Li-Ghorbani-Weisz-Hubshman Syndrome (LIGOWS): Comprehensive Research Report

1. Disease Information

Overview

Li-Ghorbani-Weisz-Hubshman syndrome (LIGOWS) is a rare, autosomal dominant (with one reported autosomal recessive family) neurodevelopmental disorder caused by heterozygous (or, rarely, biallelic) pathogenic variants in KAT8 (Lysine Acetyltransferase 8, also known as MOF/MYST1) on chromosome 16p11.2. It was first delineated in 2020 by Li, Ghorbani, Weisz-Hubshman and colleagues, who identified pathogenic KAT8 variants in 9 unrelated individuals with intellectual disability, seizures, autism, dysmorphic features, and other congenital anomalies, and mechanistically linked the disorder to impaired histone H4 lysine 16 acetylation (H4K16ac) (Li et al. 2020, J Clin Invest 130(3):1431-1445, PMID:31794431).

Key Identifiers

Synonyms

"LIGOWS," "Li-Ghorbani-Weisz-Hubshman syndrome," and informally "KAT8-related neurodevelopmental disorder" / "KAT8-associated intellectual disability."

Data provenance note

Nearly all clinical characterization derives from a single aggregated, multi-center case series (the founding 2020 report), not from population-level EHR data or disease registries — this is a very recently delineated ultra-rare Mendelian disorder with a small published cohort (9 probands in the original description; independent replication cohorts are sparse in subsequent literature searches).

2. Etiology

Disease Causal Factors

LIGOWS is caused by de novo heterozygous missense (and one nonsense) variants in KAT8, with one family showing biallelic (compound heterozygous) inheritance from unaffected carrier parents, suggesting rare autosomal recessive transmission with possible incomplete penetrance for milder alleles (PMID:31794431).

Genetic Risk Factors

• Causal variant class: De novo heterozygous missense variants clustering in two functional domains of KAT8: the chromobarrel domain (nucleosome/histone recognition) and the catalytic MYST domain (acetyl-CoA binding/enzymatic activity).
• A recurrent de novo variant, c.269A>G (p.Tyr90Cys), was found independently in three unrelated patients (T1–T3), indicating a mutational hotspot in the chromobarrel domain.
• No modifier genes have yet been reported.

Environmental Risk Factors

None identified; this is a purely monogenic disorder with no established environmental, infectious, or lifestyle contribution to causation.

Protective Factors

None reported in the literature to date.

Gene-Environment Interactions

Not applicable/not studied — no data on environmental modulation of penetrance or severity.

3. Genetic/Molecular Information

Causal Gene

KAT8 (Lysine Acetyltransferase 8; aliases MOF, MYST1, hMOF), HGNC:17933, OMIM *609912, located at 16p11.2. KAT8 encodes a MYST-family histone acetyltransferase with a chromobarrel domain (histone/nucleosome recognition), an acetyl-CoA-binding MYST catalytic domain, and a C2HC-type zinc finger (GeneCards).

Pathogenic Variants Identified (Li et al. 2020, PMID:31794431)

• Variant classification: All are classified pathogenic/likely pathogenic per ACMG/AMP criteria in ClinVar (e.g., RCV001253776 for p.Tyr90Cys; RCV001253778 for p.Lys175Glu); GenCC lists KAT8–LIGOWS as an autosomal dominant "Definitive"/"Strong" gene-disease relationship (Ambry Genetics submission, GenCC entry).
• Variant type: Predominantly missense; one nonsense allele (biallelic case only).
• Population allele frequency: Not reported in gnomAD (consistent with de novo, ultra-rare pathogenic status); not found as common polymorphisms.
• Somatic vs. germline: All germline (constitutional), no somatic mosaicism reported.
• Functional consequence: Loss-of-function at the biochemical level — all seven tested missense variants were "defective in acetylating histone H4 at lysine 5 or 16 when recombinant nucleosomes were used as substrate," despite normal protein expression levels and (for most variants) normal complex assembly with MSL proteins. Chromobarrel-domain variants (Tyr90Cys, Arg98Gln, Arg99Gln) showed the most severe functional impact, consistent with impaired nucleosome engagement.

Modifier Genes

None established.

Epigenetic Information

This is fundamentally an epigenetic-machinery disorder: KAT8 is the enzyme that writes the H4K16ac mark. Pathogenic variants cause a downstream, genome-wide epigenetic deficiency (loss of H4K16 acetylation) rather than acting through a separate epigenetic mechanism.

