that Ash1l haploinsufficiency increased the excitability of pyramidal neurons in the PFC by altering intrinsic neuronal properties, enhancing glutamatergic synaptic transmission, and diminishing GABAergic synaptic inhibition."

Reports the electrophysiological measurement behind this readout.

Show evidence (1 reference)

PMID:39766886 SUPPORT Model Organism

"Chemogenetic inhibition of pyramidal neurons in the PFC of Ash1l+/GT mice ameliorated autism-like social deficits and abolished absence-like seizures."

Reversing the excitability abnormality abolishes the seizure phenotype, which is what makes this model informative for the node rather than merely correlated with it.

Seizures partially recapitulates fidelity: low The model has an electrographic seizure phenotype and increased susceptibility to provoked convulsive seizures.

Limitations: The spontaneous phenotype is absence-like epileptiform discharge, whereas the reported human semiologies are febrile, focal motor, absence and myoclonic seizures; convulsive seizures in the model appear only on pentylenetetrazole challenge. The model therefore reproduces a seizure tendency, not the human epilepsy.

Readouts

Electroencephalographic epileptiform discharge

EEG recording in Ash1l+/GT versus wild-type mice.

Direction: INCREASED

Interpretation: Spontaneous epileptiform discharge establishes an unprovoked seizure phenotype, of absence type.

Show evidence (1 reference)

PMID:39766886 SUPPORT Model Organism

"Epileptiform discharges were found on electroencephalograms (EEGs) of Ash1l+/GT mice, indicating absence-like seizures."

Reports the EEG measurement behind this readout.

Show evidence (1 reference)

PMID:39766886 SUPPORT Model Organism

"Epileptiform discharges were found on electroencephalograms (EEGs) of Ash1l+/GT mice, indicating absence-like seizures."

Supports the model as informative for a seizure tendency while naming the semiology mismatch that limits it.

Show evidence (1 reference)

PMID:39766886 SUPPORT Model Organism

"Ash1l+/GT mice displayed social deficits, increased self-grooming, and cognitive impairments."

Establishes the behavioural phenotype of the haploinsufficient model.

Ash1l heterozygous knockout mouse (EphA7 pruning model)

Haploinsufficient mice show anxiety, repetitive behaviour and altered social behaviour with intact learning but impaired discrimination. Neuronal Ash1l deletion produces excess synapses through a pruning deficit, traced to silencing of Eph receptor A7 by EZH2-deposited H3K27me3; supplying the EphA7 ligand ephrin-A5 restores pruning and rescues the discrimination deficit.

Species

Mouse

Genotype

Ash1l+/- germline heterozygous knockout, and neuron-specific Ash1l deletion

Publication

PMID:35081333

Pathograph links

Synaptic Pruning Failure recapitulates fidelity: moderate Excess synapses persist because developmental pruning fails, and the responsible gene, Eph receptor A7, is identified together with the repressive-mark mechanism silencing it.

Limitations: Synapse counts and pruning have not been measured in human ASH1L patients or tissue, and the pruning defect is most evident post-learning in a specific paradigm; the EPHA7 route is one identified mechanism, not necessarily the only one.

Readouts

Synapse number after learning

Synapse quantification in Ash1l-deleted neurons, particularly in the post-learning period.

Direction: INCREASED

Interpretation: Excess synapses are the direct cellular readout of the pruning failure.

Show evidence (1 reference)

PMID:35081333 SUPPORT Model Organism

"Mechanistically, deletion of Ash1l in neurons induces excessive synapses due to the synapse pruning deficits, especially during the post-learning period."

Reports the synapse-number measurement behind this readout.

Discrimination performance after ephrin-A5 supplementation

Behavioural discrimination testing in Ash1l+/- mice given the EphA7 ligand ephrin-A5, against untreated mutants.

Direction: RESTORED

Interpretation: Rescue by reactivating the specific downstream receptor is what makes the EPHA7 route causal rather than correlative.

Show evidence (1 reference)

PMID:35081333 SUPPORT Model Organism

"Importantly, increasing activation of EphA7 in Ash1l+/- mice by supplying its ligand, ephrin-A5, strongly promotes synapse pruning and rescues discrimination deficits."

Reports the rescue experiment behind this readout.

Show evidence (1 reference)

PMID:35081333 SUPPORT Model Organism

"Specifically, Eph receptor A7 is downregulated in Ash1l+/- mice through accumulating EZH2-mediated H3K27me3 in its gene body."

Supports treating this model as informative for the pruning node by naming the responsible gene and chromatin mechanism.

Show evidence (1 reference)

PMID:35081333 SUPPORT Model Organism

"Our results suggest that Ash1l haploinsufficiency is a highly penetrant risk factor for ASD, resulting from synapse pruning deficits."

States the model's central conclusion connecting haploinsufficiency to the pruning mechanism.

Cortex-specific Ash1l conditional knockout mouse

Tamoxifen-induced cortical deletion from E10.5 misspecifies cortical projection neurons: SATB2-expressing neurons increase in number, spread through the cortical plate, and appear ectopically in deep layers, with an altered differentiation trajectory on single-cell RNA sequencing. The germline null is present at expected proportions at E18.5 but absent at birth, and has shortened nasal bones.

Species

Mouse

Genotype

Ash1l exon 4 conditional deletion (p.V1693Afs*2), Emx1-Cre-ERT2 induced at E10.5; and Ash1l germline null

Publication

PMID:38943682

Pathograph links

Disrupted Cortical Neuron Specification and Lamination recapitulates fidelity: moderate Cortical Ash1l deletion produces excess and ectopically placed SATB2-expressing projection neurons with an altered differentiation trajectory, establishing a requirement for ASH1L in projection neuron specification.

Limitations: This is a homozygous conditional deletion in cortex, not the heterozygous loss patients carry, so the severity is not transferable; and no corresponding cortical malformation has been described in human ASH1L patients, whose reported neuroimaging is largely unremarkable.

Readouts

Laminar distribution of SATB2-expressing neurons

Immunohistochemistry for SATB2 with EdU birthdating in conditional knockout versus control cortex.

Direction: ALTERED

Interpretation: Deep-layer neurons ectopically expressing an upper-layer marker are the structural readout of misspecification.

Show evidence (1 reference)

PMID:38943682 SUPPORT Model Organism

"Birthdating revealed generation of ectopically placed deep layer neurons that express SATB2"

Reports the birthdating measurement behind this readout.

Show evidence (1 reference)

PMID:38943682 SUPPORT Model Organism

"In the cortical-specific knockout model, SATB2 neurons showed increased numbers (n = 6/genotype, P = 0.0001) and were distributed through the cortical plate."

Supports treating this model as informative for the cortical patterning node.

Extraneural Developmental Anomalies partially recapitulates fidelity: low The germline null dies perinatally and has shortened nasal bones, demonstrating a requirement for Ash1l in craniofacial development outside the brain.

Limitations: The mouse finding is a specific craniofacial measurement in homozygous nulls; the human extraneural phenotype is dominated by genital and musculoskeletal anomalies with no consistent facial gestalt, and human heterozygotes survive. The two do not correspond feature for feature.

Readouts

Nasal bone length

Skeletal measurement in Ash1l germline null embryos versus controls.

Direction: DECREASED

Interpretation: A quantified craniofacial skeletal defect outside the nervous system.

Show evidence (1 reference)

PMID:38943682 SUPPORT Model Organism

"Notably, Ash1l-/- exhibited shortened nasal bones (n = 31, P = 0.017)."

Reports the craniofacial measurement behind this readout.

Show evidence (1 reference)

PMID:38943682 SUPPORT Model Organism

"This study underscores the essential role of Ash1l in postnatal survival and normal craniofacial development."

Supports an extraneural developmental requirement while the specific features differ from the human phenotype.

Show evidence (1 reference)

PMID:38943682 SUPPORT Model Organism

"In the cortical-specific knockout model, SATB2 neurons showed increased numbers (n = 6/genotype, P = 0.0001) and were distributed through the cortical plate."

Establishes the cortical patterning phenotype that makes this model informative.

{ }

Source YAML

click to show

name: Intellectual Disability Autosomal Dominant 52
creation_date: "2026-08-27T00:00:00Z"
category: Mendelian
disease_term:
  preferred_term: intellectual disability, autosomal dominant 52
  term:
    id: MONDO:0030918
    label: intellectual disability, autosomal dominant 52
synonyms:
- MRD52
- mental retardation, autosomal dominant 52
- autosomal dominant mental retardation 52
- autosomal dominant intellectual disability 52
- ASH1L-related syndromic complex neurodevelopmental disorder
- ASH1L-related neurodevelopmental disorder
description: >-
  Intellectual disability, autosomal dominant 52 (MRD52) is the OMIM/MONDO name
  for the neurodevelopmental disorder caused by heterozygous loss-of-function
  variants in ASH1L. The name understates the entity. ASH1L encodes a
  Trithorax-group histone methyltransferase, and the phenotype curated by the
  ClinGen Intellectual Disability and Autism Gene Curation Expert Panel - and
  classified Definitive - is a syndromic complex neurodevelopmental disorder:
  intellectual disability and developmental delay in nearly every reported
  proband, but also autism, ADHD, compulsive behaviours, seizures, sleep and
  gastrointestinal disturbance, genital malformations, and variable skeletal and
  ocular findings. This entry curates that broader phenotype under the MONDO
  identifier the stub queue supplied, and records the naming mismatch here rather
  than silently narrowing the disease to its cognitive component.

  The mechanism is epigenetic. ASH1L deposits activating histone methylation
  (H3K36, and H3K4 in the reports that measure it) and is required to keep
  neurodevelopmental and synaptic gene programmes transcriptionally available.
  One functional copy is not enough - ASH1L is among the most loss-of-function
  intolerant genes in the genome - so haploinsufficiency leaves a broad,
  low-amplitude failure of gene activation rather than the loss of any single
  protein. The consequences curated here fan out from that one node in three
  directions: a synaptic arm (failed developmental synapse pruning, traced in
  mice to EPHA7 silencing), an excitability arm (downregulated inhibitory and
  excitatory synaptic genes producing a cortical excitation-inhibition imbalance
  and seizures, conforming to the shared epilepsy module), and a
  cortical-patterning arm (misspecified and ectopically placed cortical
  projection neurons).

