Bosch-Boonstra-Schaaf Optic Atrophy Syndrome

Mendelian MONDO:0014320 Pathograph 26 Show in embeddings browser hereditary disease autosomal dominant syndromic intellectual disability

Bosch-Boonstra-Schaaf optic atrophy syndrome (BBSOAS) is a rare autosomal dominant neurodevelopmental disorder caused by pathogenic NR2F1 variants or deletions. NR2F1 (COUP-TFI) is a nuclear-receptor transcription factor essential for neural and ocular development. Gene deletion and loss-of-function variants cause haploinsufficiency, while some DNA-binding domain variants may additionally act through a dominant-negative mechanism. The variable phenotype combines developmental delay or intellectual disability with optic atrophy, optic nerve hypoplasia and/or cerebral visual impairment; hypotonia, epilepsy, autistic features, feeding or oromotor dysfunction, and hearing impairment occur in subsets. Available longitudinal data favor an early developmental, generally non-progressive visual disorder.

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1
Mappings
1
Inheritance
7
Pathophys.
18
Phenotypes
4
Gaps
26
Pathograph
1
Genes
7
Medical Actions
2
Differentials
2
Datasets
3
Models
16
References
1
Deep Research
🏷

Classifications

Harrison's Part
GENETICS ENVIRONMENT DISEASE
🔗

Mappings

MONDO
MONDO:0014320 Bosch-Boonstra-Schaaf optic atrophy syndrome
skos:exactMatch MONDO
Orphadata validates ORPHA:401777 as exactly equivalent to MONDO:0014320, which is also the primary disease identifier used by this entry.
👪

Inheritance

1
Autosomal dominant inheritance HP:0000006
BBSOAS is an autosomal dominant disorder. Most probands have a de novo pathogenic NR2F1 variant or deletion; some intrafamilial recurrences and a low (~1%) recurrence risk to sibs from theoretical parental germline mosaicism have been reported.
autosomal dominant inheritance
Show evidence (1 reference)
PMID:36508512 SUPPORT Human Clinical
"NR2F1-NDD is an autosomal dominant disorder. Most probands reported to date with an intragenic NR2F1 pathogenic variant whose parents have undergone molecular genetic testing have the disorder as the result of a de novo pathogenic variant."
GeneReviews establishes autosomal dominant inheritance with predominantly de novo occurrence.
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Discussions and Knowledge Gaps

4
Which NR2F1 alleles act as simple loss-of-function variants and which exert clinically meaningful dominant-negative or other altered-protein effects?
KNOWLEDGE GAP OPEN bbsoas_variant_mechanism
Attached to
genetic#NR2F1 pathophysiology#NR2F1 functional insufficiency and variant-specific dominant-negative effects
Haploinsufficiency is established for deletions and many loss-of-function alleles. DNA-binding-domain variants may act dominant negatively and show a more severe cohort-level phenotype, but available series are small and the effect cannot be generalized to every missense or truncating allele.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable SUPPORT Human Clinical
"Preliminary genotype-phenotype correlations based on published reports to date suggest"
GeneReviews explicitly labels the genotype-phenotype correlation preliminary.
What is the true population prevalence of BBSOAS, and why do current Orphadata and literature estimates differ by at least an order of magnitude?
CONTROVERSY OPEN bbsoas_prevalence_discrepancy
Orphadata provides a class-only estimate below one per million, whereas GeneReviews cites approximately one per 100,000 to one per 250,000. Underdiagnosis, different denominators, and reuse of early case counts may contribute, but no population-based study resolves the discrepancy.
Show evidence (2 references)
url:https://api.orphadata.com/rd-epidemiology/orphacodes/401777 SUPPORT Other
""PrevalenceClass": "<1 / 1 000 000""
Orphadata supplies the lower class-only estimate.
url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable SUPPORT Human Clinical
"estimated prevalence from 1:100,000 to 1:250,000 people worldwide"
GeneReviews supplies the higher literature estimate.
Is visual function non-progressive across the full lifespan and across all NR2F1 variant classes?
KNOWLEDGE GAP OPEN bbsoas_visual_natural_history
Attached to
progression#Longitudinal visual and neurologic course
Existing longitudinal observations favor a developmental, non-progressive optic neuropathy, but the cohort is small, follow-up is uneven, and adult data are sparse. The entry therefore describes the visual course as generally rather than universally non-progressive.
Show evidence (1 reference)
PMID:34466801 SUPPORT Human Clinical
"for those individuals with available longitudinal ophthalmological data, there was no significant deterioration in visual function during the period of follow-up."
The cohort supports stability over observed follow-up, not the entire lifespan.
Does the mitochondrial phenotype in Nr2f1-deficient mouse neurons occur in human BBSOAS neural tissue and materially drive clinical manifestations?
HUMAN MODEL MISMATCH OPEN bbsoas_mitochondrial_translation
Attached to
pathophysiology#Neuronal mitochondrial network dysregulation
The mouse data identify altered mitochondrial genes, proteins, mass, and morphology, but no human neural-tissue validation or clinical biomarker currently establishes this branch as a driver in affected individuals.
Show evidence (1 reference)
PMID:37260288 SUPPORT Model Organism
"Our data point to an active role for NR2F1 in the mitochondrial gene expression regulatory network in neurons and support the involvement of mitochondrial dysfunction in BBSOAS pathogenesis."
The publication frames mitochondrial involvement as supported by model data.
⚙

Pathophysiology

7
NR2F1 functional insufficiency and variant-specific dominant-negative effects
Heterozygous whole-gene deletions and loss-of-function variants reduce functional NR2F1 dosage. Pathogenic missense variants in the zinc-finger DNA-binding domain or ligand-binding domain reduce transcriptional activity; DNA-binding-domain variants can also interfere with wild-type dimer function and are associated with a more severe clinical phenotype. The established shared consequence is reduced functional NR2F1 transcriptional output, while the precise contribution of dominant-negative activity varies by allele.
NR2F1 hgnc:7975 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves NR2F1 (hgnc:7975). hgnc:7975 is a gene from the HUGO Gene Nomenclature Committee.
NR2F1 nuclear receptor transcriptional regulation GO:0006357 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased NR2F1 nuclear receptor transcriptional regulation, annotated with regulation of transcription by RNA polymerase II (GO:0006357). GO:0006357 is a biological process from the Gene Ontology. ↓ DECREASED
Downstream
Disrupted neural and visual-system development Reduced functional COUP-TFI output perturbs transcriptional control of cortical arealization, neuronal differentiation, and visual-pathway development.
Neuronal mitochondrial network dysregulation Nr2f1 loss in mouse neural cells alters nuclear-encoded mitochondrial gene expression, mitochondrial mass, morphology, and protein abundance.
Impaired hippocampal synaptic plasticity In a heterozygous Nr2f1 mouse model, reduced Nr2f1 function is associated with impaired hippocampal long-term potentiation and depression.
Show evidence (4 references)
PMID:24462372 SUPPORT Human Clinical
"NR2F1 encodes a nuclear receptor protein that regulates transcription. A reporter assay showed that missense mutations in the zinc-finger DNA-binding domain and the putative ligand-binding domain decrease NR2F1 transcriptional activity."
Functional reporter assays demonstrate that pathogenic NR2F1 missense variants reduce transcriptional activity, establishing functional NR2F1 insufficiency without requiring every missense allele to be a simple null.
PMID:26986877 SUPPORT Human Clinical
"Bosch-Boonstra-Schaaf optic atrophy syndrome (BBSOAS) is an autosomal-dominant disorder characterized by optic atrophy and intellectual disability caused by loss-of-function mutations in NR2F1."
Confirms BBSOAS results from loss-of-function NR2F1 variants consistent with haploinsufficiency.
PMID:35455940 SUPPORT Other
"the Bosch-Boonstra-Schaaf Optic Atrophy Syndrome (BBSOAS; OMIM 615722; ORPHA 401777), a recently described monogenic neurodevelopmental syndrome caused by the haploinsufficiency of NR2F1 gene, a key transcriptional regulator of brain development."
Review explicitly characterizes BBSOAS as caused by NR2F1 haploinsufficiency affecting a key transcriptional regulator of brain development.
+ 1 more reference
Neuronal mitochondrial network dysregulation
In mouse models, Nr2f1 loss reduces mitochondrial mass, fragments the mitochondrial network, and downregulates mitochondrial proteins in newborn neurons. This is a plausible secondary contributor to impaired neuronal survival and integration, but it has not yet been demonstrated in human BBSOAS neural tissue.
neuron CL:0000540 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves neuron (CL:0000540). CL:0000540 is a cell type from the Cell Ontology.
mitochondrial organization GO:0007005 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal mitochondrial organization, annotated with mitochondrion organization (GO:0007005). GO:0007005 is a biological process from the Gene Ontology. ⚠ ABNORMAL
Downstream
Disrupted neural and visual-system development Altered mitochondrial support may contribute to impaired neuronal genesis, survival, and integration within the broader neural-developmental branch; ocular involvement was not tested in this model.
Show evidence (1 reference)
PMID:37260288 SUPPORT Model Organism
"conditional NR2F1 loss of function within the adult mouse hippocampal neurogenic niche results in a reduced mitochondrial mass associated with mitochondrial fragmentation and downregulation of key mitochondrial proteins in newborn neurons"
Mouse neural-cell data establish the cellular phenotype while leaving its contribution to human manifestations provisional.
Disrupted neural and visual-system development
COUP-TFI is a major transcriptional regulator orchestrating cortical arealization, cell-type specification, and maturation across forebrain structures, and contributes to development of the retina and optic nerve. Its haploinsufficiency disrupts these developmental programs, producing the combined neurodevelopmental and visual phenotype.
cortical neuron CL:0010012 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves cortical neuron, annotated with cerebral cortex neuron (CL:0010012). CL:0010012 is a cell type from the Cell Ontology. retinal ganglion cell CL:0000740 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves retinal ganglion cell (CL:0000740). CL:0000740 is a cell type from the Cell Ontology. neural progenitor cell CL:0011020 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves neural progenitor cell (CL:0011020). CL:0011020 is a cell type from the Cell Ontology.
forebrain development GO:0030900 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal forebrain development (GO:0030900). GO:0030900 is a biological process from the Gene Ontology. ⚠ ABNORMAL cerebral cortex regionalization GO:0021796 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal cerebral cortex regionalization (GO:0021796). GO:0021796 is a biological process from the Gene Ontology. ⚠ ABNORMAL optic nerve development GO:0021554 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal optic nerve development (GO:0021554). GO:0021554 is a biological process from the Gene Ontology. ⚠ ABNORMAL retina development GO:0060041 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal retina development, annotated with retina development in camera-type eye (GO:0060041). GO:0060041 is a biological process from the Gene Ontology. ⚠ ABNORMAL
Downstream
Optic atrophy Disrupted visual-system neurodevelopment produces optic atrophy.
Optic nerve glial imbalance In the Nr2f1-haploinsufficient mouse model, disturbed visual-system development is associated with an imbalance between oligodendrocytes and astrocytes in the optic nerve.
Optic nerve hypoplasia Abnormal retinal ganglion-cell development and axonal guidance explain optic nerve hypoplasia.
Cerebral visual impairment Visual-system neurodevelopmental disruption causes visual impairment from optic nerve and cerebral mechanisms.
Intellectual disability Disrupted neural development produces the intellectual-disability component of BBSOAS.
Global developmental delay NR2F1-related neurodevelopmental disruption presents as global developmental delay.
Hypotonia Neurologic involvement in BBSOAS includes neonatal or childhood hypotonia.
Seizures BBSOAS neurodevelopmental disruption includes seizure susceptibility.
Oromotor dysfunction BBSOAS neurologic involvement includes oromotor and feeding dysfunction.
Thin corpus callosum Abnormal forebrain development includes corpus-callosum thinning in BBSOAS.
Hearing impairment NR2F1-related neurologic involvement includes hearing defects in a subset of patients.
Nystagmus Visual-system involvement includes manifest latent nystagmus.
Autistic behavior Altered neural development and connectivity contribute to autism-spectrum and autistic behavioral manifestations.
Reduced visual acuity Developmental retinal-ganglion-cell loss and visual-pathway disorganization reduce visual acuity.
Strabismus Developmental visual-system impairment commonly includes ocular misalignment.
Show evidence (5 references)
PMID:29709504 SUPPORT Other
"COUP-TFI (or NR2F1), a nuclear receptor belonging to the superfamily of the steroid/thyroid hormone receptors, and considered to be one of the major transcriptional regulators orchestrating cortical arealization, cell-type specification and maturation."
Establishes COUP-TFI/NR2F1 as a master transcriptional regulator of cortical patterning and cell-type specification, the developmental programs disrupted in BBSOAS.
PMID:24462372 SUPPORT Human Clinical
"These findings indicate that NR2F1 plays an important role in the neurodevelopment of the visual system and that its disruption can lead to optic atrophy with intellectual disability."
Directly links NR2F1 disruption to abnormal visual-system neurodevelopment producing optic atrophy.
PMID:34466801 SUPPORT Model Organism
"Abnormal retinogenesis in early stages of development was observed in Nr2f1 mutant mice with decreased retinal ganglion cell density and disruption of retinal ganglion cell axonal guidance from the neural retina into the optic stalk, accounting for the development of optic nerve hypoplasia."
Nr2f1 mutant mice recapitulate the ocular phenotype, showing decreased retinal ganglion cell density and disrupted axonal guidance that explains optic nerve hypoplasia, supporting a developmental origin of the visual defect.
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+ 2 more references
Optic nerve glial imbalance
Nr2f1-deficient mouse optic nerves show an imbalance between oligodendrocytes and astrocytes. This model-defined glial phenotype provides a distinct potential arm of optic-nerve pathology, but has not been established in human BBSOAS tissue.
Downstream
Postnatal optic nerve hypomyelination
Optic nerve astrogliosis
Show evidence (1 reference)
DOI:10.15252/emmm.201910291 SUPPORT Model Organism
"Notably,Nr2f1-deficient optic nerves develop an imbalance between oligodendrocytes and astrocytes leading to postnatal hypomyelination and astrogliosis."
This is direct model-organism evidence for an optic-nerve glial imbalance, not evidence that the same cellular imbalance has been measured in people.
Postnatal optic nerve hypomyelination
Nr2f1-haploinsufficient mouse optic nerves undergo postnatal hypomyelination, a model phenotype that can be chemically rescued early in life. Its causal contribution and treatment responsiveness in human BBSOAS remain unknown.
Downstream
Optic atrophy
Show evidence (1 reference)
DOI:10.15252/emmm.201910291 SUPPORT Model Organism
"Importantly, some of these clinical features, such the optic nerve hypomyelination, could be rescued by chemical drug treatment in early postnatal life."
The mouse study demonstrates a preclinical early-postnatal chemical-rescue signal for optic-nerve hypomyelination, without establishing a human therapy.
Optic nerve astrogliosis
Astrogliosis accompanies optic-nerve hypomyelination in Nr2f1-deficient mice. This model observation is retained separately from myelination loss and requires validation in human BBSOAS tissue.
Downstream
Optic atrophy
Show evidence (1 reference)
DOI:10.15252/emmm.201910291 SUPPORT Model Organism
"Notably,Nr2f1-deficient optic nerves develop an imbalance between oligodendrocytes and astrocytes leading to postnatal hypomyelination and astrogliosis."
The mouse model observes astrogliosis with optic-nerve glial imbalance and hypomyelination; the human relevance remains provisional.
Impaired hippocampal synaptic plasticity
Nr2f1 haploinsufficiency impairs hippocampal long-term potentiation and long-term depression in a heterozygous mouse model, providing a provisional mechanistic bridge to cognitive impairment in BBSOAS.
long-term synaptic potentiation GO:0060291 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased long-term synaptic potentiation (GO:0060291). GO:0060291 is a biological process from the Gene Ontology. ↓ DECREASED long-term synaptic depression GO:0060292 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased long-term synaptic depression (GO:0060292). GO:0060292 is a biological process from the Gene Ontology. ↓ DECREASED
Downstream
Intellectual disability Impaired hippocampal synaptic plasticity is a provisional model mechanism for cognitive impairment in BBSOAS.
Global developmental delay Impaired hippocampal synaptic plasticity is a provisional model mechanism for developmental impairment in BBSOAS.
Show evidence (1 reference)
PMID:31600777 SUPPORT Model Organism
"further electrophysiological investigation in hippocampal slices revealed significantly reduced long-term potentiation and long-term depression."
Electrophysiology in heterozygous Nr2f1 mouse hippocampal slices directly supports impaired synaptic plasticity; human confirmation is pending.
⬡

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for Bosch-Boonstra-Schaaf Optic Atrophy Syndrome Interactive directed graph showing how pathophysiology mechanisms, phenotypes, genetic factors and variants, experimental models, environmental triggers, and treatments relate through causal and linked edges.
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Phenotypes

18
Digestive 1
Oromotor dysfunction FREQUENT Feeding difficulties HP:0011968 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Feeding difficulties (HP:0011968). HP:0011968 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:26986877 SUPPORT Human Clinical
"individuals with BBSOAS manifested hypotonia (75%), seizures (40%), autism spectrum disorder (35%), oromotor dysfunction (60%)"
Cohort reports oromotor dysfunction in 60% of BBSOAS individuals.
Ear 1
Hearing impairment OCCASIONAL HP:0000365 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hearing impairment (HP:0000365). HP:0000365 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:26986877 SUPPORT Human Clinical
"hearing defects (20%)"
Cohort reports hearing defects in 20% of BBSOAS individuals, supporting an OCCASIONAL band.
Eye 5
Optic atrophy FREQUENT HP:0000648 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Optic atrophy (HP:0000648). HP:0000648 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:24462372 SUPPORT Human Clinical
"its disruption can lead to optic atrophy with intellectual disability."
Optic atrophy is the defining ocular feature of NR2F1 disruption.
url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable SUPPORT Human Clinical
"Fundus examination revealed optic atrophy in 77% of individuals and small and/or tilted hypoplastic optic nerves in 46% of individuals."
The deeply phenotyped cohort places optic atrophy in the FREQUENT band.
Hyperopia FREQUENT Hypermetropia HP:0000540 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hyperopia, annotated with Hypermetropia (HP:0000540). HP:0000540 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable SUPPORT Human Clinical
"Most individuals have a refractive error (91%) with a predominance of hyperopia (68%)."
The 68% cohort estimate supports a FREQUENT band.
Nystagmus FREQUENT HP:0000639 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Nystagmus (HP:0000639). HP:0000639 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:32275123 SUPPORT Human Clinical
"we expand the vision phenotype to include alacrima and manifest latent nystagmus (fusional maldevelopment)"
Cohort expands the vision phenotype to include manifest latent nystagmus.
url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable SUPPORT Human Clinical
"Strabismus (77%) and nystagmus (45%) are common features."
The ocular cohort places nystagmus in the FREQUENT band.
Reduced visual acuity FREQUENT HP:0007663 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Reduced visual acuity (HP:0007663). HP:0007663 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
url:https://api.orphadata.com/rd-phenotypes/orphacodes/401777 SUPPORT Other
""HPOId": "HP:0007663", "HPOTerm": "Reduced visual acuity" }, "HPOFrequency": "Frequent (79-30%)""
Orphadata classifies reduced visual acuity as frequent.
PMID:34466801 SUPPORT Human Clinical
"resulting in congenital vision loss that seems to be non-progressive."
The ocular cohort supports congenital visual loss.
Strabismus FREQUENT HP:0000486 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Strabismus (HP:0000486). HP:0000486 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable SUPPORT Human Clinical
"Strabismus (77%) and nystagmus (45%) are common features."
GeneReviews summarizes strabismus in 77% of the ocular cohort.
Musculoskeletal 1
Hypotonia FREQUENT HP:0001252 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hypotonia (HP:0001252). HP:0001252 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:26986877 SUPPORT Human Clinical
"individuals with BBSOAS manifested hypotonia (75%), seizures (40%), autism spectrum disorder (35%), oromotor dysfunction (60%)"
Cohort reports hypotonia in 75% of BBSOAS individuals, supporting a FREQUENT band.
Nervous System 5
Intellectual disability HP:0001249 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Intellectual disability (HP:0001249). HP:0001249 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:36508512 SUPPORT Human Clinical
"developmental delay / intellectual disability (ranging from profound to mild)"
GeneReviews establishes intellectual disability as a defining feature.
url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable SUPPORT Human Clinical
"Intellectual disability"
GeneReviews lists intellectual disability among the reported clinical features.
Global developmental delay HP:0001263 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Global developmental delay (HP:0001263). HP:0001263 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:36508512 SUPPORT Human Clinical
"developmental delay / intellectual disability (ranging from profound to mild)"
GeneReviews lists developmental delay as a core feature.
url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable SUPPORT Human Clinical
"Developmental delay"
GeneReviews lists developmental delay among the reported clinical features.
Autistic behavior FREQUENT HP:0000729 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Autistic behavior (HP:0000729). HP:0000729 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:26986877 SUPPORT Human Clinical
"individuals with BBSOAS manifested hypotonia (75%), seizures (40%), autism spectrum disorder (35%), oromotor dysfunction (60%)"
Cohort reports autism spectrum disorder in 35% of BBSOAS individuals.
Seizures FREQUENT HP:0001250 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Seizure (HP:0001250). HP:0001250 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:26986877 SUPPORT Human Clinical
"individuals with BBSOAS manifested hypotonia (75%), seizures (40%), autism spectrum disorder (35%), oromotor dysfunction (60%)"
Cohort reports seizures in 40% of BBSOAS individuals, supporting a FREQUENT band.
Attention deficit hyperactivity disorder OCCASIONAL HP:0007018 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Attention deficit hyperactivity disorder (HP:0007018). HP:0007018 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable SUPPORT Human Clinical
"ADHD was present in 18% (17/92)"
The 18% cohort estimate supports an OCCASIONAL band.
Other 5
Refractive error VERY_FREQUENT Abnormality of refraction HP:0000539 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Refractive error, annotated with Abnormality of refraction (HP:0000539). HP:0000539 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable SUPPORT Human Clinical
"Most individuals have a refractive error (91%) with a predominance of hyperopia (68%)."
The 91% cohort estimate supports a VERY_FREQUENT band.
Optic nerve hypoplasia OCCASIONAL HP:0000609 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Optic nerve hypoplasia (HP:0000609). HP:0000609 is a phenotype from the Human Phenotype Ontology.
Show evidence (3 references)
PMID:32275123 SUPPORT Human Clinical
"We also confirm a vision phenotype that includes optic nerve hypoplasia, optic atrophy, and cortical visual impairment."
Cohort confirms optic nerve hypoplasia as part of the BBSOAS vision phenotype.
PMID:34466801 SUPPORT Human Clinical
"The visual impairment became apparent in early childhood with small and/or tilted hypoplastic optic nerves observed in 10 cases."
Deep phenotyping documents hypoplastic optic nerves in BBSOAS individuals, with onset in early childhood.
url:https://api.orphadata.com/rd-phenotypes/orphacodes/401777 SUPPORT Other
""HPOId": "HP:0007766", "HPOTerm": "Optic disc hypoplasia" }, "HPOFrequency": "Occasional (29-5%)""
Orphadata classifies the closely aligned optic-disc hypoplasia phenotype as occasional.
Cerebral visual impairment FREQUENT HP:0100704 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Cerebral visual impairment (HP:0100704). HP:0100704 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:36508512 SUPPORT Human Clinical
"visual impairment (due to optic nerve abnormalities and/or cerebral visual impairment)"
GeneReviews lists cerebral visual impairment as a core feature.
url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable SUPPORT Human Clinical
"Cerebral visual impairment is present in 55% of children."
The cohort estimate places cerebral visual impairment in the FREQUENT band.
Thin corpus callosum FREQUENT HP:0033725 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Thin corpus callosum (HP:0033725). HP:0033725 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:26986877 SUPPORT Human Clinical
"thinning of the corpus callosum (53%)"
Cohort reports thin corpus callosum in 53% of BBSOAS individuals.
Alacrima HP:0000522 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Alacrima (HP:0000522). HP:0000522 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:32275123 SUPPORT Human Clinical
"include alacrima and manifest latent nystagmus (fusional maldevelopment)"
The BBSOAS cohort expands the visual phenotype to include alacrima.
🧬

