Hao-Fountain syndrome is a rare USP7-related autosomal dominant neurodevelopmental disorder characterized by speech impairment, cognitive dysfunction, behavioral abnormalities, and multisystem developmental features. Available evidence supports USP7 haploinsufficiency with downstream chromatin-associated regulatory dysfunction.
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name: Hao-Fountain syndrome
creation_date: "2026-04-15T15:45:03Z"
updated_date: "2026-04-15T18:58:00Z"
description: >-
Hao-Fountain syndrome is a rare USP7-related autosomal dominant
neurodevelopmental disorder characterized by speech impairment, cognitive
dysfunction, behavioral abnormalities, and multisystem developmental
features. Available evidence supports USP7 haploinsufficiency with
downstream chromatin-associated regulatory dysfunction.
category: Mendelian
parents:
- hereditary disease
- neurodevelopmental disorder
disease_term:
preferred_term: Hao-Fountain syndrome
term:
id: MONDO:0014805
label: Hao-Fountain syndrome
inheritance:
- name: Autosomal dominant inheritance
description: >-
Hao-Fountain syndrome is an autosomal dominant disorder caused by
pathogenic USP7 variants.
inheritance_term:
preferred_term: Autosomal dominant inheritance
term:
id: HP:0000006
label: Autosomal dominant inheritance
evidence:
- reference: DOI:10.3389/fcell.2026.1782599
reference_title: >-
Integrative epigenetic and transcriptomic profiling of whole blood and
fibroblasts in Hao-Fountain syndrome
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Hao–Fountain syndrome (HAFOUS) is a rare autosomal dominant
neurodevelopmental disorder caused by pathogenic USP7 variants.
explanation: This directly supports autosomal dominant inheritance and USP7 causality.
pathophysiology:
- name: USP7 haploinsufficiency
description: >-
Reduced USP7 dosage is the initiating molecular lesion in Hao-Fountain
syndrome and perturbs several cellular homeostatic mechanisms, including
functions linked to the MUST complex.
genes:
- preferred_term: USP7
term:
id: hgnc:12630
label: USP7
evidence:
- reference: DOI:10.3389/fcell.2026.1782599
reference_title: >-
Integrative epigenetic and transcriptomic profiling of whole blood and
fibroblasts in Hao-Fountain syndrome
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
USP7 haploinsufficiency is associated with a restricted set of regulatory
loci enriched within PRC1-associated chromatin domains.
explanation: This directly supports USP7 haploinsufficiency as the initiating molecular defect.
- reference: PMID:38221796
reference_title: "Hao-Fountain syndrome: 32 novel patients reveal new insights into the clinical spectrum."
supports: PARTIAL
evidence_source: HUMAN_CLINICAL
snippet: >-
Hao-Fountain syndrome (HAFOUS, OMIM: # 616863) is a neurodevelopmental disorder caused by pathogenic variants in the gene USP7 coding for USP7, a protein involved in several crucial cellular homeostatic mechanisms and the recently described MUST complex.
explanation: This provides partial mechanistic context that USP7 participates in broader homeostatic and MUST-complex-associated functions relevant to Hao-Fountain syndrome.
downstream:
- target: PRC1-associated chromatin dysregulation
description: Reduced USP7 dosage perturbs PRC1-associated chromatin regulation.
- name: PRC1-associated chromatin dysregulation
description: >-
Hao-Fountain syndrome shows methylation and expression abnormalities within
PRC1-associated chromatin domains and developmental genes.
biological_processes:
- preferred_term: chromatin remodeling
modifier: ABNORMAL
term:
id: GO:0006338
label: chromatin remodeling
- preferred_term: regulation of transcription by RNA polymerase II
modifier: ABNORMAL
term:
id: GO:0006357
label: regulation of transcription by RNA polymerase II
evidence:
- reference: DOI:10.3389/fcell.2026.1782599
reference_title: >-
Integrative epigenetic and transcriptomic profiling of whole blood and
fibroblasts in Hao-Fountain syndrome
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Fibroblasts revealed coherent methylation and expression changes at
developmental genes, whereas blood captured the diagnostic episignature
and a smaller set of downstream regulatory alterations.
explanation: This directly supports downstream chromatin-associated regulatory dysregulation in Hao-Fountain syndrome.
downstream:
- target: Intellectual disability
description: Developmental regulatory dysfunction contributes to cognitive impairment.