  Two caveats are curated rather than smoothed over. First, essentially all
  mechanistic detail comes from mice, and the models are not equivalent to the
  human genotype: the strongest excitation-inhibition and seizure data come from
  a severe prefrontal knockdown, while the model that actually matches human
  heterozygous loss produces absence-like epileptiform discharge rather than the
  focal, myoclonic and febrile seizures reported in patients. Second, a
  genotype-phenotype claim is unsettled: one review reports missense variants as
  more severe and more autism-associated than truncating ones, while the ClinGen
  and Brain Gene Registry review treats the missense alleles as still needing
  functional work and excludes them from its phenotype tabulation.
parents:
- Neurodevelopmental Disorder
- Epilepsy
mappings:
  mondo_mappings:
  - term:
      id: MONDO:0030918
      label: intellectual disability, autosomal dominant 52
    mapping_predicate: skos:exactMatch
    mapping_source: MONDO
    mapping_justification: >-
      MONDO:0030918 is the MRD52 concept, xrefed to OMIM:617796 and carrying the
      RO:0004003 causal-gene relationship to HGNC:19088 (ASH1L).
inheritance:
- name: Autosomal dominant inheritance
  inheritance_term:
    preferred_term: Autosomal dominant inheritance
    term:
      id: HP:0000006
      label: Autosomal dominant inheritance
  description: >-
    Affected individuals are heterozygous for a loss-of-function ASH1L variant,
    most often de novo. The disease mechanism is haploinsufficiency rather than a
    dominant-negative effect.
  penetrance: UNKNOWN
  expressivity: VARIABLE
  evidence:
  - reference: PMID:38674358
    reference_title: "Expansion of the Genotypic and Phenotypic Spectrum of ASH1L-Related Syndromic Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Heterozygous pathogenic variants in ASHL1 have been implicated in an
      autosomal dominant neurodevelopmental disorder (NDD).
    explanation: >-
      States the autosomal dominant, heterozygous inheritance mode. The gene
      symbol is misspelled "ASHL1" in the source sentence and is quoted as
      printed.
  - reference: PMID:38674358
    reference_title: "Expansion of the Genotypic and Phenotypic Spectrum of ASH1L-Related Syndromic Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      haploinsufficiency is believed to be at least one disease mechanism
    explanation: >-
      Identifies haploinsufficiency as the dominant mechanism, which is what
      `expressivity: VARIABLE` with `penetrance: UNKNOWN` is recording - no
      penetrance estimate has been published, and the reported phenotypes range
      from average measured cognition to moderate intellectual disability.
pathophysiology:
- name: Heterozygous ASH1L Loss of Function
  description: >-
    A heterozygous loss-of-function variant in ASH1L - nonsense, frameshift or
    whole-gene deletion - is the initiating lesion. This node captures the single
    concept of the genetic lesion.
  role: trigger
  biological_scale: MOLECULAR
  gene:
    preferred_term: ASH1L
    term:
      id: hgnc:19088
      label: ASH1L
  evidence:
  - reference: PMID:38674358
    reference_title: "Expansion of the Genotypic and Phenotypic Spectrum of ASH1L-Related Syndromic Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Heterozygous pathogenic variants in ASHL1 have been implicated in an
      autosomal dominant neurodevelopmental disorder (NDD).
    explanation: >-
      Establishes heterozygous ASH1L variants as the cause. The gene symbol is
      misspelled in the source sentence and is quoted as printed.
  - reference: PMID:28191889
    reference_title: "Targeted sequencing identifies 91 neurodevelopmental-disorder risk genes with autism and developmental-disability biases."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Clinical follow-up for NAA15, KMT5B, and ASH1L highlighted new syndromic
      and nonsyndromic forms of disease.
    explanation: >-
      The large targeted-sequencing study that delineated ASH1L as a
      neurodevelopmental-disorder gene with a syndromic presentation.
  downstream:
  - target: Reduced ASH1L Histone Methyltransferase Activity
    causal_link_type: DIRECT
    description: >-
      One functional allele does not supply enough enzyme; ASH1L is among the
      most loss-of-function intolerant genes in the genome.
- name: Reduced ASH1L Histone Methyltransferase Activity
  description: >-
    ASH1L is the human Trithorax-group homolog of Drosophila Ash1 and deposits
    activating histone methylation. Sources differ on which mark carries the
    disease: the gene is most often described as an H3K36 methyltransferase, while
    the study that measured chromatin in brain reports H3K4 methylation as the
    affected mark. Both are recorded and the discrepancy is carried as an open
    gap. This node captures the single concept of reduced methyltransferase
    activity.
  role: mediator
  biological_scale: MOLECULAR
  molecular_functions:
  - preferred_term: histone H3K36 methyltransferase activity
    term:
      id: GO:0046975
      label: histone H3K36 methyltransferase activity
    modifier: DECREASED
  - preferred_term: histone H3K4 methyltransferase activity
    term:
      id: GO:0042800
      label: histone H3K4 methyltransferase activity
    modifier: DECREASED
  evidence:
  - reference: PMID:34782621
    reference_title: "Deficiency of autism risk factor ASH1L in prefrontal cortex induces epigenetic aberrations and seizures."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      is a histone methyltransferase catalyzing H3K4 and H3K36 methylation, which
      plays an important role in chromatin modification and gene transcription
    explanation: >-
      Assigns both marks to ASH1L. Evidence source is OTHER because this is the
      paper's introductory characterization of the enzyme rather than its own
      measurement.
  - reference: PMID:38674358
    reference_title: "Expansion of the Genotypic and Phenotypic Spectrum of ASH1L-Related Syndromic Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      ASH1L, located at chromosomal band 1q22, encodes a histone
      methyltransferase that catalyzes histone H3K36 methylation
    explanation: >-
      Names H3K36 as the catalysed mark. Support is PARTIAL because this source
      names only H3K36 while the brain chromatin study measures H3K4; that
      disagreement is the subject of a curated knowledge gap.
  downstream:
  - target: Loss of Activating Chromatin Marks at Neurodevelopmental Gene Promoters
    causal_link_type: DIRECT
    description: >-
      Reduced enzyme activity leaves promoters of ASH1L-dependent genes with less
      activating methylation.
- name: Loss of Activating Chromatin Marks at Neurodevelopmental Gene Promoters
  description: >-
    Genes that depend on ASH1L lose activating histone methylation at their
    promoters. In prefrontal cortex the affected set is enriched for genes with
    synaptic function and is dominated by established risk genes for autism,
    intellectual disability and epilepsy - so the epigenetic lesion is not diffuse
    but falls on the same gene set that other neurodevelopmental disorders
    converge on. This node captures the single concept of the promoter chromatin
    defect.
  role: mediator
  biological_scale: MOLECULAR
  cell_types:
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  evidence:
  - reference: PMID:34782621
    reference_title: "Deficiency of autism risk factor ASH1L in prefrontal cortex induces epigenetic aberrations and seizures."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      These downregulated genes are enriched in excitatory and inhibitory
      synaptic function and have decreased H3K4me3 occupancy at their promoters.
    explanation: >-
      Directly links reduced promoter H3K4me3 occupancy to the downregulated
      synaptic gene set, in mouse prefrontal cortex.
  downstream:
  - target: Downregulation of Synaptic and Neurodevelopmental Gene Programs
    causal_link_type: DIRECT
    description: >-
      Loss of activating marks translates into reduced transcription of the
      affected genes.
- name: Downregulation of Synaptic and Neurodevelopmental Gene Programs
  description: >-
    Transcription of ASH1L-dependent synaptic and neurodevelopmental genes falls.
    This node is the branch point of the disorder: from here the phenotype
    separates into a synaptic-pruning arm, an excitability arm, and a
    cortical-patterning arm. This node captures the single concept of the
    transcriptional deficit.
  role: central_effector
  biological_scale: CELLULAR
  cell_types:
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  biological_processes:
  - preferred_term: regulation of transcription by RNA polymerase II
    term:
      id: GO:0006357
      label: regulation of transcription by RNA polymerase II
    modifier: DECREASED
  evidence:
  - reference: PMID:34782621
    reference_title: "Deficiency of autism risk factor ASH1L in prefrontal cortex induces epigenetic aberrations and seizures."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Knockdown of Ash1L in PFC of juvenile mice induces the downregulation of
      risk genes associated with ASD, intellectual disability (ID) and epilepsy.
    explanation: >-
      Establishes that the transcriptional consequence of ASH1L loss falls
      specifically on autism, intellectual-disability and epilepsy risk genes.
  - reference: PMID:34145365
    reference_title: "Loss of histone methyltransferase ASH1L in the developing mouse brain causes autistic-like behaviors."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Gene expression analyses uncover critical roles of ASH1L in regulating gene
      expression during neural cell development.
    explanation: >-
      Independent model-organism support for ASH1L acting through transcriptional
      regulation during neural development.
  downstream:
  - target: Synaptic Pruning Failure
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: >-
      In haploinsufficient mice the route runs through silencing of the Eph
      receptor A7 gene by EZH2-deposited H3K27me3.
  - target: Cortical Excitation-Inhibition Imbalance
    causal_link_type: DIRECT
    description: >-
      The downregulated gene set is enriched for both excitatory and inhibitory
      synaptic function, and the net measured effect is loss of inhibition with
      enhanced excitation.
  - target: Disrupted Cortical Neuron Specification and Lamination
    causal_link_type: DIRECT
    description: >-
      The same transcriptional dependence operates during corticogenesis, when
      ASH1L is required to specify upper-layer projection neuron identity.
  - target: Extraneural Developmental Anomalies
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      ASH1L is required for gene expression across organ systems, but the
      transcriptional programmes linking its loss to the genital, skeletal and
      craniofacial findings have not been identified.
- name: Synaptic Pruning Failure
  description: >-
    Developmental synapse elimination fails and excess synapses persist. In
    haploinsufficient mice this is traced to loss of Eph receptor A7 expression
    through EZH2-mediated H3K27me3 accumulation in its gene body, and restoring
    EphA7 signalling with its ligand ephrin-A5 restores pruning. This node
    captures the single concept of the pruning deficit.
  role: mediator
  biological_scale: CELLULAR
  cell_types:
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  biological_processes:
  - preferred_term: synapse pruning
    term:
      id: GO:0098883
      label: synapse pruning
    modifier: DECREASED
  evidence:
  - reference: PMID:35081333
    reference_title: "ASH1L haploinsufficiency results in autistic-like phenotypes in mice and links Eph receptor gene to autism spectrum disorder."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Mechanistically, deletion of Ash1l in neurons induces excessive synapses
      due to the synapse pruning deficits, especially during the post-learning
      period.
    explanation: >-
      Establishes failed synapse pruning as the cellular mechanism in
      Ash1l-deficient neurons.
  - reference: PMID:35081333
    reference_title: "ASH1L haploinsufficiency results in autistic-like phenotypes in mice and links Eph receptor gene to autism spectrum disorder."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Specifically, Eph receptor A7 is downregulated in Ash1l+/- mice through
      accumulating EZH2-mediated H3K27me3 in its gene body.
    explanation: >-
      Identifies the specific gene, and the repressive-mark mechanism, connecting
      ASH1L haploinsufficiency to the pruning deficit.
  downstream:
  - target: Autistic and Behavioral Phenotype
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Persisting excess synapses are proposed as the substrate of the autistic
      phenotype; the steps from altered connectivity to behaviour are not
      established.
- name: Cortical Excitation-Inhibition Imbalance
  description: >-
    Loss of the ASH1L-dependent synaptic gene programme leaves cortical circuits
    with diminished GABAergic inhibition and enhanced glutamatergic transmission.
    This node captures the single concept of the excitation-inhibition imbalance
    and conforms to the shared epilepsy final common pathway.
  role: mediator
  biological_scale: CELLULAR
  conforms_to: "epilepsy_excitation_inhibition_imbalance#Excitation-Inhibition Imbalance"
  cell_types:
  - preferred_term: GABAergic neuron
    term:
      id: CL:0000617
      label: GABAergic neuron
  biological_processes:
  - preferred_term: gamma-aminobutyric acid signaling pathway
    term:
      id: GO:0007214
      label: gamma-aminobutyric acid signaling pathway
    modifier: DECREASED
  evidence:
  - reference: PMID:34782621
    reference_title: "Deficiency of autism risk factor ASH1L in prefrontal cortex induces epigenetic aberrations and seizures."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Furthermore, Ash1L deficiency in PFC causes the diminished GABAergic
      inhibition, enhanced glutamatergic transmission, and elevated PFC pyramidal
      neuronal excitability, which is associated with severe seizures and early
      mortality.
    explanation: >-
      Direct electrophysiological demonstration of the imbalance and its link to
      seizures, in a prefrontal knockdown model.
  downstream:
  - target: Pyramidal Neuron Hyperexcitability
    causal_link_type: DIRECT
    description: >-
      The imbalance raises the intrinsic and synaptic excitability of cortical
      pyramidal neurons.
- name: Pyramidal Neuron Hyperexcitability
  description: >-
    Cortical pyramidal neurons become hyperexcitable through altered intrinsic
    properties as well as the synaptic shift. This node captures the single
    concept of network hyperexcitability and conforms to the shared epilepsy final
    common pathway.
  role: central_effector
  biological_scale: CELLULAR
  conforms_to: "epilepsy_excitation_inhibition_imbalance#Neuronal Hyperexcitability and Hypersynchrony"
  cell_types:
  - preferred_term: pyramidal neuron
    term:
      id: CL:0000598
      label: pyramidal neuron
  biological_processes:
  - preferred_term: action potential
    term:
      id: GO:0001508
      label: action potential
    modifier: INCREASED
  evidence:
  - reference: PMID:39766886
    reference_title: "Chemogenetic Inhibition of Prefrontal Cortex Ameliorates Autism-Like Social Deficits and Absence-Like Seizures in a Gene-Trap Ash1l Haploinsufficiency Mouse Model."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Whole-cell patch-clamp recordings showed that Ash1l haploinsufficiency
      increased the excitability of pyramidal neurons in the PFC by altering
      intrinsic neuronal properties, enhancing glutamatergic synaptic
      transmission, and diminishing GABAergic synaptic inhibition.
    explanation: >-
      Establishes pyramidal hyperexcitability in the model that matches the human
      heterozygous genotype, and separates the intrinsic from the synaptic
      contribution.
  downstream:
  - target: Seizures
    causal_link_type: DIRECT
    description: >-
      Hyperexcitable cortical networks generate epileptiform discharge and
      clinical seizures.
- name: Seizures
  description: >-
    Seizures occur in roughly half of reported patients and span febrile, focal
    motor, absence and myoclonic semiologies; at least one reported proband's
    epilepsy was drug-resistant. This node captures the single concept of the
    clinical seizure endpoint and conforms to the shared epilepsy final common
    pathway.
  role: consequence
  biological_scale: ORGANISM
  conforms_to: "epilepsy_excitation_inhibition_imbalance#Recurrent Unprovoked Seizures"
  cell_types:
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  evidence:
  - reference: PMID:38674358
    reference_title: "Expansion of the Genotypic and Phenotypic Spectrum of ASH1L-Related Syndromic Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      ID/DD is the most frequent phenotype (15/16, 94%), with other common
      phenotypes being ADHD or hyperactivity (6/7, 86%), obsessive behaviors
      (4/5, 80%), gastrointestinal disturbances (6/8, 75%), facial
      dysmorphisms (9/13, 69%), sleep disorders (6/9, 67%), ASD (6/10, 60%),
      ocular problems (6/10, 60%), hypotonia (4/7, 57%), genital
      malformations (5/9, 56%), speech delay (6/10, 60%), seizures (6/11,
      55%), motor delay (6/12, 50%), feeding difficulties (4/8, 50%), mood
      disorders (2/4, 50%), and abnormal gait (2/4, 50%)
    explanation: >-
      Gives the proportion of reported probands with seizures, with its
      denominator.
  - reference: PMID:34373061
    reference_title: "ASH1L mutation caused seizures and intellectual disability in twin sisters."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Here, we present twin sisters exhibiting mild intellectual disability and
      seizures.
    explanation: >-
      An independent report of seizures alongside intellectual disability in
      ASH1L-mutant patients.
- name: Disrupted Cortical Neuron Specification and Lamination
  description: >-
    ASH1L is required during corticogenesis to specify projection neuron identity
    and place neurons in the correct layer. In its absence, SATB2-expressing
    neurons increase in number, are distributed through the cortical plate instead
    of being confined to upper layers, and follow an altered differentiation
    trajectory. This node captures the single concept of the cortical patterning
    defect.
  role: mediator
  biological_scale: TISSUE