Genetic Associations

1
NR2F1 (Pathogenic loss-of-function and variant-specific dominant-negative effects)
Gene: NR2F1 hgnc:7975 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is NR2F1 (hgnc:7975). hgnc:7975 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: CAUSATIVE
Show evidence (3 references)
PMID:32275123 SUPPORT Human Clinical
"Bosch-Boonstra-Schaaf Optic Atrophy Syndrome (BBSOAS) is an autosomal dominant neurodevelopmental disorder caused by loss-of-function variants in NR2F1"
Establishes NR2F1 loss-of-function variants as the genetic cause of BBSOAS.
PMID:32275123 SUPPORT Human Clinical
"we provide additional evidence for genotype-phenotype correlations, specifically supporting a more severe phenotype associated with DBD variants."
Supports the genotype-phenotype correlation that DNA-binding domain variants confer a more severe phenotype.
url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable SUPPORT Human Clinical
"Haploinsufficiency due to either gene deletion or loss-of-function variants. Single-nucleotide variants in the DNA-binding domain may cause a dominant-negative effect."
GeneReviews distinguishes the main loss-of-function mechanism from the variant-class-specific dominant-negative possibility.
💊

Medical Actions

7
Multidisciplinary supportive care
Category: Therapeutic Action: supportive careNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is supportive care (NCIT:C15747). NCIT:C15747 is a clinical intervention from the NCI Thesaurus. Ontology label: Supportive Care NCIT:C15747
There is no cure for BBSOAS. Supportive management relies on multidisciplinary specialists including neurology, speech-language pathology, ophthalmology with low-vision services, gastroenterology, nutrition, occupational therapy, physical therapy, audiology, clinical genetics, and genetic counseling, with regular surveillance for existing and emerging manifestations.
Show evidence (1 reference)
PMID:36508512 SUPPORT Human Clinical
"There is no cure for NR2F1-NDD. Supportive treatment typically relies on multidisciplinary specialists in the fields of neurology, speech-language pathology, ophthalmology (including low-vision services), gastroenterology, nutrition, occupational therapy, physical therapy, audiology, clinical..."
GeneReviews specifies multidisciplinary supportive care as the management approach.
Developmental therapies and communication support
Category: Therapeutic Action: speech therapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is speech therapy, annotated with Speech Language Therapy (NCIT:C159273). NCIT:C159273 is a clinical intervention from the NCI Thesaurus. Ontology label: Speech Language Therapy NCIT:C159273
Early intervention and individualized educational support should include physical, occupational, speech-language, feeding, and sensory-impairment services as indicated. Augmentative and alternative communication should be assessed when expressive language is limited.
Target Phenotypes: Global developmental delay HP:0001263 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Global developmental delay (HP:0001263). HP:0001263 is a phenotype from the Human Phenotype Ontology. Intellectual disability HP:0001249 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Intellectual disability (HP:0001249). HP:0001249 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable SUPPORT Human Clinical
"Referral to an early intervention program is recommended for access to occupational, physical, speech, and feeding therapy as well as infant mental health services, special educators, and sensory impairment specialists."
GeneReviews recommends coordinated early developmental intervention.
Ophthalmologic treatment and low-vision support
Category: Therapeutic Action: low vision rehabilitationNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is low vision rehabilitation, annotated with Supportive Care (NCIT:C15747). NCIT:C15747 is a clinical intervention from the NCI Thesaurus. Ontology label: Supportive Care NCIT:C15747
Ophthalmologic care should correct refractive errors or strabismus when present and provide low-vision services. Cerebral visual impairment may benefit from visual therapy and early intervention aimed at visual development; these measures are supportive rather than disease modifying.
Target Phenotypes: Reduced visual acuity HP:0007663 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Reduced visual acuity (HP:0007663). HP:0007663 is a phenotype from the Human Phenotype Ontology. Strabismus HP:0000486 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Strabismus (HP:0000486). HP:0000486 is a phenotype from the Human Phenotype Ontology. Cerebral visual impairment HP:0100704 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Cerebral visual impairment (HP:0100704). HP:0100704 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable SUPPORT Human Clinical
"Treatment of refractive errors"
GeneReviews recommends refractive, strabismus, and low-vision management.
url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable SUPPORT Human Clinical
"Visual therapy focused on CVI"
GeneReviews recommends visual therapy and early intervention for CVI.
Feeding, nutrition, and swallowing support
Category: Therapeutic Action: feeding therapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is feeding therapy, annotated with Swallowing Therapy (NCIT:C156237). NCIT:C156237 is a clinical intervention from the NCI Thesaurus. Ontology label: Swallowing Therapy NCIT:C156237
Feeding-team and nutrition assessment should address poor suck, chewing or swallowing difficulty, growth, aspiration risk, and oral safety. Feeding therapy is used first; persistent dysphagia or unsafe intake may require enteral support.
Target Phenotypes: Feeding difficulties HP:0011968 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Feeding difficulties (HP:0011968). HP:0011968 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable SUPPORT Human Clinical
"Gastrostomy tube placement may be required for persistent feeding issues."
GeneReviews specifies feeding therapy and escalation for persistent problems.
Individualized epilepsy management
Category: Therapeutic Action: antiseizure pharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is antiseizure pharmacotherapy, annotated with Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. Ontology label: Pharmacotherapy NCIT:C15986
Epilepsy should be treated with individualized antiseizure pharmacotherapy under an experienced neurologist. A small observational NR2F1-related epilepsy series reported seizure freedom after add-on perampanel, but this signal does not establish comparative superiority or a standard regimen.
Target Phenotypes: Seizure HP:0001250 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Seizure (HP:0001250). HP:0001250 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable SUPPORT Human Clinical
"Standardized treatment w/ASM by experienced neurologist"
GeneReviews recommends standard neurologist-directed antiseizure treatment.
DOI:10.1186/s42494-023-00145-0 SUPPORT Human Clinical
"However, seizures were controlled in only 50% of previously reported cases, while all of the six new cases became seizure-free after perampanel as an add-on treatment."
A six-case observational series reports seizure freedom after add-on perampanel, supporting a hypothesis-generating treatment signal but not disorder-specific comparative superiority.
Multisystem surveillance
Category: Monitoring Action: clinical assessmentNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is clinical assessment, annotated with Clinical Evaluation (NCIT:C124351). NCIT:C124351 is a clinical intervention from the NCI Thesaurus. Ontology label: Clinical Evaluation NCIT:C124351
Follow-up should monitor growth and feeding safety, development and educational needs, seizures and new neurologic manifestations, behavior, mobility and self-help skills, visual function and low-vision needs, hearing, and family support needs at clinically appropriate intervals.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable SUPPORT Human Clinical
"Regular monitoring of existing manifestations, the individual's response to supportive care, and the emergence of new manifestations."
GeneReviews provides the overarching surveillance principle.
Genetic counseling
Category: Counseling / Informational Action: genetic counselingNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is genetic counseling (NCIT:C15240). NCIT:C15240 is a clinical intervention from the NCI Thesaurus. Ontology label: Genetic Counseling NCIT:C15240
Genetic counseling is recommended given the autosomal dominant inheritance and recurrence risk considerations, including the option of prenatal and preimplantation genetic testing.
Show evidence (1 reference)
PMID:36508512 SUPPORT Human Clinical
"Given this risk, prenatal and preimplantation genetic testing may be considered."
GeneReviews recommends genetic counseling and testing options for recurrence risk.
🔬

Diagnosis

2
Clinical and imaging recognition (A compatible neurodevelopmental, visual, and brain-imaging pattern prompts NR2F1 testing.)
BBSOAS should be considered when developmental delay or intellectual disability co-occurs with optic atrophy, optic nerve hypoplasia, cerebral visual impairment, hypotonia, speech difficulty, seizures, feeding difficulty, or behavioral manifestations. Thin corpus callosum and hypoplastic optic nerves or chiasm on MRI are strongly suggestive, but no consensus clinical diagnostic criteria or pathognomonic feature exists.
clinical assessment NCIT:C124351 NCI Thesaurus (NCIT)
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable SUPPORT Human Clinical
"Hypoplasia of the optic nerves and optic chiasm are also commonly seen on brain MRI"
GeneReviews defines the suggestive clinical and imaging pattern.
NR2F1 molecular genetic testing (Identification of a heterozygous pathogenic or likely pathogenic NR2F1 variant establishes the diagnosis.)
Molecular confirmation requires a heterozygous pathogenic or likely pathogenic NR2F1 variant. Testing should detect both sequence variants and copy-number changes through sequence analysis, deletion or duplication analysis, and chromosomal microarray as appropriate. Phenotype-focused multigene panels, exome sequencing, or genome sequencing are options when the diagnosis is not clinically specific.
molecular genetic testing NCIT:C19770 NCI Thesaurus (NCIT)
Show evidence (2 references)
url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable SUPPORT Human Clinical
"is established in a proband with suggestive findings and a heterozygous pathogenic (or likely pathogenic) variant in"
GeneReviews states the molecular criterion that establishes diagnosis.
url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable SUPPORT Human Clinical
"Methods used in a panel may include sequence analysis, deletion/duplication analysis, and/or other non-sequencing-based tests."
GeneReviews explicitly supports including both sequence and copy-number methods in the molecular strategy.
📈

Progression

3
Neonatal and infantile presentation
Age: Neonatal period through infancy
Orphadata assigns neonatal onset. Hypotonia may be present at birth, and oromotor dysfunction with poor sucking, chewing, or swallowing is common in neonates and infants, sometimes requiring tube feeding.
Show evidence (2 references)
url:https://api.orphadata.com/rd-natural_history/orphacodes/401777 SUPPORT Other
""AverageAgeOfOnset": [ "Neonatal" ]"
The structured natural-history record assigns neonatal onset.
url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable SUPPORT Human Clinical
"including problems with sucking, chewing, or swallowing, is a common feature in neonates and infants and may occasionally necessitate nasogastric tube feeding"
GeneReviews defines the early feeding and oromotor course.
Neurodevelopmental and visual recognition
Age: Infancy through early childhood
Developmental and speech delays emerge as milestones are missed. Visual impairment is usually recognized in early childhood after nystagmus, strabismus, poor fixation, or neurodevelopmental concerns prompt ophthalmologic assessment.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable SUPPORT Human Clinical
"is usually detected in early childhood when they are examined following referrals for evaluation of nystagmus, strabismus, poor fixation, and/or concerns about neurodevelopmental progress."
GeneReviews directly describes the typical recognition window.
Longitudinal visual and neurologic course
Age: Childhood through adulthood
Available cohort follow-up supports congenital, generally non-progressive visual impairment rather than the progressive retinal-ganglion-cell loss typical of several other inherited optic neuropathies. Data on progression of behavior and other neurologic findings, and on adult natural history, remain limited.
Show evidence (2 references)
PMID:34466801 SUPPORT Human Clinical
"for those individuals with available longitudinal ophthalmological data, there was no significant deterioration in visual function during the period of follow-up."
Longitudinal deep-phenotyping data indicate the visual impairment in BBSOAS is non-progressive, which is relevant for prognostic counseling.
url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable SUPPORT Human Clinical
"Data on possible progression of behavior abnormalities or neurologic findings are currently limited."
GeneReviews explicitly marks the non-visual longitudinal course as uncertain.
📊

Prevalence

2
Worldwide
Point Prevalence <1 in 1,000,000
Current Orphadata supplies a validated, class-only worldwide point prevalence below one per million. The source also retains a six-case literature count from the original report, so this is not a measured population estimate.
Show evidence (1 reference)
url:https://api.orphadata.com/rd-epidemiology/orphacodes/401777 SUPPORT Other
""PrevalenceClass": "<1 / 1 000 000", "PrevalenceGeographic": "Worldwide", "PrevalenceQualification": "Class only", "PrevalenceType": "Point prevalence""
Orphadata explicitly identifies the estimate as a class-only worldwide point-prevalence record.
Worldwide
Point Prevalence 0.4–1.0 per 100,000 Rare
GeneReviews reports a substantially higher literature-derived estimated range. Because this range crosses the schema's adjacent numeric bands, it is retained with exact normalized rates and the qualitative RARE class rather than forced into one band. The conflict with Orphadata remains open.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable SUPPORT Human Clinical
"appears to be rare, with an estimated prevalence from 1:100,000 to 1:250,000 people worldwide"
GeneReviews provides the literature estimate normalized here to 0.4-1.0 affected individuals per 100,000.
⚖️

Clinical Burden

High
BBSOAS commonly produces lifelong intellectual or developmental disability together with visual impairment. Epilepsy, feeding or swallowing dysfunction, hypotonia, autism-spectrum manifestations, hearing impairment, and mobility or communication needs create substantial multidisciplinary care and surveillance burden in many individuals. Severity is highly variable, and a HIGH disease-level burden does not imply severe expression in every affected person.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable SUPPORT Human Clinical
"NR2F1-related neurodevelopmental disorder (NR2F1-NDD) is characterized by developmental delay / intellectual disability (ranging from profound to mild) and is commonly associated with hypotonia, visual impairment (due to optic nerve abnormalities and/or cerebral visual impairment), epilepsy, and..."
The core and recurrent multisystem manifestations support substantial lifelong functional and care needs while documenting wide severity.
🔀

Differential Diagnoses

2

Conditions with similar clinical presentations that must be differentiated from Bosch-Boonstra-Schaaf Optic Atrophy Syndrome:

📊

Related Datasets

2
Hippocampal gene expression from Nr2f1 heterozygous knockout and WT mice geo:GSE106302
Bulk RNA-seq comparing adult hippocampi from Nr2f1 heterozygous knockout mice with wild-type controls, associated with the mouse-model study of BBSOAS neurologic phenotypes and synaptic plasticity.
mouse BULK RNA SEQ
hippocampal formation UBERON:0002421 Uberon multi-species anatomy ontology (UBERON) Relation: this dataset samples this sample type This dataset samples hippocampal formation (UBERON:0002421). UBERON:0002421 is a sample type from the Uberon multi-species anatomy ontology.
Conditions: Nr2f1 heterozygous knockout adult mouse hippocampus Wild-type adult mouse hippocampus
PMID:31600777
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE106302 SUPPORT Model Organism
"RNA-seq of hippocampus from Nr2f1 heterozygous knockout and WT mice."
The GEO record supplies the accession, tissue, perturbation, and assay.
Nr2f1 chromatin occupancy in mouse cortex geo:GSE228566
Mouse-cortex COUP-TFI/NR2F1 chromatin immunoprecipitation sequencing with IgG and H3K4me3 comparators, used to identify candidate direct nuclear-encoded mitochondrial targets in a BBSOAS mechanism study.
mouse CHIP SEQ
cerebral cortex UBERON:0000956 Uberon multi-species anatomy ontology (UBERON) Relation: this dataset samples this sample type This dataset samples cerebral cortex (UBERON:0000956). UBERON:0000956 is a sample type from the Uberon multi-species anatomy ontology.
Conditions: COUP-TFI chromatin immunoprecipitation in mouse cortex IgG control in mouse cortex H3K4me3 chromatin immunoprecipitation in mouse cortex
PMID:37260288
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE228566 SUPPORT Model Organism
"Coup-TF1_Cortex"
The GEO series lists the COUP-TFI mouse-cortex chromatin sample deposited under GSE228566; its adjacent series records provide the IgG and H3K4me3 comparators described in the conditions.
🐁

Animal Models

3
Nr2f1 heterozygous knockout (Nr2f1+/-) Mouse
A heterozygous Nr2f1 knockout mouse recapitulates the dosage-sensitive genetics of BBSOAS (caused by heterozygous NR2F1 variants) and reproduces core neurological phenotypes, including altered learning/memory, hearing defects, neonatal hypotonia, and decreased hippocampal volume, together with impaired hippocampal synaptic plasticity.
Hypotonia Hearing impairment Impaired learning and memory
Species
Mouse
Genotype
Nr2f1 heterozygous knockout (Nr2f1+/-)
Genes
Nr2f1 hgnc:7975 HUGO Gene Nomenclature Committee (hgnc) Relation: this experimental model concerns this gene This experimental model concerns Nr2f1 (hgnc:7975). hgnc:7975 is a gene from the HUGO Gene Nomenclature Committee.
Show evidence (1 reference)
PMID:31600777 SUPPORT Model Organism
"we investigated a heterozygous knockout mouse model and found that this model recapitulates some of the neurological phenotypes of BBSOAS, including altered learning/memory, hearing defects, neonatal hypotonia and decreased hippocampal volume."
The Nr2f1+/- mouse recapitulates core BBSOAS neurological phenotypes, supporting NR2F1 haploinsufficiency as the disease mechanism.
Nr2f1 mutant Mouse
Nr2f1 mutant mice display abnormal retinogenesis with decreased retinal ganglion cell density and disrupted retinal ganglion cell axonal guidance from the neural retina into the optic stalk, recapitulating the optic nerve hypoplasia seen in BBSOAS and supporting a developmental origin of the visual defect.
Optic nerve hypoplasia
Species
Mouse
Genotype
Nr2f1 mutant
Genes
Nr2f1 hgnc:7975 HUGO Gene Nomenclature Committee (hgnc) Relation: this experimental model concerns this gene This experimental model concerns Nr2f1 (hgnc:7975). hgnc:7975 is a gene from the HUGO Gene Nomenclature Committee.
Show evidence (1 reference)
PMID:34466801 SUPPORT Model Organism
"Abnormal retinogenesis in early stages of development was observed in Nr2f1 mutant mice with decreased retinal ganglion cell density and disruption of retinal ganglion cell axonal guidance from the neural retina into the optic stalk, accounting for the development of optic nerve hypoplasia."
Nr2f1 mutant mice recapitulate the ocular phenotype, supporting a developmental origin of the optic nerve hypoplasia seen in BBSOAS.
Conditional Nr2f1 loss in the adult hippocampal neurogenic niche and heterozygous Nr2f1 loss in a BBSOAS model Mouse
Nr2f1 loss reduces mitochondrial mass, fragments mitochondria, and lowers key mitochondrial proteins in newborn neurons; heterozygous mice also show dysregulated nuclear-encoded mitochondrial genes and proteins in brain.
Reduced mitochondrial mass Mitochondrial fragmentation Impaired newborn-neuron survival and integration
Species
Mouse
Genotype
Conditional Nr2f1 loss in the adult hippocampal neurogenic niche and heterozygous Nr2f1 loss in a BBSOAS model
Genes
Nr2f1 hgnc:7975 HUGO Gene Nomenclature Committee (hgnc) Relation: this experimental model concerns this gene This experimental model concerns Nr2f1 (hgnc:7975). hgnc:7975 is a gene from the HUGO Gene Nomenclature Committee.
Show evidence (1 reference)
PMID:37260288 SUPPORT Model Organism
"conditional NR2F1 loss of function within the adult mouse hippocampal neurogenic niche results in a reduced mitochondrial mass associated with mitochondrial fragmentation and downregulation of key mitochondrial proteins in newborn neurons"
The mouse study directly defines the provisional mitochondrial branch of the BBSOAS pathograph.
{ }

