BEST1-Related Dominant Retinopathy

Mendelian MONDO:0700238 Pathograph 15 Show in embeddings browser Ophthalmological Disease Retinal Dystrophy Inherited retinal dystrophy

BEST1-related dominant retinopathy is the gene-level umbrella for retinal disease caused by a heterozygous pathogenic BEST1 variant. Its prototypic phenotype is Best vitelliform macular dystrophy (BVMD/Best disease), in which retinal pigment epithelium (RPE) dysfunction, abnormal subretinal material, reduced electrooculogram (EOG) light-rise, and slowly progressive central visual impairment form the core clinical picture. Adult-onset vitelliform macular dystrophy and autosomal dominant vitreoretinochoroidopathy are also recognized dominant BEST1 phenotypes, but the detailed causal and phenotype graph in this entry is intentionally BVMD-centered. Dominant variants can produce loss-of-function, dominant-negative, or gain-of-function effects, and penetrance and expressivity are variable. No approved disease-modifying treatment exists; OPGx-BEST1 gene augmentation is being evaluated in the recruiting BIRD-1 study (NCT07185256).

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1
Definitions
1
Inheritance
4
Pathophys.
6
Phenotypes
3
Gaps
15
Pathograph
1
Genes
4
Medical Actions
2
Differentials
2
Trials
3
Models
22
References
1
Deep Research
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Classifications

Harrison's Part
GENETICS ENVIRONMENT DISEASE
Channelopathy
epithelial channelopathy
📘

Definitions

1
Molecular definition of autosomal-dominant bestrophinopathy
A proband with suggestive ophthalmic findings and a heterozygous pathogenic or likely pathogenic BEST1 variant meets the GeneReviews molecular definition of autosomal-dominant bestrophinopathy.
DIAGNOSTIC_CRITERIA
Show evidence (1 reference)
PMID:20301346 SUPPORT Human Clinical
"The diagnosis of autosomal dominant bestrophinopathy is established in a proband with suggestive findings and a heterozygous BEST1 pathogenic (or likely pathogenic) variant identified by molecular genetic testing."
GeneReviews directly states the clinical-plus-molecular diagnostic definition for dominant BEST1 disease.
👪

Inheritance

1
Autosomal dominant HP:0000006
BVMD follows autosomal dominant inheritance with incomplete penetrance and marked variable expressivity. Asymptomatic carriers with pathogenic BEST1 variants may show only reduced EOG without visible macular lesions. Intrafamilial phenotypic diversity is pronounced, with some heterozygous carriers showing no visible fundus changes.
Autosomal dominant inheritance
Show evidence (4 references)
DOI:10.1002/mgg3.2095 SUPPORT Human Clinical
"patients carrying a pathogenic heterozygous variant of BEST1 to develop obvious intrafamilial phenotypic diversity"
Family-based clinical genetic study demonstrates marked intrafamilial phenotypic diversity characteristic of dominant BEST1 disease with variable expressivity.
DOI:10.1177/2515841421997191 SUPPORT Human Clinical
"over 250 individual pathological mutations have been identified in the BEST1 gene, with many reported to have various clinical expressivity and incomplete penetrance"
Documents incomplete penetrance and variable clinical expressivity as characteristic features of dominant BEST1 inheritance.
PMID:20301346 SUPPORT Human Clinical
"BVMD, AVMD, and ADVIRC are inherited in an autosomal dominant (AD) manner."
GeneReviews explicitly confirms autosomal dominant inheritance as the mode for all three dominant BEST1 bestrophinopathy phenotypes.
+ 1 more reference
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Discussions and Knowledge Gaps

3
To what extent does dominant BEST1 retinopathy result from altered chloride conductance versus calcium signaling, fluid transport, and handling of photoreceptor outer segments?
CONTROVERSY OPEN best1_channel_versus_calcium_and_pos_handling
Attached to
pathophysiology#BEST1 Calcium-Activated Chloride Channel Dysfunction pathophysiology#RPE Dysfunction and Impaired Phagocytosis
BEST1 is a calcium-activated chloride channel, yet a dominant W93C mouse model reproduces the light-peak phenotype with normal RPE chloride conductance, while patient-derived RPE implicates calcium-store regulation and outer-segment processing. The entry therefore does not reduce every dominant variant to a single channel-loss mechanism.
Show evidence (2 references)
PMID:20053664 SUPPORT Model Organism
"RPE cells from Best1(W93C) mice exhibited normal Cl(-) conductances"
The dominant mouse model separates a disease phenotype from simple chloride-conductance loss.
PMID:23139242 SUPPORT In Vitro
"further linked BEST1 to the regulation and release of endoplasmic reticulum calcium stores."
Patient-derived RPE provides an alternative calcium-regulatory mechanism.
How well does gene augmentation in recessive canine BEST1 disease predict efficacy across dominant-negative and gain-of-function human BVMD variants?
HUMAN MODEL MISMATCH OPEN recessive_canine_model_for_dominant_human_disease
Attached to
pathophysiology#BEST1 Calcium-Activated Chloride Channel Dysfunction
The canine model supplies strong safety and structural-rescue evidence but uses homozygous or compound-heterozygous BEST1 genotypes. Dominant human alleles can interfere with wild-type subunits or increase channel activity, so rescue by augmentation may be variant-class dependent.
Show evidence (2 references)
PMID:42411064 SUPPORT Model Organism
"dogs that were homozygous mutant or compound heterozygotes for 3 naturally occurring mutations in BEST1."
The IND-enabling model uses recessive genotypes rather than heterozygous dominant human variants.
DOI:10.4103/sjopt.sjopt_175_23 SUPPORT In Vitro
"individuals harboring GOF variants would require a combination of gene silencing and gene augmentation"
Variant mechanism may limit direct extrapolation from recessive augmentation models.
Which structural or functional measures are sufficiently sensitive and reproducible for early-phase BVMD treatment trials?
KNOWLEDGE GAP OPEN bvmd_trial_endpoints_for_slow_variable_progression
Attached to
pathophysiology#Progressive Photoreceptor Damage and Vision Loss
Visual acuity and retinal thickness decline slowly and variably, which can obscure treatment effects in small early-phase trials. Longitudinal lesion dimensions, outer-nuclear-layer thickness, and dark-adapted chromatic sensitivity are promising but remain to be qualified as endpoints.
Show evidence (2 references)
PMID:40086732 SUPPORT Human Clinical
"The slow and variable disease course may pose a challenge in identification of early end points for therapeutic trials aimed at altering kinetics of degeneration."
The large natural-history imaging study explicitly identifies the endpoint problem.
PMID:40688488 SUPPORT Human Clinical
"may serve as valuable outcome measurements for treatment trials for BVMD."
The longitudinal study nominates imaging and dark-adapted sensitivity measures for trials.
⚙