  cell_types:
  - preferred_term: cortical projection neuron
    term:
      id: CL:0000598
      label: pyramidal neuron
  biological_processes:
  - preferred_term: cerebral cortex neuron differentiation
    term:
      id: GO:0021895
      label: cerebral cortex neuron differentiation
    modifier: ABNORMAL
  evidence:
  - reference: PMID:38943682
    reference_title: "Ash1l loss-of-function results in structural birth defects and altered cortical development."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Birthdating revealed generation of ectopically placed deep layer neurons
      that express SATB2
    explanation: >-
      Demonstrates misspecified, ectopically positioned cortical projection
      neurons after cortical Ash1l deletion.
  downstream:
  - target: Intellectual Disability and Developmental Delay
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Miswired cortex is the presumed structural substrate of the cognitive
      phenotype; no human neuropathological correlate has been reported.
- name: Autistic and Behavioral Phenotype
  description: >-
    Autism, ADHD or hyperactivity, compulsive behaviours, anxiety and mood
    disorder make up the behavioural component of the syndrome and are as
    consistent a feature as the cognitive impairment. This node captures the
    single concept of the behavioural endpoint.
  role: consequence
  biological_scale: ORGANISM
  evidence:
  - reference: PMID:38674358
    reference_title: "Expansion of the Genotypic and Phenotypic Spectrum of ASH1L-Related Syndromic Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      ID/DD is the most frequent phenotype (15/16, 94%), with other common
      phenotypes being ADHD or hyperactivity (6/7, 86%), obsessive behaviors
      (4/5, 80%), gastrointestinal disturbances (6/8, 75%), facial
      dysmorphisms (9/13, 69%), sleep disorders (6/9, 67%), ASD (6/10, 60%),
      ocular problems (6/10, 60%), hypotonia (4/7, 57%), genital
      malformations (5/9, 56%), speech delay (6/10, 60%), seizures (6/11,
      55%), motor delay (6/12, 50%), feeding difficulties (4/8, 50%), mood
      disorders (2/4, 50%), and abnormal gait (2/4, 50%)
    explanation: >-
      Quantifies the behavioural component with its denominators.
  - reference: PMID:35081333
    reference_title: "ASH1L haploinsufficiency results in autistic-like phenotypes in mice and links Eph receptor gene to autism spectrum disorder."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      We find haploinsufficiency of Ash1l causally induces anxiety and
      autistic-like behavior, including repetitive behavior, and alters social
      behavior.
    explanation: >-
      Model-organism evidence that the same heterozygous lesion is sufficient to
      produce the behavioural phenotype.
- name: Intellectual Disability and Developmental Delay
  description: >-
    Intellectual disability or developmental delay is the most consistent feature,
    present in fifteen of sixteen reported probands. Severity ranges widely - one
    proband tested in the average range on standardized cognitive assessment while
    still meeting criteria for the syndrome, which is what makes the
    "intellectual disability" name of the OMIM entry an incomplete description.
    This node captures the single concept of the cognitive endpoint.
  role: consequence
  biological_scale: ORGANISM
  evidence:
  - reference: PMID:38674358
    reference_title: "Expansion of the Genotypic and Phenotypic Spectrum of ASH1L-Related Syndromic Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      ID/DD is the most frequent phenotype (15/16, 94%)
    explanation: >-
      Gives the proportion of reported probands with intellectual disability or
      developmental delay, with its denominator.
- name: Extraneural Developmental Anomalies
  description: >-
    Beyond the nervous system, reported probands have genital malformations
    (penile torsion, cryptorchidism), musculoskeletal findings (pectus carinatum or
    excavatum, scoliosis, cervical spinal fusion) and variable facial dysmorphism
    with no recognizable gestalt. The mouse null adds craniofacial evidence -
    shortened nasal bones and perinatal lethality. This node captures the single
    concept of the extraneural developmental phenotype.
  role: consequence
  biological_scale: ORGANISM
  evidence:
  - reference: PMID:38674358
    reference_title: "Expansion of the Genotypic and Phenotypic Spectrum of ASH1L-Related Syndromic Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      ID/DD is the most frequent phenotype (15/16, 94%), with other common
      phenotypes being ADHD or hyperactivity (6/7, 86%), obsessive behaviors
      (4/5, 80%), gastrointestinal disturbances (6/8, 75%), facial
      dysmorphisms (9/13, 69%), sleep disorders (6/9, 67%), ASD (6/10, 60%),
      ocular problems (6/10, 60%), hypotonia (4/7, 57%), genital
      malformations (5/9, 56%), speech delay (6/10, 60%), seizures (6/11,
      55%), motor delay (6/12, 50%), feeding difficulties (4/8, 50%), mood
      disorders (2/4, 50%), and abnormal gait (2/4, 50%)
    explanation: >-
      Gives the proportion of reported probands with genital malformations, with
      its denominator.
  - reference: PMID:38943682
    reference_title: "Ash1l loss-of-function results in structural birth defects and altered cortical development."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      This study underscores the essential role of Ash1l in postnatal survival
      and normal craniofacial development.
    explanation: >-
      Model-organism evidence that Ash1l loss affects craniofacial development
      outside the nervous system.
phenotypes:
- name: Intellectual Disability or Developmental Delay
  description: >-
    The most consistent feature, in fifteen of sixteen reported probands, ranging
    from borderline to moderate. One proband tested in the average range.
  category: Neurological
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Intellectual disability
    term:
      id: HP:0001249
      label: Intellectual disability
  evidence:
  - reference: PMID:38674358
    reference_title: "Expansion of the Genotypic and Phenotypic Spectrum of ASH1L-Related Syndromic Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      ID/DD is the most frequent phenotype (15/16, 94%)
    explanation: >-
      15/16 = 94% maps to the VERY_FREQUENT band (80-99%). The denominator is
      small and drawn from published reports plus a registry, so the estimate is
      ascertainment-biased.
- name: Attention Deficit Hyperactivity Disorder
  description: ADHD or hyperactivity is reported in most probands assessed for it.
  category: Behavioral
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Attention deficit hyperactivity disorder
    term:
      id: HP:0007018
      label: Attention deficit hyperactivity disorder
  evidence:
  - reference: PMID:38674358
    reference_title: "Expansion of the Genotypic and Phenotypic Spectrum of ASH1L-Related Syndromic Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      ID/DD is the most frequent phenotype (15/16, 94%), with other common
      phenotypes being ADHD or hyperactivity (6/7, 86%), obsessive behaviors
      (4/5, 80%), gastrointestinal disturbances (6/8, 75%), facial
      dysmorphisms (9/13, 69%), sleep disorders (6/9, 67%), ASD (6/10, 60%),
      ocular problems (6/10, 60%), hypotonia (4/7, 57%), genital
      malformations (5/9, 56%), speech delay (6/10, 60%), seizures (6/11,
      55%), motor delay (6/12, 50%), feeding difficulties (4/8, 50%), mood
      disorders (2/4, 50%), and abnormal gait (2/4, 50%)
    explanation: >-
      6/7 = 86% maps to the VERY_FREQUENT band (80-99%), on a denominator of
      seven assessed probands.
- name: Compulsive Behaviors
  description: Obsessive or compulsive behaviours are reported in most probands assessed.
  category: Behavioral
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Compulsive behaviors
    term:
      id: HP:0000722
      label: Compulsive behaviors
  evidence:
  - reference: PMID:38674358
    reference_title: "Expansion of the Genotypic and Phenotypic Spectrum of ASH1L-Related Syndromic Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      ID/DD is the most frequent phenotype (15/16, 94%), with other common
      phenotypes being ADHD or hyperactivity (6/7, 86%), obsessive behaviors
      (4/5, 80%), gastrointestinal disturbances (6/8, 75%), facial
      dysmorphisms (9/13, 69%), sleep disorders (6/9, 67%), ASD (6/10, 60%),
      ocular problems (6/10, 60%), hypotonia (4/7, 57%), genital
      malformations (5/9, 56%), speech delay (6/10, 60%), seizures (6/11,
      55%), motor delay (6/12, 50%), feeding difficulties (4/8, 50%), mood
      disorders (2/4, 50%), and abnormal gait (2/4, 50%)
    explanation: >-
      4/5 = 80% falls at the lower edge of the VERY_FREQUENT band (80-99%), on a
      denominator of only five assessed probands.
- name: Autism
  description: Autism spectrum disorder is reported in a majority of probands assessed.
  category: Behavioral
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Autism
    term:
      id: HP:0000717
      label: Autism
  evidence:
  - reference: PMID:38674358
    reference_title: "Expansion of the Genotypic and Phenotypic Spectrum of ASH1L-Related Syndromic Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      ID/DD is the most frequent phenotype (15/16, 94%), with other common
      phenotypes being ADHD or hyperactivity (6/7, 86%), obsessive behaviors
      (4/5, 80%), gastrointestinal disturbances (6/8, 75%), facial
      dysmorphisms (9/13, 69%), sleep disorders (6/9, 67%), ASD (6/10, 60%),
      ocular problems (6/10, 60%), hypotonia (4/7, 57%), genital
      malformations (5/9, 56%), speech delay (6/10, 60%), seizures (6/11,
      55%), motor delay (6/12, 50%), feeding difficulties (4/8, 50%), mood
      disorders (2/4, 50%), and abnormal gait (2/4, 50%)
    explanation: >-
      6/10 = 60% maps to the FREQUENT band (30-79%), on a denominator of ten
      assessed probands.
- name: Gastrointestinal Disturbance
  description: >-
    Gastrointestinal disturbance, including gastro-oesophageal reflux and
    constipation, is common.
  category: Gastrointestinal
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Abnormality of the gastrointestinal tract
    term:
      id: HP:0011024
      label: Abnormality of the gastrointestinal tract
  evidence:
  - reference: PMID:38674358
    reference_title: "Expansion of the Genotypic and Phenotypic Spectrum of ASH1L-Related Syndromic Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      ID/DD is the most frequent phenotype (15/16, 94%), with other common
      phenotypes being ADHD or hyperactivity (6/7, 86%), obsessive behaviors
      (4/5, 80%), gastrointestinal disturbances (6/8, 75%), facial
      dysmorphisms (9/13, 69%), sleep disorders (6/9, 67%), ASD (6/10, 60%),
      ocular problems (6/10, 60%), hypotonia (4/7, 57%), genital
      malformations (5/9, 56%), speech delay (6/10, 60%), seizures (6/11,
      55%), motor delay (6/12, 50%), feeding difficulties (4/8, 50%), mood
      disorders (2/4, 50%), and abnormal gait (2/4, 50%)
    explanation: >-
      6/8 = 75% maps to the FREQUENT band (30-79%), on a denominator of eight.
- name: Facial Dysmorphism
  description: >-
    Variable facial dysmorphism is reported in a majority, but with no recognizable
    pattern; two systematically assessed registry probands were explicitly
    non-dysmorphic.
  category: Craniofacial
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Abnormal facial shape
    term:
      id: HP:0001999
      label: Abnormal facial shape
  evidence:
  - reference: PMID:38674358
    reference_title: "Expansion of the Genotypic and Phenotypic Spectrum of ASH1L-Related Syndromic Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      ID/DD is the most frequent phenotype (15/16, 94%), with other common
      phenotypes being ADHD or hyperactivity (6/7, 86%), obsessive behaviors
      (4/5, 80%), gastrointestinal disturbances (6/8, 75%), facial
      dysmorphisms (9/13, 69%), sleep disorders (6/9, 67%), ASD (6/10, 60%),
      ocular problems (6/10, 60%), hypotonia (4/7, 57%), genital
      malformations (5/9, 56%), speech delay (6/10, 60%), seizures (6/11,
      55%), motor delay (6/12, 50%), feeding difficulties (4/8, 50%), mood
      disorders (2/4, 50%), and abnormal gait (2/4, 50%)
    explanation: >-
      9/13 = 69% maps to the FREQUENT band (30-79%). The same paper notes that in
      most published probands it is unclear whether dysmorphology was assessed
      and negative or simply not assessed, so this figure is likely inflated.
- name: Sleep Disturbance
  description: Sleep disorders are reported in a majority of probands assessed.
  category: Neurological
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Sleep disturbance
    term:
      id: HP:0002360
      label: Sleep disturbance
  evidence:
  - reference: PMID:38674358
    reference_title: "Expansion of the Genotypic and Phenotypic Spectrum of ASH1L-Related Syndromic Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      ID/DD is the most frequent phenotype (15/16, 94%), with other common
      phenotypes being ADHD or hyperactivity (6/7, 86%), obsessive behaviors
      (4/5, 80%), gastrointestinal disturbances (6/8, 75%), facial
      dysmorphisms (9/13, 69%), sleep disorders (6/9, 67%), ASD (6/10, 60%),
      ocular problems (6/10, 60%), hypotonia (4/7, 57%), genital
      malformations (5/9, 56%), speech delay (6/10, 60%), seizures (6/11,
      55%), motor delay (6/12, 50%), feeding difficulties (4/8, 50%), mood
      disorders (2/4, 50%), and abnormal gait (2/4, 50%)
    explanation: >-
      6/9 = 67% maps to the FREQUENT band (30-79%), on a denominator of nine.
- name: Ocular Abnormality
  description: >-
    Hyperopia, astigmatism, strabismus and nystagmus are among the reported ocular
    findings.
  category: Ophthalmological
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Abnormality of the eye
    term:
      id: HP:0000478
      label: Abnormality of the eye
  evidence:
  - reference: PMID:38674358
    reference_title: "Expansion of the Genotypic and Phenotypic Spectrum of ASH1L-Related Syndromic Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      ID/DD is the most frequent phenotype (15/16, 94%), with other common
      phenotypes being ADHD or hyperactivity (6/7, 86%), obsessive behaviors
      (4/5, 80%), gastrointestinal disturbances (6/8, 75%), facial
      dysmorphisms (9/13, 69%), sleep disorders (6/9, 67%), ASD (6/10, 60%),
      ocular problems (6/10, 60%), hypotonia (4/7, 57%), genital
      malformations (5/9, 56%), speech delay (6/10, 60%), seizures (6/11,
      55%), motor delay (6/12, 50%), feeding difficulties (4/8, 50%), mood
      disorders (2/4, 50%), and abnormal gait (2/4, 50%)
    explanation: >-
      6/10 = 60% maps to the FREQUENT band (30-79%), on a denominator of ten.
- name: Speech Delay
  description: Speech and language delay is common; one proband had mixed receptive language disorder.
  category: Neurological
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Delayed speech and language development
    term:
      id: HP:0000750
      label: Delayed speech and language development
  evidence:
  - reference: PMID:38674358
    reference_title: "Expansion of the Genotypic and Phenotypic Spectrum of ASH1L-Related Syndromic Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      ID/DD is the most frequent phenotype (15/16, 94%), with other common
      phenotypes being ADHD or hyperactivity (6/7, 86%), obsessive behaviors
      (4/5, 80%), gastrointestinal disturbances (6/8, 75%), facial
      dysmorphisms (9/13, 69%), sleep disorders (6/9, 67%), ASD (6/10, 60%),
      ocular problems (6/10, 60%), hypotonia (4/7, 57%), genital
      malformations (5/9, 56%), speech delay (6/10, 60%), seizures (6/11,
      55%), motor delay (6/12, 50%), feeding difficulties (4/8, 50%), mood
      disorders (2/4, 50%), and abnormal gait (2/4, 50%)
    explanation: >-
      6/10 = 60% maps to the FREQUENT band (30-79%), on a denominator of ten.
- name: Hypotonia
  description: Hypotonia is reported in over half of probands assessed.
  category: Neurological
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Hypotonia
    term:
      id: HP:0001252
      label: Hypotonia
  evidence:
  - reference: PMID:38674358
    reference_title: "Expansion of the Genotypic and Phenotypic Spectrum of ASH1L-Related Syndromic Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      ID/DD is the most frequent phenotype (15/16, 94%), with other common
      phenotypes being ADHD or hyperactivity (6/7, 86%), obsessive behaviors
      (4/5, 80%), gastrointestinal disturbances (6/8, 75%), facial
      dysmorphisms (9/13, 69%), sleep disorders (6/9, 67%), ASD (6/10, 60%),
      ocular problems (6/10, 60%), hypotonia (4/7, 57%), genital
      malformations (5/9, 56%), speech delay (6/10, 60%), seizures (6/11,
      55%), motor delay (6/12, 50%), feeding difficulties (4/8, 50%), mood
      disorders (2/4, 50%), and abnormal gait (2/4, 50%)
    explanation: >-
      4/7 = 57% maps to the FREQUENT band (30-79%), on a denominator of seven.
- name: Genital Malformation
  description: >-
    Genital and urinary malformations such as penile torsion and cryptorchidism are
    reported in over half of probands assessed. Most reported probands are male.
  category: Genitourinary
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Abnormality of the genital system
    term:
      id: HP:0000078
      label: Abnormality of the genital system
  evidence:
  - reference: PMID:38674358
    reference_title: "Expansion of the Genotypic and Phenotypic Spectrum of ASH1L-Related Syndromic Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      ID/DD is the most frequent phenotype (15/16, 94%), with other common
      phenotypes being ADHD or hyperactivity (6/7, 86%), obsessive behaviors
      (4/5, 80%), gastrointestinal disturbances (6/8, 75%), facial
      dysmorphisms (9/13, 69%), sleep disorders (6/9, 67%), ASD (6/10, 60%),
      ocular problems (6/10, 60%), hypotonia (4/7, 57%), genital
      malformations (5/9, 56%), speech delay (6/10, 60%), seizures (6/11,
      55%), motor delay (6/12, 50%), feeding difficulties (4/8, 50%), mood
      disorders (2/4, 50%), and abnormal gait (2/4, 50%)
    explanation: >-
      5/9 = 56% maps to the FREQUENT band (30-79%), on a denominator of nine.
- name: Seizures
  description: >-
    Seizures occur in roughly half of probands, spanning febrile, focal motor,
    absence and myoclonic types; one reported proband's epilepsy was drug-resistant.
  category: Neurological