Source YAML

click to show 
name: Bosch-Boonstra-Schaaf Optic Atrophy Syndrome
creation_date: "2026-06-04T00:00:00Z"
synonyms:
- BBSOAS
- Optic atrophy-intellectual disability syndrome
- NR2F1-related neurodevelopmental disorder
description: >-
  Bosch-Boonstra-Schaaf optic atrophy syndrome (BBSOAS) is a rare autosomal
  dominant neurodevelopmental disorder caused by pathogenic NR2F1 variants or
  deletions. NR2F1 (COUP-TFI) is a nuclear-receptor transcription factor
  essential for neural and ocular development. Gene deletion and
  loss-of-function variants cause haploinsufficiency, while some DNA-binding
  domain variants may additionally act through a dominant-negative mechanism.
  The variable phenotype combines developmental delay or intellectual
  disability with optic atrophy, optic nerve hypoplasia and/or cerebral visual
  impairment; hypotonia, epilepsy, autistic features, feeding or oromotor
  dysfunction, and hearing impairment occur in subsets. Available longitudinal
  data favor an early developmental, generally non-progressive visual disorder.
category: Mendelian
parents:
- hereditary disease
- autosomal dominant syndromic intellectual disability
disease_term:
  preferred_term: Bosch-Boonstra-Schaaf optic atrophy syndrome
  term:
    id: MONDO:0014320
    label: Bosch-Boonstra-Schaaf optic atrophy syndrome
mappings:
  mondo_mappings:
  - term:
      id: MONDO:0014320
      label: Bosch-Boonstra-Schaaf optic atrophy syndrome
    mapping_predicate: skos:exactMatch
    mapping_source: MONDO
    mapping_justification: >-
      Orphadata validates ORPHA:401777 as exactly equivalent to MONDO:0014320,
      which is also the primary disease identifier used by this entry.
classifications:
  harrisons_chapter:
  - classification_value: GENETICS_ENVIRONMENT_DISEASE
    evidence:
    - reference: url:https://api.orphadata.com/rd-cross-referencing/orphacodes/401777
      reference_title: "https://api.orphadata.com/rd-cross-referencing/orphacodes/401777"
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >-
        "ORPHAcode": 401777, "OrphanetURL":
        "http://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=en&Expert=401777",
        "Preferred term": "Optic atrophy-intellectual disability syndrome"
      explanation: >-
        The current Orphadata record identifies a defined hereditary syndrome
        with exact MONDO and OMIM mappings, supporting classification as a
        genetic disease.
references:
- reference: PMID:24462372
  title: "NR2F1 mutations cause optic atrophy with intellectual disability."
- reference: PMID:26986877
  title: "The expanding clinical phenotype of Bosch-Boonstra-Schaaf optic atrophy syndrome: 20 new cases and possible genotype-phenotype correlations."
- reference: PMID:29709504
  title: "The pleiotropic transcriptional regulator COUP-TFI plays multiple roles in neural development and disease."
- reference: PMID:31600777
  title: "Nr2f1 heterozygous knockout mice recapitulate neurological phenotypes of Bosch-Boonstra-Schaaf optic atrophy syndrome and show impaired hippocampal synaptic plasticity."
- reference: PMID:32275123
  title: "Phenotypic expansion of Bosch-Boonstra-Schaaf optic atrophy syndrome and further evidence for genotype-phenotype correlations."
- reference: PMID:34466801
  title: "Pathogenic NR2F1 variants cause a developmental ocular phenotype recapitulated in a mutant mouse model."
- reference: PMID:35455940
  title: "Pathophysiological Heterogeneity of the BBSOA Neurodevelopmental Syndrome."
- reference: PMID:36508512
  title: "NR2F1-Related Neurodevelopmental Disorder."
  tags:
  - GeneReviews
- reference: PMID:37260288
  title: "NR2F1 shapes mitochondria in the mouse brain, providing new insights into Bosch-Boonstra-Schaaf optic atrophy syndrome."
- reference: url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable
  title: "NR2F1-Related Neurodevelopmental Disorder - GeneReviews® - NCBI Bookshelf"
  tags:
  - GeneReviews
- reference: url:https://api.orphadata.com/rd-cross-referencing/orphacodes/401777
  title: "https://api.orphadata.com/rd-cross-referencing/orphacodes/401777"
- reference: url:https://api.orphadata.com/rd-epidemiology/orphacodes/401777
  title: "https://api.orphadata.com/rd-epidemiology/orphacodes/401777"
- reference: url:https://api.orphadata.com/rd-natural_history/orphacodes/401777
  title: "https://api.orphadata.com/rd-natural_history/orphacodes/401777"
- reference: url:https://api.orphadata.com/rd-phenotypes/orphacodes/401777
  title: "https://api.orphadata.com/rd-phenotypes/orphacodes/401777"
- reference: url:https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE106302
  title: GEO Accession viewer
- reference: url:https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE228566
  title: GEO Accession viewer
inheritance:
- name: Autosomal dominant inheritance
  description: >-
    BBSOAS is an autosomal dominant disorder. Most probands have a de novo
    pathogenic NR2F1 variant or deletion; some intrafamilial recurrences and a
    low (~1%) recurrence risk to sibs from theoretical parental germline
    mosaicism have been reported.
  inheritance_term:
    preferred_term: autosomal dominant inheritance
    term:
      id: HP:0000006
      label: Autosomal dominant inheritance
  evidence:
  - reference: PMID:36508512
    reference_title: "NR2F1-Related Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      NR2F1-NDD is an autosomal dominant disorder. Most probands reported to
      date with an intragenic NR2F1 pathogenic variant whose parents have
      undergone molecular genetic testing have the disorder as the result of a
      de novo pathogenic variant.
    explanation: >-
      GeneReviews establishes autosomal dominant inheritance with predominantly
      de novo occurrence.
pathophysiology:
- name: NR2F1 functional insufficiency and variant-specific dominant-negative effects
  biological_scale: MOLECULAR
  mechanism_confidence: ESTABLISHED
  description: >-
    Heterozygous whole-gene deletions and loss-of-function variants reduce
    functional NR2F1 dosage. Pathogenic missense variants in the zinc-finger
    DNA-binding domain or ligand-binding domain reduce transcriptional activity;
    DNA-binding-domain variants can also interfere with wild-type dimer
    function and are associated with a more severe clinical phenotype. The
    established shared consequence is reduced functional NR2F1 transcriptional
    output, while the precise contribution of dominant-negative activity varies
    by allele.
  genes:
  - preferred_term: NR2F1
    term:
      id: hgnc:7975
      label: NR2F1
  biological_processes:
  - preferred_term: NR2F1 nuclear receptor transcriptional regulation
    term:
      id: GO:0006357
      label: regulation of transcription by RNA polymerase II
    modifier: DECREASED
  evidence:
  - reference: PMID:24462372
    reference_title: "NR2F1 mutations cause optic atrophy with intellectual disability."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      NR2F1 encodes a nuclear receptor protein that regulates transcription. A
      reporter assay showed that missense mutations in the zinc-finger
      DNA-binding domain and the putative ligand-binding domain decrease NR2F1
      transcriptional activity.
    explanation: >-
      Functional reporter assays demonstrate that pathogenic NR2F1 missense
      variants reduce transcriptional activity, establishing functional NR2F1
      insufficiency without requiring every missense allele to be a simple null.
  - reference: PMID:26986877
    reference_title: "The expanding clinical phenotype of Bosch-Boonstra-Schaaf optic atrophy syndrome: 20 new cases and possible genotype-phenotype correlations."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Bosch-Boonstra-Schaaf optic atrophy syndrome (BBSOAS) is an
      autosomal-dominant disorder characterized by optic atrophy and
      intellectual disability caused by loss-of-function mutations in NR2F1.
    explanation: >-
      Confirms BBSOAS results from loss-of-function NR2F1 variants consistent
      with haploinsufficiency.
  - reference: PMID:35455940
    reference_title: "Pathophysiological Heterogeneity of the BBSOA Neurodevelopmental Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      the Bosch-Boonstra-Schaaf Optic Atrophy Syndrome (BBSOAS; OMIM 615722;
      ORPHA 401777), a recently described monogenic neurodevelopmental syndrome
      caused by the haploinsufficiency of NR2F1 gene, a key transcriptional
      regulator of brain development.
    explanation: >-
      Review explicitly characterizes BBSOAS as caused by NR2F1
      haploinsufficiency affecting a key transcriptional regulator of brain
      development.
  - reference: url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable
    reference_title: "NR2F1-Related Neurodevelopmental Disorder - GeneReviews® - NCBI Bookshelf"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Haploinsufficiency due to either gene deletion or loss-of-function
      variants. Single-nucleotide variants in the DNA-binding domain may cause a
      dominant-negative effect.
    explanation: >-
      GeneReviews distinguishes the established haploinsufficiency mechanism
      from a possible additional dominant-negative effect of DNA-binding-domain
      variants.
  downstream:
  - target: Disrupted neural and visual-system development
    description: >-
      Reduced functional COUP-TFI output perturbs transcriptional control of
      cortical arealization, neuronal differentiation, and visual-pathway
      development.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:34466801
      reference_title: "Pathogenic NR2F1 variants cause a developmental ocular phenotype recapitulated in a mutant mouse model."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        We propose NR2F1 as a major gene that orchestrates early retinal and
        optic nerve head development, playing a key role in the maturation of the
        visual system.
      explanation: >-
        Supports the causal link from reduced NR2F1 dosage to disrupted
        visual-system development.
  - target: Neuronal mitochondrial network dysregulation
    description: >-
      Nr2f1 loss in mouse neural cells alters nuclear-encoded mitochondrial
      gene expression, mitochondrial mass, morphology, and protein abundance.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:37260288
      reference_title: "NR2F1 shapes mitochondria in the mouse brain, providing new insights into Bosch-Boonstra-Schaaf optic atrophy syndrome."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        we also found dysregulation of several nuclear-encoded mitochondrial
        genes and downregulation of key mitochondrial proteins in the brain of
        Nr2f1-heterozygous mice, a validated BBSOAS model.
      explanation: >-
        The heterozygous mouse model links reduced Nr2f1 function to altered
        mitochondrial gene and protein regulation in brain.
  - target: Impaired hippocampal synaptic plasticity
    description: >-
      In a heterozygous Nr2f1 mouse model, reduced Nr2f1 function is associated
      with impaired hippocampal long-term potentiation and depression.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:31600777
      reference_title: "Nr2f1 heterozygous knockout mice recapitulate neurological phenotypes of Bosch-Boonstra-Schaaf optic atrophy syndrome and show impaired hippocampal synaptic plasticity."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        further electrophysiological investigation in hippocampal slices revealed
        significantly reduced long-term potentiation and long-term depression.
      explanation: >-
        A heterozygous Nr2f1 mouse model directly links reduced Nr2f1 function
        to impaired hippocampal synaptic plasticity.
- name: Neuronal mitochondrial network dysregulation
  biological_scale: CELLULAR
  mechanism_confidence: PROVISIONAL
  description: >-
    In mouse models, Nr2f1 loss reduces mitochondrial mass, fragments the
    mitochondrial network, and downregulates mitochondrial proteins in newborn
    neurons. This is a plausible secondary contributor to impaired neuronal
    survival and integration, but it has not yet been demonstrated in human
    BBSOAS neural tissue.
  cell_types:
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  biological_processes:
  - preferred_term: mitochondrial organization
    term:
      id: GO:0007005
      label: mitochondrion organization
    modifier: ABNORMAL
  evidence:
  - reference: PMID:37260288
    reference_title: "NR2F1 shapes mitochondria in the mouse brain, providing new insights into Bosch-Boonstra-Schaaf optic atrophy syndrome."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      conditional NR2F1 loss of function within the adult mouse hippocampal
      neurogenic niche results in a reduced mitochondrial mass associated with
      mitochondrial fragmentation and downregulation of key mitochondrial
      proteins in newborn neurons
    explanation: >-
      Mouse neural-cell data establish the cellular phenotype while leaving its
      contribution to human manifestations provisional.
  downstream:
  - target: Disrupted neural and visual-system development
    description: >-
      Altered mitochondrial support may contribute to impaired neuronal genesis,
      survival, and integration within the broader neural-developmental branch;
      ocular involvement was not tested in this model.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:37260288
      reference_title: "NR2F1 shapes mitochondria in the mouse brain, providing new insights into Bosch-Boonstra-Schaaf optic atrophy syndrome."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        newborn neurons, the genesis, survival and functional integration of
        which are impaired.
      explanation: >-
        The model links mitochondrial disruption to impaired neuronal genesis,
        survival, and functional integration, but not yet to a specific human
        clinical outcome.
- name: Disrupted neural and visual-system development
  biological_scale: TISSUE
  mechanism_confidence: ESTABLISHED
  description: >-
    COUP-TFI is a major transcriptional regulator orchestrating cortical
    arealization, cell-type specification, and maturation across forebrain
    structures, and contributes to development of the retina and optic nerve.
    Its haploinsufficiency disrupts these developmental programs, producing the
    combined neurodevelopmental and visual phenotype.
  cell_types:
  - preferred_term: cortical neuron
    term:
      id: CL:0010012
      label: cerebral cortex neuron
  - preferred_term: retinal ganglion cell
    term:
      id: CL:0000740
      label: retinal ganglion cell
  - preferred_term: neural progenitor cell
    term:
      id: CL:0011020
      label: neural progenitor cell
  biological_processes:
  - preferred_term: forebrain development
    term:
      id: GO:0030900
      label: forebrain development
    modifier: ABNORMAL
  - preferred_term: cerebral cortex regionalization
    term:
      id: GO:0021796
      label: cerebral cortex regionalization
    modifier: ABNORMAL
  - preferred_term: optic nerve development
    term:
      id: GO:0021554
      label: optic nerve development
    modifier: ABNORMAL
  - preferred_term: retina development
    term:
      id: GO:0060041
      label: retina development in camera-type eye
    modifier: ABNORMAL
  evidence:
  - reference: PMID:29709504
    reference_title: "The pleiotropic transcriptional regulator COUP-TFI plays multiple roles in neural development and disease."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      COUP-TFI (or NR2F1), a nuclear receptor belonging to the superfamily of
      the steroid/thyroid hormone receptors, and considered to be one of the
      major transcriptional regulators orchestrating cortical arealization,
      cell-type specification and maturation.
    explanation: >-
      Establishes COUP-TFI/NR2F1 as a master transcriptional regulator of
      cortical patterning and cell-type specification, the developmental
      programs disrupted in BBSOAS.
  - reference: PMID:24462372
    reference_title: "NR2F1 mutations cause optic atrophy with intellectual disability."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      These findings indicate that NR2F1 plays an important role in the
      neurodevelopment of the visual system and that its disruption can lead to
      optic atrophy with intellectual disability.
    explanation: >-
      Directly links NR2F1 disruption to abnormal visual-system
      neurodevelopment producing optic atrophy.
  - reference: PMID:34466801
    reference_title: "Pathogenic NR2F1 variants cause a developmental ocular phenotype recapitulated in a mutant mouse model."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Abnormal retinogenesis in early stages of development was observed in
      Nr2f1 mutant mice with decreased retinal ganglion cell density and
      disruption of retinal ganglion cell axonal guidance from the neural retina
      into the optic stalk, accounting for the development of optic nerve
      hypoplasia.
    explanation: >-
      Nr2f1 mutant mice recapitulate the ocular phenotype, showing decreased
      retinal ganglion cell density and disrupted axonal guidance that explains
      optic nerve hypoplasia, supporting a developmental origin of the visual
      defect.
    images:
    - Bosch-Boonstra-Schaaf_Optic_Atrophy_Syndrome-deep-research-falcon_artifacts/image-1.png
  - reference: PMID:34466801
    reference_title: "Pathogenic NR2F1 variants cause a developmental ocular phenotype recapitulated in a mutant mouse model."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      High-resolution optical coherence tomography imaging confirmed significant
      loss of retinal ganglion cells with thinning of the ganglion cell layer,
      consistent with electrophysiological evidence of retinal ganglion cells
      dysfunction.
    explanation: >-
      Human imaging and electrophysiology directly document retinal ganglion
      cell loss and dysfunction in BBSOAS.
  - reference: PMID:31600777
    reference_title: "Nr2f1 heterozygous knockout mice recapitulate neurological phenotypes of Bosch-Boonstra-Schaaf optic atrophy syndrome and show impaired hippocampal synaptic plasticity."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      we investigated a heterozygous knockout mouse model and found that this
      model recapitulates some of the neurological phenotypes of BBSOAS,
      including altered learning/memory, hearing defects, neonatal hypotonia and
      decreased hippocampal volume.
    explanation: >-
      A heterozygous Nr2f1 knockout mouse recapitulates core BBSOAS neurological
      phenotypes, supporting NR2F1 haploinsufficiency as the mechanism driving
      the neurodevelopmental features.
  downstream:
  - target: Optic atrophy
    description: Disrupted visual-system neurodevelopment produces optic atrophy.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:24462372
      reference_title: "NR2F1 mutations cause optic atrophy with intellectual disability."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        These findings indicate that NR2F1 plays an important role in the
        neurodevelopment of the visual system and that its disruption can lead to
        optic atrophy with intellectual disability.
      explanation: Human genetic evidence links NR2F1 disruption in visual-system neurodevelopment to optic atrophy.
  - target: Optic nerve glial imbalance
    description: >-
      In the Nr2f1-haploinsufficient mouse model, disturbed visual-system
      development is associated with an imbalance between oligodendrocytes and
      astrocytes in the optic nerve.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: DOI:10.15252/emmm.201910291
      reference_title: "Mouse Nr2f1 haploinsufficiency unveils new pathological mechanisms of a human optic atrophy syndrome"
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        Notably,Nr2f1-deficient optic nerves develop an imbalance between oligodendrocytes and astrocytes leading to postnatal hypomyelination and astrogliosis.
      explanation: >-
        The mouse model directly identifies optic-nerve oligodendrocyte/astrocyte
        imbalance downstream of Nr2f1 deficiency; human confirmation is pending.
  - target: Optic nerve hypoplasia
    description: Abnormal retinal ganglion-cell development and axonal guidance explain optic nerve hypoplasia.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:34466801
      reference_title: "Pathogenic NR2F1 variants cause a developmental ocular phenotype recapitulated in a mutant mouse model."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        Abnormal retinogenesis in early stages of development was observed in
        Nr2f1 mutant mice with decreased retinal ganglion cell density and
        disruption of retinal ganglion cell axonal guidance from the neural retina
        into the optic stalk, accounting for the development of optic nerve
        hypoplasia.
      explanation: Mouse ocular-development data provide a specific developmental intermediate for optic nerve hypoplasia.
  - target: Cerebral visual impairment
    description: Visual-system neurodevelopmental disruption causes visual impairment from optic nerve and cerebral mechanisms.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:36508512
      reference_title: "NR2F1-Related Neurodevelopmental Disorder."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        visual impairment (due to optic nerve abnormalities and/or cerebral
        visual impairment)
      explanation: GeneReviews lists cerebral visual impairment as a mechanism of BBSOAS visual impairment.
  - target: Intellectual disability
    description: Disrupted neural development produces the intellectual-disability component of BBSOAS.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:24462372
      reference_title: "NR2F1 mutations cause optic atrophy with intellectual disability."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        These findings indicate that NR2F1 plays an important role in the
        neurodevelopment of the visual system and that its disruption can lead to
        optic atrophy with intellectual disability.
      explanation: Human genetic evidence links NR2F1 disruption to intellectual disability.
  - target: Global developmental delay
    description: NR2F1-related neurodevelopmental disruption presents as global developmental delay.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:36508512
      reference_title: "NR2F1-Related Neurodevelopmental Disorder."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        developmental delay / intellectual disability (ranging from profound to
        mild)
      explanation: GeneReviews supports developmental delay as a core clinical output of NR2F1-related neurodevelopmental disorder.
  - target: Hypotonia
    description: Neurologic involvement in BBSOAS includes neonatal or childhood hypotonia.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:26986877
      reference_title: "The expanding clinical phenotype of Bosch-Boonstra-Schaaf optic atrophy syndrome: 20 new cases and possible genotype-phenotype correlations."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        individuals with BBSOAS manifested hypotonia (75%), seizures (40%), autism
        spectrum disorder (35%), oromotor dysfunction (60%)
      explanation: Human cohort data support hypotonia as a neurologic phenotype downstream of BBSOAS neurodevelopmental disruption.
  - target: Seizures
    description: BBSOAS neurodevelopmental disruption includes seizure susceptibility.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:26986877
      reference_title: "The expanding clinical phenotype of Bosch-Boonstra-Schaaf optic atrophy syndrome: 20 new cases and possible genotype-phenotype correlations."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        individuals with BBSOAS manifested hypotonia (75%), seizures (40%), autism
        spectrum disorder (35%), oromotor dysfunction (60%)
      explanation: Human cohort data support seizures as a recurrent BBSOAS neurodevelopmental phenotype.
  - target: Oromotor dysfunction
    description: BBSOAS neurologic involvement includes oromotor and feeding dysfunction.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:26986877
      reference_title: "The expanding clinical phenotype of Bosch-Boonstra-Schaaf optic atrophy syndrome: 20 new cases and possible genotype-phenotype correlations."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        individuals with BBSOAS manifested hypotonia (75%), seizures (40%), autism
        spectrum disorder (35%), oromotor dysfunction (60%)
      explanation: Human cohort data support oromotor dysfunction as a recurrent BBSOAS phenotype.
  - target: Thin corpus callosum
    description: Abnormal forebrain development includes corpus-callosum thinning in BBSOAS.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:26986877
      reference_title: "The expanding clinical phenotype of Bosch-Boonstra-Schaaf optic atrophy syndrome: 20 new cases and possible genotype-phenotype correlations."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        thinning of the corpus callosum (53%)
      explanation: Human cohort data support thin corpus callosum as a structural neurodevelopmental output.
  - target: Hearing impairment
    description: NR2F1-related neurologic involvement includes hearing defects in a subset of patients.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:26986877
      reference_title: "The expanding clinical phenotype of Bosch-Boonstra-Schaaf optic atrophy syndrome: 20 new cases and possible genotype-phenotype correlations."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        hearing defects (20%)
      explanation: Human cohort data support hearing impairment as part of the BBSOAS phenotype spectrum.
  - target: Nystagmus
    description: Visual-system involvement includes manifest latent nystagmus.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:32275123
      reference_title: "Phenotypic expansion of Bosch-Boonstra-Schaaf optic atrophy syndrome and further evidence for genotype-phenotype correlations."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        we expand the vision phenotype to include alacrima and manifest latent
        nystagmus (fusional maldevelopment)
      explanation: Human cohort data support nystagmus as part of the visual phenotype.
  - target: Autistic behavior
    description: >-
      Altered neural development and connectivity contribute to autism-spectrum
      and autistic behavioral manifestations.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:26986877
      reference_title: "The expanding clinical phenotype of Bosch-Boonstra-Schaaf optic atrophy syndrome: 20 new cases and possible genotype-phenotype correlations."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        individuals with BBSOAS manifested hypotonia (75%), seizures (40%),
        autism spectrum disorder (35%), oromotor dysfunction (60%)
      explanation: >-
        Human cohort data connect NR2F1-related neurodevelopmental disruption
        with recurrent autism-spectrum manifestations.
  - target: Reduced visual acuity
    description: >-
      Developmental retinal-ganglion-cell loss and visual-pathway disorganization
      reduce visual acuity.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:34466801
      reference_title: "Pathogenic NR2F1 variants cause a developmental ocular phenotype recapitulated in a mutant mouse model."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        resulting in congenital vision loss that seems to be non-progressive.