Pathophysiology

4
BEST1 Calcium-Activated Chloride Channel Dysfunction
Heterozygous pathogenic BEST1 variants produce mutant bestrophin-1 subunits that co-assemble with wild-type subunits in the homopentameric CaCC complex in the RPE basolateral membrane. The large majority of dominant BEST1 pathogenic variants cause loss-of-function (LOF) or dominant-negative (DN) impairment of calcium-activated chloride conductance; a minority cause toxic gain-of-function (GOF) with excess channel activity. The resulting abnormal chloride transport disrupts RPE transepithelial ion flux and calcium homeostasis.
retinal pigment epithelial cell CL:0002586 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves retinal pigment epithelial cell (CL:0002586). CL:0002586 is a cell type from the Cell Ontology.
BEST1 hgnc:12703 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves BEST1 (hgnc:12703). hgnc:12703 is a gene from the HUGO Gene Nomenclature Committee.
chloride transport GO:0006821 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased chloride transport (GO:0006821). GO:0006821 is a biological process from the Gene Ontology. ↓ DECREASED
Downstream
RPE Dysfunction and Impaired Phagocytosis Impaired CaCC activity disrupts calcium signaling, transepithelial fluid transport, and phagocytic uptake of shed photoreceptor outer segments in the RPE.
Show evidence (4 references)
DOI:10.4103/sjopt.sjopt_175_23 SUPPORT In Vitro
"most BEST1 pathogenic variants have been shown to cause either loss of function (LOF) of the protein or a dominant-negative (DN) effect, with a smaller subset causing a toxic gain of function (GOF)"
Review of bestrophinopathy gene therapy preclinical studies characterizes the three molecular mechanisms (LOF, DN, GOF) by which dominant BEST1 variants impair bestrophin-1 channel function, with implications for therapeutic strategy.
DOI:10.1177/2515841421997191 SUPPORT In Vitro
"This spectrum of disorders is caused by mutations in bestrophin1"
The review directly identifies pathogenic BEST1 variation as the cause of the bestrophinopathy spectrum.
DOI:10.3390/ijms26199421 SUPPORT In Vitro
"BEST1 gene encodes a transmembrane protein in the retinal pigment epithelium (RPE) in the eye, that functions as a calcium-dependent chloride channel (CaCC)"
Gene therapy strategy review confirms bestrophin-1 CaCC identity and RPE localization as the basis of BEST1-related retinopathy mechanisms.
+ 1 more reference
RPE Dysfunction and Impaired Phagocytosis
Bestrophin-1 CaCC dysfunction impairs multiple interdependent RPE functions: calcium homeostasis, transepithelial fluid transport, and phagocytic uptake of daily-shed photoreceptor outer segments (POS). Failure of RPE phagocytosis allows undigested POS to accumulate in the subretinal space. The pathognomonic reduction of the EOG Arden ratio (light-rise) is the electrophysiological readout of this RPE-level dysfunction, present even in asymptomatic BEST1 carriers.
retinal pigment epithelial cell CL:0002586 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves retinal pigment epithelial cell (CL:0002586). CL:0002586 is a cell type from the Cell Ontology.
phagocytosis GO:0006909 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased phagocytosis (GO:0006909). GO:0006909 is a biological process from the Gene Ontology. ↓ DECREASED retina homeostasis GO:0001895 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased retina homeostasis (GO:0001895). GO:0001895 is a biological process from the Gene Ontology. ↓ DECREASED
Experimental models
Patient-derived Best disease iPSC-RPE model IPSC DERIVED MODEL Models RPE fluid transport, calcium signaling, and photoreceptor-outer-segment handling.
Downstream
Vitelliform Material Accumulation Impaired RPE phagocytosis and fluid transport lead to subretinal accumulation of lipofuscin-rich unphagocytosed outer-segment material, forming the characteristic vitelliform deposit.
Abnormal electrooculogram The reduced EOG light-rise is a functional clinical readout of RPE dysfunction in BEST1 disease.
Show evidence (3 references)
DOI:10.3390/ijms23137432 SUPPORT In Vitro
"mutations in this gene induce functional problems in the RPE cell layer with an accumulation of lipofucsin that evolves into cell death and loss of sight"
iPSC-RPE model of BVMD demonstrates that BEST1 mutations cause RPE dysfunction leading to lipofuscin accumulation and eventual cell death.
DOI:10.1007/s10633-026-10093-y SUPPORT Human Clinical
"The light-rise of the electro-oculogram (EOG) is used as a clinical marker"
The reduced EOG light-rise is the pathognomonic RPE electrophysiological signature of bestrophinopathy, reflecting the underlying bestrophin-1 CaCC dysfunction in RPE.
DOI:10.1111/aos.14958 SUPPORT Human Clinical
"The Arden ratio was significantly lower in ARB patients and in eyes with stage 5 of BVMD"
Clinical cohort study confirms reduced EOG Arden ratio across BVMD stages, with the most severe reduction in end-stage (atrophic) disease.
Vitelliform Material Accumulation
Impaired RPE phagocytosis of shed photoreceptor outer segments and disrupted subretinal fluid homeostasis lead to progressive subretinal accumulation of lipofuscin-rich, hyperautofluorescent material beneath the macula. Quantitative autofluorescence studies indicate that lipofuscin accumulation is not a primary consequence of the genetic defect, but reflects secondary failure of RPE-photoreceptor apposition and POS clearance. The hallmark "egg-yolk" vitelliform lesion evolves through five classical stages over years to decades: previtelliform, vitelliform, pseudohypopyon, vitelliruptive ("scrambled-egg"), and atrophic/fibroatrophic.
retinal pigment epithelial cell CL:0002586 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves retinal pigment epithelial cell (CL:0002586). CL:0002586 is a cell type from the Cell Ontology.
photoreceptor cell maintenance GO:0045494 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased photoreceptor cell maintenance (GO:0045494). GO:0045494 is a biological process from the Gene Ontology. ↓ DECREASED
macula lutea UBERON:0000053 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in macula lutea (UBERON:0000053). UBERON:0000053 is an anatomical location from the Uberon multi-species anatomy ontology. fovea centralis UBERON:0001786 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in fovea centralis (UBERON:0001786). UBERON:0001786 is an anatomical location from the Uberon multi-species anatomy ontology.
Experimental models
Patient-derived Best disease iPSC-RPE model IPSC DERIVED MODEL Models accumulation of autofluorescent material after chronic outer-segment feeding.
Downstream
Progressive Photoreceptor Damage and Vision Loss Chronic subretinal lipofuscin-rich deposit disrupts photoreceptor-RPE apposition and causes progressive structural cone photoreceptor damage, outer-nuclear-layer thinning, and ellipsoid-zone disruption.
Vitelliform macular lesion Subretinal accumulation of autofluorescent material produces the clinically visible vitelliform lesion.
Show evidence (1 reference)
DOI:10.1177/11206721231166434 SUPPORT Human Clinical
"lipofuscin accumulation, the hallmark of BVMD, is unlikely to be a primary effect of the genetic defect. It could be due to a lack of apposition between photoreceptors and retinal pigment epithelium in the macula with subsequent accumulation of shed outer segments over time"
Quantitative FAF imaging review establishes that vitelliform material accumulates secondary to impaired RPE-photoreceptor apposition and POS phagocytosis, not as a direct primary effect of BEST1 dysfunction.
Progressive Photoreceptor Damage and Vision Loss
The subretinal vitelliform deposit progressively disrupts photoreceptor-RPE apposition and causes structural damage to the cone-dominated macular photoreceptors. OCT and adaptive optics imaging demonstrate progressive disruption of the cone mosaic, followed by outer-nuclear-layer thinning and ellipsoid-zone disruption. In late stages, choroidal neovascularization (CNV) can develop beneath the damaged RPE, causing exudative complications and acute vision loss on a background of slow chronic progression.
cone photoreceptor cell CL:0000573 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves cone photoreceptor cell, annotated with retinal cone cell (CL:0000573). CL:0000573 is a cell type from the Cell Ontology.
photoreceptor cell maintenance GO:0045494 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased photoreceptor cell maintenance (GO:0045494). GO:0045494 is a biological process from the Gene Ontology. ↓ DECREASED visual perception GO:0007601 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased visual perception (GO:0007601). GO:0007601 is a biological process from the Gene Ontology. ↓ DECREASED
macula lutea UBERON:0000053 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in macula lutea (UBERON:0000053). UBERON:0000053 is an anatomical location from the Uberon multi-species anatomy ontology.
Downstream
Reduced visual acuity Progressive outer-retinal and photoreceptor damage reduces central visual acuity.
Metamorphopsia Macular structural distortion can manifest as distorted central vision.
Macular atrophy Progressive RPE and photoreceptor injury culminates in macular atrophy.
Choroidal neovascularization Late RPE/outer-retinal damage can be complicated by choroidal neovascularization.
Show evidence (2 references)
DOI:10.1177/11206721231166434 SUPPORT Human Clinical
"vitelliform lesions are characterized by progressive changes in the cone mosaic corresponding to a thinning of the outer nuclear layer and then disruption of the ellipsoid zone, which are associated with a decreased sensitivity and visual acuity"
OCT and adaptive optics imaging directly demonstrate progressive cone mosaic disruption and outer-nuclear-layer thinning as the structural basis of visual loss in BVMD.
DOI:10.1177/11206721231166434 SUPPORT Human Clinical
"OCT Angiography proved a greater prevalence of macular neovascularization, the majority of which are non-exudative and develop in late disease stages"
OCT angiography demonstrates that macular neovascularization is prevalent in late-stage BVMD, with most cases non-exudative; exudative CNV represents a serious complication requiring anti-VEGF treatment.
⬡