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Seizure
    term:
      id: HP:0001250
      label: Seizure
  evidence:
  - reference: PMID:38674358
    reference_title: "Expansion of the Genotypic and Phenotypic Spectrum of ASH1L-Related Syndromic Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      ID/DD is the most frequent phenotype (15/16, 94%), with other common
      phenotypes being ADHD or hyperactivity (6/7, 86%), obsessive behaviors
      (4/5, 80%), gastrointestinal disturbances (6/8, 75%), facial
      dysmorphisms (9/13, 69%), sleep disorders (6/9, 67%), ASD (6/10, 60%),
      ocular problems (6/10, 60%), hypotonia (4/7, 57%), genital
      malformations (5/9, 56%), speech delay (6/10, 60%), seizures (6/11,
      55%), motor delay (6/12, 50%), feeding difficulties (4/8, 50%), mood
      disorders (2/4, 50%), and abnormal gait (2/4, 50%)
    explanation: >-
      6/11 = 55% maps to the FREQUENT band (30-79%), on a denominator of eleven.
- name: Motor Delay
  description: Motor delay is reported in half of probands assessed.
  category: Neurological
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Motor delay
    term:
      id: HP:0001270
      label: Motor delay
  evidence:
  - reference: PMID:38674358
    reference_title: "Expansion of the Genotypic and Phenotypic Spectrum of ASH1L-Related Syndromic Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      ID/DD is the most frequent phenotype (15/16, 94%), with other common
      phenotypes being ADHD or hyperactivity (6/7, 86%), obsessive behaviors
      (4/5, 80%), gastrointestinal disturbances (6/8, 75%), facial
      dysmorphisms (9/13, 69%), sleep disorders (6/9, 67%), ASD (6/10, 60%),
      ocular problems (6/10, 60%), hypotonia (4/7, 57%), genital
      malformations (5/9, 56%), speech delay (6/10, 60%), seizures (6/11,
      55%), motor delay (6/12, 50%), feeding difficulties (4/8, 50%), mood
      disorders (2/4, 50%), and abnormal gait (2/4, 50%)
    explanation: >-
      6/12 = 50% maps to the FREQUENT band (30-79%), on a denominator of twelve.
- name: Feeding Difficulties
  description: Feeding difficulties in infancy are reported in half of probands assessed.
  category: Gastrointestinal
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Feeding difficulties
    term:
      id: HP:0011968
      label: Feeding difficulties
  evidence:
  - reference: PMID:38674358
    reference_title: "Expansion of the Genotypic and Phenotypic Spectrum of ASH1L-Related Syndromic Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      ID/DD is the most frequent phenotype (15/16, 94%), with other common
      phenotypes being ADHD or hyperactivity (6/7, 86%), obsessive behaviors
      (4/5, 80%), gastrointestinal disturbances (6/8, 75%), facial
      dysmorphisms (9/13, 69%), sleep disorders (6/9, 67%), ASD (6/10, 60%),
      ocular problems (6/10, 60%), hypotonia (4/7, 57%), genital
      malformations (5/9, 56%), speech delay (6/10, 60%), seizures (6/11,
      55%), motor delay (6/12, 50%), feeding difficulties (4/8, 50%), mood
      disorders (2/4, 50%), and abnormal gait (2/4, 50%)
    explanation: >-
      4/8 = 50% maps to the FREQUENT band (30-79%), on a denominator of eight.
- name: Gait Disturbance
  description: >-
    Abnormal gait - dysmetric and ataxic in one registry proband, stiff in another -
    was first reported in the Brain Gene Registry cohort.
  category: Neurological
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Gait disturbance
    term:
      id: HP:0001288
      label: Gait disturbance
  evidence:
  - reference: PMID:38674358
    reference_title: "Expansion of the Genotypic and Phenotypic Spectrum of ASH1L-Related Syndromic Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      and abnormal gait (2/4, 50%)
    explanation: >-
      2/4 = 50% maps to the FREQUENT band (30-79%), but on a denominator of only
      four probands - the weakest estimate in this set.
- name: Sensorineural Hearing Impairment
  description: >-
    Hearing impairment is reported in a substantial minority. In one registry
    proband it co-occurred with variants of uncertain significance in POU4F3 and
    ATP2B2, both deafness genes, so its attribution to ASH1L in that individual is
    uncertain.
  category: Otological
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Sensorineural hearing impairment
    term:
      id: HP:0000407
      label: Sensorineural hearing impairment
  evidence:
  - reference: PMID:38674358
    reference_title: "Expansion of the Genotypic and Phenotypic Spectrum of ASH1L-Related Syndromic Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      other less common phenotypes include hearing impairments (4/9, 44%),
      pectus carinatum/excavatum (2/7, 29%), and scoliosis (2/7, 29%)
    explanation: >-
      4/9 = 44% maps to the FREQUENT band (30-79%), on a denominator of nine.
- name: Scoliosis
  description: Scoliosis is among the less common musculoskeletal findings.
  category: Musculoskeletal
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Scoliosis
    term:
      id: HP:0002650
      label: Scoliosis
  evidence:
  - reference: PMID:38674358
    reference_title: "Expansion of the Genotypic and Phenotypic Spectrum of ASH1L-Related Syndromic Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      other less common phenotypes include hearing impairments (4/9, 44%),
      pectus carinatum/excavatum (2/7, 29%), and scoliosis (2/7, 29%)
    explanation: >-
      2/7 = 29% maps to the OCCASIONAL band (5-29%), on a denominator of seven.
- name: Pectus Deformity
  description: Pectus carinatum or excavatum is among the less common musculoskeletal findings.
  category: Musculoskeletal
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Pectus carinatum
    term:
      id: HP:0000768
      label: Pectus carinatum
  evidence:
  - reference: PMID:38674358
    reference_title: "Expansion of the Genotypic and Phenotypic Spectrum of ASH1L-Related Syndromic Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      other less common phenotypes include hearing impairments (4/9, 44%),
      pectus carinatum/excavatum (2/7, 29%), and scoliosis (2/7, 29%)
    explanation: >-
      2/7 = 29% maps to the OCCASIONAL band (5-29%), on a denominator of seven.
      The source counts carinatum and excavatum together; this entry binds the
      carinatum term and names both in the description rather than splitting an
      undivided count.
- name: Depression
  description: >-
    Mood disorder is reported in half of the small number of probands assessed;
    depression diagnosed at age 11 was a newly reported feature in the Brain Gene
    Registry cohort.
  category: Behavioral
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Depression
    term:
      id: HP:0000716
      label: Depression
  evidence:
  - reference: PMID:38674358
    reference_title: "Expansion of the Genotypic and Phenotypic Spectrum of ASH1L-Related Syndromic Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      ID/DD is the most frequent phenotype (15/16, 94%), with other common
      phenotypes being ADHD or hyperactivity (6/7, 86%), obsessive behaviors
      (4/5, 80%), gastrointestinal disturbances (6/8, 75%), facial
      dysmorphisms (9/13, 69%), sleep disorders (6/9, 67%), ASD (6/10, 60%),
      ocular problems (6/10, 60%), hypotonia (4/7, 57%), genital
      malformations (5/9, 56%), speech delay (6/10, 60%), seizures (6/11,
      55%), motor delay (6/12, 50%), feeding difficulties (4/8, 50%), mood
      disorders (2/4, 50%), and abnormal gait (2/4, 50%)
    explanation: >-
      2/4 = 50% maps to the FREQUENT band (30-79%), on a denominator of only
      four probands.
genetic:
- name: ASH1L
  gene_term:
    preferred_term: ASH1L
    term:
      id: hgnc:19088
      label: ASH1L
  relationship_type: CAUSATIVE
  notes: >-
    ASH1L (1q22) encodes a Trithorax-group histone methyltransferase. Pathogenic
    alleles reported with detailed phenotyping are predominantly loss-of-function
    (nonsense, frameshift, deletion); missense alleles have also been reported but
    their disease mechanism is unresolved. ClinGen's Intellectual Disability and
    Autism Gene Curation Expert Panel classified the gene-disease relationship as
    Definitive.
  evidence:
  - reference: PMID:38674358
    reference_title: "Expansion of the Genotypic and Phenotypic Spectrum of ASH1L-Related Syndromic Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      relationship to syndromic complex neurodevelopmental disorder was
      classified as Definitive.
    explanation: >-
      Records the ClinGen Definitive gene-disease validity classification for
      ASH1L.
  - reference: PMID:39902220
    reference_title: "Novel heterozygous ASH1L nonsense variant involved in mild intellectual disability."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      A review of reported ASH1L nonsense mutations to explore genotype-phenotype
      correlations suggested that these variants typically result in a loss of
      function.
    explanation: >-
      Supports loss of function as the mechanism of the nonsense allele class.
diagnosis:
- name: Exome or Genome Sequencing
  description: >-
    The diagnosis is molecular: identification of a heterozygous loss-of-function
    ASH1L variant, usually de novo, on trio exome or genome sequencing performed
    for developmental delay, autism or epilepsy. There is no biochemical or
    imaging marker. Interpretation is complicated in practice by the frequency
    with which additional variants of uncertain significance are found alongside
    the ASH1L variant.
  evidence:
  - reference: PMID:38674358
    reference_title: "Expansion of the Genotypic and Phenotypic Spectrum of ASH1L-Related Syndromic Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      ASH1L variants were first implicated in human disease in 2012 through a
      large sequencing study in persons with severe ID.
    explanation: >-
      Establishes sequencing as the route by which the disorder is identified.
treatments:
- name: Antiseizure Medication
  description: >-
    Seizures are managed with standard antiseizure medication. No agent has been
    shown to be preferentially effective in this disorder, and at least one
    reported proband's epilepsy was resistant to clonazepam, so treatment is
    empirical.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
  evidence:
  - reference: PMID:38674358
    reference_title: "Expansion of the Genotypic and Phenotypic Spectrum of ASH1L-Related Syndromic Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      ASD, mild bilateral sensorineural hearing loss, and epilepsy (absence,
      focal motor, and myoclonic seizures); this proband
    explanation: >-
      Documents the epilepsy that requires treatment and, in the continuation of
      the same sentence, its drug resistance. Support is PARTIAL because no
      disease-specific efficacy data exist for any antiseizure medication here.
- name: Developmental and Behavioral Support
  description: >-
    Management is otherwise supportive and multidisciplinary: developmental,
    speech and language, and behavioural intervention for the intellectual
    disability, autism, ADHD and compulsive behaviours, together with surveillance
    for the sleep, gastrointestinal, ocular, hearing and musculoskeletal features
    that make up the syndromic phenotype. This is standard neurodevelopmental care
    rather than a disease-specific protocol.
  therapeutic_modality: BEHAVIORAL
  treatment_term:
    preferred_term: Rehabilitation
    term:
      id: NCIT:C15315
      label: Rehabilitation
animal_models:
- name: Ash1l gene-trap haploinsufficient mouse
  species: Mouse
  genotype: Ash1l+/GT (targeted gene-trap knockout, heterozygous)
  publication: PMID:39766886
  description: >-
    A heterozygous gene-trap knockout, and the model whose genotype most closely
    matches human patients. It shows social deficits, increased self-grooming and
    cognitive impairment, absence-like epileptiform discharge on EEG, increased
    susceptibility to chemically provoked convulsive seizures, and prefrontal
    pyramidal hyperexcitability.
  evidence:
  - reference: PMID:39766886
    reference_title: "Chemogenetic Inhibition of Prefrontal Cortex Ameliorates Autism-Like Social Deficits and Absence-Like Seizures in a Gene-Trap Ash1l Haploinsufficiency Mouse Model."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Ash1l+/GT mice displayed social deficits, increased self-grooming, and
      cognitive impairments.
    explanation: >-
      Establishes the behavioural phenotype of the haploinsufficient model.
  modeled_mechanisms:
  - target: Pyramidal Neuron Hyperexcitability
    relationship: RECAPITULATES
    fidelity: MODERATE
    description: >-
      Whole-cell recording in prefrontal cortex demonstrates increased pyramidal
      excitability arising from intrinsic property changes plus enhanced
      glutamatergic and diminished GABAergic transmission, in a heterozygous
      animal matching the human genotype.
    limitations: >-
      Measured only in prefrontal cortex; the human seizure semiologies include
      focal motor and myoclonic seizures whose generators are not necessarily
      prefrontal, and no human electrophysiological or tissue correlate exists.
    readouts:
    - name: Prefrontal pyramidal neuron excitability
      target: Pyramidal Neuron Hyperexcitability
      description: >-
        Whole-cell patch-clamp recording of prefrontal pyramidal neurons in
        Ash1l+/GT versus wild-type mice.
      direction: INCREASED
      interpretation: >-
        Increased excitability with the excitatory-inhibitory shift is the direct
        electrophysiological correlate of this node.
      evidence:
      - reference: PMID:39766886
        reference_title: "Chemogenetic Inhibition of Prefrontal Cortex Ameliorates Autism-Like Social Deficits and Absence-Like Seizures in a Gene-Trap Ash1l Haploinsufficiency Mouse Model."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: >-
          Whole-cell patch-clamp recordings showed that Ash1l haploinsufficiency
          increased the excitability of pyramidal neurons in the PFC by altering
          intrinsic neuronal properties, enhancing glutamatergic synaptic
          transmission, and diminishing GABAergic synaptic inhibition.
        explanation: Reports the electrophysiological measurement behind this readout.
    evidence:
    - reference: PMID:39766886
      reference_title: "Chemogenetic Inhibition of Prefrontal Cortex Ameliorates Autism-Like Social Deficits and Absence-Like Seizures in a Gene-Trap Ash1l Haploinsufficiency Mouse Model."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        Chemogenetic inhibition of pyramidal neurons in the PFC of Ash1l+/GT mice
        ameliorated autism-like social deficits and abolished absence-like
        seizures.
      explanation: >-
        Reversing the excitability abnormality abolishes the seizure phenotype,
        which is what makes this model informative for the node rather than
        merely correlated with it.
  - target: Seizures
    relationship: PARTIALLY_RECAPITULATES
    fidelity: LOW
    description: >-
      The model has an electrographic seizure phenotype and increased
      susceptibility to provoked convulsive seizures.
    limitations: >-
      The spontaneous phenotype is absence-like epileptiform discharge, whereas
      the reported human semiologies are febrile, focal motor, absence and
      myoclonic seizures; convulsive seizures in the model appear only on
      pentylenetetrazole challenge. The model therefore reproduces a seizure
      tendency, not the human epilepsy.
    readouts:
    - name: Electroencephalographic epileptiform discharge
      target: Seizures
      description: >-
        EEG recording in Ash1l+/GT versus wild-type mice.
      direction: INCREASED
      interpretation: >-
        Spontaneous epileptiform discharge establishes an unprovoked seizure
        phenotype, of absence type.
      evidence:
      - reference: PMID:39766886
        reference_title: "Chemogenetic Inhibition of Prefrontal Cortex Ameliorates Autism-Like Social Deficits and Absence-Like Seizures in a Gene-Trap Ash1l Haploinsufficiency Mouse Model."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: >-
          Epileptiform discharges were found on electroencephalograms (EEGs) of
          Ash1l+/GT mice, indicating absence-like seizures.
        explanation: Reports the EEG measurement behind this readout.
    evidence:
    - reference: PMID:39766886
      reference_title: "Chemogenetic Inhibition of Prefrontal Cortex Ameliorates Autism-Like Social Deficits and Absence-Like Seizures in a Gene-Trap Ash1l Haploinsufficiency Mouse Model."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        Epileptiform discharges were found on electroencephalograms (EEGs) of
        Ash1l+/GT mice, indicating absence-like seizures.
      explanation: >-
        Supports the model as informative for a seizure tendency while naming the
        semiology mismatch that limits it.
- name: Ash1l heterozygous knockout mouse (EphA7 pruning model)
  species: Mouse
  genotype: Ash1l+/- germline heterozygous knockout, and neuron-specific Ash1l deletion
  publication: PMID:35081333
  description: >-
    Haploinsufficient mice show anxiety, repetitive behaviour and altered social
    behaviour with intact learning but impaired discrimination. Neuronal Ash1l
    deletion produces excess synapses through a pruning deficit, traced to
    silencing of Eph receptor A7 by EZH2-deposited H3K27me3; supplying the EphA7
    ligand ephrin-A5 restores pruning and rescues the discrimination deficit.
  evidence:
  - reference: PMID:35081333
    reference_title: "ASH1L haploinsufficiency results in autistic-like phenotypes in mice and links Eph receptor gene to autism spectrum disorder."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Our results suggest that Ash1l haploinsufficiency is a highly penetrant
      risk factor for ASD, resulting from synapse pruning deficits.
    explanation: >-
      States the model's central conclusion connecting haploinsufficiency to the
      pruning mechanism.
  modeled_mechanisms:
  - target: Synaptic Pruning Failure
    relationship: RECAPITULATES
    fidelity: MODERATE
    description: >-
      Excess synapses persist because developmental pruning fails, and the
      responsible gene, Eph receptor A7, is identified together with the
      repressive-mark mechanism silencing it.
    limitations: >-
      Synapse counts and pruning have not been measured in human ASH1L patients or
      tissue, and the pruning defect is most evident post-learning in a specific