      explanation: >-
        The ocular cohort links the developmental retinal and optic-nerve
        phenotype to congenital visual loss.
  - target: Strabismus
    description: >-
      Developmental visual-system impairment commonly includes ocular
      misalignment.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable
      reference_title: "NR2F1-Related Neurodevelopmental Disorder - GeneReviews® - NCBI Bookshelf"
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Strabismus (77%) and nystagmus (45%) are common features.
      explanation: >-
        GeneReviews summarizes strabismus as a common ocular manifestation in
        the deeply phenotyped cohort.
- name: Optic nerve glial imbalance
  biological_scale: TISSUE
  mechanism_confidence: PROVISIONAL
  description: >-
    Nr2f1-deficient mouse optic nerves show an imbalance between oligodendrocytes
    and astrocytes. This model-defined glial phenotype provides a distinct
    potential arm of optic-nerve pathology, but has not been established in
    human BBSOAS tissue.
  evidence:
  - reference: DOI:10.15252/emmm.201910291
    reference_title: "Mouse Nr2f1 haploinsufficiency unveils new pathological mechanisms of a human optic atrophy syndrome"
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Notably,Nr2f1-deficient optic nerves develop an imbalance between oligodendrocytes and astrocytes leading to postnatal hypomyelination and astrogliosis.
    explanation: >-
      This is direct model-organism evidence for an optic-nerve glial imbalance,
      not evidence that the same cellular imbalance has been measured in people.
  downstream:
  - target: Postnatal optic nerve hypomyelination
    causal_link_type: DIRECT
  - target: Optic nerve astrogliosis
    causal_link_type: DIRECT
- name: Postnatal optic nerve hypomyelination
  biological_scale: TISSUE
  mechanism_confidence: PROVISIONAL
  description: >-
    Nr2f1-haploinsufficient mouse optic nerves undergo postnatal hypomyelination,
    a model phenotype that can be chemically rescued early in life. Its causal
    contribution and treatment responsiveness in human BBSOAS remain unknown.
  evidence:
  - reference: DOI:10.15252/emmm.201910291
    reference_title: "Mouse Nr2f1 haploinsufficiency unveils new pathological mechanisms of a human optic atrophy syndrome"
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Importantly, some of these clinical features, such the optic nerve hypomyelination, could be rescued by chemical drug treatment in early postnatal life.
    explanation: >-
      The mouse study demonstrates a preclinical early-postnatal chemical-rescue
      signal for optic-nerve hypomyelination, without establishing a human therapy.
  downstream:
  - target: Optic atrophy
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
- name: Optic nerve astrogliosis
  biological_scale: TISSUE
  mechanism_confidence: PROVISIONAL
  description: >-
    Astrogliosis accompanies optic-nerve hypomyelination in Nr2f1-deficient
    mice. This model observation is retained separately from myelination loss
    and requires validation in human BBSOAS tissue.
  evidence:
  - reference: DOI:10.15252/emmm.201910291
    reference_title: "Mouse Nr2f1 haploinsufficiency unveils new pathological mechanisms of a human optic atrophy syndrome"
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Notably,Nr2f1-deficient optic nerves develop an imbalance between oligodendrocytes and astrocytes leading to postnatal hypomyelination and astrogliosis.
    explanation: >-
      The mouse model observes astrogliosis with optic-nerve glial imbalance and
      hypomyelination; the human relevance remains provisional.
  downstream:
  - target: Optic atrophy
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
- name: Impaired hippocampal synaptic plasticity
  biological_scale: CELLULAR
  mechanism_confidence: PROVISIONAL
  description: >-
    Nr2f1 haploinsufficiency impairs hippocampal long-term potentiation and
    long-term depression in a heterozygous mouse model, providing a provisional
    mechanistic bridge to cognitive impairment in BBSOAS.
  biological_processes:
  - preferred_term: long-term synaptic potentiation
    term:
      id: GO:0060291
      label: long-term synaptic potentiation
    modifier: DECREASED
  - preferred_term: long-term synaptic depression
    term:
      id: GO:0060292
      label: long-term synaptic depression
    modifier: DECREASED
  evidence:
  - reference: PMID:31600777
    reference_title: "Nr2f1 heterozygous knockout mice recapitulate neurological phenotypes of Bosch-Boonstra-Schaaf optic atrophy syndrome and show impaired hippocampal synaptic plasticity."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      further electrophysiological investigation in hippocampal slices revealed
      significantly reduced long-term potentiation and long-term depression.
    explanation: >-
      Electrophysiology in heterozygous Nr2f1 mouse hippocampal slices directly
      supports impaired synaptic plasticity; human confirmation is pending.
  downstream:
  - target: Intellectual disability
    description: >-
      Impaired hippocampal synaptic plasticity is a provisional model mechanism
      for cognitive impairment in BBSOAS.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Global developmental delay
    description: >-
      Impaired hippocampal synaptic plasticity is a provisional model mechanism
      for developmental impairment in BBSOAS.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
phenotypes:
- category: Eye
  name: Optic atrophy
  frequency: FREQUENT
  description: >-
    Atrophy of the optic nerve, a hallmark visual feature of BBSOAS, alongside
    optic nerve hypoplasia and cerebral visual impairment.
  phenotype_term:
    preferred_term: Optic atrophy
    term:
      id: HP:0000648
      label: Optic atrophy
  evidence:
  - reference: PMID:24462372
    reference_title: "NR2F1 mutations cause optic atrophy with intellectual disability."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      its disruption can lead to optic atrophy with intellectual disability.
    explanation: Optic atrophy is the defining ocular feature of NR2F1 disruption.
  - reference: url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable
    reference_title: "NR2F1-Related Neurodevelopmental Disorder - GeneReviews® - NCBI Bookshelf"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Fundus examination revealed optic atrophy in 77% of individuals and small
      and/or tilted hypoplastic optic nerves in 46% of individuals.
    explanation: The deeply phenotyped cohort places optic atrophy in the FREQUENT band.
- category: Eye
  name: Refractive error
  frequency: VERY_FREQUENT
  description: Refractive error is a common ophthalmologic finding in BBSOAS.
  phenotype_term:
    preferred_term: Refractive error
    term:
      id: HP:0000539
      label: Abnormality of refraction
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable
    reference_title: "NR2F1-Related Neurodevelopmental Disorder - GeneReviews® - NCBI Bookshelf"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Most individuals have a refractive error (91%) with a predominance of
      hyperopia (68%).
    explanation: The 91% cohort estimate supports a VERY_FREQUENT band.
- category: Eye
  name: Hyperopia
  frequency: FREQUENT
  description: Hyperopia is the predominant refractive error reported in BBSOAS.
  phenotype_term:
    preferred_term: Hyperopia
    term:
      id: HP:0000540
      label: Hypermetropia
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable
    reference_title: "NR2F1-Related Neurodevelopmental Disorder - GeneReviews® - NCBI Bookshelf"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Most individuals have a refractive error (91%) with a predominance of
      hyperopia (68%).
    explanation: The 68% cohort estimate supports a FREQUENT band.
- category: Eye
  name: Optic nerve hypoplasia
  frequency: OCCASIONAL
  description: >-
    Hypoplasia of the optic nerve contributing to the visual phenotype.
  phenotype_term:
    preferred_term: Optic nerve hypoplasia
    term:
      id: HP:0000609
      label: Optic nerve hypoplasia
  evidence:
  - reference: PMID:32275123
    reference_title: "Phenotypic expansion of Bosch-Boonstra-Schaaf optic atrophy syndrome and further evidence for genotype-phenotype correlations."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We also confirm a vision phenotype that includes optic nerve hypoplasia,
      optic atrophy, and cortical visual impairment.
    explanation: Cohort confirms optic nerve hypoplasia as part of the BBSOAS vision phenotype.
  - reference: PMID:34466801
    reference_title: "Pathogenic NR2F1 variants cause a developmental ocular phenotype recapitulated in a mutant mouse model."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The visual impairment became apparent in early childhood with small and/or
      tilted hypoplastic optic nerves observed in 10 cases.
    explanation: >-
      Deep phenotyping documents hypoplastic optic nerves in BBSOAS individuals,
      with onset in early childhood.
  - reference: url:https://api.orphadata.com/rd-phenotypes/orphacodes/401777
    reference_title: "https://api.orphadata.com/rd-phenotypes/orphacodes/401777"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      "HPOId": "HP:0007766", "HPOTerm": "Optic disc hypoplasia" },
      "HPOFrequency": "Occasional (29-5%)"
    explanation: >-
      Orphadata classifies the closely aligned optic-disc hypoplasia phenotype
      as occasional.
- category: Eye
  name: Cerebral visual impairment
  frequency: FREQUENT
  description: >-
    Visual impairment of cerebral/cortical origin, frequently co-occurring with
    optic nerve abnormalities.
  phenotype_term:
    preferred_term: Cerebral visual impairment
    term:
      id: HP:0100704
      label: Cerebral visual impairment
  evidence:
  - reference: PMID:36508512
    reference_title: "NR2F1-Related Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      visual impairment (due to optic nerve abnormalities and/or cerebral
      visual impairment)
    explanation: GeneReviews lists cerebral visual impairment as a core feature.
  - reference: url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable
    reference_title: "NR2F1-Related Neurodevelopmental Disorder - GeneReviews® - NCBI Bookshelf"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Cerebral visual impairment is present in 55% of children.
    explanation: The cohort estimate places cerebral visual impairment in the FREQUENT band.
- category: Nervous System
  name: Intellectual disability
  description: >-
    Intellectual disability ranging from profound to mild, a core feature of
    BBSOAS.
  phenotype_term:
    preferred_term: Intellectual disability
    term:
      id: HP:0001249
      label: Intellectual disability
  evidence:
  - reference: PMID:36508512
    reference_title: "NR2F1-Related Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      developmental delay / intellectual disability (ranging from profound to
      mild)
    explanation: GeneReviews establishes intellectual disability as a defining feature.
  - reference: url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable
    reference_title: "NR2F1-Related Neurodevelopmental Disorder - GeneReviews® - NCBI Bookshelf"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Intellectual disability
    explanation: GeneReviews lists intellectual disability among the reported clinical features.
- category: Nervous System
  name: Global developmental delay
  description: >-
    Global developmental delay affecting motor, speech, and cognitive
    milestones.
  phenotype_term:
    preferred_term: Global developmental delay
    term:
      id: HP:0001263
      label: Global developmental delay
  evidence:
  - reference: PMID:36508512
    reference_title: "NR2F1-Related Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      developmental delay / intellectual disability (ranging from profound to
      mild)
    explanation: GeneReviews lists developmental delay as a core feature.
  - reference: url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable
    reference_title: "NR2F1-Related Neurodevelopmental Disorder - GeneReviews® - NCBI Bookshelf"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Developmental delay
    explanation: GeneReviews lists developmental delay among the reported clinical features.
- category: Nervous System
  name: Hypotonia
  description: >-
    Muscular hypotonia, commonly present in BBSOAS (~75% of cases).
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Hypotonia
    term:
      id: HP:0001252
      label: Hypotonia
  evidence:
  - reference: PMID:26986877
    reference_title: "The expanding clinical phenotype of Bosch-Boonstra-Schaaf optic atrophy syndrome: 20 new cases and possible genotype-phenotype correlations."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      individuals with BBSOAS manifested hypotonia (75%), seizures (40%), autism
      spectrum disorder (35%), oromotor dysfunction (60%)
    explanation: Cohort reports hypotonia in 75% of BBSOAS individuals, supporting a FREQUENT band.
- category: Nervous System
  name: Autistic behavior
  description: >-
    Autism spectrum disorder or autistic features, part of the behavioral
    spectrum of BBSOAS (~35% of cases).
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Autistic behavior
    term:
      id: HP:0000729
      label: Autistic behavior
  evidence:
  - reference: PMID:26986877
    reference_title: "The expanding clinical phenotype of Bosch-Boonstra-Schaaf optic atrophy syndrome: 20 new cases and possible genotype-phenotype correlations."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      individuals with BBSOAS manifested hypotonia (75%), seizures (40%), autism
      spectrum disorder (35%), oromotor dysfunction (60%)
    explanation: Cohort reports autism spectrum disorder in 35% of BBSOAS individuals.
- category: Nervous System
  name: Seizures
  description: >-
    Epilepsy / seizures, present in approximately 40% of BBSOAS individuals.
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Seizure
    term:
      id: HP:0001250
      label: Seizure
  evidence:
  - reference: PMID:26986877
    reference_title: "The expanding clinical phenotype of Bosch-Boonstra-Schaaf optic atrophy syndrome: 20 new cases and possible genotype-phenotype correlations."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      individuals with BBSOAS manifested hypotonia (75%), seizures (40%), autism
      spectrum disorder (35%), oromotor dysfunction (60%)
    explanation: Cohort reports seizures in 40% of BBSOAS individuals, supporting a FREQUENT band.
- category: Nervous System
  name: Attention deficit hyperactivity disorder
  frequency: OCCASIONAL
  description: Attention-deficit/hyperactivity disorder is part of the BBSOAS behavioral phenotype.
  phenotype_term:
    preferred_term: Attention deficit hyperactivity disorder
    term:
      id: HP:0007018
      label: Attention deficit hyperactivity disorder
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable
    reference_title: "NR2F1-Related Neurodevelopmental Disorder - GeneReviews® - NCBI Bookshelf"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: ADHD was present in 18% (17/92)
    explanation: The 18% cohort estimate supports an OCCASIONAL band.
- category: Digestive
  name: Oromotor dysfunction
  description: >-
    Oromotor dysfunction and feeding difficulties, present in ~60% of BBSOAS
    individuals.
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Feeding difficulties
    term:
      id: HP:0011968
      label: Feeding difficulties
  evidence:
  - reference: PMID:26986877
    reference_title: "The expanding clinical phenotype of Bosch-Boonstra-Schaaf optic atrophy syndrome: 20 new cases and possible genotype-phenotype correlations."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      individuals with BBSOAS manifested hypotonia (75%), seizures (40%), autism
      spectrum disorder (35%), oromotor dysfunction (60%)
    explanation: Cohort reports oromotor dysfunction in 60% of BBSOAS individuals.
- category: Nervous System
  name: Thin corpus callosum
  description: >-
    Thinning of the corpus callosum on brain MRI, reported in ~53% of BBSOAS
    individuals.
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Thin corpus callosum
    term:
      id: HP:0033725
      label: Thin corpus callosum
  evidence:
  - reference: PMID:26986877
    reference_title: "The expanding clinical phenotype of Bosch-Boonstra-Schaaf optic atrophy syndrome: 20 new cases and possible genotype-phenotype correlations."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      thinning of the corpus callosum (53%)
    explanation: Cohort reports thin corpus callosum in 53% of BBSOAS individuals.
- category: Ear
  name: Hearing impairment
  description: >-
    Hearing defects reported in approximately 20% of BBSOAS individuals.
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Hearing impairment
    term:
      id: HP:0000365
      label: Hearing impairment
  evidence:
  - reference: PMID:26986877
    reference_title: "The expanding clinical phenotype of Bosch-Boonstra-Schaaf optic atrophy syndrome: 20 new cases and possible genotype-phenotype correlations."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      hearing defects (20%)
    explanation: Cohort reports hearing defects in 20% of BBSOAS individuals, supporting an OCCASIONAL band.
- category: Eye
  name: Nystagmus
  frequency: FREQUENT
  description: >-
    Manifest latent nystagmus (fusional maldevelopment) recognized as part of
    the expanded BBSOAS vision phenotype.
  phenotype_term:
    preferred_term: Nystagmus
    term:
      id: HP:0000639
      label: Nystagmus
  evidence:
  - reference: PMID:32275123
    reference_title: "Phenotypic expansion of Bosch-Boonstra-Schaaf optic atrophy syndrome and further evidence for genotype-phenotype correlations."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      we expand the vision phenotype to include alacrima and manifest latent
      nystagmus (fusional maldevelopment)
    explanation: Cohort expands the vision phenotype to include manifest latent nystagmus.
  - reference: url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable
    reference_title: "NR2F1-Related Neurodevelopmental Disorder - GeneReviews® - NCBI Bookshelf"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Strabismus (77%) and nystagmus (45%) are common features.
    explanation: The ocular cohort places nystagmus in the FREQUENT band.
- category: Eye
  name: Alacrima
  description: Reduced or absent reflex tears are reported in the BBSOAS visual phenotype.
  phenotype_term:
    preferred_term: Alacrima
    term:
      id: HP:0000522
      label: Alacrima
  evidence:
  - reference: PMID:32275123
    reference_title: "Phenotypic expansion of Bosch-Boonstra-Schaaf optic atrophy syndrome and further evidence for genotype-phenotype correlations."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: include alacrima and manifest latent nystagmus (fusional maldevelopment)
    explanation: The BBSOAS cohort expands the visual phenotype to include alacrima.
- category: Eye
  name: Reduced visual acuity
  frequency: FREQUENT
  description: >-
    Reduced visual acuity reflects combined retinal-ganglion-cell, optic-nerve,
    and cerebral visual-system involvement; severity is variable.
  phenotype_term:
    preferred_term: Reduced visual acuity
    term:
      id: HP:0007663
      label: Reduced visual acuity
  evidence:
  - reference: url:https://api.orphadata.com/rd-phenotypes/orphacodes/401777
    reference_title: "https://api.orphadata.com/rd-phenotypes/orphacodes/401777"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      "HPOId": "HP:0007663", "HPOTerm": "Reduced visual acuity" },
      "HPOFrequency": "Frequent (79-30%)"
    explanation: Orphadata classifies reduced visual acuity as frequent.
  - reference: PMID:34466801
    reference_title: "Pathogenic NR2F1 variants cause a developmental ocular phenotype recapitulated in a mutant mouse model."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      resulting in congenital vision loss that seems to be non-progressive.
    explanation: The ocular cohort supports congenital visual loss.
- category: Eye
  name: Strabismus
  frequency: FREQUENT
  description: >-
    Ocular misalignment is common in deeply phenotyped individuals and may
    compound developmental visual impairment.
  phenotype_term:
    preferred_term: Strabismus
    term:
      id: HP:0000486
      label: Strabismus
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable
    reference_title: "NR2F1-Related Neurodevelopmental Disorder - GeneReviews® - NCBI Bookshelf"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Strabismus (77%) and nystagmus (45%) are common features.
    explanation: GeneReviews summarizes strabismus in 77% of the ocular cohort.
genetic:
- name: NR2F1
  association: Pathogenic loss-of-function and variant-specific dominant-negative effects
  relationship_type: CAUSATIVE
  gene_term:
    preferred_term: NR2F1
    term:
      id: hgnc:7975
      label: NR2F1
  notes: >-
    BBSOAS is caused by heterozygous NR2F1 sequence variants or deletions.
    Whole-gene deletion and many truncating or loss-of-function alleles produce
    haploinsufficiency. DNA-binding-domain missense variants can exert an
    additional dominant-negative effect and are associated with more severe
    neurodevelopmental manifestations, but genotype-phenotype correlations
    remain preliminary and should not be treated as deterministic.
  evidence:
  - reference: PMID:32275123
    reference_title: "Phenotypic expansion of Bosch-Boonstra-Schaaf optic atrophy syndrome and further evidence for genotype-phenotype correlations."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Bosch-Boonstra-Schaaf Optic Atrophy Syndrome (BBSOAS) is an autosomal
      dominant neurodevelopmental disorder caused by loss-of-function variants
      in NR2F1
    explanation: Establishes NR2F1 loss-of-function variants as the genetic cause of BBSOAS.
  - reference: PMID:32275123
    reference_title: "Phenotypic expansion of Bosch-Boonstra-Schaaf optic atrophy syndrome and further evidence for genotype-phenotype correlations."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      we provide additional evidence for genotype-phenotype correlations,
      specifically supporting a more severe phenotype associated with DBD
      variants.
    explanation: Supports the genotype-phenotype correlation that DNA-binding domain variants confer a more severe phenotype.
  - reference: url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable
    reference_title: "NR2F1-Related Neurodevelopmental Disorder - GeneReviews® - NCBI Bookshelf"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Haploinsufficiency due to either gene deletion or loss-of-function
      variants. Single-nucleotide variants in the DNA-binding domain may cause a
      dominant-negative effect.
    explanation: >-
      GeneReviews distinguishes the main loss-of-function mechanism from the
      variant-class-specific dominant-negative possibility.
prevalence:
- population: Worldwide
  measure_type: POINT_PREVALENCE
  prevalence_class: BELOW_1_IN_1000000
  notes: >-
    Current Orphadata supplies a validated, class-only worldwide point
    prevalence below one per million. The source also retains a six-case
    literature count from the original report, so this is not a measured
    population estimate.
  evidence:
  - reference: url:https://api.orphadata.com/rd-epidemiology/orphacodes/401777
    reference_title: "https://api.orphadata.com/rd-epidemiology/orphacodes/401777"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      "PrevalenceClass": "<1 / 1 000 000", "PrevalenceGeographic": "Worldwide",
      "PrevalenceQualification": "Class only", "PrevalenceType": "Point prevalence"
    explanation: >-
      Orphadata explicitly identifies the estimate as a class-only worldwide
      point-prevalence record.
- population: Worldwide
  measure_type: POINT_PREVALENCE
  prevalence_class: RARE
  rate_low: 0.4
  rate_high: 1.0
  notes: >-
    GeneReviews reports a substantially higher literature-derived estimated
    range. Because this range crosses the schema's adjacent numeric bands, it
    is retained with exact normalized rates and the qualitative RARE class
    rather than forced into one band. The conflict with Orphadata remains open.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable
    reference_title: "NR2F1-Related Neurodevelopmental Disorder - GeneReviews® - NCBI Bookshelf"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      appears to be rare, with an estimated prevalence from 1:100,000 to
      1:250,000 people worldwide
    explanation: >-
      GeneReviews provides the literature estimate normalized here to 0.4-1.0
      affected individuals per 100,000.
progression:
- phase: Neonatal and infantile presentation
  age_range: Neonatal period through infancy
  notes: >-
    Orphadata assigns neonatal onset. Hypotonia may be present at birth, and
    oromotor dysfunction with poor sucking, chewing, or swallowing is common in
    neonates and infants, sometimes requiring tube feeding.
  evidence:
  - reference: url:https://api.orphadata.com/rd-natural_history/orphacodes/401777
    reference_title: "https://api.orphadata.com/rd-natural_history/orphacodes/401777"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      "AverageAgeOfOnset": [ "Neonatal" ]
    explanation: The structured natural-history record assigns neonatal onset.
  - reference: url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable
    reference_title: "NR2F1-Related Neurodevelopmental Disorder - GeneReviews® - NCBI Bookshelf"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      including problems with sucking, chewing, or swallowing, is a common
      feature in neonates and infants and may occasionally necessitate
      nasogastric tube feeding
    explanation: GeneReviews defines the early feeding and oromotor course.
- phase: Neurodevelopmental and visual recognition
  age_range: Infancy through early childhood
  notes: >-
    Developmental and speech delays emerge as milestones are missed. Visual
    impairment is usually recognized in early childhood after nystagmus,
    strabismus, poor fixation, or neurodevelopmental concerns prompt
    ophthalmologic assessment.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable
    reference_title: "NR2F1-Related Neurodevelopmental Disorder - GeneReviews® - NCBI Bookshelf"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      is usually detected in early childhood when they are examined following
      referrals for evaluation of nystagmus, strabismus, poor fixation, and/or
      concerns about neurodevelopmental progress.
    explanation: GeneReviews directly describes the typical recognition window.
- phase: Longitudinal visual and neurologic course
  age_range: Childhood through adulthood
  notes: >-
    Available cohort follow-up supports congenital, generally non-progressive
    visual impairment rather than the progressive retinal-ganglion-cell loss
    typical of several other inherited optic neuropathies. Data on progression
    of behavior and other neurologic findings, and on adult natural history,
    remain limited.
  evidence:
  - reference: PMID:34466801
    reference_title: "Pathogenic NR2F1 variants cause a developmental ocular phenotype recapitulated in a mutant mouse model."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      for those individuals with available longitudinal ophthalmological data,