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for BEST1-Related Dominant Retinopathy 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

6
Eye 3
Abnormal electrooculogram VERY_FREQUENT Abnormal visual electrophysiology HP:0030453 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Abnormal electrooculogram, annotated with Abnormal visual electrophysiology (HP:0030453). HP:0030453 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
DOI:10.1007/s10633-026-10093-y SUPPORT Human Clinical
"The light-rise of the electro-oculogram (EOG) is used as a clinical marker"
The EOG light-rise reduction is the pathognomonic functional RPE marker used clinically to diagnose and classify bestrophinopathies.
DOI:10.1111/aos.14958 SUPPORT Human Clinical
"The Arden ratio was significantly lower in ARB patients and in eyes with stage 5 of BVMD"
Clinical cohort data confirm that reduced Arden ratio (EOG light-rise) is present across BVMD stages, with severity correlating with disease stage.
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), qualified as course progressive. HP:0007663 is a phenotype from the Human Phenotype Ontology.
Course: PROGRESSIVE
Show evidence (3 references)
DOI:10.1177/11206721231166434 SUPPORT Human Clinical
"vitelliform lesions are characterized by progressive changes in the cone mosaic corresponding to a thinning of the outer nuclear layer and then disruption of the ellipsoid zone, which are associated with a decreased sensitivity and visual acuity"
OCT studies demonstrate that progressive structural cone and outer-nuclear-layer damage directly correlates with reduced visual acuity in BVMD.
DOI:10.1111/aos.14958 SUPPORT Human Clinical
"The genotype does not always predict the phenotype in patients with BVMD and ARB"
Clinical cohort study confirms that disease course is not strictly determined by genotype, consistent with the variable expressivity and often slowly progressive character of BVMD with relatively preserved visual function in many patients over 5 years of follow-up.
PMID:20301346 SUPPORT Human Clinical
"Slow visual deterioration is the usual course."
GeneReviews confirms slowly progressive visual impairment as the typical clinical trajectory of bestrophinopathies, consistent with often-preserved VA in early stages and the long window of opportunity for intervention.
Macular atrophy OCCASIONAL HP:0007401 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Macular atrophy (HP:0007401). HP:0007401 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
DOI:10.1111/aos.14958 SUPPORT Human Clinical
"categorization of 52 eyes as Best vitelliform macular dystrophy (BVMD) with stages 1 to 5"
Clinical staging in a 62-eye cohort demonstrates the full BVMD progression from stage 1 (previtelliform) through stage 5 (atrophic/cicatricial), confirming macular atrophy as a recognized end-stage phenotype.
DOI:10.1111/aos.14958 SUPPORT Human Clinical
"the atrophic stage of BVMD"
The same cohort study identifies the atrophic stage of BVMD as the disease end-stage with the worst visual function and EOG results, directly anchoring macular atrophy as the terminal BVMD phenotype.
Other 3
Vitelliform macular lesion VERY_FREQUENT Vitelliform-like macular lesions HP:0007677 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Vitelliform macular lesion, annotated with Vitelliform-like macular lesions (HP:0007677). HP:0007677 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
DOI:10.1177/11206721231166434 SUPPORT Human Clinical
"Best Vitelliform Macular Dystrophy (BVMD) is a dominantly inherited retinal disease caused by dominant variants in the BEST1 gene"
Multimodal imaging review establishes the vitelliform macular lesion as the defining hallmark of BVMD, caused by dominant BEST1 variants.
PMID:20301346 SUPPORT Human Clinical
"The four recognized phenotypes are the three autosomal dominant disorders: Best vitelliform macular dystrophy (BVMD), BEST1 adult-onset vitelliform macular dystrophy (AVMD), and autosomal dominant vitreoretinochoroidopathy (ADVIRC); and autosomal recessive bestrophinopathy (ARB)."
GeneReviews identifies BVMD (with its vitelliform macular lesion) as the prototypic autosomal-dominant BEST1 phenotype, anchoring the cardinal diagnostic feature in the authoritative clinical reference.
Metamorphopsia OCCASIONAL HP:0012508 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Metamorphopsia (HP:0012508). HP:0012508 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:36281445 SUPPORT Human Clinical
"A 12-year-old boy complaining of metamorphopsia presented with bilateral yellowish subfoveal deposits, suggestive of BVMD, which was confirmed by fundus autofluorescence and electrooculography"
Case report of BVMD in which metamorphopsia was the presenting symptom, directly documenting metamorphopsia arising from the subfoveal vitelliform lesion.
Choroidal neovascularization OCCASIONAL HP:0011506 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Choroidal neovascularization (HP:0011506). HP:0011506 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
DOI:10.1177/11206721231166434 SUPPORT Human Clinical
"OCT Angiography proved a greater prevalence of macular neovascularization, the majority of which are non-exudative and develop in late disease stages"
OCT angiography studies demonstrate macular neovascularization as a frequent late-stage BVMD finding, with the majority non-exudative.
PMID:20301346 SUPPORT Human Clinical
"Choroidal neovascularization can occur in rare cases."
GeneReviews confirms choroidal neovascularization as a recognized, though uncommon, late complication of bestrophinopathies, warranting annual ophthalmologic surveillance for its detection.
🧬