Chromosomal Abnormalities

Not applicable — LIGOWS results from point mutations in KAT8, not large chromosomal rearrangements. (Note: microdeletion of the adjacent/nearby 16p11.2 region causes a distinct, well-known 16p11.2 deletion syndrome, which should be considered as a differential rather than confused with LIGOWS.)

Suggested ontology terms: Gene — hgnc:17933 (KAT8); functional impact — LOSS_OF_FUNCTION (catalytic/enzymatic) at functional_impact_category.

4. Phenotypes

Neurological / Developmental (Human, HP-codable)

Brain Imaging (structural)

• Ventriculomegaly / enlarged ventricles — HP:0002119
• Thin/hypoplastic corpus callosum — HP:0002079 / HP:0033725
• Periventricular / gray matter nodular heterotopia — HP:0002185
• Decreased white matter volume — HP:0034185

Craniofacial Dysmorphism (recurrent pattern)

Upper lateral eyelid fullness, telecanthus (HP:0000506), epicanthus (HP:0000286), upslanted palpebral fissures (HP:0000582), depressed/prominent nasal bridge (HP:0000431/HP:0000426), mild malar hypoplasia (HP:0000272), thick vermilion border (HP:0012471), downturned corners of the mouth (HP:0002714), low-set ears (HP:0000369).

Cardiac

Cardiac defects (atrial septal defect, ventricular septal defect, patent ductus arteriosus) in 4/9 patients — HP:0001631, HP:0001629, HP:0001643.

Ophthalmologic

Esotropia (HP:0000565), hypermetropia (HP:0000540), hypotelorism (HP:0000601).

Other Systemic

Feeding difficulties in infancy (HP:0011968); limb anomalies including clinodactyly (HP:0030084) and overlapping toes (HP:0001845).

Phenotype Characteristics

• Onset: Congenital/infantile (developmental delay and dysmorphism present from early childhood).
• Severity: Mild-to-moderate intellectual disability predominates (not severe/profound in the reported cohort).
• Progression: Static/developmental (not degenerative) — a neurodevelopmental rather than neurodegenerative course.
• Frequency data: As tabulated above from the n=9 founding cohort; broader population-level frequencies are not yet established given the rarity of the condition.

Quality of Life

Not formally studied with standardized instruments (EQ-5D/SF-36) in the literature to date; qualitatively, affected individuals require developmental/educational support consistent with mild-moderate intellectual disability.

5. Mechanism / Pathophysiology

Molecular Function of KAT8

KAT8 is a MYST-family lysine acetyltransferase that operates as the catalytic subunit of two distinct, evolutionarily conserved multiprotein complexes: - MSL complex (Male-Specific Lethal: MSL1, MSL2, MSL3) — within this complex, KAT8 catalyzes the bulk of genome-wide H4K16 acetylation, marking open chromatin and decompacting the chromatin fiber. - NSL complex (Non-Specific Lethal, containing KANSL1 and related subunits) — within this complex, KAT8 instead acetylates H4K5 and H4K8 at gene promoters, driving transcriptional activation of essential/housekeeping genes.

("KAT8 serves as a catalytic subunit of two independent protein complexes conserved from Drosophila to mammals... it catalyzes H4K5ac and H4K8ac as part of the NSL complex, whereas it catalyzes the bulk of H4K16ac as part of the MSL complex" — Molecular Cell 2021.)

Causal Chain (Mechanism → Phenotype)

1. Molecular trigger: De novo missense variant in KAT8 chromobarrel or catalytic domain → impaired nucleosome recognition or catalytic (acetyl-CoA transfer) activity.
2. Biochemical consequence: Severely reduced H4K16 (and H4K5) acetylation on nucleosomal substrates in vitro, despite normal protein expression and (mostly) normal MSL-complex assembly.
3. Cellular consequence (from Kat8 cerebrum-conditional knockout mice):
4. Loss of H4K16ac in the cerebrocortical neuroepithelium as early as E12.5.
5. Reduced SOX2+ neural stem/progenitor cells (NSPCs) by E13.5.
6. Premature/excessive neurogenesis: increased Tuj1+ neurons with aberrant migration.
7. Reduced proliferation (fewer BrdU+/Ki-67+ cells) and massive apoptosis (TUNEL+, cleaved caspase-3) at E12.5–E13.5.
8. Complete failure of mutant NSPCs to form neurospheres in vitro; pharmacologic KAT8 inhibition (MG149) similarly abolished wild-type neurosphere formation.
9. Tissue/organ consequence: Severe cerebral (neocortical and hippocampal) hypoplasia, altered cortical lamination, "flat-head" skull phenotype, and perinatal lethality in the mouse model.
10. Organism-level phenotype: In humans — global developmental delay, intellectual disability, seizures, structural brain anomalies (ventriculomegaly, thin corpus callosum, heterotopia), and craniofacial dysmorphism.