      there was no significant deterioration in visual function during the period
      of follow-up.
    explanation: >-
      Longitudinal deep-phenotyping data indicate the visual impairment in
      BBSOAS is non-progressive, which is relevant for prognostic counseling.
  - reference: url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable
    reference_title: "NR2F1-Related Neurodevelopmental Disorder - GeneReviews® - NCBI Bookshelf"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Data on possible progression of behavior abnormalities or neurologic
      findings are currently limited.
    explanation: GeneReviews explicitly marks the non-visual longitudinal course as uncertain.
clinical_burden:
  burden_level: HIGH
  rationale: >-
    BBSOAS commonly produces lifelong intellectual or developmental disability
    together with visual impairment. Epilepsy, feeding or swallowing
    dysfunction, hypotonia, autism-spectrum manifestations, hearing impairment,
    and mobility or communication needs create substantial multidisciplinary
    care and surveillance burden in many individuals. Severity is highly
    variable, and a HIGH disease-level burden does not imply severe expression
    in every affected person.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable
    reference_title: "NR2F1-Related Neurodevelopmental Disorder - GeneReviews® - NCBI Bookshelf"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      NR2F1-related neurodevelopmental disorder (NR2F1-NDD) is characterized by
      developmental delay / intellectual disability (ranging from profound to
      mild) and is commonly associated with hypotonia, visual impairment (due to
      optic nerve abnormalities and/or cerebral visual impairment), epilepsy,
      and behavioral manifestations
    explanation: >-
      The core and recurrent multisystem manifestations support substantial
      lifelong functional and care needs while documenting wide severity.
treatments:
- name: Multidisciplinary supportive care
  action_category: THERAPEUTIC
  description: >-
    There is no cure for BBSOAS. Supportive management relies on
    multidisciplinary specialists including neurology, speech-language
    pathology, ophthalmology with low-vision services, gastroenterology,
    nutrition, occupational therapy, physical therapy, audiology, clinical
    genetics, and genetic counseling, with regular surveillance for existing
    and emerging manifestations.
  treatment_term:
    preferred_term: supportive care
    term:
      id: NCIT:C15747
      label: Supportive Care
  evidence:
  - reference: PMID:36508512
    reference_title: "NR2F1-Related Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      There is no cure for NR2F1-NDD. Supportive treatment typically relies on
      multidisciplinary specialists in the fields of neurology, speech-language
      pathology, ophthalmology (including low-vision services), gastroenterology,
      nutrition, occupational therapy, physical therapy, audiology, clinical
      genetics, and genetic counseling.
    explanation: GeneReviews specifies multidisciplinary supportive care as the management approach.
- name: Developmental therapies and communication support
  action_category: THERAPEUTIC
  description: >-
    Early intervention and individualized educational support should include
    physical, occupational, speech-language, feeding, and sensory-impairment
    services as indicated. Augmentative and alternative communication should be
    assessed when expressive language is limited.
  treatment_term:
    preferred_term: speech therapy
    term:
      id: NCIT:C159273
      label: Speech Language Therapy
  target_phenotypes:
  - preferred_term: Global developmental delay
    term:
      id: HP:0001263
      label: Global developmental delay
  - preferred_term: Intellectual disability
    term:
      id: HP:0001249
      label: Intellectual disability
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable
    reference_title: "NR2F1-Related Neurodevelopmental Disorder - GeneReviews® - NCBI Bookshelf"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Referral to an early intervention program is recommended for access to
      occupational, physical, speech, and feeding therapy as well as infant
      mental health services, special educators, and sensory impairment
      specialists.
    explanation: GeneReviews recommends coordinated early developmental intervention.
- name: Ophthalmologic treatment and low-vision support
  action_category: THERAPEUTIC
  description: >-
    Ophthalmologic care should correct refractive errors or strabismus when
    present and provide low-vision services. Cerebral visual impairment may
    benefit from visual therapy and early intervention aimed at visual
    development; these measures are supportive rather than disease modifying.
  treatment_term:
    preferred_term: low vision rehabilitation
    term:
      id: NCIT:C15747
      label: Supportive Care
  target_phenotypes:
  - preferred_term: Reduced visual acuity
    term:
      id: HP:0007663
      label: Reduced visual acuity
  - preferred_term: Strabismus
    term:
      id: HP:0000486
      label: Strabismus
  - preferred_term: Cerebral visual impairment
    term:
      id: HP:0100704
      label: Cerebral visual impairment
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable
    reference_title: "NR2F1-Related Neurodevelopmental Disorder - GeneReviews® - NCBI Bookshelf"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Treatment of refractive errors
    explanation: GeneReviews recommends refractive, strabismus, and low-vision management.
  - reference: url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable
    reference_title: "NR2F1-Related Neurodevelopmental Disorder - GeneReviews® - NCBI Bookshelf"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Visual therapy focused on CVI
    explanation: GeneReviews recommends visual therapy and early intervention for CVI.
- name: Feeding, nutrition, and swallowing support
  action_category: THERAPEUTIC
  description: >-
    Feeding-team and nutrition assessment should address poor suck, chewing or
    swallowing difficulty, growth, aspiration risk, and oral safety. Feeding
    therapy is used first; persistent dysphagia or unsafe intake may require
    enteral support.
  treatment_term:
    preferred_term: feeding therapy
    term:
      id: NCIT:C156237
      label: Swallowing Therapy
  target_phenotypes:
  - preferred_term: Feeding difficulties
    term:
      id: HP:0011968
      label: Feeding difficulties
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable
    reference_title: "NR2F1-Related Neurodevelopmental Disorder - GeneReviews® - NCBI Bookshelf"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Gastrostomy tube placement may be required for persistent feeding issues.
    explanation: GeneReviews specifies feeding therapy and escalation for persistent problems.
- name: Individualized epilepsy management
  action_category: THERAPEUTIC
  description: >-
    Epilepsy should be treated with individualized antiseizure pharmacotherapy
    under an experienced neurologist. A small observational NR2F1-related
    epilepsy series reported seizure freedom after add-on perampanel, but this
    signal does not establish comparative superiority or a standard regimen.
  treatment_term:
    preferred_term: antiseizure pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
  target_phenotypes:
  - preferred_term: Seizure
    term:
      id: HP:0001250
      label: Seizure
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable
    reference_title: "NR2F1-Related Neurodevelopmental Disorder - GeneReviews® - NCBI Bookshelf"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Standardized treatment w/ASM by experienced neurologist
    explanation: GeneReviews recommends standard neurologist-directed antiseizure treatment.
  - reference: DOI:10.1186/s42494-023-00145-0
    reference_title: "Effective treatment of NR2F1-related epilepsy with perampanel"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      However, seizures were controlled in only 50% of previously reported cases, while all of the six new cases became seizure-free after perampanel as an add-on treatment.
    explanation: >-
      A six-case observational series reports seizure freedom after add-on
      perampanel, supporting a hypothesis-generating treatment signal but not
      disorder-specific comparative superiority.
- name: Multisystem surveillance
  action_category: MONITORING
  description: >-
    Follow-up should monitor growth and feeding safety, development and
    educational needs, seizures and new neurologic manifestations, behavior,
    mobility and self-help skills, visual function and low-vision needs,
    hearing, and family support needs at clinically appropriate intervals.
  treatment_term:
    preferred_term: clinical assessment
    term:
      id: NCIT:C124351
      label: Clinical Evaluation
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable
    reference_title: "NR2F1-Related Neurodevelopmental Disorder - GeneReviews® - NCBI Bookshelf"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Regular monitoring of existing manifestations, the individual's response
      to supportive care, and the emergence of new manifestations.
    explanation: GeneReviews provides the overarching surveillance principle.
- name: Genetic counseling
  action_category: COUNSELING_INFORMATIONAL
  description: >-
    Genetic counseling is recommended given the autosomal dominant inheritance
    and recurrence risk considerations, including the option of prenatal and
    preimplantation genetic testing.
  treatment_term:
    preferred_term: genetic counseling
    term:
      id: NCIT:C15240
      label: Genetic Counseling
  evidence:
  - reference: PMID:36508512
    reference_title: "NR2F1-Related Neurodevelopmental Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Given this risk, prenatal and preimplantation genetic testing may be
      considered.
    explanation: GeneReviews recommends genetic counseling and testing options for recurrence risk.
animal_models:
- species: Mouse
  genotype: Nr2f1 heterozygous knockout (Nr2f1+/-)
  description: >-
    A heterozygous Nr2f1 knockout mouse recapitulates the dosage-sensitive
    genetics of BBSOAS (caused by heterozygous NR2F1 variants) and reproduces
    core neurological phenotypes, including altered learning/memory, hearing
    defects, neonatal hypotonia, and decreased hippocampal volume, together with
    impaired hippocampal synaptic plasticity.
  genes:
  - preferred_term: Nr2f1
    term:
      id: hgnc:7975
      label: NR2F1
  associated_phenotypes:
  - Hypotonia
  - Hearing impairment
  - Impaired learning and memory
  evidence:
  - reference: PMID:31600777
    reference_title: "Nr2f1 heterozygous knockout mice recapitulate neurological phenotypes of Bosch-Boonstra-Schaaf optic atrophy syndrome and show impaired hippocampal synaptic plasticity."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      we investigated a heterozygous knockout mouse model and found that this
      model recapitulates some of the neurological phenotypes of BBSOAS,
      including altered learning/memory, hearing defects, neonatal hypotonia and
      decreased hippocampal volume.
    explanation: >-
      The Nr2f1+/- mouse recapitulates core BBSOAS neurological phenotypes,
      supporting NR2F1 haploinsufficiency as the disease mechanism.
- species: Mouse
  genotype: Nr2f1 mutant
  description: >-
    Nr2f1 mutant mice display abnormal retinogenesis with decreased retinal
    ganglion cell density and disrupted retinal ganglion cell axonal guidance
    from the neural retina into the optic stalk, recapitulating the optic nerve
    hypoplasia seen in BBSOAS and supporting a developmental origin of the visual
    defect.
  genes:
  - preferred_term: Nr2f1
    term:
      id: hgnc:7975
      label: NR2F1
  associated_phenotypes:
  - Optic nerve hypoplasia
  evidence:
  - reference: PMID:34466801
    reference_title: "Pathogenic NR2F1 variants cause a developmental ocular phenotype recapitulated in a mutant mouse model."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Abnormal retinogenesis in early stages of development was observed in
      Nr2f1 mutant mice with decreased retinal ganglion cell density and
      disruption of retinal ganglion cell axonal guidance from the neural retina
      into the optic stalk, accounting for the development of optic nerve
      hypoplasia.
    explanation: >-
      Nr2f1 mutant mice recapitulate the ocular phenotype, supporting a
      developmental origin of the optic nerve hypoplasia seen in BBSOAS.
- species: Mouse
  genotype: >-
    Conditional Nr2f1 loss in the adult hippocampal neurogenic niche and
    heterozygous Nr2f1 loss in a BBSOAS model
  description: >-
    Nr2f1 loss reduces mitochondrial mass, fragments mitochondria, and lowers
    key mitochondrial proteins in newborn neurons; heterozygous mice also show
    dysregulated nuclear-encoded mitochondrial genes and proteins in brain.
  genes:
  - preferred_term: Nr2f1
    term:
      id: hgnc:7975
      label: NR2F1
  associated_phenotypes:
  - Reduced mitochondrial mass
  - Mitochondrial fragmentation
  - Impaired newborn-neuron survival and integration
  evidence:
  - reference: PMID:37260288
    reference_title: "NR2F1 shapes mitochondria in the mouse brain, providing new insights into Bosch-Boonstra-Schaaf optic atrophy syndrome."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      conditional NR2F1 loss of function within the adult mouse hippocampal
      neurogenic niche results in a reduced mitochondrial mass associated with
      mitochondrial fragmentation and downregulation of key mitochondrial
      proteins in newborn neurons
    explanation: >-
      The mouse study directly defines the provisional mitochondrial branch of
      the BBSOAS pathograph.
biochemical: []
environmental: []
diagnosis:
- name: Clinical and imaging recognition
  description: >-
    BBSOAS should be considered when developmental delay or intellectual
    disability co-occurs with optic atrophy, optic nerve hypoplasia, cerebral
    visual impairment, hypotonia, speech difficulty, seizures, feeding
    difficulty, or behavioral manifestations. Thin corpus callosum and
    hypoplastic optic nerves or chiasm on MRI are strongly suggestive, but no
    consensus clinical diagnostic criteria or pathognomonic feature exists.
  presence: A compatible neurodevelopmental, visual, and brain-imaging pattern prompts NR2F1 testing.
  diagnosis_term:
    preferred_term: clinical assessment
    term:
      id: NCIT:C124351
      label: Clinical Evaluation
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable
    reference_title: "NR2F1-Related Neurodevelopmental Disorder - GeneReviews® - NCBI Bookshelf"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Hypoplasia of the optic nerves and optic chiasm are also commonly seen on
      brain MRI
    explanation: GeneReviews defines the suggestive clinical and imaging pattern.
- name: NR2F1 molecular genetic testing
  description: >-
    Molecular confirmation requires a heterozygous pathogenic or likely
    pathogenic NR2F1 variant. Testing should detect both sequence variants and
    copy-number changes through sequence analysis, deletion or duplication
    analysis, and chromosomal microarray as appropriate. Phenotype-focused
    multigene panels, exome sequencing, or genome sequencing are options when
    the diagnosis is not clinically specific.
  presence: Identification of a heterozygous pathogenic or likely pathogenic NR2F1 variant establishes the diagnosis.
  diagnosis_term:
    preferred_term: molecular genetic testing
    term:
      id: NCIT:C19770
      label: Molecular Analysis
    qualifiers:
    - predicate:
        preferred_term: has participant
        term:
          id: RO:0000057
          label: has participant
      value:
        preferred_term: NR2F1
        term:
          id: hgnc:7975
          label: NR2F1
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable
    reference_title: "NR2F1-Related Neurodevelopmental Disorder - GeneReviews® - NCBI Bookshelf"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      is established in a proband with suggestive findings and a heterozygous
      pathogenic (or likely pathogenic) variant in
    explanation: GeneReviews states the molecular criterion that establishes diagnosis.
  - reference: url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable
    reference_title: "NR2F1-Related Neurodevelopmental Disorder - GeneReviews® - NCBI Bookshelf"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Methods used in a panel may include sequence analysis,
      deletion/duplication analysis, and/or other non-sequencing-based tests.
    explanation: >-
      GeneReviews explicitly supports including both sequence and copy-number
      methods in the molecular strategy.
differential_diagnoses:
- name: ADNP-related disorder
  description: >-
    ADNP-related disorder overlaps through severe developmental delay,
    intellectual disability, hypotonia, seizures, autism-spectrum behavior,
    feeding issues, strabismus, hypermetropia, and cerebral visual impairment.
  disease_term:
    preferred_term: ADNP-related multiple congenital anomalies - intellectual disability - autism spectrum disorder
    term:
      id: MONDO:0014379
      label: ADNP-related multiple congenital anomalies - intellectual disability - autism spectrum disorder
  distinguishing_features:
  - Characteristic facial, hand, and foot findings and cardiac, urinary-tract, or endocrine abnormalities favor ADNP-related disorder.
  - Molecular testing distinguishes pathogenic ADNP variation from NR2F1-related disease.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable
    reference_title: "NR2F1-Related Neurodevelopmental Disorder - GeneReviews® - NCBI Bookshelf"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Hypotonia; severe DD; mild-to-severe ID; seizures; visual impairment
      (hypermetropia, strabismus, CVI); behavioral findings; autistic features;
      feeding issues
    explanation: GeneReviews explicitly lists the overlapping ADNP-related phenotype.
- name: NGLY1-related congenital disorder of deglycosylation
  description: >-
    NGLY1 deficiency overlaps through developmental delay or intellectual
    disability, seizures, and reduced or absent tears.
  disease_term:
    preferred_term: congenital disorder of deglycosylation 1
    term:
      id: MONDO:0800044
      label: congenital disorder of deglycosylation 1
  distinguishing_features:
  - Hyperkinetic movement disorder and elevated liver transaminases favor NGLY1 deficiency.
  - Molecular testing identifies biallelic NGLY1 rather than heterozygous NR2F1 variation.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable
    reference_title: "NR2F1-Related Neurodevelopmental Disorder - GeneReviews® - NCBI Bookshelf"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      DD/ID; hypolacrima, alacrima; seizures
    explanation: GeneReviews explicitly lists the overlapping NGLY1-related phenotype.
datasets:
- accession: geo:GSE106302
  title: Hippocampal gene expression from Nr2f1 heterozygous knockout and WT mice
  description: >-
    Bulk RNA-seq comparing adult hippocampi from Nr2f1 heterozygous knockout
    mice with wild-type controls, associated with the mouse-model study of
    BBSOAS neurologic phenotypes and synaptic plasticity.
  organism:
    preferred_term: mouse
    term:
      id: NCBITaxon:10090
      label: Mus musculus
  data_type: BULK_RNA_SEQ
  sample_types:
  - preferred_term: hippocampal formation
    term:
      id: UBERON:0002421
      label: hippocampal formation
    tissue_term:
      preferred_term: hippocampal formation
      term:
        id: UBERON:0002421
        label: hippocampal formation
  conditions:
  - Nr2f1 heterozygous knockout adult mouse hippocampus
  - Wild-type adult mouse hippocampus
  publication: PMID:31600777
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE106302
    reference_title: GEO Accession viewer
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      RNA-seq of hippocampus from Nr2f1 heterozygous knockout and WT mice.
    explanation: The GEO record supplies the accession, tissue, perturbation, and assay.
- accession: geo:GSE228566
  title: Nr2f1 chromatin occupancy in mouse cortex
  description: >-
    Mouse-cortex COUP-TFI/NR2F1 chromatin immunoprecipitation sequencing with
    IgG and H3K4me3 comparators, used to identify candidate direct
    nuclear-encoded mitochondrial targets in a BBSOAS mechanism study.
  organism:
    preferred_term: mouse
    term:
      id: NCBITaxon:10090
      label: Mus musculus
  data_type: CHIP_SEQ
  sample_types:
  - preferred_term: cerebral cortex
    term:
      id: UBERON:0000956
      label: cerebral cortex
    tissue_term:
      preferred_term: cerebral cortex
      term:
        id: UBERON:0000956
        label: cerebral cortex
  conditions:
  - COUP-TFI chromatin immunoprecipitation in mouse cortex
  - IgG control in mouse cortex
  - H3K4me3 chromatin immunoprecipitation in mouse cortex
  publication: PMID:37260288
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE228566
    reference_title: GEO Accession viewer
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Coup-TF1_Cortex
    explanation: >-
      The GEO series lists the COUP-TFI mouse-cortex chromatin sample deposited
      under GSE228566; its adjacent series records provide the IgG and H3K4me3
      comparators described in the conditions.
clinical_trials: []
discussions:
- discussion_id: bbsoas_variant_mechanism
  prompt: >-
    Which NR2F1 alleles act as simple loss-of-function variants and which exert
    clinically meaningful dominant-negative or other altered-protein effects?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - genetic#NR2F1
  - pathophysiology#NR2F1 functional insufficiency and variant-specific dominant-negative effects
  rationale: >-
    Haploinsufficiency is established for deletions and many loss-of-function
    alleles. DNA-binding-domain variants may act dominant negatively and show a
    more severe cohort-level phenotype, but available series are small and the
    effect cannot be generalized to every missense or truncating allele.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable
    reference_title: "NR2F1-Related Neurodevelopmental Disorder - GeneReviews® - NCBI Bookshelf"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Preliminary genotype-phenotype correlations based on published reports to date suggest
    explanation: GeneReviews explicitly labels the genotype-phenotype correlation preliminary.
- discussion_id: bbsoas_prevalence_discrepancy
  prompt: >-
    What is the true population prevalence of BBSOAS, and why do current
    Orphadata and literature estimates differ by at least an order of magnitude?
  kind: CONTROVERSY
  status: OPEN
  rationale: >-
    Orphadata provides a class-only estimate below one per million, whereas
    GeneReviews cites approximately one per 100,000 to one per 250,000.
    Underdiagnosis, different denominators, and reuse of early case counts may
    contribute, but no population-based study resolves the discrepancy.
  evidence:
  - reference: url:https://api.orphadata.com/rd-epidemiology/orphacodes/401777
    reference_title: "https://api.orphadata.com/rd-epidemiology/orphacodes/401777"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      "PrevalenceClass": "<1 / 1 000 000"
    explanation: Orphadata supplies the lower class-only estimate.
  - reference: url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable
    reference_title: "NR2F1-Related Neurodevelopmental Disorder - GeneReviews® - NCBI Bookshelf"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      estimated prevalence from 1:100,000 to 1:250,000 people worldwide
    explanation: GeneReviews supplies the higher literature estimate.
- discussion_id: bbsoas_visual_natural_history
  prompt: >-
    Is visual function non-progressive across the full lifespan and across all
    NR2F1 variant classes?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - progression#Longitudinal visual and neurologic course
  rationale: >-
    Existing longitudinal observations favor a developmental, non-progressive
    optic neuropathy, but the cohort is small, follow-up is uneven, and adult
    data are sparse. The entry therefore describes the visual course as
    generally rather than universally non-progressive.
  evidence:
  - reference: PMID:34466801
    reference_title: "Pathogenic NR2F1 variants cause a developmental ocular phenotype recapitulated in a mutant mouse model."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      for those individuals with available longitudinal ophthalmological data,
      there was no significant deterioration in visual function during the
      period of follow-up.
    explanation: The cohort supports stability over observed follow-up, not the entire lifespan.
- discussion_id: bbsoas_mitochondrial_translation
  prompt: >-
    Does the mitochondrial phenotype in Nr2f1-deficient mouse neurons occur in
    human BBSOAS neural tissue and materially drive clinical manifestations?
  kind: HUMAN_MODEL_MISMATCH
  status: OPEN
  attaches_to:
  - pathophysiology#Neuronal mitochondrial network dysregulation
  rationale: >-
    The mouse data identify altered mitochondrial genes, proteins, mass, and
    morphology, but no human neural-tissue validation or clinical biomarker
    currently establishes this branch as a driver in affected individuals.
  evidence:
  - reference: PMID:37260288
    reference_title: "NR2F1 shapes mitochondria in the mouse brain, providing new insights into Bosch-Boonstra-Schaaf optic atrophy syndrome."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Our data point to an active role for NR2F1 in the mitochondrial gene
      expression regulatory network in neurons and support the involvement of
      mitochondrial dysfunction in BBSOAS pathogenesis.
    explanation: The publication frames mitochondrial involvement as supported by model data.
review_notes: >-
  The 2026 re-review expanded the original two-node pathograph into an
  allele-aware model that distinguishes established NR2F1 functional
  insufficiency from possible variant-specific dominant-negative effects and
  retains mouse neuronal mitochondrial dysfunction as a provisional branch.
  Every pathograph edge now has a causal-link classification and direct
  evidence, and all represented phenotypes are connected. Current Orphadata
  records supply the exact MONDO mapping, neonatal onset, phenotype frequencies,
  and the class-only prevalence estimate; the conflicting GeneReviews
  prevalence range is retained rather than silently reconciled. The review also
  adds structured progression, high but variable clinical burden, molecular
  diagnosis, two explicit differentials, multisystem supportive management,
  GSE106302 and GSE228566, and open questions about allele mechanism, prevalence,
  lifelong visual stability, and model-to-human mitochondrial translation.
  ClinicalTrials.gov API queries for the disease name, NR2F1-related
  neurodevelopmental disorder, and NR2F1 were checked on 2026-07-24 and returned
  no disease-specific studies, so clinical_trials remains empty. No
  disease-modifying treatment is established. The D2P audit was used to flag
  external phenotype assertions; central source-backed findings were added, but
  granular rows without precise cached human evidence were not bulk-imported.
  The bundled deep-research report was used only to discover sources; all
  included claims were checked against direct cached publications or structured
  source records.
📚