Genetic Associations

1
BEST1 heterozygous pathogenic variant (Causative)
Gene: BEST1 hgnc:12703 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is BEST1 (hgnc:12703). hgnc:12703 is a gene from the HUGO Gene Nomenclature Committee.
Show evidence (3 references)
DOI:10.1177/2515841421997191 SUPPORT Human Clinical
"over 250 individual pathological mutations have been identified in the BEST1 gene, with many reported to have various clinical expressivity and incomplete penetrance"
Establishes the genetic landscape: over 250 BEST1 pathogenic variants underlie the bestrophinopathies, with variable expressivity and incomplete penetrance characterizing the dominant forms.
DOI:10.1002/mgg3.2095 SUPPORT Human Clinical
"A total of 9 variants on the BEST1 gene were identified, containing 7 missense variants, 1 nonsense variant, and 1 frameshift variant"
Family-based genetic study of bestrophinopathies demonstrates the variant type distribution: predominantly missense, with minority frameshift/nonsense variants.
DOI:10.4103/sjopt.sjopt_175_23 SUPPORT In Vitro
"most BEST1 pathogenic variants have been shown to cause either loss of function (LOF) of the protein or a dominant-negative (DN) effect, with a smaller subset causing a toxic gain of function (GOF)"
Categorizes BEST1 variant molecular mechanisms with important therapeutic implications: GOF variants require combined gene silencing + augmentation versus augmentation alone for LOF/DN.
🗃️

External Assertions

1
💊

Medical Actions

4
Anti-VEGF Therapy for Choroidal Neovascularization
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: angiogenesis inhibitor (anti-VEGF) NCIT:C1742 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses angiogenesis inhibitor (anti-VEGF), annotated with Angiogenesis Inhibitor (NCIT:C1742). NCIT:C1742 is a therapeutic agent from the NCI Thesaurus.
Intravitreal anti-VEGF agents (e.g., bevacizumab, ranibizumab) are the current standard of care for exudative choroidal neovascularization complicating late-stage BVMD. No approved disease-modifying therapy exists for the underlying bestrophinopathy.
Target Phenotypes: Choroidal neovascularization HP:0011506 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Choroidal neovascularization (HP:0011506). HP:0011506 is a phenotype from the Human Phenotype Ontology.
Show evidence (3 references)
DOI:10.1177/2515841421997191 SUPPORT Human Clinical
"no current clinical treatments available for patients with bestrophinopathies"
Confirms that no approved disease-modifying treatment exists for bestrophinopathies; anti-VEGF for CNV is the only currently available targeted intervention.
PMID:36281445 SUPPORT Human Clinical
"suggest a favorable long-term prognosis for intravitreal anti-VEGF injections in eyes with BVMD presenting with early complicating MNVs"
Case report with 2-year follow-up documents a favorable response to intravitreal anti-VEGF (ranibizumab) for macular neovascularization complicating BVMD, supporting anti-VEGF as standard of care for the exudative/neovascular complication.
PMID:38278445 SUPPORT Human Clinical
"Eyes with CNV that received treatment with an anti-vascular endothelial growth factor (VEGF) agent showed better mean BCVA compared with eyes that were not treated with an anti-VEGF agent"
The 222-patient natural-history cohort found better mean visual acuity in treated than untreated eyes with CNV; the observational comparison does not establish randomized efficacy.
OPGx-BEST1 Gene Augmentation Therapy (BIRD-1 Trial)
Action: gene therapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is gene therapy (NCIT:C15238). NCIT:C15238 is a clinical intervention from the NCI Thesaurus. Ontology label: Gene Therapy NCIT:C15238
OPGx-BEST1 (Opus Genetics) is a recombinant AAV vector delivering a codon-optimized full-length human BEST1 cDNA under an RPE-specific VMD2 promoter, administered by subretinal injection. The Phase 1b/2a BIRD-1 trial (NCT07185256) opened for enrollment in 2025, exploring two doses (1.5E9 and 4.5E9 vg/eye) with 5-year follow-up. Both LOF and DN mutations are potentially amenable to gene augmentation alone; GOF variants would require concurrent gene silencing.
Target Phenotypes: Vitelliform macular lesion HP:0007677 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Vitelliform macular lesion, annotated with Vitelliform-like macular lesions (HP:0007677). HP:0007677 is a phenotype from the Human Phenotype Ontology.
Show evidence (4 references)
clinicaltrials:NCT07185256 SUPPORT Human Clinical
"Evaluate the safety and tolerability of drug OPGx-BEST1 in one eye (the treatment eye), for 5 years post-injection, in participants with BVMD or ARB"
The first interventional gene therapy trial for bestrophinopathies is actively recruiting; OPGx-BEST1 subretinal gene delivery targets both BVMD (dominant) and ARB (recessive) patients.
DOI:10.3390/ijms26199421 SUPPORT In Vitro
"gene augmentation may be effective for a subset of bestrophinopathies, others require allele-specific silencing or correction of the disease-causing variant"
Establishes that gene augmentation (the OPGx-BEST1 approach) is appropriate for LOF/DN variants but that GOF variants require additional silencing strategies, informing patient eligibility and future trial design.
DOI:10.4103/sjopt.sjopt_175_23 SUPPORT In Vitro
"individuals harboring GOF variants would require a combination of gene silencing and gene augmentation, which has been shown to be effective in RPE cells derived from patients with Best disease"
Demonstrates proof-of-concept for combined silencing + augmentation for GOF BEST1 variants in iPSC-RPE, supporting the therapeutic rationale for BEST1 gene therapy.
+ 1 more reference
Annual Ophthalmologic Surveillance
Action: eye examinationNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is eye examination (NCIT:C38060). NCIT:C38060 is a clinical intervention from the NCI Thesaurus. Ontology label: Eye Examination NCIT:C38060
Annual ophthalmologic examination including best-corrected visual acuity, visual fields, and spectral-domain OCT to monitor fundus lesion progression and detect the development of choroidal neovascularization. In children with BVMD, annual ophthalmologic examinations also help prevent amblyopia development.
Target Phenotypes: Choroidal neovascularization HP:0011506 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Choroidal neovascularization (HP:0011506). HP:0011506 is a phenotype from the Human Phenotype Ontology. 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.
Show evidence (1 reference)
PMID:20301346 SUPPORT Human Clinical
"Annual ophthalmologic examination (including best corrected visual acuity, visual fields, and spectral domain optical coherence tomography) to monitor progression of fundus lesions and to evaluate for coincidental development of CNV; in childhood, perform annual ophthalmologic examinations to..."
GeneReviews recommends annual ophthalmologic surveillance including BCVA, visual fields, and SD-OCT as standard of care for bestrophinopathies, specifically to monitor disease progression and detect CNV.
Genetic Counseling
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. NCIT:C15240
Genetic counseling is recommended for all affected individuals and their families, particularly given the autosomal dominant inheritance with incomplete penetrance and marked variable expressivity, and the availability of cascade genetic testing for at-risk family members.
Show evidence (3 references)
DOI:10.1177/2515841421997191 SUPPORT Human Clinical
"over 250 individual pathological mutations have been identified in the BEST1 gene, with many reported to have various clinical expressivity and incomplete penetrance"
The broad genetic heterogeneity and variable penetrance/expressivity of dominant BEST1 disease make genetic counseling essential for accurate risk assessment and family planning guidance.
PMID:20301346 SUPPORT Human Clinical
"Once the BEST1 pathogenic variant(s) have been identified in an affected family member, prenatal testing for a pregnancy at increased risk and preimplantation genetic testing for a bestrophinopathy are possible."
GeneReviews confirms that once a causative BEST1 variant is identified, prenatal diagnostic testing and preimplantation genetic testing are available options, which should be communicated during genetic counseling.
PMID:20301346 SUPPORT Human Clinical
"Evaluation of relatives at risk: It is appropriate to clarify the genetic status of apparently asymptomatic older and younger at-risk relatives of an affected individual in order to identify as early as possible those who would benefit from prompt ophthalmologic evaluation and routine follow up."
GeneReviews recommends cascade genetic testing for at-risk relatives, because asymptomatic carriers may have subclinical RPE dysfunction detectable only by EOG or molecular testing.
🔬