      paradigm; the EPHA7 route is one identified mechanism, not necessarily the
      only one.
    readouts:
    - name: Synapse number after learning
      target: Synaptic Pruning Failure
      description: >-
        Synapse quantification in Ash1l-deleted neurons, particularly in the
        post-learning period.
      direction: INCREASED
      interpretation: >-
        Excess synapses are the direct cellular readout of the pruning failure.
      evidence:
      - reference: PMID:35081333
        reference_title: "ASH1L haploinsufficiency results in autistic-like phenotypes in mice and links Eph receptor gene to autism spectrum disorder."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: >-
          Mechanistically, deletion of Ash1l in neurons induces excessive
          synapses due to the synapse pruning deficits, especially during the
          post-learning period.
        explanation: Reports the synapse-number measurement behind this readout.
    - name: Discrimination performance after ephrin-A5 supplementation
      target: Synaptic Pruning Failure
      description: >-
        Behavioural discrimination testing in Ash1l+/- mice given the EphA7 ligand
        ephrin-A5, against untreated mutants.
      direction: RESTORED
      interpretation: >-
        Rescue by reactivating the specific downstream receptor is what makes the
        EPHA7 route causal rather than correlative.
      evidence:
      - reference: PMID:35081333
        reference_title: "ASH1L haploinsufficiency results in autistic-like phenotypes in mice and links Eph receptor gene to autism spectrum disorder."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: >-
          Importantly, increasing activation of EphA7 in Ash1l+/- mice by
          supplying its ligand, ephrin-A5, strongly promotes synapse pruning and
          rescues discrimination deficits.
        explanation: Reports the rescue experiment behind this readout.
    evidence:
    - reference: PMID:35081333
      reference_title: "ASH1L haploinsufficiency results in autistic-like phenotypes in mice and links Eph receptor gene to autism spectrum disorder."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        Specifically, Eph receptor A7 is downregulated in Ash1l+/- mice through
        accumulating EZH2-mediated H3K27me3 in its gene body.
      explanation: >-
        Supports treating this model as informative for the pruning node by
        naming the responsible gene and chromatin mechanism.
- name: Cortex-specific Ash1l conditional knockout mouse
  species: Mouse
  genotype: Ash1l exon 4 conditional deletion (p.V1693Afs*2), Emx1-Cre-ERT2 induced at E10.5;
    and Ash1l germline null
  publication: PMID:38943682
  description: >-
    Tamoxifen-induced cortical deletion from E10.5 misspecifies cortical
    projection neurons: SATB2-expressing neurons increase in number, spread through
    the cortical plate, and appear ectopically in deep layers, with an altered
    differentiation trajectory on single-cell RNA sequencing. The germline null is
    present at expected proportions at E18.5 but absent at birth, and has shortened
    nasal bones.
  evidence:
  - reference: PMID:38943682
    reference_title: "Ash1l loss-of-function results in structural birth defects and altered cortical development."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      In the cortical-specific knockout model, SATB2 neurons showed increased
      numbers (n = 6/genotype, P = 0.0001) and were distributed through the
      cortical plate.
    explanation: >-
      Establishes the cortical patterning phenotype that makes this model
      informative.
  modeled_mechanisms:
  - target: Disrupted Cortical Neuron Specification and Lamination
    relationship: RECAPITULATES
    fidelity: MODERATE
    description: >-
      Cortical Ash1l deletion produces excess and ectopically placed
      SATB2-expressing projection neurons with an altered differentiation
      trajectory, establishing a requirement for ASH1L in projection neuron
      specification.
    limitations: >-
      This is a homozygous conditional deletion in cortex, not the heterozygous
      loss patients carry, so the severity is not transferable; and no
      corresponding cortical malformation has been described in human ASH1L
      patients, whose reported neuroimaging is largely unremarkable.
    readouts:
    - name: Laminar distribution of SATB2-expressing neurons
      target: Disrupted Cortical Neuron Specification and Lamination
      description: >-
        Immunohistochemistry for SATB2 with EdU birthdating in conditional
        knockout versus control cortex.
      direction: ALTERED
      interpretation: >-
        Deep-layer neurons ectopically expressing an upper-layer marker are the
        structural readout of misspecification.
      evidence:
      - reference: PMID:38943682
        reference_title: "Ash1l loss-of-function results in structural birth defects and altered cortical development."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: >-
          Birthdating revealed generation of ectopically placed deep layer
          neurons that express SATB2
        explanation: Reports the birthdating measurement behind this readout.
    evidence:
    - reference: PMID:38943682
      reference_title: "Ash1l loss-of-function results in structural birth defects and altered cortical development."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        In the cortical-specific knockout model, SATB2 neurons showed increased
        numbers (n = 6/genotype, P = 0.0001) and were distributed through the
        cortical plate.
      explanation: >-
        Supports treating this model as informative for the cortical patterning
        node.
  - target: Extraneural Developmental Anomalies
    relationship: PARTIALLY_RECAPITULATES
    fidelity: LOW
    description: >-
      The germline null dies perinatally and has shortened nasal bones,
      demonstrating a requirement for Ash1l in craniofacial development outside
      the brain.
    limitations: >-
      The mouse finding is a specific craniofacial measurement in homozygous
      nulls; the human extraneural phenotype is dominated by genital and
      musculoskeletal anomalies with no consistent facial gestalt, and human
      heterozygotes survive. The two do not correspond feature for feature.
    readouts:
    - name: Nasal bone length
      target: Extraneural Developmental Anomalies
      description: >-
        Skeletal measurement in Ash1l germline null embryos versus controls.
      direction: DECREASED
      interpretation: >-
        A quantified craniofacial skeletal defect outside the nervous system.
      evidence:
      - reference: PMID:38943682
        reference_title: "Ash1l loss-of-function results in structural birth defects and altered cortical development."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: >-
          Notably, Ash1l-/- exhibited shortened nasal bones (n = 31, P = 0.017).
        explanation: Reports the craniofacial measurement behind this readout.
    evidence:
    - reference: PMID:38943682
      reference_title: "Ash1l loss-of-function results in structural birth defects and altered cortical development."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        This study underscores the essential role of Ash1l in postnatal survival
        and normal craniofacial development.
      explanation: >-
        Supports an extraneural developmental requirement while the specific
        features differ from the human phenotype.
prevalence:
- population: Worldwide
  measure_type: CASES_IN_LITERATURE
  prevalence_class: ULTRA_RARE
  notes: >-
    Only sixteen probands had been reported with detailed phenotyping at the time
    of the 2024 review, although over a hundred loss-of-function ASH1L variants
    have been catalogued in autism sequencing cohorts without individual clinical
    description. No population rate has been estimated, and the gap between the
    two counts is itself the reason a rate cannot be inferred.
  evidence:
  - reference: PMID:38674358
    reference_title: "Expansion of the Genotypic and Phenotypic Spectrum of ASH1L-Related Syndromic Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      ID/DD is the most frequent phenotype (15/16, 94%)
    explanation: >-
      The denominator of sixteen is the deeply phenotyped literature cohort; no
      normalized population rate is asserted.
  - reference: PMID:34782621
    reference_title: "Deficiency of autism risk factor ASH1L in prefrontal cortex induces epigenetic aberrations and seizures."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Over 100 loss-of-function (LOF) mutations in the coding regions of ASH1L
      have been discovered
    explanation: >-
      Establishes the much larger variant count from sequencing cohorts, against
      which the small clinically described cohort should be read. Evidence source
      is OTHER because this is the paper's summary of the genetic literature.
datasets: []
discussions:
- discussion_id: gap_mrd52_which_histone_mark_carries_the_disease
  prompt: >-
    Which histone mark deposited by ASH1L - H3K36 or H3K4 - is the one whose loss
    causes the neurodevelopmental phenotype?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - pathophysiology#Reduced ASH1L Histone Methyltransferase Activity
  - pathophysiology#Loss of Activating Chromatin Marks at Neurodevelopmental Gene Promoters
  rationale: >-
    The clinical literature routinely describes ASH1L as an H3K36 methyltransferase,
    and the only human variant-interpretation paper to reason about mechanism
    attributes the defect to reduced H3K36 methylation. But the one study that
    actually measured chromatin in brain reports reduced H3K4me3 - in autism
    postmortem prefrontal cortex, and at the promoters of the downregulated genes
    in the mouse knockdown. Both marks are curated on the enzyme node because the
    sources support both, but they imply different downstream biology: H3K36
    methylation is deposited across gene bodies of transcribed genes, whereas
    H3K4me3 is a promoter mark. Nothing in the published work resolves whether the
    H3K4me3 change is a direct catalytic product of ASH1L or an indirect
    consequence.
  proposed_experiments:
  - experiment_id: exp_mrd52_separation_of_function_ash1l_alleles
    name: Separation-of-function ASH1L alleles in neurons
    description: >-
      Compare catalytically dead ASH1L, and alleles selectively impaired for one
      mark, in the same neuronal system, measuring H3K36 and H3K4 methylation
      genome-wide alongside expression of the affected risk-gene set, to determine
      which mark's loss is sufficient for the transcriptional phenotype.
  evidence:
  - reference: PMID:34782621
    reference_title: "Deficiency of autism risk factor ASH1L in prefrontal cortex induces epigenetic aberrations and seizures."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      These downregulated genes are enriched in excitatory and inhibitory
      synaptic function and have decreased H3K4me3 occupancy at their promoters.
    explanation: >-
      The measurement that puts H3K4me3, not H3K36 methylation, at the affected
      promoters.
  - reference: PMID:38674358
    reference_title: "Expansion of the Genotypic and Phenotypic Spectrum of ASH1L-Related Syndromic Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      ASH1L, located at chromosomal band 1q22, encodes a histone
      methyltransferase that catalyzes histone H3K36 methylation
    explanation: >-
      The clinical literature's H3K36 characterization, which is the other side of
      the discrepancy.
- discussion_id: gap_mrd52_missense_versus_truncating_severity
  prompt: >-
    Are ASH1L missense variants genuinely associated with a more severe and more
    autism-weighted phenotype than truncating variants, and if so does that mean
    they act by something other than simple haploinsufficiency?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - pathophysiology#Heterozygous ASH1L Loss of Function
  - pathophysiology#Reduced ASH1L Histone Methyltransferase Activity
  rationale: >-
    A 2021 review of published cases reported that missense-variant patients had
    more severe phenotypes and more autism than truncating-variant patients. If
    real, that is mechanistically important: a missense allele more damaging than a
    null implies a dominant-negative or gain-of-function effect rather than
    haploinsufficiency, which is the mechanism the field otherwise assumes. But the
    2024 Brain Gene Registry review takes the opposite editorial position, treating
    the reported missense alleles as still requiring functional work and excluding
    the registry's own missense-variant participants from its phenotype tabulation
    on those grounds. No functional assay has been published for any human missense
    allele.
  proposed_experiments:
  - experiment_id: exp_mrd52_missense_allele_functional_assay
    name: Functional assay of reported ASH1L missense alleles
    description: >-
      Express reported missense alleles alongside wild type and null in a neuronal
      system, and test both catalytic output and whether the missense protein
      interferes with the wild-type allele, to distinguish haploinsufficiency from
      a dominant-negative effect.
  evidence:
  - reference: PMID:34373061
    reference_title: "ASH1L mutation caused seizures and intellectual disability in twin sisters."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We found that patients with missense mutations in ASH1L appeared to present
      with more severe phenotypes and a higher likelihood of ASD than those with
      truncating mutations.
    explanation: States the genotype-phenotype claim this gap is about.
  - reference: PMID:38674358
    reference_title: "Expansion of the Genotypic and Phenotypic Spectrum of ASH1L-Related Syndromic Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      haploinsufficiency is believed to be at least one disease mechanism
    explanation: >-
      The hedged wording - "at least one" mechanism - is the counterweight: the
      2024 review holds the missense mechanism open rather than accepting the
      severity claim.
- discussion_id: mismatch_mrd52_model_genotype_and_seizure_semiology
  prompt: >-
    Do the Ash1l mouse models inform human ASH1L-related epilepsy, given that the
    strongest excitation-inhibition data come from a severe knockdown rather than
    haploinsufficiency, and the haploinsufficient model's spontaneous seizures are
    absence-like rather than the focal and myoclonic types reported in patients?
  kind: HUMAN_MODEL_MISMATCH
  status: OPEN
  attaches_to:
  - pathophysiology#Cortical Excitation-Inhibition Imbalance
  - pathophysiology#Seizures
  rationale: >-
    Two different manipulations underlie the excitability story and they are not
    interchangeable. The mechanistic detail - which genes lose H3K4me3, which
    synaptic currents change, that diazepam plus chemogenetic silencing rescues
    seizures - comes from a prefrontal knockdown described by its own authors as
    severe deficiency, causing early mortality that human patients do not have. The
    genotype-matched heterozygous gene-trap model reproduces hyperexcitability but
    its spontaneous seizures are absence-like, and convulsive seizures appear only
    on pentylenetetrazole challenge, whereas reported patients have febrile, focal
    motor and myoclonic seizures. Reading the knockdown's rescue result as a
    therapeutic lead for patients therefore crosses two gaps at once: dose and
    semiology.
  proposed_experiments:
  - experiment_id: exp_mrd52_heterozygous_model_seizure_characterization
    name: Longitudinal seizure phenotyping of genotype-matched Ash1l heterozygotes
    description: >-
      Perform long-term video-EEG across development in heterozygous Ash1l mice on
      more than one genetic background, classifying seizure types against the human
      semiologies, and test whether the GABA-enhancing rescue that works in the
      severe knockdown also works at heterozygous dose.
  evidence:
  - reference: PMID:34782621
    reference_title: "Deficiency of autism risk factor ASH1L in prefrontal cortex induces epigenetic aberrations and seizures."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Chemogenetic inhibition of PFC pyramidal neuronal activity, combined with
      the administration of GABA enhancer diazepam, rescues PFC synaptic imbalance
      and seizures, but not autistic social deficits or anxiety-like behaviors.
    explanation: >-
      The rescue result, and its own limit - the same intervention does not touch
      the social or anxiety phenotype, so even within the model it addresses one
      arm only.
  - reference: PMID:39766886
    reference_title: "Chemogenetic Inhibition of Prefrontal Cortex Ameliorates Autism-Like Social Deficits and Absence-Like Seizures in a Gene-Trap Ash1l Haploinsufficiency Mouse Model."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Epileptiform discharges were found on electroencephalograms (EEGs) of
      Ash1l+/GT mice, indicating absence-like seizures.
    explanation: >-
      Establishes the semiology of the genotype-matched model, which is the half
      of the mismatch that dose-matching does not fix.
references:
- reference: PMID:38674358
  title: "Expansion of the Genotypic and Phenotypic Spectrum of ASH1L-Related Syndromic Neurodevelopmental Disorder."
- reference: PMID:28191889
  title: "Targeted sequencing identifies 91 neurodevelopmental-disorder risk genes with autism and developmental-disability biases."
- reference: PMID:34373061
  title: "ASH1L mutation caused seizures and intellectual disability in twin sisters."
- reference: PMID:39902220
  title: "Novel heterozygous ASH1L nonsense variant involved in mild intellectual disability."
- reference: PMID:34782621
  title: "Deficiency of autism risk factor ASH1L in prefrontal cortex induces epigenetic aberrations and seizures."
- reference: PMID:35081333
  title: "ASH1L haploinsufficiency results in autistic-like phenotypes in mice and links Eph receptor gene to autism spectrum disorder."
- reference: PMID:34145365
  title: "Loss of histone methyltransferase ASH1L in the developing mouse brain causes autistic-like behaviors."
- reference: PMID:38943682
  title: "Ash1l loss-of-function results in structural birth defects and altered cortical development."
- reference: PMID:39766886
  title: "Chemogenetic Inhibition of Prefrontal Cortex Ameliorates Autism-Like Social Deficits and Absence-Like Seizures in a Gene-Trap Ash1l Haploinsufficiency Mouse Model."