- target: Borderline intellectual functioning
description: Cognitive dysfunction is often borderline on average, with some individuals reaching the range of intellectual disability.
- target: Delayed speech and language development
description: Neurodevelopmental dysregulation contributes to prominent speech impairment.
- target: Behavioral abnormality
description: Developmental regulatory dysfunction contributes to characteristic behavioral differences.
- target: Abnormal facial shape
description: Developmental dysregulation contributes to the dysmorphic phenotype.
- target: Hyperphagia
description: Developmental dysregulation contributes to appetite and weight abnormalities in a subset of affected individuals.
phenotypes:
- name: Delayed speech and language development
category: Neurologic
diagnostic: true
description: Speech impairment is a major and potentially hallmark feature of Hao-Fountain syndrome.
phenotype_term:
preferred_term: Delayed speech and language development
term:
id: HP:0000750
label: Delayed speech and language development
evidence:
- reference: PMID:38221796
reference_title: "Hao-Fountain syndrome: 32 novel patients reveal new insights into the clinical spectrum."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Speech impairment emerges as a potential hallmark of Hao-Fountain
syndrome.
explanation: This directly supports speech impairment as a central syndrome feature.
- name: Intellectual disability
category: Neurologic
description: Cognitive dysfunction ranges from borderline intellectual functioning to intellectual disability in Hao-Fountain syndrome.
phenotype_term:
preferred_term: Intellectual disability
term:
id: HP:0001249
label: Intellectual disability
evidence:
- reference: PMID:35627274
reference_title: >-
Complex Presentation of Hao-Fountain Syndrome Solved by Exome Sequencing
Highlighting Co-Occurring Genomic Variants.
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
A 20-year-old woman affected by moderate intellectual disability (ID),
dysmorphic features, hypertrichosis, scoliosis, recurrent bronchitis, and
pneumonia with bronchiectasis, colelithiasis, chronic severe
constipation, and a family history suggestive of autosomal dominant
recurrence of polycystic kidney disease was analyzed by WES to identify
the genomic events underlying the condition.
explanation: This directly supports intellectual disability as a clinical manifestation of Hao-Fountain syndrome.
- reference: PMID:38221796
reference_title: "Hao-Fountain syndrome: 32 novel patients reveal new insights into the clinical spectrum."
supports: PARTIAL
evidence_source: HUMAN_CLINICAL
snippet: >-
Cognitive testing reports reveal borderline intellectual functioning on average, although some individuals score in the range of intellectual disability.
explanation: This provides partial support for intellectual disability while clarifying that cognitive impairment spans a broader spectrum in the larger cohort.
- name: Borderline intellectual functioning
category: Neurologic
description: Cognitive function is often borderline on average in Hao-Fountain syndrome.
phenotype_term:
preferred_term: Borderline intellectual functioning
term:
id: HP:0006889
label: Borderline intellectual disability
evidence:
- reference: PMID:38221796
reference_title: "Hao-Fountain syndrome: 32 novel patients reveal new insights into the clinical spectrum."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Cognitive testing reports reveal borderline intellectual functioning on average, although some individuals score in the range of intellectual disability.
explanation: This directly supports borderline intellectual disability as the average cognitive phenotype in the larger cohort.
- name: Behavioral abnormality
category: Neurologic
description: Distinctive behavioral abnormalities are part of the Hao-Fountain syndrome phenotype.
phenotype_term:
preferred_term: Behavioral abnormality
term:
id: HP:0000708
label: Atypical behavior
evidence:
- reference: PMID:35627274
reference_title: >-
Complex Presentation of Hao-Fountain Syndrome Solved by Exome Sequencing
Highlighting Co-Occurring Genomic Variants.
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
A de novo truncating USP7 variant was disclosed as the cause of
Hao-Fountain syndrome, a disorder characterized by syndromic ID and
distinctive behavior.
explanation: This directly supports behavioral abnormality as part of the Hao-Fountain syndrome phenotype.