Diagnosis

3
Multimodal retinal examination
Dilated examination and color fundus photography establish the lesion pattern, while spectral-domain OCT and fundus autofluorescence characterize subretinal material, fluid, outer-retinal integrity, fibrosis, and atrophy. OCT angiography is useful when macular neovascularization is suspected.
eye examination NCIT:C38060 NCI Thesaurus (NCIT)
Show evidence (2 references)
PMID:40086732 SUPPORT Human Clinical
"Retinal imaging with OCT and fundus autofluorescence (FAF) was analyzed cross-sectionally and longitudinally."
The large BVMD natural-history cohort establishes OCT and FAF as core structural modalities for diagnosis, staging, and longitudinal assessment.
DOI:10.1177/11206721231166434 SUPPORT Human Clinical
"effective diagnosis, staging, and clinical management of BVMD will likely require a deep understanding of the multimodal imaging features of this disease"
The imaging review supports a multimodal rather than single-test assessment.
Electrooculography
EOG measurement of the light-peak-to-dark-trough (Arden) ratio evaluates generalized RPE dysfunction. A reduced light-rise strongly supports a bestrophinopathy, including in some clinically unaffected heterozygotes, but it is not independently molecularly specific.
diagnostic procedure NCIT:C18020 NCI Thesaurus (NCIT)
Show evidence (1 reference)
DOI:10.1007/s10633-026-10093-y SUPPORT Human Clinical
"The light-rise of the electro-oculogram (EOG) is used as a clinical marker"
The current clinical review identifies EOG light-rise as a bestrophinopathy marker.
BEST1 molecular genetic testing
Sequence and copy-number analysis of BEST1 confirms the gene-level diagnosis and determines whether the genotype is heterozygous (dominant disease) or biallelic (autosomal-recessive bestrophinopathy). Interpretation must combine the variant classification with the ocular phenotype because expressivity and penetrance are variable.
genetic testing NCIT:C15709 NCI Thesaurus (NCIT)
Show evidence (1 reference)
PMID:20301346 SUPPORT Human Clinical
"The diagnosis of autosomal dominant bestrophinopathy is established in a proband with suggestive findings and a heterozygous BEST1 pathogenic (or likely pathogenic) variant identified by molecular genetic testing."
GeneReviews requires a compatible phenotype plus a heterozygous pathogenic BEST1 variant.
📈

Progression

2
Five-stage macular evolution (BVMD)
BVMD evolves through five classical stages: (1) Previtelliform — subtle RPE irregularity or normal fundus, relatively normal VA; (2) Vitelliform — classic dome-shaped "egg-yolk" subfoveal yellow lesion, often preserved VA; (3) Pseudohypopyon — vitelliform material layers inferiorly within the lesion, variable VA; (4) Vitelliruptive/"scrambled-egg" — fragmented lesion with outer-nuclear-layer thinning and ellipsoid-zone disruption, declining VA; (5) Atrophic/fibroatrophic — macular atrophy or fibrosis with severe and often irreversible central vision loss. Visual acuity is characteristically preserved longer than structural appearance suggests, consistent with the slow disease progression.
Show evidence (4 references)
DOI:10.1111/aos.14958 SUPPORT Human Clinical
"categorization of 52 eyes as Best vitelliform macular dystrophy (BVMD) with stages 1 to 5"
Clinical cohort of 62 bestrophinopathy eyes demonstrates the five-stage BVMD classification system, including stage 5 (atrophic/cicatricial).
DOI:10.1177/11206721231166434 SUPPORT Human Clinical
"effective diagnosis, staging, and clinical management of BVMD will likely require a deep understanding of the multimodal imaging features of this disease"
Multimodal imaging review establishes that BVMD staging requires integration of fundoscopy, OCT, FAF, and OCT-A data across disease stages.
PMID:20301346 SUPPORT Human Clinical
"Onset is usually in the first decade (except AVMD in which onset is age 30 to 50 years). Slow visual deterioration is the usual course."
GeneReviews anchors onset (first decade for BVMD) and the characteristically slow clinical trajectory, underpinning the five-stage natural history model and the long therapeutic window for future interventions.
+ 1 more reference
Slow structural and functional decline (BVMD)
Longitudinal cohorts show slow average visual-acuity and central retinal thickness loss, with substantial between-patient and between-variant variation. Atrophy, fibrosis, intraretinal fluid, and CNV identify more advanced disease, while lesion dimensions, outer-nuclear-layer thickness, and dark-adapted chromatic sensitivity are candidate trial outcomes.
Show evidence (2 references)
PMID:38278445 SUPPORT Human Clinical
"with a mean annual loss rate of 0.013 logMAR and 0.009 logMAR, respectively, over a mean follow-up of 9.7 years."
The cohort quantifies slow mean annual visual-acuity decline.
PMID:40086732 SUPPORT Human Clinical
"with a mean annual thickness loss of 5.7 and 5.2 μm, respectively."
The imaging cohort quantifies slow bilateral central-retinal-thickness loss.
🌍