Suggested GO terms: GO:0043984 (histone H4-K16 acetylation), GO:0043974 (histone H4-K5 acetylation), GO:0043982 (histone H4-K8 acetylation), GO:0022008 (neurogenesis), GO:0007399 (nervous system development), GO:0006325 (chromatin organization). Suggested CL terms: CL:0000047 (neural stem cell) / neural progenitor cell equivalents.

Additional Molecular Finding

KAT8 also catalyzes H4K16 propionylation in vivo (a novel, less-studied acyl mark), with distinct subnuclear distribution from acetylation; this mark was virtually absent in Kat8-mutant neuroepithelium, suggesting a "complementary mechanism" active when propionyl-CoA levels are elevated.

Counterbalancing Deacetylases

SIRT1 and SIRT2 are candidate H4K16 deacetylases; HDAC1/2/3 are also important for cerebral development (HDAC3 loss causes H4K16 hyperacetylation), framing KAT8 loss-of-function within a broader acetylation/deacetylation balance relevant to potential therapeutic modulation.

Related Disease Mechanisms (for context/differential)

The paper situates LIGOWS within a family of "Mendelian disorders of the epigenetic machinery" acting on H4/H3 acetylation: CREBBP/EP300 (Rubinstein-Taybi syndrome, H3K27ac), KAT6A/KAT6B (H3K23ac), BRPF1, KANSL1 (Koolen-de Vries syndrome, part of the NSL complex), and MSL3 (recently linked to an X-linked developmental disorder, Basilicata-Akhtar syndrome).

6. Anatomical Structures Affected

• Organ level (primary): Central nervous system — cerebral cortex, hippocampus (UBERON:0000956, UBERON:0002421).
• Secondary/associated: Heart (septal structures, ductus arteriosus), craniofacial skeleton, eyes.
• Tissue/cell level: Neuroepithelium; neural stem/progenitor cells; cortical neurons (Tuj1+); chromatin/nucleosomes at the subcellular level.
• Subcellular: Nucleus/chromatin — GO Cellular Component GO:0000786 (nucleosome), GO:0005634 (nucleus).
• Localization: Bilateral, diffuse cerebral involvement (not lateralized); structural brain findings (ventriculomegaly, thin corpus callosum, heterotopia) are typically bilateral/symmetric.

7. Temporal Development

• Onset: Congenital/prenatal at the molecular-developmental level (mouse data show defects from E12.5–E16.5); clinically apparent as infantile/early childhood developmental delay.
• Progression: Neurodevelopmental (static/non-degenerative) — features reflect an early developmental insult rather than progressive tissue loss; seizures may emerge in childhood.
• Disease course: Chronic, lifelong intellectual disability; no reports of regression.
• Critical period: Embryonic corticogenesis (E12.5–E16.5 in mouse models) represents the developmental window of maximal vulnerability to KAT8 loss-of-function.

8. Inheritance and Population

Epidemiology

LIGOWS is an ultra-rare, only recently delineated disorder (2020). No formal prevalence or incidence estimates exist in Orphanet, GBD, or other epidemiological databases; the literature to date describes single-digit numbers of published cases (originally 9 in the founding cohort), so it should be treated as CASES_IN_LITERATURE-tier for prevalence purposes rather than a population rate.

Inheritance Pattern

• Predominant: Autosomal dominant, de novo (8 of 9 original patients).
• Rare alternative: Autosomal recessive/biallelic — one patient (T9) inherited compound heterozygous variants from unaffected parents, suggesting incomplete penetrance of milder alleles in the heterozygous carrier state.
• Penetrance: Appears high for de novo heterozygous variants (all reported de novo carriers were affected); incomplete for at least one biallelic-context allele (unaffected heterozygous parents).
• Expressivity: Variable — severity and specific features (seizures, cardiac defects, autism) vary among carriers of different (and even the same) variant.
• Anticipation, mosaicism, founder effects, consanguinity, carrier frequency: Not reported/not applicable given the ultra-rare de novo nature of the disorder.

Population Demographics

• Affected populations: No specific ethnic or geographic enrichment reported; patients were ascertained through international collaborative exome-sequencing efforts.
• Sex ratio: Not reported as skewed (autosomal gene, not X-linked).
• Age distribution: Pediatric ascertainment predominant (patients described in the founding cohort ranged from early childhood through adolescence, e.g., ages 2–18 reported across summaries).