- name: Abnormal facial shape
category: Morphological
description: Dysmorphic facial features are common in Hao-Fountain syndrome.
phenotype_term:
preferred_term: Abnormal facial shape
term:
id: HP:0001999
label: Abnormal facial shape
evidence:
- reference: PMID:35627274
reference_title: >-
Complex Presentation of Hao-Fountain Syndrome Solved by Exome Sequencing
Highlighting Co-Occurring Genomic Variants.
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
A 20-year-old woman affected by moderate intellectual disability (ID),
dysmorphic features, hypertrichosis, scoliosis, recurrent bronchitis, and
pneumonia with bronchiectasis, colelithiasis, chronic severe
constipation, and a family history suggestive of autosomal dominant
recurrence of polycystic kidney disease was analyzed by WES to identify
the genomic events underlying the condition.
explanation: This directly supports dysmorphic facial features as part of the Hao-Fountain syndrome phenotype.
- name: Hyperphagia
category: Metabolic
description: Hyperphagia with increased body weight is reported in a subset of individuals with Hao-Fountain syndrome.
phenotype_term:
preferred_term: Hyperphagia
term:
id: HP:0002591
label: Polyphagia
evidence:
- reference: PMID:38221796
reference_title: "Hao-Fountain syndrome: 32 novel patients reveal new insights into the clinical spectrum."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
In addition to confirming previously described features, we report hyperphagia and increased body weight in a subset of individuals.
explanation: This directly supports hyperphagia as part of the expanded Hao-Fountain syndrome phenotype spectrum.
biochemical: []
genetic:
- name: USP7
association: Causal haploinsufficient variant
gene_term:
preferred_term: USP7
term:
id: hgnc:12630
label: USP7
notes: >-
Hao-Fountain syndrome is caused by pathogenic USP7 variants, including de
novo truncating alleles.
evidence:
- reference: PMID:35627274
reference_title: >-
Complex Presentation of Hao-Fountain Syndrome Solved by Exome Sequencing
Highlighting Co-Occurring Genomic Variants.
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
A de novo truncating USP7 variant was disclosed as the cause of
Hao-Fountain syndrome, a disorder characterized by syndromic ID and
distinctive behavior.
explanation: This directly supports USP7 as the causal gene for Hao-Fountain syndrome.
- reference: CGGV:assertion_7e4961fa-f972-4e82-ac29-a511ff954529-2021-09-03T182145.545Z
reference_title: "USP7 / Hao-Fountain syndrome (Definitive)"
supports: SUPPORT
evidence_source: OTHER
snippet: "USP7 | HGNC:12630 | Hao-Fountain syndrome | MONDO:0014805 | AD | Definitive"
explanation: ClinGen classifies the USP7-Hao-Fountain syndrome gene-disease relationship as definitive with autosomal dominant inheritance.
environmental: []
treatments: []
diagnosis:
- name: USP7 molecular genetic testing
description: Exome sequencing or targeted molecular testing that identifies a pathogenic USP7 variant confirms the diagnosis.
presence: Identification of a pathogenic USP7 variant confirms the diagnosis.
diagnosis_term:
preferred_term: molecular genetic testing
term:
id: MAXO:0000533
label: molecular genetic testing
qualifiers:
- predicate:
preferred_term: has participant
term:
id: RO:0000057
label: has participant
value:
preferred_term: USP7
term:
id: hgnc:12630
label: USP7
evidence:
- reference: PMID:35627274
reference_title: >-
Complex Presentation of Hao-Fountain Syndrome Solved by Exome Sequencing
Highlighting Co-Occurring Genomic Variants.
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Here, we used whole-exome sequencing (WES) to solve an unclassified
multisystem clinical presentation.
explanation: This supports molecular genetic testing, specifically exome sequencing, as the diagnostic approach used to establish the syndrome.
differential_diagnoses: []
clinical_trials: []
datasets: []
notes: >-
Asta deep research was completed for this disorder. Final curation combined
the 2024 clinical spectrum paper with a disease-specific 2026 epigenetic and
transcriptomic study to support mechanistic pathophysiology. The expanded
cohort also reported abnormal pain thresholds, but that finding was not
promoted to a phenotype entry here because a confident best-fit HPO mapping
was not established in this pass.
This report is retrieval-only and is generated directly from Asta results.
search_papers_by_relevance with snippet_search.