Epidemiology

1
Prevalence
BVMD is among the more prevalent inherited macular dystrophies. Over 250 pathogenic BEST1 variants have been catalogued worldwide, with phenotypic and variant frequency differences across populations.
Show evidence (1 reference)
DOI:10.1177/2515841421997191 SUPPORT Human Clinical
"Bestrophinopathies are a group of clinically distinct inherited retinal dystrophies that typically affect the macular region, an area synonymous with central high acuity vision."
Characterizes bestrophinopathies as an important class of inherited macular dystrophies affecting the central high-acuity retina.
🔀

Differential Diagnoses

2

Conditions with similar clinical presentations that must be differentiated from BEST1-Related Dominant Retinopathy:

Autosomal recessive bestrophinopathy Not Yet Curated MONDO:0012733
Overlapping Features ARB shares RPE dysfunction, abnormal EOG, subretinal fluid, and vitelliform material with dominant BEST1 disease. Demonstration of biallelic pathogenic BEST1 variants rather than a single heterozygous variant is the defining molecular discriminator.
Distinguishing Features
  • Biallelic pathogenic BEST1 variants support ARB; one heterozygous pathogenic variant supports dominant BEST1 disease.
  • ARB is often a more diffuse retinal disease than the BVMD-centered macular pattern modeled here.
Show evidence (1 reference)
PMID:20301346 SUPPORT Human Clinical
"The diagnosis of autosomal recessive bestrophinopathy is established in a proband with suggestive findings and biallelic BEST1 pathogenic variants."
GeneReviews directly states the biallelic molecular discriminator for ARB.
Genetically heterogeneous adult-onset vitelliform macular dystrophy
Overlapping Features Adult-onset vitelliform lesions can be caused by BEST1, PRPH2, IMPG1, IMPG2, HTRA1, CTNNA1, or non-genetic mimics. Multigene testing and the complete retinal phenotype are therefore needed before assigning a gene-level BEST1 diagnosis.
Distinguishing Features
  • A heterozygous pathogenic BEST1 variant establishes the BEST1-defined subtype in a compatible phenotype.
  • PRPH2 and other macular-dystrophy genes should be assessed when BEST1 testing is negative or the phenotype is atypical.
Show evidence (1 reference)
DOI:10.1007/s10633-026-10093-y SUPPORT Human Clinical
"genetically heterogeneous, with PRPH2"
The clinical review identifies adult-onset vitelliform presentations as genetically heterogeneous and lists multiple non-BEST1 genes.
🔬

Clinical Trials

2
NCT07185256 PHASE_I RECRUITING
BIRD-1 is a phase 1b/2a open-label dose-exploration basket study of a single subretinal OPGx-BEST1 injection in one eye of participants with BVMD or ARB. It evaluates safety, tolerability, dose selection, and exploratory efficacy over five years. The schema's PHASE_I value represents the combined early phase 1b/2a designation.
Target Phenotypes: Vitelliform macular lesion HP:0007677 Human Phenotype Ontology (HP) Relation: this clinical trial targets this phenotype This clinical trial targets Vitelliform macular lesion, annotated with Vitelliform-like macular lesions (HP:0007677). HP:0007677 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
clinicaltrials:NCT07185256 SUPPORT Human Clinical
"Evaluate the safety and tolerability of drug OPGx-BEST1 in one eye (the treatment eye), for 5 years post-injection, in participants with BVMD or ARB."
The registry record directly states the population, treated eye, and five-year safety objective.
NCT05809635 NOT_APPLICABLE RECRUITING
Prospective observational natural-history study of molecularly confirmed BEST1 vitelliform macular dystrophy. It follows structural and functional measures for up to three years to select outcomes, assess fellow-eye comparability, and define populations for later interventional trials.
Show evidence (1 reference)
clinicaltrials:NCT05809635 SUPPORT Human Clinical
"Identify sensitive structural and functional outcome measures to use for future multicenter clinical trials for the treatment of BESTROPHIN 1 VMD."
The registry summary directly states the trial-readiness and outcome-measure objective.
🧫

Experimental Models

1
Patient-derived Best disease iPSC-RPE model IPSC_DERIVED_MODEL
Patient-derived RPE reproduces abnormal fluid flux, delayed rhodopsin degradation, autofluorescent-material accumulation, altered stimulated calcium responses, and oxidative stress. The matched unaffected-sibling comparison provides a human cellular bridge between BEST1 variation and RPE handling of photoreceptor outer segments.
Best disease patient-derived RPE Unaffected sibling-derived RPE Long-term photoreceptor-outer-segment feeding
retinal pigment epithelial cell CL:0002586 Cell Ontology (CL) Relation: this experimental model uses this cell type This experimental model uses retinal pigment epithelial cell (CL:0002586). CL:0002586 is a cell type from the Cell Ontology.
Organism
human NCBITaxon:9606 NCBI Taxonomy (NCBITaxon) Relation: this experimental model is built in this organism This experimental model is built in human, annotated with Homo sapiens (NCBITaxon:9606). NCBITaxon:9606 is an organism from the NCBI Taxonomy.
Cell source
RPE differentiated from induced pluripotent stem cells from individuals with Best disease and their unaffected siblings
Culture
Polarized hiPSC-RPE with chronic photoreceptor-outer-segment feeding
Publication
PMID:23139242
Pathograph links
RPE Dysfunction and Impaired Phagocytosis Models RPE fluid transport, calcium signaling, and photoreceptor-outer-segment handling.
Show evidence (1 reference)
PMID:23139242 SUPPORT In Vitro
"RHODOPSIN degradation after POS feeding was delayed in BD hiPSC-RPE relative to unaffected sibling hiPSC-RPE, directly implicating impaired POS handling in the pathophysiology of the disease."
The matched human model directly demonstrates impaired photoreceptor-outer-segment handling.
Vitelliform Material Accumulation Models accumulation of autofluorescent material after chronic outer-segment feeding.
Show evidence (1 reference)
PMID:23139242 SUPPORT In Vitro
"RPE from mutant hiPSCs displayed disrupted fluid flux and increased accrual of autofluorescent material after long-term POS feeding when compared with hiPSC-RPE from unaffected siblings."
The disease model reproduces the material-accumulation phenotype.
Show evidence (1 reference)
PMID:23139242 SUPPORT In Vitro
"We employed human iPS cell (hiPSC) technology to generate RPE from BD patients and unaffected siblings"
This establishes the patient-derived, sibling-controlled human RPE model.
🐁