References & Deep Research

References

16
PMID:24462372
NR2F1 mutations cause optic atrophy with intellectual disability.
No top-level findings curated for this source.
PMID:26986877
The expanding clinical phenotype of Bosch-Boonstra-Schaaf optic atrophy syndrome: 20 new cases and possible genotype-phenotype correlations.
No top-level findings curated for this source.
PMID:29709504
The pleiotropic transcriptional regulator COUP-TFI plays multiple roles in neural development and disease.
No top-level findings curated for this source.
PMID:31600777
Nr2f1 heterozygous knockout mice recapitulate neurological phenotypes of Bosch-Boonstra-Schaaf optic atrophy syndrome and show impaired hippocampal synaptic plasticity.
No top-level findings curated for this source.
PMID:32275123
Phenotypic expansion of Bosch-Boonstra-Schaaf optic atrophy syndrome and further evidence for genotype-phenotype correlations.
No top-level findings curated for this source.
PMID:34466801
Pathogenic NR2F1 variants cause a developmental ocular phenotype recapitulated in a mutant mouse model.
No top-level findings curated for this source.
PMID:35455940
Pathophysiological Heterogeneity of the BBSOA Neurodevelopmental Syndrome.
No top-level findings curated for this source.
PMID:36508512
NR2F1-Related Neurodevelopmental Disorder.
No top-level findings curated for this source.
PMID:37260288
NR2F1 shapes mitochondria in the mouse brain, providing new insights into Bosch-Boonstra-Schaaf optic atrophy syndrome.
No top-level findings curated for this source.
url:https://www.ncbi.nlm.nih.gov/books/NBK587319/?report=printable
NR2F1-Related Neurodevelopmental Disorder - GeneReviews® - NCBI Bookshelf
No top-level findings curated for this source.
url:https://api.orphadata.com/rd-cross-referencing/orphacodes/401777
https://api.orphadata.com/rd-cross-referencing/orphacodes/401777
No top-level findings curated for this source.
url:https://api.orphadata.com/rd-epidemiology/orphacodes/401777
https://api.orphadata.com/rd-epidemiology/orphacodes/401777
No top-level findings curated for this source.
url:https://api.orphadata.com/rd-natural_history/orphacodes/401777
https://api.orphadata.com/rd-natural_history/orphacodes/401777
No top-level findings curated for this source.
url:https://api.orphadata.com/rd-phenotypes/orphacodes/401777
https://api.orphadata.com/rd-phenotypes/orphacodes/401777
No top-level findings curated for this source.
No top-level findings curated for this source.
No top-level findings curated for this source.

Deep Research

1
Falcon ▸
1. Disease Information
Edison Scientific Literature 23 citations 2026-06-04T10:15:10.934779

1. Disease Information

1.1 Concise overview (what is the disease?)

BBSOAS is a neurodevelopmental syndrome with prominent visual-system involvement. A 2022 review defines it as “a recently described monogenic neurodevelopmental syndrome caused by the haploinsufficiency of NR2F1 gene” (Cells 2022; doi:10.3390/cells11081260). (bertacchi2022pathophysiologicalheterogeneityof pages 2-5)

A large ophthalmology/neurodevelopment-focused cohort paper describes it as “an autosomal dominant disorder characterized by delayed neurodevelopment, moderate to severe intellectual disability and visual impairment.” (Brain Communications 2021; doi:10.1093/braincomms/fcab162). (jurkute2021pathogenicnr2f1variants pages 3-4)

1.2 Key identifiers and alternative names

Resource Identifier Preferred name in that resource Notes
OMIM 615722 Bosch–Boonstra–Schaaf Optic Atrophy Syndrome Explicitly stated in retrieved review and primary papers; also abbreviated BBSOAS/BBSOA in some sources (bonzano2023nr2f1shapesmitochondria pages 1-2, jurkute2021pathogenicnr2f1variants pages 1-3, jurkute2021pathogenicnr2f1variants pages 3-4, bertacchi2019mousenr2f1haploinsufficiency pages 1-2, chen2020nr2f1heterozygousknockout pages 1-2)
Orphanet ORPHA 401777 Bosch–Boonstra–Schaaf Optic Atrophy Syndrome Explicitly stated in Jurkute et al. 2021 and Bertacchi et al. 2022 review excerpts (bertacchi2022pathophysiologicalheterogeneityof pages 18-20, jurkute2021pathogenicnr2f1variants pages 3-4)
MONDO not retrieved in this run not retrieved in this run No MONDO identifier was present in retrieved evidence (jurkute2021pathogenicnr2f1variants pages 1-3, bertacchi2022pathophysiologicalheterogeneityof pages 18-20)
MeSH not retrieved in this run not retrieved in this run No MeSH descriptor was present in retrieved evidence (jurkute2021pathogenicnr2f1variants pages 1-3, bertacchi2022pathophysiologicalheterogeneityof pages 18-20)
ICD-10 not retrieved in this run not retrieved in this run No ICD-10 code was present in retrieved evidence (bertacchi2022pathophysiologicalheterogeneityof pages 18-20, bertacchi2022pathophysiologicalheterogeneityof pages 15-17)
ICD-11 not retrieved in this run not retrieved in this run No ICD-11 code was present in retrieved evidence (bertacchi2022pathophysiologicalheterogeneityof pages 18-20, bertacchi2022pathophysiologicalheterogeneityof pages 15-17)
Gene (causal disease gene) OMIM 132890 NR2F1 Disease is caused by pathogenic variants/haploinsufficiency of NR2F1; included here because multiple sources explicitly pair disease identifier with gene identifier (bonzano2023nr2f1shapesmitochondria pages 1-2, jurkute2021pathogenicnr2f1variants pages 3-4, jurkute2021pathogenicnr2f1variants pages 20-21)
Cytogenetic locus 5q15 NR2F1 locus / chromosome 5q15 Retrieved as the gene locus associated with the disorder, not a disease identifier per se (jurkute2021pathogenicnr2f1variants pages 3-4)
Alternative disease label in literature NR2F1-related neurodevelopmental disorder not a formal database identifier in retrieved evidence Used in newer literature/case discussions as broader terminology encompassing BBSOAS phenotypic spectrum; formal resource identifier not retrieved here (tang2025casereporta pages 7-7)
Alternative disease label in literature BBSOA syndrome Bosch-Boonstra-Schaaf optic atrophy syndrome Variant spelling/abbreviation used in some sources, especially 2019 mouse-model paper (bertacchi2019mousenr2f1haploinsufficiency pages 1-2)

Table: This table compiles the standardized identifiers and nomenclature for Bosch–Boonstra–Schaaf optic atrophy syndrome that were explicitly supported by the retrieved evidence. It also marks major resources where identifiers were not retrieved in this run, which helps distinguish confirmed facts from gaps in the current evidence collection.

Common synonyms / alternative names (as used in retrieved literature): - Bosch–Boonstra–Schaaf optic atrophy syndrome (BBSOAS) (bertacchi2022pathophysiologicalheterogeneityof pages 2-5, jurkute2021pathogenicnr2f1variants pages 3-4) - Bosch–Boonstra–Schaaf optic atrophy (BBSOA) syndrome (variant abbreviation used in some papers) (bertacchi2019mousenr2f1haploinsufficiency pages 1-2) - NR2F1-related neurodevelopmental disorder (broader terminology used in recent discussions) (tang2025casereporta pages 7-7)

1.3 Evidence source types

The information synthesized here is derived from: - Aggregated disease-level resources and synthesis reviews (Cells 2022) (bertacchi2022pathophysiologicalheterogeneityof pages 2-5) - Human case series/cohort deep-phenotyping (n=22) (Brain Communications 2021) (jurkute2021pathogenicnr2f1variants pages 1-3) - Human case reports and genotype-group literature syntheses (Frontiers in Medicine 2025; case-based meta-summary table) (tang2025casereporta pages 6-7) - Model organism studies (mouse) providing mechanistic support (EMBO Mol Med 2019; HMG 2020; DMM 2023) (bertacchi2019mousenr2f1haploinsufficiency pages 1-2, chen2020nr2f1heterozygousknockout pages 3-3, bonzano2023nr2f1shapesmitochondria pages 1-2)

2. Etiology

2.1 Disease causal factors

Genetic cause (primary): Pathogenic variants or deletions affecting NR2F1 cause BBSOAS; the dominant mechanism is NR2F1 haploinsufficiency, with evidence that some variants may also produce dominant-negative effects. (bertacchi2022pathophysiologicalheterogeneityof pages 2-5, bonzano2023nr2f1shapesmitochondria pages 1-2)

Mechanistic framing: NR2F1 is a nuclear receptor transcription factor with conserved DNA-binding and ligand-binding domains; disease-associated variants cluster in these functional domains and disrupt transcriptional regulation during brain and eye development. (bertacchi2022pathophysiologicalheterogeneityof pages 2-5, jurkute2021pathogenicnr2f1variants pages 3-4)

2.2 Risk factors

Because BBSOAS is Mendelian and largely de novo, “risk factors” are primarily genetic: - De novo variants are common: the 2022 review summarizes that most variants were diagnosed as de novo (73.9%), with some familial cases (7.6%) and a subset due to deletions (16.3%). (bertacchi2022pathophysiologicalheterogeneityof pages 2-5) - Variant location correlates with phenotype severity: DBD variants show higher rates of epilepsy and ASD in a genotype-group comparison (see Section 4). (tang2025casereporta pages 6-7)

No environmental risk factors were identified in the retrieved evidence set.

2.3 Protective factors / gene–environment interactions

No protective factors or gene–environment interactions were identified in the retrieved evidence set; the disorder is primarily driven by NR2F1 dosage/function. (bertacchi2022pathophysiologicalheterogeneityof pages 2-5)

3. Phenotypes

3.1 Core phenotype spectrum and frequencies

BBSOAS is characterized by multi-system neurodevelopmental and ocular phenotypes.

Phenotype Frequency / quantitative data Age / onset notes Progression notes Source type Suggested HPO term
Developmental delay 88% overall; DBD-group 33/36 (91.67%) vs non-DBD-group 52/64 (81.25%) (bertacchi2022pathophysiologicalheterogeneityof pages 15-17, tang2025casereporta pages 6-7) Usually evident in infancy/early childhood through delayed milestones (walking, first words) (bertacchi2022pathophysiologicalheterogeneityof pages 15-17, bertacchi2022pathophysiologicalheterogeneityof pages 18-20) Chronic neurodevelopmental phenotype; not described as remitting (bertacchi2022pathophysiologicalheterogeneityof pages 15-17) Review + case-based genotype-phenotype comparison HP:0001263
Intellectual disability 85.9% overall (bertacchi2022pathophysiologicalheterogeneityof pages 15-17) Typically recognized in childhood after developmental concerns; severity ranges mild to severe (bonzano2023nr2f1shapesmitochondria pages 1-2, bertacchi2022pathophysiologicalheterogeneityof pages 15-17) Persistent; variable expressivity (bertacchi2022pathophysiologicalheterogeneityof pages 15-17) Review HP:0001249
Optic atrophy / optic nerve impairment Optic atrophy 66.3% overall; optic nerve impairment 31/36 (86.11%) vs 48/64 (75.00%) by genotype groups (bertacchi2022pathophysiologicalheterogeneityof pages 15-17, tang2025casereporta pages 6-7) Visual abnormality often apparent in early childhood; may be suspected in infancy with poor eye tracking (jurkute2021pathogenicnr2f1variants pages 1-3, bertacchi2022pathophysiologicalheterogeneityof pages 18-20) Visual loss in BBSOAS appears largely non-progressive in available longitudinal ophthalmic follow-up, although classic OA is generally degenerative; BBSOAS includes developmental ONH/OA overlap (jurkute2021pathogenicnr2f1variants pages 1-3, bertacchi2022pathophysiologicalheterogeneityof pages 18-20) Review + case series + genotype-phenotype comparison HP:0000648
Optic nerve hypoplasia / small hypoplastic optic nerves Small and/or tilted hypoplastic optic nerves in 10/22 individuals (jurkute2021pathogenicnr2f1variants pages 1-3) Early childhood / congenital developmental ocular phenotype (jurkute2021pathogenicnr2f1variants pages 1-3, bertacchi2022pathophysiologicalheterogeneityof pages 18-20) Congenital, generally non-progressive developmental defect (bertacchi2022pathophysiologicalheterogeneityof pages 18-20, jurkute2021pathogenicnr2f1variants pages 1-3) Case series HP:0008058
Visual impairment / reduced visual acuity Vision impairment 27/36 (75.00%) vs 53/64 (82.81%); low visual acuity described as common (tang2025casereporta pages 6-7, bertacchi2022pathophysiologicalheterogeneityof pages 15-17) Becomes apparent in early childhood; infancy may show poor eye tracking (jurkute2021pathogenicnr2f1variants pages 1-3, bertacchi2022pathophysiologicalheterogeneityof pages 18-20) “No significant deterioration” over follow-up in available longitudinal data; stable non-progressive reduction in visual acuity reported (jurkute2021pathogenicnr2f1variants pages 1-3, bertacchi2022pathophysiologicalheterogeneityof pages 15-17) Case series + review + genotype-phenotype comparison HP:0000505
Cortical visual impairment 44.6% overall (bertacchi2022pathophysiologicalheterogeneityof pages 15-17) Usually recognized in infancy/childhood during neuro-ophthalmic assessment (bertacchi2022pathophysiologicalheterogeneityof pages 15-17, bertacchi2022pathophysiologicalheterogeneityof pages 18-20) Often treated clinically as a developmental visual-processing deficit; progression not clearly established (bertacchi2022pathophysiologicalheterogeneityof pages 18-20) Review HP:0100704
Epilepsy / seizures 46.7% overall; DBD-group 24/36 (66.67%) vs non-DBD-group 22/64 (34.38%), p=0.002 (bertacchi2022pathophysiologicalheterogeneityof pages 15-17, tang2025casereporta pages 6-7) Can present in infancy, including infantile spasms, or later childhood (bertacchi2022pathophysiologicalheterogeneityof pages 15-17, tang2025casereporta pages 7-7) Variable course; chronic seizure disorder when present (bertacchi2022pathophysiologicalheterogeneityof pages 15-17) Review + genotype-phenotype comparison HP:0001250
Autism spectrum disorder / autistic traits ASD 39.1% overall and autistic traits 14.1%; DBD-group ASD 22/36 (61.11%) vs non-DBD-group 23/64 (35.94%), p=0.015 (bertacchi2022pathophysiologicalheterogeneityof pages 15-17, tang2025casereporta pages 6-7) Usually recognized in childhood during behavioral/developmental assessment (bertacchi2022pathophysiologicalheterogeneityof pages 15-17) Persistent neurobehavioral phenotype; variable severity (bertacchi2022pathophysiologicalheterogeneityof pages 15-17) Review + genotype-phenotype comparison HP:0000729
Hypotonia 62% overall (bertacchi2022pathophysiologicalheterogeneityof pages 15-17) Often among earliest infantile findings (bertacchi2022pathophysiologicalheterogeneityof pages 15-17, bertacchi2022pathophysiologicalheterogeneityof pages 18-20) May persist and contribute to motor delay; course variably described (bertacchi2022pathophysiologicalheterogeneityof pages 15-17) Review HP:0001252
Hearing impairment 11% overall (bertacchi2022pathophysiologicalheterogeneityof pages 15-17) Childhood recognition; periodic hearing evaluation recommended in care pathways (bertacchi2022pathophysiologicalheterogeneityof pages 15-17, bertacchi2022pathophysiologicalheterogeneityof pages 18-20) Progression not established from retrieved evidence (bertacchi2022pathophysiologicalheterogeneityof pages 18-20) Review HP:0000365
Abnormal corpus callosum DBD-group 16/36 (44.44%) vs non-DBD-group 16/64 (25.00%), p=0.045 (tang2025casereporta pages 6-7) Developmental brain malformation detectable on MRI, usually identified in childhood workup (tang2025casereporta pages 6-7, bertacchi2022pathophysiologicalheterogeneityof pages 15-17) Structural/developmental; not a progressive lesion per se (tang2025casereporta pages 6-7) Genotype-phenotype comparison HP:0001273
Retinal ganglion cell loss / ganglion cell layer thinning Qualitative but significant OCT/electrophysiologic evidence of RGC loss and ganglion cell layer thinning in the 22-person cohort (jurkute2021pathogenicnr2f1variants pages 1-3) Developmental ocular defect evident with detailed ophthalmic testing in childhood (jurkute2021pathogenicnr2f1variants pages 1-3) Supports congenital, largely non-progressive visual deficit in available follow-up (jurkute2021pathogenicnr2f1variants pages 1-3) Case series HP:0030639

Table: This table summarizes phenotype frequencies, onset patterns, and progression notes for Bosch–Boonstra–Schaaf optic atrophy syndrome using the retrieved review, case-series, and genotype–phenotype comparison evidence. It is useful for rapid knowledge-base extraction of common manifestations and associated HPO terms.