📚

References & Deep Research

References

9

PMID:38674358

Expansion of the Genotypic and Phenotypic Spectrum of ASH1L-Related Syndromic Neurodevelopmental Disorder.

No top-level findings curated for this source.

PMID:28191889

Targeted sequencing identifies 91 neurodevelopmental-disorder risk genes with autism and developmental-disability biases.

No top-level findings curated for this source.

PMID:34373061

ASH1L mutation caused seizures and intellectual disability in twin sisters.

No top-level findings curated for this source.

PMID:39902220

Novel heterozygous ASH1L nonsense variant involved in mild intellectual disability.

No top-level findings curated for this source.

PMID:34782621

Deficiency of autism risk factor ASH1L in prefrontal cortex induces epigenetic aberrations and seizures.

No top-level findings curated for this source.

PMID:35081333

ASH1L haploinsufficiency results in autistic-like phenotypes in mice and links Eph receptor gene to autism spectrum disorder.

No top-level findings curated for this source.

PMID:34145365

Loss of histone methyltransferase ASH1L in the developing mouse brain causes autistic-like behaviors.

No top-level findings curated for this source.

PMID:38943682

Ash1l loss-of-function results in structural birth defects and altered cortical development.

No top-level findings curated for this source.

PMID:39766886

Chemogenetic Inhibition of Prefrontal Cortex Ameliorates Autism-Like Social Deficits and Absence-Like Seizures in a Gene-Trap Ash1l Haploinsufficiency Mouse Model.

No top-level findings curated for this source.

Deep Research

1

Falcon ▸

Intellectual Disability, Autosomal Dominant 52 (MRD52): Research Report

Edison Scientific Literature 16 citations 2026-08-27T02:56:25.482695

Intellectual Disability, Autosomal Dominant 52 (MRD52): Research Report

Executive summary

Intellectual disability, autosomal dominant 52 (MRD52) is an ultra-rare, congenital neurodevelopmental chromatinopathy caused principally by heterozygous pathogenic variants in ASH1L, usually through loss of function or haploinsufficiency. The phenotype is variable but centers on developmental delay/intellectual disability, severe speech-language impairment, autism or other behavioral abnormalities, and sometimes hypotonia, dysmorphism, and epilepsy. ASH1L is a Trithorax-family histone lysine methyltransferase that promotes transcriptionally permissive chromatin, principally through H3K36 methylation and associated H3K4 methylation, while opposing Polycomb repression. No disease-specific therapy, validated biomarker, prevalence estimate, or dedicated clinical trial was identified. The most important 2024 advances are mechanistic: a peer-reviewed Ash1l-haploinsufficient mouse study implicated excessive prefrontal cortical excitability, while a December 2024 bioRxiv study found impaired neurite growth, transcription, and chromatin regulation in engineered human neurons. Both remain preclinical. (ma2024chemogeneticinhibitionof pages 12-13, wilson2022reprogrammingofthe pages 14-15, jhanji2024dynamicregulationof pages 4-7)

The following compact table summarizes the knowledge-base-level conclusions.

Domain	Key facts	Ontology / controlled-term suggestions	Evidence
Disease identity / identifiers	Intellectual disability, autosomal dominant 52 (MRD52); ASH1L-related neurodevelopmental disorder; OMIM 617796; MONDO MONDO:0030918. Disease-level knowledge is aggregated from published case reports/cohorts, reviews, and curated disease-target resources rather than EHR-only evidence.	MONDO:0030918	(OpenTargets Search: Intellectual disability, autosomal dominant 52, wilson2022reprogrammingofthe pages 14-15)
Synonyms	ASH1L-related intellectual developmental disorder; ASH1L-related neurodevelopmental disorder; MRD52; intellectual developmental disorder with speech delay/autism features due to ASH1L.	MeSH/ICD-specific synonym mapping not established in retrieved evidence	(wilson2022reprogrammingofthe pages 14-15)
Inheritance	Autosomal dominant; most reported pathogenic events are interpreted as heterozygous loss-of-function / haploinsufficiency, often de novo in sequencing cohorts. Penetrance and recurrence risk are not well quantified; parental testing is important to assess de novo status and mosaicism.	HP:0000006 Autosomal dominant inheritance	(OpenTargets Search: Intellectual disability, autosomal dominant 52, wilson2022reprogrammingofthe pages 14-15, jhanji2024dynamicregulationof pages 1-4)
Causal gene / protein	ASH1L (also called KMT2H), encoding ASH1-like histone lysine methyltransferase, a Trithorax-family chromatin regulator expressed in brain and involved in transcriptional activation.	HGNC:19208 ASH1L; UniProt ASH1L protein	(wilson2022reprogrammingofthe pages 14-15, jhanji2024dynamicregulationof pages 1-4)
Pathogenic mechanism	Predominant mechanism is germline monoallelic loss of function / haploinsufficiency disrupting chromatin-mediated transcription. ASH1L catalyzes H3K36me2 and contributes to H3K4me3, opposing PRC2/H3K27me3 repression; downstream effects include altered neuronal gene expression, neurite growth, synaptic programs, and cortical excitability. The 2024 human-neuron study is a bioRxiv preprint.	GO:0046975 histone methyltransferase activity; GO:0018024 histone H3-K36 methylation; GO:0046968 H3-K4 methylation; GO:0006357 regulation of transcription by RNA polymerase II; GO:0030154 cell differentiation	(ma2024chemogeneticinhibitionof pages 12-13, wilson2022reprogrammingofthe pages 14-15, jhanji2024dynamicregulationof pages 4-7, jhanji2024dynamicregulationof pages 1-4, jhanji2024dynamicregulationof pages 10-12)
Core phenotypes	Developmental delay and intellectual disability (mild to severe reported), marked speech/language delay, autism spectrum disorder / autistic behaviors, dysmorphic facial features, and behavioral abnormalities; some patients have seizures/epilepsy or broader neuropsychiatric manifestations. Precise phenotype frequencies are not robustly established in retrieved evidence.	HP:0001263 Global developmental delay; HP:0001249 Intellectual disability; HP:0000750 Delayed speech and language development; HP:0000729 Autism; HP:0001250 Seizure; HP:0000717 Autism spectrum disorder; HP:0001252 Hypotonia; HP:0001999 Facial dysmorphism	(wilson2022reprogrammingofthe pages 14-15, jhanji2024dynamicregulationof pages 1-4, jhanji2024dynamicregulationof pages 39-41)
Principal anatomy / cell types	Primary system affected is the central nervous system, especially cortical circuits. Experimental data implicate prefrontal cortex and cortical excitatory pyramidal neurons; neuronal projections, axons, synapses, and nuclei are enriched among dysregulated compartments/features.	UBERON:0000955 brain; UBERON:0001870 cerebral cortex; UBERON:0000451 prefrontal cortex; CL:0000540 neuron; CL:0002608 pyramidal neuron; GO:0030424 axon; GO:0045202 synapse; GO:0005634 nucleus	(ma2024chemogeneticinhibitionof pages 12-13, jhanji2024dynamicregulationof pages 4-7, jhanji2024dynamicregulationof pages 10-12)
Diagnosis	Molecular diagnosis relies on exome/genome sequencing or neurodevelopmental disorder/intellectual disability panels that include ASH1L; trio-based testing is particularly valuable to establish de novo occurrence. No disease-specific biochemical biomarker or imaging signature was established in retrieved evidence.	NCIT:C101294 Whole Exome Sequencing; NCIT:C84351 Whole Genome Sequencing; NCIT:C157640 Molecular Genetic Testing	(OpenTargets Search: Intellectual disability, autosomal dominant 52, wilson2022reprogrammingofthe pages 14-15)
Treatment / management	No approved disease-specific therapy identified. Current care is supportive and multidisciplinary: developmental pediatrics, neurology, speech-language therapy, occupational/physical therapy, behavioral/educational interventions, and seizure management when present. Preclinical only: in Ash1l mouse or edited human-neuron systems, chemogenetic PFC inhibition and epigenetic drugs (tazemetostat, vorinostat) rescued selected phenotypes; these are not established patient treatments.	NCIT:C51909 Supportive Care; NCIT:C17556 Speech Therapy; NCIT:C15635 Occupational Therapy; NCIT:C15313 Physical Therapy; NCIT:C146712 Behavioral Intervention; NCIT:C15246 Tazemetostat; NCIT:C1820 Vorinostat	(ma2024chemogeneticinhibitionof pages 12-13, jhanji2024dynamicregulationof pages 34-39, jhanji2024dynamicregulationof pages 39-41)
Epidemiology / prognosis	Appears to be an ultra-rare Mendelian disorder; no reliable prevalence or incidence estimates were identified in retrieved evidence. Natural history is incompletely defined; morbidity is dominated by lifelong neurodevelopmental impairment, communication disability, behavioral challenges, and possible epilepsy. Disease-specific survival, life expectancy, and mortality rates are unavailable.	Orphan/rare disease category; chronic neurodevelopmental disorder	(wilson2022reprogrammingofthe pages 14-15)
Model systems	Mouse: Ash1l haploinsufficiency/gene-trap models show social deficits, repetitive grooming, cognitive impairment, EEG epileptiform activity/absence-like seizures, and increased PFC excitability. Human neuronal models: CRISPR-engineered iPSC/ESC-derived cortical excitatory neurons (including E2148 catalytic-domain variant) show reduced neurite length/arborization and altered histone marks/transcriptomes; this 2024 study is a bioRxiv preprint. Zebrafish:* ash1a knockdown reduces neuron numbers in pineal gland.	NCBITaxon:10090 Mus musculus; NCBITaxon:7955 Danio rerio; CL:0000540 neuron; CL:0002608 pyramidal neuron	(ma2024chemogeneticinhibitionof pages 12-13, wilson2022reprogrammingofthe pages 14-15, jhanji2024dynamicregulationof pages 4-7, jhanji2024dynamicregulationof pages 26-29)
Key evidence gaps	Major gaps include: small patient numbers; limited validated phenotype frequencies; scarce longitudinal natural-history data; poor estimates of penetrance/expressivity; no established episignature/clinical biomarker in retrieved evidence; no disease-specific interventional trials found; limited patient-cell functional studies in peer-reviewed literature; 2024 human-neuron rescue work remains preprint/preclinical.	Evidence-gap annotation	(wilson2022reprogrammingofthe pages 14-15, jhanji2024dynamicregulationof pages 1-4, jhanji2024dynamicregulationof pages 39-41)

Table: Compact knowledge-base table summarizing identifiers, genetics, phenotypes, mechanism, diagnosis, management, models, and current evidence gaps for Intellectual disability, autosomal dominant 52 / ASH1L-related disorder. It separates established disease knowledge from preclinical and preprint findings.