Animal Models

2
Best1 loss-of-function (CMR1/2/3 — canine multifocal retinopathy) Dog
Canine multifocal retinopathy (CMR) is a naturally occurring bestrophinopathy in multiple dog breeds caused by autosomal-recessive BEST1 mutations (cmr1: p.Arg25Ter in Great Pyrenees/mastiff; cmr2: p.Gly161Asp in Coton de Tulear; cmr3: two variants in Swedish Lapponian Herder). Although CMR inheritance is recessive (unlike human BVMD), it recapitulates key features: multifocal retinal microdetachments, lipofuscin accumulation, and RPE microvilli loss. Subretinal AAV2-mediated BEST1 gene augmentation therapy in CMR dogs reversed both clinically detectable subretinal lesions and the diffuse RPE-photoreceptor microdetachment and corrected the RPE-photoreceptor interface across three canine BEST1 genotypes, providing the key preclinical proof-of-concept for the OPGx-BEST1 gene therapy approach. A 2026 dose-ranging study in 12 mutant dogs reported improved rod- and cone-mediated responses and retinal structure without systemic or ocular toxicity.
Species
Dog
Genotype
Best1 loss-of-function (CMR1/2/3 — canine multifocal retinopathy)
Show evidence (5 references)
PMID:29507198 SUPPORT Model Organism
"Subretinal BEST1 gene augmentation therapy using adeno-associated virus 2 reversed not only clinically detectable subretinal lesions but also the diffuse microdetachments"
In the canine BEST1 (CMR) model, subretinal AAV2-BEST1 gene augmentation reversed both clinically visible subretinal lesions and the diffuse RPE-photoreceptor microdetachment, the pivotal preclinical proof-of-concept underpinning the OPGx-BEST1 clinical gene therapy program.
DOI:10.3390/cells9040882 SUPPORT Model Organism
"Studies utilizing large animal models of inherited retinal degeneration (IRD) have proven important in not only the development of translational therapeutic approaches, but also in improving our understanding of disease mechanisms"
Large animal model review establishes the critical translational role of canine IRD models for inherited retinal disease gene therapy development, including for bestrophinopathy.
DOI:10.1007/s00335-024-10091-y SUPPORT Model Organism
"Large animal models of inherited retinal diseases, particularly dogs, have been extensively used over the past decades to study disease natural history and evaluate therapeutic interventions"
Canine IRD model review highlights the central role of dog models in bestrophinopathy translational research, from natural history to gene therapy preclinical evaluation.
+ 2 more references
Best1 W93C knock-in and Best1 knockout Mouse
Best1 W93C knock-in mice (heterozygous and homozygous) exhibit an altered EOG light-peak luminance response reminiscent of BVMD patients, together with fluid- and debris-filled retinal detachments and enhanced RPE lipofuscin accumulation, yet retain normal chloride conductances — indicating that the dominant disease is not simply loss of bestrophin-1 chloride-channel function. The knock-in phenotype is distinct from that of Best1 knockout mice (with respect to lipofuscin accumulation and ATP-stimulated calcium responses), and the W93C knock-in is regarded as a valid model of BVMD. Overall, mouse models incompletely recapitulate human BVMD, limiting their translational utility relative to canine models and iPSC-RPE systems.
Species
Mouse
Genotype
Best1 W93C knock-in and Best1 knockout
Show evidence (2 references)
PMID:20053664 SUPPORT Model Organism
"Both Best1(+/W93C)and Best1(W93C/W93C) mice had normal ERG a- and b-waves, but exhibited an altered LP luminance response reminiscent of that observed in BVMD patients"
Knock-in mouse study shows the dominant BVMD-causing W93C variant produces the hallmark altered EOG light-peak (LP) response with normal ERG, modeling the human electrophysiological phenotype of BVMD.
PMID:20053664 SUPPORT Model Organism
"RPE cells from Best1(W93C) mice exhibited normal Cl(-) conductances"
Despite reproducing the disease phenotype, W93C knock-in RPE retains normal chloride conductance, showing that dominant BVMD pathology is not simply loss of bestrophin-1 chloride-channel function.
{ }