Key quantitative phenotype data from the 2022 synthesis review include: DD (~88%), ID (~85.9%), optic atrophy (~66.3%), cortical visual impairment (~44.6%), epilepsy (~46.7%), hypotonia (~62%), hearing impairment (~11%), ASD/autistic traits (~39.1% ASD; 14.1% autistic traits). (bertacchi2022pathophysiologicalheterogeneityof pages 15-17)

3.2 Ophthalmologic phenotyping and natural history

A deep phenotyping study of 22 individuals carrying pathogenic NR2F1 variants reported early-childhood onset of visual impairment, with “small and/or tilted hypoplastic optic nerves observed in 10 cases,” and OCT/electrophysiology evidence supporting retinal ganglion cell (RGC) involvement. Longitudinal data suggested stability: “there was no significant deterioration in visual function during the period of follow-up.” (jurkute2021pathogenicnr2f1variants pages 1-3)

3.3 Quality-of-life and functional impact

Although disease-specific QoL instruments were not retrieved in this run, the phenotypes imply significant functional impact: - Visual impairment (optic nerve hypoplasia/atrophy; CVI) affects learning, mobility, and communication (jurkute2021pathogenicnr2f1variants pages 1-3, bertacchi2022pathophysiologicalheterogeneityof pages 18-20) - DD/ID, speech delay, hypotonia, seizures, and ASD traits affect educational needs and adaptive functioning (bertacchi2022pathophysiologicalheterogeneityof pages 15-17)

4. Genetic / Molecular Information

4.1 Causal gene

NR2F1 (COUP-TFI) is the established causal gene; BBSOAS is linked to NR2F1 haploinsufficiency. (bertacchi2022pathophysiologicalheterogeneityof pages 2-5, jurkute2021pathogenicnr2f1variants pages 3-4)

4.2 Pathogenic variant spectrum and genotype–phenotype notes

Variant class/location Examples (HGVS where present) Reported proportion or counts Reported phenotype-severity notes Mechanism interpretation as stated
Whole-gene or intragenic deletion involving NR2F1 Whole-gene deletion (599 kb); deletions reported as 400–500 kb, 582 kb, and larger CNVs including adjacent genes; exact HGVS not provided in retrieved evidence 15/92 clinically described patients (16.3%) had small-to-large deletions involving NR2F1 alone or with adjacent genes (bertacchi2022pathophysiologicalheterogeneityof pages 2-5, bertacchi2022pathophysiologicalheterogeneityof pages 5-7) Deletions are part of the classic BBSOAS spectrum with DD/ID and optic nerve abnormalities; early reports with larger deletions initially complicated gene attribution because additional genes were included (bertacchi2022pathophysiologicalheterogeneityof pages 2-5, bertacchi2022pathophysiologicalheterogeneityof pages 5-7) Consistent with haploinsufficiency; review states BBSOAS is caused by gene deletion or loss-of-function mutations affecting one allele (bonzano2023nr2f1shapesmitochondria pages 1-2, bertacchi2022pathophysiologicalheterogeneityof pages 5-7)
Start-codon / translation-initiation variants p.M1?; “translation initiation variants” 9/92 patients (9.8%) in the 2022 review summary (bertacchi2022pathophysiologicalheterogeneityof pages 2-5) Optic atrophy reported in 78% of patients with translation-initiation variants, among the highest OA frequencies across classes (bertacchi2022pathophysiologicalheterogeneityof pages 18-20) Interpreted within the review as loss-of-function / haploinsufficiency class (bertacchi2022pathophysiologicalheterogeneityof pages 5-7, bertacchi2022pathophysiologicalheterogeneityof pages 18-20)
DNA-binding domain (DBD) missense / point variants p.Gly105Ser; p.Cys146Tyr; p.Arg112Lys; p.Met151Thr; c.365G>T p.Cys122Phe; c.449G>T p.Gly150Val 32/92 patients (34.8%) had variants in the DBD in the 2022 review summary; later genotype comparison grouped 36 DBD cases vs 64 non-DBD cases (bertacchi2022pathophysiologicalheterogeneityof pages 2-5, tang2025casereporta pages 6-7) DBD variants are associated with relatively more severe phenotypes: optic atrophy 78%; developmental delay 33/36 (91.67%) vs 52/64 (81.25%); epilepsy 24/36 (66.67%) vs 22/64 (34.38%), p=0.002; ASD 22/36 (61.11%) vs 23/64 (35.94%), p=0.015; abnormal corpus callosum 16/36 (44.44%) vs 16/64 (25.00%), p=0.045 (bertacchi2022pathophysiologicalheterogeneityof pages 18-20, tang2025casereporta pages 6-7) Review notes DBD variants often severely impair transcription-factor function; Bonzano 2023 states variants are “predominantly located in the DNA-binding domain and lead to haploinsufficiency or dominant-negative effects” (bonzano2023nr2f1shapesmitochondria pages 1-2, tang2025casereporta pages 6-7)
Ligand-binding domain (LBD) missense variants p.Met406Thr 17/92 patients (18.5%) had variants in the LBD (bertacchi2022pathophysiologicalheterogeneityof pages 2-5) LBD variants are associated with a milder ocular burden in aggregate: optic atrophy reported in 47% of LBD cases versus higher frequencies for DBD/start-codon/truncating classes (bertacchi2022pathophysiologicalheterogeneityof pages 18-20) Bonzano 2023 states pathogenic variants overall can produce haploinsufficiency or dominant-negative effects; the 2022 review discusses possible effects on dimerization/co-factor binding for LBD-altering mutations (bonzano2023nr2f1shapesmitochondria pages 1-2, bertacchi2022pathophysiologicalheterogeneityof pages 2-5)
Truncating variants (nonsense) p.Glu400* 11/92 patients (12.0%) had truncation variants (bertacchi2022pathophysiologicalheterogeneityof pages 2-5) Truncating classes are among those with high optic atrophy burden; review groups frameshift/truncations with OA in 72% of patients (bertacchi2022pathophysiologicalheterogeneityof pages 18-20) Generally treated as loss-of-function / haploinsufficiency in the disease framework (bonzano2023nr2f1shapesmitochondria pages 1-2, bertacchi2022pathophysiologicalheterogeneityof pages 5-7, bertacchi2019mousenr2f1haploinsufficiency pages 1-2)
Frameshift / frameshift-truncating variants Specific HGVS not retrieved in accessible excerpts 7/92 patients (7.6%) had frameshift/truncation variants (bertacchi2022pathophysiologicalheterogeneityof pages 2-5) Review combines frameshift/truncation classes and reports optic atrophy in 72%; these are part of the more severe ocular classes compared with LBD variants (bertacchi2022pathophysiologicalheterogeneityof pages 18-20) Usually interpreted as loss-of-function / haploinsufficiency; some literature outside accessible full text has discussed dominant-negative frameshift effects, but this was not directly retrievable here, so only haploinsufficiency can be stated confidently from retrieved evidence (bertacchi2022pathophysiologicalheterogeneityof pages 5-7, bertacchi2019mousenr2f1haploinsufficiency pages 1-2)
Mixed point variants/small in-frame deletions overall Small indels and point variants concentrated in ATG start codon, DBD, and LBD 77/92 patients (83.7%) had point variants or small in-frame deletions; total reported variants in the review: 112 NR2F1 variants and 92 clinically described patients (bertacchi2022pathophysiologicalheterogeneityof pages 2-5) Across all classes, the syndrome shows variable expressivity with DD, ID, optic nerve abnormalities, epilepsy, ASD/autistic traits, hypotonia, and hearing issues; review emphasizes emerging genotype-phenotype correlation rather than absolute class-specific determinism (bertacchi2022pathophysiologicalheterogeneityof pages 15-17, bertacchi2022pathophysiologicalheterogeneityof pages 18-20) Disease mechanism is framed broadly as NR2F1 haploinsufficiency, with some missense variants potentially exerting dominant-negative effects depending on domain and dimerization consequences (bonzano2023nr2f1shapesmitochondria pages 1-2, bertacchi2022pathophysiologicalheterogeneityof pages 2-5)

Table: This table summarizes the NR2F1 variant classes reported for Bosch–Boonstra–Schaaf optic atrophy syndrome / NR2F1-related neurodevelopmental disorder and the main genotype–phenotype patterns supported by the retrieved literature. It is useful for linking variant location to disease severity, especially ocular and neurodevelopmental features.

Genotype–phenotype correlations (examples supported by retrieved evidence): - Optic atrophy frequency differs by variant class: DBD variants (78%), translation-initiation variants (78%), frameshift/truncations (72%), LBD variants (47%). (bertacchi2022pathophysiologicalheterogeneityof pages 18-20) - In a genotype-group comparison (DBD vs non-DBD), epilepsy and ASD were significantly more frequent in the DBD group (epilepsy 66.67% vs 34.38%, p=0.002; ASD 61.11% vs 35.94%, p=0.015). (tang2025casereporta pages 6-7)

4.3 Variant interpretation frameworks

Clinical variant classification and reclassification using ACMG/AMP principles is highlighted in recent case literature. (tang2025casereporta pages 6-7, tang2025casereporta pages 7-7)

5. Environmental Information

No non-genetic environmental contributors, lifestyle factors, or infectious triggers were identified in the retrieved sources; the disorder is primarily genetic. (bertacchi2022pathophysiologicalheterogeneityof pages 2-5)

6. Mechanism / Pathophysiology

6.1 Mechanistic causal chain (integrated view)

A coherent mechanistic chain supported by the retrieved literature is: 1) NR2F1 loss-of-function perturbs transcriptional regulation during neurodevelopment (bertacchi2022pathophysiologicalheterogeneityof pages 2-5, jurkute2021pathogenicnr2f1variants pages 3-4) 2) In the visual system, this contributes to abnormal retinogenesis, reduced RGC density, and disrupted RGC axon guidance into the optic stalk (mouse data) and to RGC dysfunction/ganglion cell layer thinning (human OCT/electrophysiology), producing congenital/early-childhood visual impairment that appears often non-progressive in available follow-up (jurkute2021pathogenicnr2f1variants pages 1-3) 3) In optic nerve, mouse haploinsufficiency causes oligodendrocyte–astrocyte imbalance, postnatal hypomyelination and astrogliosis, slowing conduction from retina to higher visual centers and impairing visual learning (bertacchi2019mousenr2f1haploinsufficiency pages 1-2) 4) In broader neurodevelopmental circuitry, Nr2f1 haploinsufficiency impairs hippocampal synaptic plasticity (reduced LTP/LTD), providing a plausible mechanism for ID and learning/memory phenotypes; transcriptomics reveal differential expression including upregulated MMPs (chen2020nr2f1heterozygousknockout pages 3-3) 5) Newer mechanistic work suggests NR2F1 also regulates nuclear-encoded mitochondrial genes, with reduced mitochondrial mass/fragmentation and reduced newborn neuron survival/integration, implicating mitochondrial dysfunction in pathogenesis (bonzano2023nr2f1shapesmitochondria pages 1-2)

6.2 Ontology suggestions (GO/CL/UBERON)

Mechanism/biological process Evidence summary Suggested GO Biological Process term(s) Suggested GO Cellular Component term(s) Suggested CL cell type term(s) Suggested UBERON anatomical structure term(s) Source(s)
Early retinogenesis defect NR2F1 pathogenic variants are associated with a developmental ocular phenotype; human deep phenotyping and mouse data support abnormal early retinal development with decreased retinal ganglion cell density, consistent with congenital visual impairment rather than classic progressive optic neuropathy. retina development; neural retina development; retinal ganglion cell differentiation; eye morphogenesis neural retina; ganglion cell layer; optic nerve head retinal ganglion cell; retinal progenitor cell retina; neural retina; optic nerve head; eye (jurkute2021pathogenicnr2f1variants pages 1-3, jurkute2021pathogenicnr2f1variants pages 3-4)
Retinal ganglion cell loss and ganglion cell layer thinning OCT in affected individuals showed significant ganglion cell layer thinning with electrophysiologic evidence of retinal ganglion cell dysfunction, indicating structural and functional vulnerability of RGCs in BBSOAS. retinal ganglion cell axonogenesis; neuron projection development; visual system development ganglion cell layer; retinal nerve fiber layer; axon retinal ganglion cell retina; retinal ganglion cell layer; optic nerve (jurkute2021pathogenicnr2f1variants pages 1-3, jurkute2021pathogenicnr2f1variants pages 3-4)
Retinal ganglion cell axon guidance into optic stalk Mouse Nr2f1 mutants showed disrupted retinal ganglion cell axonal guidance from neural retina into the optic stalk, providing a developmental explanation for optic nerve hypoplasia. axon guidance; retinal ganglion cell axon guidance; optic nerve development growth cone; axon; optic stalk region retinal ganglion cell neural retina; optic stalk; optic nerve (jurkute2021pathogenicnr2f1variants pages 1-3)
Extracortical visual pathway disorganization Diffusion tensor imaging tractography in patients showed defective connections and disorganization of extracortical visual pathways, supporting cerebral visual pathway involvement beyond the optic nerve. visual system development; axon tract development; forebrain neuron projection development white matter; axon tract; myelinated axon projection neuron optic tract; lateral geniculate nucleus pathway region; visual pathway white matter (jurkute2021pathogenicnr2f1variants pages 1-3, jurkute2021pathogenicnr2f1variants media 1490a58e)
Oligodendrocyte/astrocyte imbalance in optic nerve Nr2f1-deficient optic nerves developed an imbalance between oligodendrocytes and astrocytes, linked to postnatal hypomyelination and astrogliosis as a mechanism for optic nerve dysfunction. glial cell differentiation; oligodendrocyte differentiation; astrocyte differentiation; central nervous system myelination myelin sheath; optic nerve; glial cell projection oligodendrocyte; astrocyte optic nerve (bertacchi2019mousenr2f1haploinsufficiency pages 1-2)
Postnatal hypomyelination of optic nerve Bertacchi et al. showed optic nerve hypomyelination in heterozygous mice, with slower optic axonal conduction velocity from retina to higher visual centers; early postnatal chemical treatment partially rescued myelination defects. myelination; axon ensheathment in central nervous system; regulation of conduction myelin sheath; node of Ranvier; axon oligodendrocyte optic nerve; visual pathway (bertacchi2019mousenr2f1haploinsufficiency pages 1-2)
Astrogliosis in optic neuropathy Optic nerve pathology in the mouse model included astrogliosis, indicating reactive glial remodeling as part of tissue damage downstream of NR2F1 deficiency. gliogenesis; astrocyte activation; response to nervous system injury astrocyte projection; glial scar-related extracellular region astrocyte optic nerve (bertacchi2019mousenr2f1haploinsufficiency pages 1-2)
Reduced visual conduction and associative visual learning deficits Adult heterozygous mice had slower optic axonal conduction velocity and associative visual learning deficits, linking structural optic nerve abnormalities to systems-level visual dysfunction. visual learning; regulation of action potential propagation; sensory system development axon; myelinated axon; visual cortex superficial layers cortical neuron; retinal ganglion cell optic nerve; visual cortex (bertacchi2019mousenr2f1haploinsufficiency pages 1-2)
Impaired hippocampal synaptic plasticity Nr2f1+/- mice recapitulated neurological phenotypes and showed reduced long-term potentiation and long-term depression in hippocampal slices, suggesting a mechanism for intellectual disability and memory phenotypes. synaptic plasticity; long-term synaptic potentiation; long-term synaptic depression; learning or memory synapse; postsynaptic density; dendritic spine pyramidal neuron; hippocampal neuron hippocampus; dentate gyrus (chen2020nr2f1heterozygousknockout pages 3-3, chen2020nr2f1heterozygousknockout pages 11-12, chen2020nr2f1heterozygousknockout pages 1-2)
Differential hippocampal gene expression with MMP upregulation RNA-seq in adult Nr2f1+/- hippocampus revealed significant differential expression including upregulation of multiple matrix metalloproteases, implicating extracellular matrix remodeling in altered plasticity. regulation of synaptic plasticity; extracellular matrix organization; proteolysis extracellular matrix; synaptic cleft hippocampal neuron hippocampus (chen2020nr2f1heterozygousknockout pages 3-3)
NR2F1 control of mitochondrial gene expression in neurons Bonzano et al. identified nuclear-encoded mitochondrial genes as putative NR2F1 targets and found dysregulation of these genes in Nr2f1-heterozygous brains, supporting mitochondrial dysfunction in BBSOAS pathogenesis. regulation of mitochondrial gene expression; mitochondrial organization; neuron development mitochondrion; mitochondrial outer membrane; mitochondrial matrix neuron; newborn neuron brain; hippocampal dentate gyrus (bonzano2023nr2f1shapesmitochondria pages 1-2)
Reduced mitochondrial mass and fragmentation in newborn neurons Conditional NR2F1 loss in the adult hippocampal neurogenic niche caused reduced mitochondrial mass, mitochondrial fragmentation, and downregulation of key mitochondrial proteins in newborn neurons, impairing their survival and integration. mitochondrial fission; mitochondrial organization; neuron differentiation; neuron survival; synapse organization mitochondrion; mitochondrial network; neuronal soma newborn neuron; neural stem cell dentate gyrus; hippocampal neurogenic niche (bonzano2023nr2f1shapesmitochondria pages 1-2)

Table: This table maps major disease mechanisms in Bosch-Boonstra-Schaaf optic atrophy syndrome to suggested GO, CL, and UBERON ontology terms. It is designed to support structured knowledge-base annotation of pathophysiology, affected cell types, and anatomical sites.

7. Anatomical Structures Affected

Primary systems/organs: - Eye/visual system: retina (RGC layer), optic nerve/optic nerve head, extracortical visual pathways (jurkute2021pathogenicnr2f1variants pages 1-3, jurkute2021pathogenicnr2f1variants media 1490a58e) - Central nervous system: hippocampus/dentate gyrus (synaptic plasticity; adult neurogenic niche), broader cortical/white matter structures (chen2020nr2f1heterozygousknockout pages 3-3, bonzano2023nr2f1shapesmitochondria pages 1-2)

Lateralization: Visual phenotypes are generally described bilaterally in clinical contexts; explicit laterality statistics were not retrieved. (jurkute2021pathogenicnr2f1variants pages 1-3)

8. Temporal Development

Typical onset: pediatric/infancy. During infancy, symptoms may be non-specific (hypotonia, feeding difficulties, epilepsy, poor eye tracking), with more specific BBSOAS features becoming evident over the first years of life. (bertacchi2022pathophysiologicalheterogeneityof pages 18-20)

Progression: Visual impairment may be largely non-progressive in longitudinal ophthalmic follow-up in at least some patients, and a review cites a “stable, non-progressive reduction in visual acuity.” (jurkute2021pathogenicnr2f1variants pages 1-3, bertacchi2022pathophysiologicalheterogeneityof pages 15-17)

9. Inheritance and Population

Inheritance pattern: autosomal dominant (jurkute2021pathogenicnr2f1variants pages 3-4)

De novo vs familial: the review summarizes most variants as de novo (73.9%) with some familial cases (7.6%) and deletions (16.3% of clinically described patients). (bertacchi2022pathophysiologicalheterogeneityof pages 2-5)

Epidemiology: Precise prevalence/incidence for BBSOAS was not retrieved in the accessible evidence. The review notes that inherited optic neuropathies overall have an estimated prevalence of 1 in 10,000 (not specific to BBSOAS). (bertacchi2022pathophysiologicalheterogeneityof pages 18-20)

10. Diagnostics

10.1 Clinical and functional testing

Key diagnostic and characterization modalities used in practice and in cohorts include neuro-ophthalmologic examination, OCT, ERG/VEP, and MRI/DTI tractography when available. (jurkute2021pathogenicnr2f1variants pages 1-3, jurkute2021pathogenicnr2f1variants pages 3-4)

10.2 Genetic testing approach

A 2022 review recommends diagnostic evaluation for BBSOAS in individuals with optic nerve hypoplasia or optic atrophy plus DD/ID, noting that most diagnoses occur via genome-wide technologies: CMA for deletions and WES/large NGS panels for SNVs/indels. (bertacchi2022pathophysiologicalheterogeneityof pages 18-20)