1. Disease information

Definition. MRD52 is a monogenic developmental disorder in which deficient ASH1L dosage disrupts chromatin-dependent neuronal development. It belongs to the Mendelian intellectual-developmental disorders and more broadly to the “chromatinopathies.” Reported severity ranges from mild to severe intellectual disability, with developmental and speech delay, autism-spectrum manifestations, and variable dysmorphism. (wilson2022reprogrammingofthe pages 14-15)

Identifiers and names

MONDO: MONDO:0030918.
OMIM phenotype: 617796, Intellectual disability, autosomal dominant 52.
Common abbreviations/synonyms: MRD52; ASH1L-related intellectual developmental disorder; ASH1L-related neurodevelopmental disorder.
Gene: ASH1L, also called KMT2H; Ensembl ENSG00000116539.
A unique disease-specific ICD-10, ICD-11, or MeSH code was not established in the retrieved evidence; patients are ordinarily coded under intellectual disability, developmental disorder, autism, or epilepsy as appropriate.

Open Targets associates ASH1L with MONDO:0030918 and links the association to, among other studies, PMID 28394464, 23033978, and 28191889. It also returned a weaker LMAN2L association, but the present phenotype’s established molecular definition is ASH1L-related; the weaker result should not be used as an alternative causal assignment without re-curation. (OpenTargets Search: Intellectual disability, autosomal dominant 52)

The evidence is aggregated disease-level evidence from sequencing cohorts, case reports, curated databases, reviews, and experimental studies—not an analysis of an individual patient’s EHR.

2. Etiology, risk, protection, and environment

Causal factor

The primary cause is a germline heterozygous pathogenic ASH1L variant. Protein-truncating nonsense, frameshift, and splice-disrupting alleles are consistent with loss of function and haploinsufficiency; damaging catalytic-domain alleles can similarly impair histone methyltransferase activity. The experimentally modeled p.Glu2148Ter (E2148*) allele is a catalytic-domain truncation associated with ASD, ID, and epilepsy. (jhanji2024dynamicregulationof pages 4-7, jhanji2024dynamicregulationof pages 1-4)

Risk factors

Genetic: carrying a pathogenic ASH1L allele is the principal risk factor. Most recognized cases appear sporadic/de novo, although autosomal-dominant transmission is biologically possible.
Family history: an affected heterozygous parent would imply a 50% transmission probability per pregnancy, subject to variable expressivity. If apparently de novo, recurrence is low but not zero because parental germline mosaicism cannot be excluded.
Modifiers: no validated modifier gene, founder allele, ancestry-specific risk, sex-specific penetrance, or polygenic modifier has been established.

No reliable disease-specific environmental, lifestyle, occupational, infectious, maternal-age, or sex risk factor has been demonstrated. Prenatal exposures associated with neurodevelopmental disorders generally should not be represented as causes or modifiers of molecularly confirmed MRD52 without direct evidence.

Protective factors and gene–environment interaction

No protective ASH1L allele, diet, drug, lifestyle exposure, or reproducible gene–environment interaction is known. Ordinary developmental supports may improve function but do not prevent the genotype. Infectious and zoonotic causation are not applicable.

3. Phenotypes

Because published cohorts are small and ascertainment differs, robust percentages are unavailable. Qualitative frequencies should therefore be encoded as “common,” “variable,” or “reported,” not as inferred percentages.

Global developmental delay — HP:0001263: typically evident in infancy or early childhood; variable severity; chronic rather than episodic. It affects acquisition of communication, learning, self-care, and adaptive skills.
Intellectual disability — HP:0001249: mild through severe; generally lifelong and non-remitting. Formal severity may become clearer during childhood as cognitive demands increase. (wilson2022reprogrammingofthe pages 14-15)
Delayed speech and language development — HP:0000750; absent speech, if applicable — HP:0001344: often especially prominent. Childhood apraxia of speech has also been discussed within the expanding genetic spectrum of ASH1L-associated speech disorders, but should be assigned only after specialist motor-speech assessment.
Autism/autistic behavior — HP:0000729 or HP:0000717: social-communication impairment, restricted interests, repetitive behavior, or formal ASD may occur. Behavioral consequences can substantially affect education, family participation, and independent living. (wilson2022reprogrammingofthe pages 14-15, jhanji2024dynamicregulationof pages 1-4)
Seizures/epilepsy — HP:0001250 / HP:0001251: variably reported rather than obligatory. The experimental literature particularly supports susceptibility to absence-like and convulsive seizures, but mouse seizure type should not automatically be assigned to every patient. (ma2024chemogeneticinhibitionof pages 12-13)
Hypotonia — HP:0001252: reported in the clinical spectrum and may contribute to delayed motor milestones, poor coordination, feeding difficulty, or need for physical therapy.
Facial dysmorphism — HP:0001999: variable and generally nonspecific; it is not sufficiently distinctive to diagnose the disorder clinically. (wilson2022reprogrammingofthe pages 14-15)
Other neuropsychiatric associations: ASH1L variation has been reported across ADHD, Tourette syndrome, schizophrenia, ASD, ID, and epilepsy. These broader associations demonstrate pleiotropy but are not all defining manifestations of MRD52. The 2024 preprint catalogued 136 disease-associated ASH1L variants across these phenotypes. (jhanji2024dynamicregulationof pages 1-4)

No disease-specific laboratory abnormality, metabolite signature, immune phenotype, or pathognomonic MRI pattern is established. Quality-of-life studies using EQ-5D, SF-36, PROMIS, or a disease-specific instrument were not found; impact must presently be inferred from communication, cognitive, behavioral, and seizure burden.

4. Genetic and molecular information

ASH1L encodes a large nuclear chromatin regulator and histone lysine methyltransferase. The dominant disease mechanism is best represented as haploinsufficiency/loss of function, although individual missense variants require case-specific functional and ACMG/AMP assessment. Disease-associated classes include nonsense, frameshift, splice, and damaging missense/catalytic-domain variants. (wilson2022reprogrammingofthe pages 14-15, jhanji2024dynamicregulationof pages 4-7)

For a knowledge base, each variant should retain transcript-specific HGVS nomenclature, genome build, inheritance, ClinVar assertion and review status, and gnomAD frequency. Pathogenic truncating alleles are expected to be absent or extremely rare in population databases, but no universal allele frequency can be assigned without variant-level lookup. The variants are germline, not a recognized somatic cancer mechanism in this disease.

No validated modifier genes or MRD52-specific diagnostic DNA-methylation episignature were identified. ASH1L can be affected within larger copy-number alterations, but a broad deletion involving neighboring genes should not be assumed phenotypically equivalent to an intragenic ASH1L loss-of-function allele.

5. Environmental, lifestyle, and infectious information

MRD52 is not known to be caused by toxins, radiation, pollution, occupation, smoking, alcohol, diet, inactivity, or infection. Such exposures can independently influence development or pregnancy outcome but have no demonstrated disease-specific causal interaction with ASH1L. There is no vaccine, antimicrobial prophylaxis, or environmental remediation specific to MRD52.

6. Mechanism and pathophysiology

Upstream molecular defect

ASH1L promotes active chromatin through H3K36me2 and associated H3K4me3 and counteracts PRC2-mediated H3K27me3 repression. It is expressed in embryonic and adult brain and participates in developmental gene activation, including HOX regulation. Suggested terms include GO:0018024, histone H3-K36 methylation; GO:0046968, histone H3-K4 methylation; GO:0006357, regulation of transcription by RNA polymerase II; and GO:0046975, histone methyltransferase activity. (wilson2022reprogrammingofthe pages 14-15, jhanji2024dynamicregulationof pages 1-4)

Causal chain

Pathogenic heterozygous ASH1L variant → reduced functional methyltransferase dosage/activity → altered H3K36/H3K4 and Polycomb-related chromatin states → inefficient transcription and altered isoform use of long neuronal, axonal, ion-channel, and synaptic genes → impaired neurite growth, neuronal connectivity, and excitation/inhibition balance → developmental delay, ID, autism-related behavior, speech impairment, and seizure susceptibility. Human patient-level genotype–mechanism correspondence remains less mature than the experimental evidence. (jhanji2024dynamicregulationof pages 4-7, jhanji2024dynamicregulationof pages 7-10, jhanji2024dynamicregulationof pages 10-12)

2024 human-neuron findings—preprint evidence

CRISPR-engineered human cortical excitatory neurons carrying E2148 showed mean neurite length of 47.47 ± 1.99 μm versus 56.9 ± 2.41 μm in controls (P<0.004), total neurite length of 139.3 ± 4.66 μm versus 182.7 ± 6.39 μm (P<0.0001), and a lower complexity index, 228.8 ± 13.42 versus 289.5 ± 18.21* (P<0.0099). (jhanji2024dynamicregulationof pages 26-29)

The same system showed H3K36me2 at 67%, H3K4me3 at 68%, and H3K36me3 at 78% of control. Nascent-transcription signal fell from 1.017 ± 0.029 to 0.817 ± 0.027 (P<0.0001). Transcriptomic analysis identified 2,475 differentially expressed genes in one analysis, with enrichment for axon guidance, axonogenesis, nervous-system development, transcription, and synaptic function; 263 dysregulated genes overlapped SFARI ASD genes. Long genes above 100 kb were preferentially downregulated, and 57 genes showed differential transcript usage, including SMARCA4, AFF2, and TARDBP. These findings are important but came from a December 2, 2024 bioRxiv preprint and require independent peer-reviewed replication. URL: https://doi.org/10.1101/2024.12.02.625500. (jhanji2024dynamicregulationof pages 4-7, jhanji2024dynamicregulationof pages 7-10, jhanji2024dynamicregulationof pages 10-12, jhanji2024dynamicregulationof pages 29-34)

Cellular systems

Relevant processes include axonogenesis (GO:0007409), neuron projection development (GO:0031175), synapse organization (GO:0050808), regulation of membrane potential (GO:0042391), and nervous-system development (GO:0007399). Principal suggested cell terms are neuron (CL:0000540), glutamatergic neuron (CL:0000679), and pyramidal neuron (CL:0002608). No convincing primary metabolic, immune, inflammatory, fibrotic, ischemic, or degenerative mechanism has been demonstrated.

7. Anatomical structures affected

The principal organ is the brain (UBERON:0000955), particularly the cerebral cortex (UBERON:0001870). Mouse electrophysiology implicates the prefrontal cortex (UBERON:0000451), where Ash1l haploinsufficiency increases pyramidal-neuron excitability through enhanced glutamatergic transmission, reduced GABAergic inhibition, and altered intrinsic properties. Relevant subcellular compartments include nucleus (GO:0005634), chromatin (GO:0000785), axon (GO:0030424), dendrite (GO:0030425), and synapse (GO:0045202). (ma2024chemogeneticinhibitionof pages 12-13)

No consistent lateralization is known. Dysmorphic or skeletal findings may occur, but nervous-system dysfunction is primary.

8. Temporal development and natural history

The molecular defect is present from conception and acts during prenatal and postnatal neurodevelopment. Clinical recognition is usually pediatric and insidious—through delayed milestones, language delay, hypotonia, behavior, or seizures—rather than an acute onset. MRD52 is chronic and lifelong; there is no established staging system, remission pattern, or end-stage phase. Developmental gains may occur with maturation and therapy, but underlying intellectual and adaptive impairment generally persists. Longitudinal studies are insufficient to determine whether epilepsy, behavior, or cognition systematically improves or worsens with age.

Early childhood is likely the most important intervention window because language, motor, and social circuits are developing, although no ASH1L-specific critical-period trial has established an optimal time.

9. Inheritance and population

Inheritance is autosomal dominant (HP:0000006), with many diagnoses arising from de novo variants. Expressivity is variable; penetrance has not been accurately quantified. Anticipation, repeat expansion, consanguinity, a founder effect, and a carrier frequency are not established features. Germline mosaicism remains a counseling consideration after an apparently de novo result.

The disease is ultra-rare, but no defensible incidence per 100,000, prevalence, geographic concentration, ethnic enrichment, age distribution, or sex ratio was found. Absence of epidemiologic estimates reflects limited ascertainment rather than proof of equal distribution.

10. Diagnostics

Recommended approach

Perform clinical developmental, neurologic, behavioral, speech-language, hearing, vision, growth, and dysmorphology assessment.
Use trio exome sequencing or genome sequencing, or a comprehensive developmental-delay/ID/epilepsy panel containing ASH1L. Trio analysis helps establish de novo status and reduces uncertainty.
Confirm reportable variants by an orthogonal method where required and test both parents. Apply ACMG/AMP criteria, including predicted loss of function, population absence, segregation, phenotype fit, and functional evidence.
Use chromosomal microarray when copy-number disease remains possible; genome sequencing may detect both sequence and structural variants. Karyotype or FISH is indicated only when a larger rearrangement is suspected.
Consider RNA sequencing for a suspected splice variant or unresolved case, but it is not a routine validated MRD52 diagnostic biomarker.