9. Diagnostics

Genetic Testing (primary diagnostic modality)

• Exome sequencing (WES) was the method by which all founding-cohort variants were identified — the most direct approach given the absence of a specific hotspot outside the recurrent p.Tyr90Cys allele.
• Whole genome sequencing (WGS): Not specifically reported but would be expected to detect the same coding variants.
• Gene panels: Intellectual disability/epilepsy/neurodevelopmental gene panels including KAT8 would be expected to capture pathogenic variants.
• Single-gene (Sanger) testing: Appropriate for confirming a specific familial variant or the recurrent p.Tyr90Cys allele.
• Chromosomal microarray / karyotype / FISH: Not causal for this disorder (point mutations, not large CNVs), though CMA is often part of a standard ID/developmental-delay diagnostic workup to exclude 16p11.2 deletion/duplication and other CNV syndromes as differentials.

Functional/Research-Level Diagnostics

Patient-derived cell acetyltransferase assays (H4K16/H4K5 acetylation on nucleosome substrates) were used in the discovery study to establish variant pathogenicity but are not standard clinical diagnostics.

Clinical Criteria

No formal consensus diagnostic criteria (DSM/ICD-specific) exist; diagnosis rests on the combination of the clinical phenotype (developmental delay, dysmorphism, brain imaging findings) plus confirmatory KAT8 variant identification.

Differential Diagnosis

Other "Mendelian disorders of the epigenetic machinery" with overlapping intellectual disability/dysmorphism phenotypes: Rubinstein-Taybi syndrome (CREBBP/EP300), KAT6A syndrome (Arboleda-Tham syndrome), KAT6B disorders, Koolen-de Vries syndrome (KANSL1 — same NSL complex), Basilicata-Akhtar syndrome (MSL3 — same MSL complex as KAT8), and 16p11.2 microdeletion/duplication syndrome (distinct etiology, nearby locus).

Screening

No population or newborn screening programs exist; this is a variant-level, symptomatic diagnostic pathway (typically initiated by developmental delay/ID/seizure workup).

10. Outcome / Prognosis

• Survival/mortality: No mortality data reported in the human cohort (contrast with the fully penetrant perinatal lethality of the cerebrum-specific Kat8 mouse knockout, which is a complete-loss-of-function model rather than the partial-loss-of-function missense alleles seen in patients).
• Morbidity/function: Lifelong mild-to-moderate intellectual disability with associated speech/language impairment; a minority have autism or ADHD features; epilepsy present in ~78% (7/9) of the founding cohort.
• Complications: Structural cardiac defects requiring cardiology follow-up in ~44% (4/9); seizure disorder requiring anticonvulsant management.
• Prognostic factors: Variant domain may correlate with severity — chromobarrel-domain variants showed the most severe biochemical (H4K16ac) impairment in functional assays, though a clear genotype-severity correlation in patients has not yet been formally established in a larger cohort.

11. Treatment

Pharmacotherapy — Seizure Management

Valproate (valproic acid) was used in 2 of the 7 patients with epilepsy in the founding cohort, and both were responsive. The proposed mechanistic rationale is that valproate, a histone deacetylase (HDAC) inhibitor, may partially compensate for the acetylation deficiency caused by KAT8 loss-of-function ("may ameliorate potential acetylation deficiency resulting from KAT8 impairment" — PMID:31794431).

Suggested NCIT term: NCIT:C15986 (Pharmacotherapy), with therapeutic_agent bound to valproic acid (CHEBI, if available) as an anticonvulsant/HDAC inhibitor.

Experimental/Preclinical

Authors propose that Kat8-mutant mice may serve as preclinical models for testing deacetylase inhibitor drugs (e.g., valproic acid) as a therapeutic strategy — this remains a research-stage concept, not an established clinical protocol, and no clinical trials specific to LIGOWS (NCT identifiers) were identified in the literature searched.

Supportive/Multidisciplinary Care

As for intellectual disability generally, management requires a multidisciplinary team: special education, speech-language therapy, behavioral therapy, occupational therapy, and social/community support services (NCIT:C15302 Physical Therapy, NCIT:C15747 Supportive Care, as broadly applicable but not KAT8-specific).

Cardiac

Standard cardiology management/surgical correction as indicated for septal defects/PDA in affected patients (NCIT:C15329 Surgical Procedure where structural repair is needed).

Gene-targeted/Precision Approaches

None reported — no gene therapy, ASO, or targeted molecular therapy has been developed or trialed for KAT8-related disease as of the literature available.