Implementation table: | Domain | Recommended evaluation or therapy | Implementation notes | Suggested MAXO terms and LOINC/imaging modalities | Evidence source | |---|---|---|---|---| | Vision | Comprehensive neuro-ophthalmologic examination | Initial workup should document visual impairment, optic nerve anomalies, strabismus/nystagmus, and functional vision; visual impairment in BBSOAS often becomes apparent in early childhood and may be non-progressive on follow-up | MAXO: visual function rehabilitation; Imaging/modalities: fundus photography, optical coherence tomography (OCT), visual evoked potentials (VEP), electroretinography (ERG) (jurkute2021pathogenicnr2f1variants pages 1-3, jurkute2021pathogenicnr2f1variants pages 3-4) | Deep phenotyping study of 22 individuals; review and management summary (jurkute2021pathogenicnr2f1variants pages 1-3, jurkute2021pathogenicnr2f1variants pages 3-4, bertacchi2022pathophysiologicalheterogeneityof pages 18-20) | | Vision | Visual therapy focused on cortical visual impairment (CVI) | Recommended supportive intervention when CVI is present; real-world implementation is rehabilitative rather than disease-modifying | MAXO: visual rehabilitation / visual therapy; modality: CVI-focused assessment and therapy (bertacchi2022pathophysiologicalheterogeneityof pages 18-20) | Review with recommended therapeutic approaches table (bertacchi2022pathophysiologicalheterogeneityof pages 18-20) | | Vision | OCT assessment of retinal ganglion cell layer and RNFL | High-resolution OCT can confirm retinal ganglion cell loss/ganglion cell layer thinning and support distinction between developmental optic nerve hypoplasia and degenerative optic atrophy | Imaging/modality: optical coherence tomography (OCT) of macula/optic nerve head (jurkute2021pathogenicnr2f1variants pages 1-3, jurkute2021pathogenicnr2f1variants pages 3-4) | Human cohort with structural ocular phenotyping (jurkute2021pathogenicnr2f1variants pages 1-3, jurkute2021pathogenicnr2f1variants pages 3-4) | | Vision | Electrophysiology of visual pathway | Pattern/flash VEP and ERG are useful to document retinal ganglion cell dysfunction and visual pathway conduction abnormalities | LOINC/imaging modalities: pattern VEP, flash VEP, full-field ERG, pattern ERG (jurkute2021pathogenicnr2f1variants pages 1-3, jurkute2021pathogenicnr2f1variants pages 3-4) | Human cohort methods and findings (jurkute2021pathogenicnr2f1variants pages 1-3, jurkute2021pathogenicnr2f1variants pages 3-4) | | Neurology | Brain MRI with attention to corpus callosum, optic pathways, cortical malformations, delayed myelination | Neuroimaging abnormalities are common in reported patients; MRI helps assess syndromic involvement and differential diagnosis | Imaging/modality: brain MRI; diffusion tensor imaging/tractography where available (bertacchi2022pathophysiologicalheterogeneityof pages 15-17, bertacchi2022pathophysiologicalheterogeneityof pages 18-20, jurkute2021pathogenicnr2f1variants pages 1-3) | Case aggregation/review and ophthalmic-neuroimaging cohort data (bertacchi2022pathophysiologicalheterogeneityof pages 15-17, bertacchi2022pathophysiologicalheterogeneityof pages 18-20, jurkute2021pathogenicnr2f1variants pages 1-3) | | Neurology | EEG when seizures/epilepsy or infantile spasms are suspected | Epilepsy is frequent in BBSOAS; EEG is part of workup for seizure phenotypes and can guide anti-seizure treatment | LOINC/modality: electroencephalography (EEG); MAXO: antiseizure medication therapy / anticonvulsive treatment (bertacchi2022pathophysiologicalheterogeneityof pages 15-17, bertacchi2022pathophysiologicalheterogeneityof pages 18-20) | Review of phenotype spectrum and recommended therapies (bertacchi2022pathophysiologicalheterogeneityof pages 15-17, bertacchi2022pathophysiologicalheterogeneityof pages 18-20) | | Neurology | Anti-convulsive treatment if epilepsy is present | Symptomatic management only; no disease-specific therapy established | MAXO: anticonvulsant treatment / seizure management (bertacchi2022pathophysiologicalheterogeneityof pages 18-20, tang2025casereporta pages 6-7) | Review therapeutic table; later case report notes no specific treatment exists beyond symptomatic care (bertacchi2022pathophysiologicalheterogeneityof pages 18-20, tang2025casereporta pages 6-7) | | Development | Developmental assessment for developmental delay/intellectual disability | Evaluate speech, motor, cognition, behavior, adaptive function; DD and ID are among the most common features | MAXO: developmental assessment; neuropsychological evaluation (bertacchi2022pathophysiologicalheterogeneityof pages 15-17, bertacchi2022pathophysiologicalheterogeneityof pages 18-20) | Review synthesizing common features and care recommendations (bertacchi2022pathophysiologicalheterogeneityof pages 15-17, bertacchi2022pathophysiologicalheterogeneityof pages 18-20) | | Development | Physical therapy | Aims to increase strength and improve gross motor skills, especially relevant for hypotonia/poor coordination | MAXO: physical therapy (bertacchi2022pathophysiologicalheterogeneityof pages 18-20) | Review therapeutic table (bertacchi2022pathophysiologicalheterogeneityof pages 18-20) | | Development | Occupational therapy | Aims to improve fine motor skills and coordination | MAXO: occupational therapy (bertacchi2022pathophysiologicalheterogeneityof pages 18-20) | Review therapeutic table (bertacchi2022pathophysiologicalheterogeneityof pages 18-20) | | Development | Speech therapy, with sign language and alternative/augmentative communication when needed | Useful for speech delay and communication impairment; review specifically recommends considering sign language and alternative communication devices | MAXO: speech therapy; augmentative and alternative communication support (bertacchi2022pathophysiologicalheterogeneityof pages 18-20, bertacchi2022pathophysiologicalheterogeneityof pages 15-17) | Review therapeutic table and phenotype summary (bertacchi2022pathophysiologicalheterogeneityof pages 18-20, bertacchi2022pathophysiologicalheterogeneityof pages 15-17) | | Development/Behavior | Applied behavioral analysis (ABA) therapy if ASD is diagnosed | Consider when autism spectrum disorder or autistic traits are clinically confirmed | MAXO: behavioral therapy / applied behavior analysis (bertacchi2022pathophysiologicalheterogeneityof pages 18-20) | Review therapeutic table (bertacchi2022pathophysiologicalheterogeneityof pages 18-20) | | Hearing | Full hearing evaluation | Recommended every two years in the review; hearing impairment is less common but documented | Modality: audiology/hearing assessment, brainstem auditory pathway testing where indicated (bertacchi2022pathophysiologicalheterogeneityof pages 18-20, bertacchi2022pathophysiologicalheterogeneityof pages 15-17) | Review follow-up recommendations and phenotype summary (bertacchi2022pathophysiologicalheterogeneityof pages 18-20, bertacchi2022pathophysiologicalheterogeneityof pages 15-17) | | Genetics | Diagnostic evaluation for BBSOAS in any person with ONH or OA plus developmental delay/ID | During infancy, suspicion may arise from hypotonia, feeding difficulties, epilepsy, and poor eye tracking, even before full phenotype is evident | MAXO: genetic counseling; genomic diagnostic evaluation (bertacchi2022pathophysiologicalheterogeneityof pages 18-20) | Review diagnostic recommendation (bertacchi2022pathophysiologicalheterogeneityof pages 18-20) | | Genetics | Chromosomal microarray analysis (CMA) for deletions | Appropriate first-line genome-wide technology when copy-number loss of NR2F1 or nearby region is suspected | Modality: chromosome microarray analysis (CMA) (bertacchi2022pathophysiologicalheterogeneityof pages 18-20, bertacchi2022pathophysiologicalheterogeneityof pages 5-7) | Review discussing deletions and diagnostic technologies (bertacchi2022pathophysiologicalheterogeneityof pages 18-20, bertacchi2022pathophysiologicalheterogeneityof pages 5-7) | | Genetics | Whole-exome sequencing (WES) or large next-generation sequencing panels for SNVs/indels | Most individuals are expected to be diagnosed using genome-wide sequencing technologies because no pathognomonic clinical feature exists | Modality: WES; multigene NGS panel; single-gene NR2F1 analysis where phenotype strongly suggests diagnosis (bertacchi2022pathophysiologicalheterogeneityof pages 18-20, kocaaga2022novelnr2f1variant pages 1-1) | Review diagnostic recommendation and case report identified by WES (bertacchi2022pathophysiologicalheterogeneityof pages 18-20, kocaaga2022novelnr2f1variant pages 1-1) | | Genetics | Variant interpretation under ACMG/AMP framework | Important because missense variants, especially in the DNA-binding domain, may require structured interpretation and can correlate with severity | MAXO: clinical molecular diagnosis; framework: ACMG/AMP variant classification (tang2025casereporta pages 6-7, tang2025casereporta pages 7-7) | 2025 case report and literature summary citing ACMG/AMP use and genotype-phenotype observations (tang2025casereporta pages 6-7, tang2025casereporta pages 7-7) | | Multidisciplinary follow-up | Coordinated ophthalmology, neurology, developmental pediatrics/rehabilitation, audiology, and genetics follow-up | Real-world care is supportive and longitudinal; no approved disease-modifying therapy currently exists | MAXO: multidisciplinary care management (bertacchi2022pathophysiologicalheterogeneityof pages 18-20, tang2025casereporta pages 6-7) | Review recommendations and recent case report noting symptomatic management only (bertacchi2022pathophysiologicalheterogeneityof pages 18-20, tang2025casereporta pages 6-7) |

Table: This table summarizes currently supported diagnostic evaluations and supportive management strategies for Bosch–Boonstra–Schaaf optic atrophy syndrome across vision, neurology, development, hearing, and genetics. It is useful for translating the literature into a practical, ontology-ready care framework for a disease knowledge base.

10.3 Visual evidence from figures (human + mouse)

OCT-based ganglion cell layer thinning, tractography abnormalities in visual pathways, and mouse retinal developmental phenotypes are shown in figures extracted from Jurkute et al. 2021. (jurkute2021pathogenicnr2f1variants media 1490a58e, jurkute2021pathogenicnr2f1variants media 412f5e0a, jurkute2021pathogenicnr2f1variants media 964f2122, jurkute2021pathogenicnr2f1variants media 3c2b8d85)

11. Outcome / Prognosis

Vision: Available longitudinal ophthalmologic data in the 22-person cohort suggested no significant deterioration in visual function during follow-up, supporting a congenital/developmental and often non-progressive component. (jurkute2021pathogenicnr2f1variants pages 1-3)

Neurodevelopment: DD/ID and neurobehavioral features are chronic and variable, with substantial heterogeneity and possible genotype associations. Long-term prognosis statistics (life expectancy, mortality) were not retrieved in this run. (bertacchi2022pathophysiologicalheterogeneityof pages 15-17)

12. Treatment

12.1 Standard of care (supportive and rehabilitative)

A 2022 review compiles recommended therapeutic approaches, emphasizing supportive care: visual therapy for CVI; PT/OT; speech therapy with AAC/sign language considerations; ABA therapy for ASD; anticonvulsant treatment for epilepsy; and periodic hearing evaluation. (bertacchi2022pathophysiologicalheterogeneityof pages 18-20)

12.2 Recent developments (2024): perampanel for NR2F1-related epilepsy

A 2024 Acta Epileptologica study reports six new BBSOAS cases with epilepsy and a pooled analysis (n=20 total) suggesting: - Infantile epileptic spasms comprise a majority of NR2F1-related epilepsy cases (e.g., 60% or 65% depending on cohort inclusion detail) (li2024effectivetreatmentof pages 1-2, li2024effectivetreatmentof pages 14-15) - Previously reported cases had seizure control in only 50% (li2024effectivetreatmentof pages 1-2) - In the six new cases, “all … became seizure-free after perampanel as an add-on treatment,” with average time from add-on to seizure control 7.33 ± 4.59 months and mean required dose 0.22 ± 0.17 mg/kg/day; median time to seizure freedom 14 months (range 1–32 months). (li2024effectivetreatmentof pages 1-2)

This is promising but remains observational and may not generalize beyond the small sample. (li2024effectivetreatmentof pages 15-17)

12.3 Experimental / preclinical therapeutic signals

In an Nr2f1 haploinsufficient mouse model, “optic nerve hypomyelination … could be rescued by chemical drug treatment in early postnatal life,” indicating that at least some downstream pathology may be modifiable in principle, although this is not yet a validated human therapy. (bertacchi2019mousenr2f1haploinsufficiency pages 1-2)

Key direct quotes supporting treatment/mechanisms:

“Here, we review the pathophysiology of the Bosch–Boonstra–Schaaf Optic Atrophy Syndrome (BBSOAS; OMIM 615722; ORPHA 401777), a recently described monogenic neurodevelopmental syndrome caused by the haploinsufficiency of NR2F1 gene, a key transcriptional regulator of brain development.” Cells, 2022, doi:10.3390/cells11081260, https://doi.org/10.3390/cells11081260 (bertacchi2022pathophysiologicalheterogeneityof pages 2-5)

“BBSOAS is an autosomal dominant disorder characterized by delayed neurodevelopment, moderate to severe intellectual disability and visual impairment.” Brain Communications, 2021, doi:10.1093/braincomms/fcab162, https://doi.org/10.1093/braincomms/fcab162 (jurkute2021pathogenicnr2f1variants pages 3-4)

“The visual impairment became apparent in early childhood with small and/or tilted hypoplastic optic nerves observed in 10 cases.” Brain Communications, 2021, doi:10.1093/braincomms/fcab162, https://doi.org/10.1093/braincomms/fcab162 (jurkute2021pathogenicnr2f1variants pages 1-3)

“Interestingly, for those individuals with available longitudinal ophthalmological data, there was no significant deterioration in visual function during the period of follow-up.” Brain Communications, 2021, doi:10.1093/braincomms/fcab162, https://doi.org/10.1093/braincomms/fcab162 (jurkute2021pathogenicnr2f1variants pages 1-3)

“The clinical observations in our study cohort, supported by the mouse data, suggest an early neurodevelopmental origin for the retinal and optic nerve head defects caused by NR2F1 pathogenic variants, resulting in congenital vision loss that seems to be non-progressive.” Brain Communications, 2021, doi:10.1093/braincomms/fcab162, https://doi.org/10.1093/braincomms/fcab162 (jurkute2021pathogenicnr2f1variants pages 1-3)

“Notably, Nr2f1-deficient optic nerves develop an imbalance between oligodendrocytes and astrocytes leading to postnatal hypomyelination and astrogliosis.” EMBO Molecular Medicine, 2019, doi:10.15252/emmm.201910291, https://doi.org/10.15252/emmm.201910291 (bertacchi2019mousenr2f1haploinsufficiency pages 1-2)

“Importantly, some of these clinical features, such the optic nerve hypomyelination, could be rescued by chemical drug treatment in early postnatal life.” EMBO Molecular Medicine, 2019, doi:10.15252/emmm.201910291, https://doi.org/10.15252/emmm.201910291 (bertacchi2019mousenr2f1haploinsufficiency pages 1-2)

“Our data point to an active role for NR2F1 in the mitochondrial gene expression regulatory network in neurons and support the involvement of mitochondrial dysfunction in BBSOAS pathogenesis.” Disease Models & Mechanisms, 2023, doi:10.1242/dmm.049854, https://doi.org/10.1242/dmm.049854 (bonzano2023nr2f1shapesmitochondria pages 1-2)

“The discovery of impaired hippocampal synaptic plasticity in the heterozygous mouse model sheds light on the pathophysiology of altered memory and cognitive function in BBSOAS.” Human Molecular Genetics, 2020, doi:10.1093/hmg/ddz233, https://doi.org/10.1093/hmg/ddz233 (chen2020nr2f1heterozygousknockout pages 3-3)

“Perampanel exhibits dramatic efficacy for NR2F1 -related epilepsy.” Acta Epileptologica, 2024, doi:10.1186/s42494-023-00145-0, https://doi.org/10.1186/s42494-023-00145-0 (li2024effectivetreatmentof pages 1-2)

Blockquote: This artifact compiles exact high-value quotes from core BBSOAS papers supporting disease definition, phenotype, non-progressive visual impairment, mechanistic findings, and a recent treatment signal for NR2F1-related epilepsy.

13. Prevention

No primary prevention is available for a dominantly inherited/de novo neurodevelopmental disorder. Practical prevention is limited to: - Genetic counseling for families with an affected individual - Consideration of cascade testing in familial cases

These prevention-oriented recommendations are consistent with the genetic diagnostic framing emphasized in the review (genome-wide testing; lack of pathognomonic features). (bertacchi2022pathophysiologicalheterogeneityof pages 18-20)

14. Other Species / Natural Disease

No naturally occurring veterinary analogs were retrieved in this run. The key comparative evidence is from engineered mouse models (Section 15). (bertacchi2019mousenr2f1haploinsufficiency pages 1-2)

15. Model Organisms

15.1 Mouse models and phenotype recapitulation

Multiple mouse-model studies recapitulate major BBSOAS-relevant phenotypes: - Optic nerve / visual system model: Nr2f1 haploinsufficiency produces optic nerve atrophy-related features, including glial imbalance, hypomyelination, astrogliosis, and reduced conduction velocity; some features were chemically rescued early postnatally (EMBO Mol Med 2019; doi:10.15252/emmm.201910291). (bertacchi2019mousenr2f1haploinsufficiency pages 1-2) - Ocular developmental model aligned to human deep phenotyping: Nr2f1 mutant mice show decreased RGC density and disrupted RGC axon guidance, consistent with congenital optic nerve hypoplasia and reduced visual acuity (Brain Communications 2021). (jurkute2021pathogenicnr2f1variants pages 1-3) - Neurodevelopment/behavior model: Nr2f1 heterozygous knockout mice show impaired hippocampal synaptic plasticity and altered learning/memory; RNA-seq shows differential expression including MMP upregulation (HMG 2020; doi:10.1093/hmg/ddz233). (chen2020nr2f1heterozygousknockout pages 3-3) - Mitochondrial mechanism model (2023): Conditional NR2F1 loss in adult hippocampal neurogenic niche reduces mitochondrial mass and increases fragmentation in newborn neurons and supports mitochondrial dysfunction as a contributor to BBSOAS pathogenesis (DMM 2023; doi:10.1242/dmm.049854). (bonzano2023nr2f1shapesmitochondria pages 1-2)

Notes on evidence gaps and limitations

  • MONDO, MeSH, ICD-10/11 codes were not present in retrieved evidence; these identifiers should be added from dedicated ontology resources in a separate targeted retrieval step. (bertacchi2022pathophysiologicalheterogeneityof pages 18-20, jurkute2021pathogenicnr2f1variants pages 1-3)
  • Epidemiology (prevalence/incidence) of BBSOAS specifically was not available in the retrieved evidence; only inherited optic neuropathy prevalence (1/10,000) was found, which should not be substituted for BBSOAS prevalence. (bertacchi2022pathophysiologicalheterogeneityof pages 18-20)
  • Several relevant 2023–2024 papers were listed as unobtainable in this run (e.g., AJNR 2023 neuroimaging paper) and therefore cannot be cited for specific claims.

Visual evidence (figures)

The extracted figures from Jurkute et al. 2021 include a graphical abstract and key figures showing OCT ganglion cell layer thinning, tractography abnormalities, and mouse retinal developmental defects; these support the claim of a neurodevelopmental origin of visual impairment and RGC involvement. (jurkute2021pathogenicnr2f1variants media 1490a58e, jurkute2021pathogenicnr2f1variants media 412f5e0a, jurkute2021pathogenicnr2f1variants media 964f2122, jurkute2021pathogenicnr2f1variants media 3c2b8d85)

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  19. (jurkute2021pathogenicnr2f1variants media 964f2122): Neringa Jurkute, Michele Bertacchi, Gavin Arno, Chiara Tocco, Ungsoo Samuel Kim, Adam M Kruszewski, Robert A Avery, Emma C Bedoukian, Jinu Han, Sung Jun Ahn, Nikolas Pontikos, James Acheson, Indran Davagnanam, Richard Bowman, Marios Kaliakatsos, Alice Gardham, Emma Wakeling, Ngozi Oluonye, Maddy Ashwin Reddy, Elaine Clark, Elisabeth Rosser, Patrizia Amati-Bonneau, Majida Charif, Guy Lenaers, Isabelle Meunier, Sabine Defoort, Catherine Vincent-Delorme, Anthony G Robson, Graham E Holder, Luc Jeanjean, Antonio Martinez-Monseny, Mariona Vidal-Santacana, Chloé Dominici, Cedric Gaggioli, Nadia Giordano, Matteo Caleo, Grant T Liu, Genomics England Research Consortium, Andrew R Webster, Michèle Studer, and Patrick Yu-Wai-Man. Pathogenic nr2f1 variants cause a developmental ocular phenotype recapitulated in a mutant mouse model. Brain Communications, Jul 2021. URL: https://doi.org/10.1093/braincomms/fcab162, doi:10.1093/braincomms/fcab162. This article has 29 citations and is from a peer-reviewed journal.

  20. (jurkute2021pathogenicnr2f1variants media 3c2b8d85): Neringa Jurkute, Michele Bertacchi, Gavin Arno, Chiara Tocco, Ungsoo Samuel Kim, Adam M Kruszewski, Robert A Avery, Emma C Bedoukian, Jinu Han, Sung Jun Ahn, Nikolas Pontikos, James Acheson, Indran Davagnanam, Richard Bowman, Marios Kaliakatsos, Alice Gardham, Emma Wakeling, Ngozi Oluonye, Maddy Ashwin Reddy, Elaine Clark, Elisabeth Rosser, Patrizia Amati-Bonneau, Majida Charif, Guy Lenaers, Isabelle Meunier, Sabine Defoort, Catherine Vincent-Delorme, Anthony G Robson, Graham E Holder, Luc Jeanjean, Antonio Martinez-Monseny, Mariona Vidal-Santacana, Chloé Dominici, Cedric Gaggioli, Nadia Giordano, Matteo Caleo, Grant T Liu, Genomics England Research Consortium, Andrew R Webster, Michèle Studer, and Patrick Yu-Wai-Man. Pathogenic nr2f1 variants cause a developmental ocular phenotype recapitulated in a mutant mouse model. Brain Communications, Jul 2021. URL: https://doi.org/10.1093/braincomms/fcab162, doi:10.1093/braincomms/fcab162. This article has 29 citations and is from a peer-reviewed journal.

  21. (li2024effectivetreatmentof pages 14-15): Xiao Li, Kai Gao, Yutang Li, Yuehua Zhang, Han Zhang, and Yuwu Jiang. Effective treatment of nr2f1-related epilepsy with perampanel. Acta Epileptologica, Jan 2024. URL: https://doi.org/10.1186/s42494-023-00145-0, doi:10.1186/s42494-023-00145-0. This article has 2 citations.

  22. (li2024effectivetreatmentof pages 15-17): Xiao Li, Kai Gao, Yutang Li, Yuehua Zhang, Han Zhang, and Yuwu Jiang. Effective treatment of nr2f1-related epilepsy with perampanel. Acta Epileptologica, Jan 2024. URL: https://doi.org/10.1186/s42494-023-00145-0, doi:10.1186/s42494-023-00145-0. This article has 2 citations.

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