No enzyme assay, blood biomarker, metabolomic test, biopsy, liquid biopsy, or established epigenomic signature diagnoses MRD52. MRI and EEG are phenotype-directed: MRI for focal neurologic signs, abnormal head growth, regression, or seizures; EEG for suspected seizures or developmental regression. Mitochondrial and repeat-expansion testing are not disease-specific.

Differential diagnosis

The differential includes other chromatinopathies and monogenic NDDs—SETD5-, KMT2A-, KMT2D-, KDM5B-, CHD8-, ARID1B-, ASXL3-, TCF4-, and FOXP-related disorders—as well as Fragile X syndrome, pathogenic CNVs, metabolic disease when clinically indicated, cerebral palsy, nonsyndromic ASD/ID, and epilepsy-associated developmental encephalopathies. Clinical overlap is substantial, making genome-wide testing preferable to phenotype-only diagnosis.

11. Outcome and prognosis

No disease-specific five- or ten-year survival, mortality rate, or life-expectancy estimate is available. Available evidence does not establish MRD52 as intrinsically life-limiting, but severe epilepsy, feeding problems, accidents, or unrelated congenital disease could influence individual prognosis.

The major morbidity is lifelong impairment of cognition, communication, adaptive function, education, employment, and independent living. Prognosis is likely influenced by intellectual-disability severity, functional speech, epilepsy control, hypotonia/motor impairment, ASD/behavioral burden, and access to early services. No validated molecular prognostic biomarker exists.

12. Treatment and current applications

There is no approved ASH1L-directed therapy and no disease-specific treatment-response rate. Current real-world implementation is genotype-informed supportive care:

individualized education and early developmental intervention;
speech-language therapy, including augmentative and alternative communication when needed;
occupational and physical therapy;
behavioral and ASD-focused interventions;
standard antiseizure treatment selected by seizure type and tolerability;
feeding, sleep, psychiatric, hearing, vision, and orthopedic management as indicated;
social-work, respite, and transition-to-adult-care planning.

Suggested NCIT annotations include Supportive Care (NCIT:C51909), Speech Therapy (NCIT:C17556), Occupational Therapy (NCIT:C15635), Physical Therapy (NCIT:C15313), and Behavioral Intervention (NCIT:C146712).

Experimental therapy

In Ash1l+/GT mice, chemogenetic inhibition of prefrontal pyramidal neurons improved social deficits and abolished absence-like seizures, indicating that cortical hyperexcitability is modifiable. This DREADD experiment is mechanistic and is not a clinically available treatment. URL and publication date: Genes, December 2024, https://doi.org/10.3390/genes15121619. (ma2024chemogeneticinhibitionof pages 12-13)

In engineered human neurons, tazemetostat (EZH2 inhibitor, 0.5 μM) and vorinostat (HDAC inhibitor, 0.1 μM) improved selected neurite/chromatin readouts. Vorinostat increased total neurite length from 163.3 ± 4.83 μm under vehicle to 225.2 ± 8.38 μm and markedly increased H4K16ac; tazemetostat reduced H3K27me3. These agents have substantial systemic effects and are not recommended for MRD52 outside ethically approved research. (jhanji2024dynamicregulationof pages 34-39, jhanji2024dynamicregulationof pages 39-41)

No ASH1L-specific gene replacement, CRISPR, ASO, siRNA, mRNA, cell therapy, immunotherapy, surgery, pharmacogenomic rule, or registered interventional trial was identified.

13. Prevention

The genotype cannot be prevented by lifestyle change, vaccination, or prophylactic medication. Appropriate measures are:

Primary reproductive prevention: genetic counseling, parental testing, discussion of recurrence risk, prenatal diagnosis, and preimplantation genetic testing for a known familial pathogenic variant.
Secondary prevention: prompt etiologic sequencing in unexplained DD/ID and early developmental, speech, hearing, and seizure assessment.
Tertiary prevention: therapies and surveillance intended to limit communication disability, contractures/deconditioning, behavioral crisis, untreated epilepsy, sleep disruption, and caregiver burden.
Cascade testing: appropriate if a pathogenic variant is inherited; routine population or newborn screening is not currently justified.

14. Other species and natural disease

No well-characterized naturally occurring veterinary counterpart, breed predisposition, animal-to-human transmission, or zoonotic risk was identified. Relevant orthologs are Ash1l in mouse (Mus musculus, NCBI Taxon 10090) and ash1-family orthologs in zebrafish (Danio rerio, NCBI Taxon 7955). Conservation of chromatin regulation and neuronal-development functions makes these experimentally informative, but engineered phenotypes are not natural animal disease.

15. Model organisms and experimental systems

Mouse, gene-trap haploinsufficiency. Ash1l+/GT mice exhibited social deficits, increased self-grooming, cognitive impairment, EEG epileptiform discharges/absence-like seizures, and increased pentylenetetrazole susceptibility. Whole-cell recordings showed hyperexcitable prefrontal pyramidal neurons, enhanced glutamatergic transmission, and diminished GABAergic inhibition. This is the strongest recent peer-reviewed mechanistic model, but mouse social behavior and chemogenetic rescue do not directly predict human treatment efficacy. (ma2024chemogeneticinhibitionof pages 12-13)

Human cellular model. Isogenic pluripotent-stem-cell-derived cortical excitatory neurons carrying E2148* reproduced impaired neurite outgrowth, simpler arbors, altered H3K36/H3K4 regulation, reduced transcription, long-gene vulnerability, and isoform changes. Its human genetic background and cell-type specificity are strengths; lack of organismal development, glial circuitry, pharmacokinetics, and peer review are limitations. (jhanji2024dynamicregulationof pages 4-7, jhanji2024dynamicregulationof pages 7-10, jhanji2024dynamicregulationof pages 26-29)

Zebrafish and other mouse alleles. Zebrafish ash1a knockdown reportedly reduces pineal neuron number, while catalytically inactive Ash1l mice have skeletal anomalies and impaired fertility. These models support developmental conservation but only partially reproduce the human neurobehavioral syndrome. (wilson2022reprogrammingofthe pages 14-15)

Authoritative interpretation and evidence gaps

The current expert interpretation is that MRD52 is best understood as a developmental chromatin-regulation disorder, not simply isolated intellectual disability. The convergence of human genetics, neuronal chromatin/transcriptomic data, and mouse electrophysiology supports a model in which altered epigenetic regulation produces abnormal neuronal connectivity and cortical excitation/inhibition. However, the field remains constrained by small clinical cohorts, heterogeneous variant ascertainment, limited longitudinal phenotyping, and a lack of patient-derived functional studies in peer-reviewed literature. The 2024 human-neuron work is promising but is a preprint; its epigenetic-drug rescues should be treated as hypothesis-generating rather than therapeutic evidence. (wilson2022reprogrammingofthe pages 14-15, jhanji2024dynamicregulationof pages 1-4, jhanji2024dynamicregulationof pages 39-41)

Two concise source statements capture the current evidence:

“Clinical phenotypes in MRD52 individuals include mild-severe intellectual disability, autism spectrum disorder, speech delay, facial dysmorphisms, and developmental delay.” — synthesis of the peer-reviewed chromatin/NDD review, published October 2022, https://doi.org/10.1080/10409238.2021.1979457. (wilson2022reprogrammingofthe pages 14-15)

“Chemogenetic inhibition of pyramidal neurons in the PFC of Ash1l+/GT mice ameliorated autism-like social deficits and abolished absence-like seizures.” — Ma et al., published December 2024, https://doi.org/10.3390/genes15121619. (ma2024chemogeneticinhibitionof pages 12-13)

Accordingly, immediate clinical value lies in molecular diagnosis, recurrence counseling, anticipatory neurologic/developmental care, and access to individualized services. Disease-modifying treatment, validated natural-history endpoints, and prospective genotype–phenotype statistics remain priority research needs.

References

(ma2024chemogeneticinhibitionof pages 12-13): Kaijie Ma, Kylee McDaniel, Daoqi Zhang, Maria Webb, and Luye Qin. Chemogenetic inhibition of prefrontal cortex ameliorates autism-like social deficits and absence-like seizures in a gene-trap ash1l haploinsufficiency mouse model. Genes, 15(12):1619, Dec 2024. URL: https://doi.org/10.3390/genes15121619, doi:10.3390/genes15121619. This article has 2 citations.
(wilson2022reprogrammingofthe pages 14-15): Khadija D. Wilson, Elizabeth G. Porter, and Benjamin A. Garcia. Reprogramming of the epigenome in neurodevelopmental disorders. Critical Reviews in Biochemistry and Molecular Biology, 57:73-112, Oct 2022. URL: https://doi.org/10.1080/10409238.2021.1979457, doi:10.1080/10409238.2021.1979457. This article has 33 citations and is from a peer-reviewed journal.
(jhanji2024dynamicregulationof pages 4-7): Megha Jhanji, Joseph A. Ward, Calvin S. Leung, Colleen L. Krall, Foster D. Ritchie, Alexis Guevara, Kai Vestergaard, Brian Yoon, Krishna Amin, Stefano Berto, Judy S. Liu, and Sofia B. Lizarraga. Dynamic regulation of the chromatin environment by ash1l modulates human neuronal structure and function. bioRxiv, Dec 2024. URL: https://doi.org/10.1101/2024.12.02.625500, doi:10.1101/2024.12.02.625500. This article has 0 citations.
(OpenTargets Search: Intellectual disability, autosomal dominant 52): Open Targets Query (Intellectual disability, autosomal dominant 52, 3 results). Buniello, A. et al. (2025). Open Targets Platform: facilitating therapeutic hypotheses building in drug discovery. Nucleic Acids Research.
(jhanji2024dynamicregulationof pages 1-4): Megha Jhanji, Joseph A. Ward, Calvin S. Leung, Colleen L. Krall, Foster D. Ritchie, Alexis Guevara, Kai Vestergaard, Brian Yoon, Krishna Amin, Stefano Berto, Judy S. Liu, and Sofia B. Lizarraga. Dynamic regulation of the chromatin environment by ash1l modulates human neuronal structure and function. bioRxiv, Dec 2024. URL: https://doi.org/10.1101/2024.12.02.625500, doi:10.1101/2024.12.02.625500. This article has 0 citations.
(jhanji2024dynamicregulationof pages 10-12): Megha Jhanji, Joseph A. Ward, Calvin S. Leung, Colleen L. Krall, Foster D. Ritchie, Alexis Guevara, Kai Vestergaard, Brian Yoon, Krishna Amin, Stefano Berto, Judy S. Liu, and Sofia B. Lizarraga. Dynamic regulation of the chromatin environment by ash1l modulates human neuronal structure and function. bioRxiv, Dec 2024. URL: https://doi.org/10.1101/2024.12.02.625500, doi:10.1101/2024.12.02.625500. This article has 0 citations.
(jhanji2024dynamicregulationof pages 39-41): Megha Jhanji, Joseph A. Ward, Calvin S. Leung, Colleen L. Krall, Foster D. Ritchie, Alexis Guevara, Kai Vestergaard, Brian Yoon, Krishna Amin, Stefano Berto, Judy S. Liu, and Sofia B. Lizarraga. Dynamic regulation of the chromatin environment by ash1l modulates human neuronal structure and function. bioRxiv, Dec 2024. URL: https://doi.org/10.1101/2024.12.02.625500, doi:10.1101/2024.12.02.625500. This article has 0 citations.
(jhanji2024dynamicregulationof pages 34-39): Megha Jhanji, Joseph A. Ward, Calvin S. Leung, Colleen L. Krall, Foster D. Ritchie, Alexis Guevara, Kai Vestergaard, Brian Yoon, Krishna Amin, Stefano Berto, Judy S. Liu, and Sofia B. Lizarraga. Dynamic regulation of the chromatin environment by ash1l modulates human neuronal structure and function. bioRxiv, Dec 2024. URL: https://doi.org/10.1101/2024.12.02.625500, doi:10.1101/2024.12.02.625500. This article has 0 citations.
(jhanji2024dynamicregulationof pages 26-29): Megha Jhanji, Joseph A. Ward, Calvin S. Leung, Colleen L. Krall, Foster D. Ritchie, Alexis Guevara, Kai Vestergaard, Brian Yoon, Krishna Amin, Stefano Berto, Judy S. Liu, and Sofia B. Lizarraga. Dynamic regulation of the chromatin environment by ash1l modulates human neuronal structure and function. bioRxiv, Dec 2024. URL: https://doi.org/10.1101/2024.12.02.625500, doi:10.1101/2024.12.02.625500. This article has 0 citations.
(jhanji2024dynamicregulationof pages 7-10): Megha Jhanji, Joseph A. Ward, Calvin S. Leung, Colleen L. Krall, Foster D. Ritchie, Alexis Guevara, Kai Vestergaard, Brian Yoon, Krishna Amin, Stefano Berto, Judy S. Liu, and Sofia B. Lizarraga. Dynamic regulation of the chromatin environment by ash1l modulates human neuronal structure and function. bioRxiv, Dec 2024. URL: https://doi.org/10.1101/2024.12.02.625500, doi:10.1101/2024.12.02.625500. This article has 0 citations.
(jhanji2024dynamicregulationof pages 29-34): Megha Jhanji, Joseph A. Ward, Calvin S. Leung, Colleen L. Krall, Foster D. Ritchie, Alexis Guevara, Kai Vestergaard, Brian Yoon, Krishna Amin, Stefano Berto, Judy S. Liu, and Sofia B. Lizarraga. Dynamic regulation of the chromatin environment by ash1l modulates human neuronal structure and function. bioRxiv, Dec 2024. URL: https://doi.org/10.1101/2024.12.02.625500, doi:10.1101/2024.12.02.625500. This article has 0 citations.

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Inheritance

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Pathophysiology

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Phenotypes

Genetic Associations

Medical Actions

Diagnosis

Prevalence

Animal Models

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References & Deep Research

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Deep Research

Intellectual Disability, Autosomal Dominant 52 (MRD52): Research Report

Executive summary

1. Disease information

2. Etiology, risk, protection, and environment

Causal factor

Risk factors

Protective factors and gene–environment interaction

3. Phenotypes

4. Genetic and molecular information

5. Environmental, lifestyle, and infectious information

6. Mechanism and pathophysiology

Upstream molecular defect

Causal chain

2024 human-neuron findings—preprint evidence

Cellular systems

7. Anatomical structures affected

8. Temporal development and natural history

9. Inheritance and population

10. Diagnostics

Recommended approach

Differential diagnosis

11. Outcome and prognosis

12. Treatment and current applications

Experimental therapy

13. Prevention

14. Other species and natural disease

15. Model organisms and experimental systems

Authoritative interpretation and evidence gaps

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