12. Prevention

No primary, secondary, or tertiary prevention strategies exist for this de novo genetic disorder beyond standard genetic counseling for recurrence risk (low for de novo cases; up to 25% per pregnancy in the rare biallelic/autosomal-recessive family pattern) and prenatal/preimplantation genetic testing where a familial variant is known. No immunization, screening program, or behavioral intervention is applicable to primary prevention of this monogenic disorder.

13. Other Species / Model Organisms

Mouse Model (primary animal evidence)

Cerebrum-specific Kat8 conditional knockout mice (Emx1-Cre driven, complete loss-of-function in cerebral tissue) were generated and characterized in the founding study: - Phenotype: Early lethality before weaning (by ~3 weeks); "flat-head" phenotype from skull flattening; severe cerebral hypoplasia (neocortex + hippocampus), reduced brain weight from birth. - Developmental timeline: Defects traceable to E12.5 (loss of H4K16ac) through E16.5 (progressive hypoplasia); altered cortical lamination by E13.5. - Cellular phenotype: Depleted SOX2+ neural stem/progenitor cells, premature neurogenesis (excess Tuj1+ neurons), reduced proliferation (BrdU+/Ki-67+), massive apoptosis (TUNEL+/cleaved caspase-3+), and complete failure of neurosphere formation in vitro. - Fidelity: This is a complete-null model (not the patient's partial-loss-of-function missense alleles), so it recapitulates the qualitative developmental mechanism (H4K16ac loss → NSPC failure → cerebral hypoplasia) but represents a more severe phenotype (perinatal lethality) than the human disease, which is compatible with survival to adulthood. This fidelity gap (complete knockout vs. partial-function missense variants) is a notable human-model consideration for future curation (HUMAN_MODEL_MISMATCH pattern).

Drosophila

KAT8 is the direct ortholog of Drosophila MOF, the catalytic subunit of the Drosophila male-specific lethal (MSL) core complex that mediates dosage compensation on the male X chromosome via H4K16 acetylation — establishing deep evolutionary conservation of the H4K16ac-writing function, though this Drosophila biology (dosage compensation) is not itself a disease model.

Zebrafish

No zebrafish KAT8 loss-of-function neurodevelopmental model was identified in the literature searched.

Cell-based/in vitro models

Patient-variant-expressing HEK293/cell-line systems (FLAG-tagged KAT8 constructs co-expressed with HA-tagged MSL proteins) were used for biochemical acetyltransferase activity and complex-assembly assays; primary mouse embryonic neurosphere cultures were used to model NSPC self-renewal defects.

Natural Disease in Other Species

No naturally occurring veterinary/companion-animal KAT8-related disease has been reported (OMIA has no listing found in this search); this is an engineered/experimental mouse model only, not a spontaneous natural-disease model.

Summary Table of Suggested Ontology Bindings for KB Curation

Sources

• Entry - #618974 - LI-GHORBANI-WEISZ-HUBSHMAN SYNDROME; LIGOWS - OMIM
• Clinical Synopsis - #618974 - OMIM
• Entry - *609912 - LYSINE ACETYLTRANSFERASE 8; KAT8 - OMIM
• Li-Ghorbani-Weisz-Hubshman syndrome (Concept Id: C5436525) - MedGen - NCBI
• Li-Ghorbani-Weisz-Hubshman syndrome | Monarch Initiative (MONDO:0033547)
• Li-Ghorbani-Weisz-Hubshman Syndrome - MalaCards
• KAT8 | Li-Ghorbani-Weisz-Hubshman syndrome | GenCC
• Li, Ghorbani, Weisz-Hubshman et al., "Lysine acetyltransferase 8 is involved in cerebral development and syndromic intellectual disability," J Clin Invest 2020;130(3):1431-1445, PMID:31794431 - PMC7269600
• NM_032188.3(KAT8):c.269A>G (p.Tyr90Cys) AND LIGOWS - ClinVar RCV001253776
• NM_032188.3(KAT8):c.523A>G (p.Lys175Glu) AND LIGOWS - ClinVar RCV001253778
• KAT8 gene - GeneCards
• Complex-dependent histone acetyltransferase activity of KAT8 determines its role in transcription and cellular homeostasis - Molecular Cell 2021
• The non-specific lethal (NSL) complex at the crossroads of transcriptional control and cellular homeostasis - PMC6607013
• Li-Ghorbani-Weisz-Hubshman Syndrome (LIGOWS) - RDDC
• Li-Ghorbani-Weisz-Hubshman syndrome profile page - Open Targets Platform

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