Source YAML

click to show 
name: BEST1-Related Dominant Retinopathy
creation_date: "2026-06-23T00:00:00Z"
category: Mendelian
description: >-
  BEST1-related dominant retinopathy is the gene-level umbrella for retinal
  disease caused by a heterozygous pathogenic BEST1 variant. Its prototypic
  phenotype is Best vitelliform macular dystrophy (BVMD/Best disease), in which
  retinal pigment epithelium (RPE) dysfunction, abnormal subretinal material,
  reduced electrooculogram (EOG) light-rise, and slowly progressive central
  visual impairment form the core clinical picture. Adult-onset vitelliform
  macular dystrophy and autosomal dominant vitreoretinochoroidopathy are also
  recognized dominant BEST1 phenotypes, but the detailed causal and phenotype
  graph in this entry is intentionally BVMD-centered. Dominant variants can
  produce loss-of-function, dominant-negative, or gain-of-function effects,
  and penetrance and expressivity are variable. No approved disease-modifying
  treatment exists; OPGx-BEST1 gene augmentation is being evaluated in the
  recruiting BIRD-1 study (NCT07185256).
disease_term:
  preferred_term: BEST1-related dominant retinopathy
  term:
    id: MONDO:0700238
    label: BEST1-related dominant retinopathy
synonyms:
- Best vitelliform macular dystrophy
- BVMD
- Best disease
- vitelliform macular dystrophy 2
- VMD2
parents:
- Ophthalmological Disease
- Retinal Dystrophy
- Inherited retinal dystrophy
classifications:
  harrisons_chapter:
  - classification_value: GENETICS_ENVIRONMENT_DISEASE
    evidence:
    - reference: PMID:20301346
      reference_title: "Bestrophinopathies."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "the spectrum of ophthalmic disorders caused by pathogenic variants in BEST1"
      explanation: The gene-defined inherited disease spectrum supports the genetics classification.
  channelopathy_category:
    classification_value: epithelial channelopathy
    evidence:
    - reference: DOI:10.3390/ijms26199421
      reference_title: "Gene Therapy Strategies for the Treatment of Bestrophinopathies"
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "BEST1 gene encodes a transmembrane protein in the retinal pigment epithelium (RPE) in the eye, that functions as a calcium-dependent chloride channel (CaCC)"
      explanation: BEST1 is an ion channel expressed in the retinal pigment epithelium.
external_assertions:
- name: ClinGen BEST1-related dominant retinopathy gene-disease validity assertion
  source: ClinGen
  assertion_type: gene_disease_validity
  external_id: CGGV:assertion_487a42cc-7dd0-4991-ac9d-1346f59073c0-2023-08-03T160000.000Z
  url: https://search.clinicalgenome.org/kb/gene-validity/CGGV:assertion_487a42cc-7dd0-4991-ac9d-1346f59073c0-2023-08-03T160000.000Z
  description: >-
    The ClinGen Retina Gene Curation Expert Panel classifies the autosomal-dominant
    BEST1 relationship with MONDO:0700238 as definitive under SOP9.
  evidence:
  - reference: CGGV:assertion_487a42cc-7dd0-4991-ac9d-1346f59073c0-2023-08-03T160000.000Z
    reference_title: BEST1 / BEST1-related dominant retinopathy (Definitive)
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "BEST1 | HGNC:12703 | BEST1-related dominant retinopathy | MONDO:0700238 | AD | Definitive"
    explanation: >-
      The structured ClinGen assertion anchors the gene, disease identifier,
      autosomal-dominant inheritance, and definitive validity classification.
definitions:
- name: Molecular definition of autosomal-dominant bestrophinopathy
  definition_type: DIAGNOSTIC_CRITERIA
  derivation_basis: ESTABLISHED_CRITERIA
  description: >-
    A proband with suggestive ophthalmic findings and a heterozygous pathogenic
    or likely pathogenic BEST1 variant meets the GeneReviews molecular
    definition of autosomal-dominant bestrophinopathy.
  evidence:
  - reference: PMID:20301346
    reference_title: "Bestrophinopathies."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The diagnosis of autosomal dominant bestrophinopathy is established in a proband with suggestive findings and a heterozygous BEST1 pathogenic (or likely pathogenic) variant identified by molecular genetic testing."
    explanation: >-
      GeneReviews directly states the clinical-plus-molecular diagnostic
      definition for dominant BEST1 disease.
notes: >-
  MONDO:0700238 captures autosomal-dominant BEST1 retinopathies only. The
  broader bestrophinopathy spectrum (including autosomal recessive
  bestrophinopathy, ADVIRC, MRCS, and BEST1-associated RP) is covered in
  BEST1_Bestrophinopathies.yaml (MONDO:0000390). Adult-onset foveomacular
  vitelliform dystrophy (AVMD) includes BEST1-related cases as a gene-defined
  subtype in Adult_Onset_Foveomacular_Vitelliform_Dystrophy.yaml
  (MONDO:0011979). Autosomal recessive bestrophinopathy (ARB; OMIM 611809;
  MONDO:0012733, mapped from the gene-level grouping term MONDO:0700239
  "BEST1-related recessive retinopathy") requires biallelic BEST1 mutations
  and is not captured here. Because the available quantitative natural-history
  literature is predominantly about BVMD, frequency and progression statements
  below should not be generalized to every dominant BEST1 phenotype.
pathophysiology:
- name: BEST1 Calcium-Activated Chloride Channel Dysfunction
  description: >-
    Heterozygous pathogenic BEST1 variants produce mutant bestrophin-1 subunits
    that co-assemble with wild-type subunits in the homopentameric CaCC complex
    in the RPE basolateral membrane. The large majority of dominant BEST1
    pathogenic variants cause loss-of-function (LOF) or dominant-negative (DN)
    impairment of calcium-activated chloride conductance; a minority cause toxic
    gain-of-function (GOF) with excess channel activity. The resulting abnormal
    chloride transport disrupts RPE transepithelial ion flux and calcium
    homeostasis.
  genes:
  - preferred_term: BEST1
    term:
      id: hgnc:12703
      label: BEST1
  cell_types:
  - preferred_term: retinal pigment epithelial cell
    term:
      id: CL:0002586
      label: retinal pigment epithelial cell
  biological_processes:
  - preferred_term: chloride transport
    term:
      id: GO:0006821
      label: chloride transport
    modifier: DECREASED
  evidence:
  - reference: DOI:10.4103/sjopt.sjopt_175_23
    reference_title: "Gene therapy in bestrophinopathies: Insights from preclinical studies in preparation for clinical trials"
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "most BEST1 pathogenic variants have been shown to cause either loss of function (LOF) of the protein or a dominant-negative (DN) effect, with a smaller subset causing a toxic gain of function (GOF)"
    explanation: >-
      Review of bestrophinopathy gene therapy preclinical studies characterizes
      the three molecular mechanisms (LOF, DN, GOF) by which dominant BEST1
      variants impair bestrophin-1 channel function, with implications for
      therapeutic strategy.
  - reference: DOI:10.1177/2515841421997191
    reference_title: "Bestrophinopathies: perspectives on clinical disease, Bestrophin-1 function and developing therapies"
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "This spectrum of disorders is caused by mutations in bestrophin1"
    explanation: >-
      The review directly identifies pathogenic BEST1 variation as the cause of
      the bestrophinopathy spectrum.
  - reference: DOI:10.3390/ijms26199421
    reference_title: "Gene Therapy Strategies for the Treatment of Bestrophinopathies"
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "BEST1 gene encodes a transmembrane protein in the retinal pigment epithelium (RPE) in the eye, that functions as a calcium-dependent chloride channel (CaCC)"
    explanation: >-
      Gene therapy strategy review confirms bestrophin-1 CaCC identity and RPE
      localization as the basis of BEST1-related retinopathy mechanisms.
  - reference: DOI:10.3390/ijms23137432
    reference_title: "Impaired Bestrophin Channel Activity in an iPSC-RPE Model of Best Vitelliform Macular Dystrophy (BVMD) from an Early Onset Patient Carrying the P77S Dominant Mutation"
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "presents an increased chloride entrance, indicating that the p.Pro77Ser variant might be a gain-of-function mutation"
    explanation: >-
      iPSC-RPE model of BVMD demonstrates a GOF mechanism for the p.Pro77Ser
      dominant mutation: increased chloride conductance, establishing that
      dominant BEST1 mutations act through multiple distinct mechanisms.
  downstream:
  - target: RPE Dysfunction and Impaired Phagocytosis
    description: >-
      Impaired CaCC activity disrupts calcium signaling, transepithelial fluid
      transport, and phagocytic uptake of shed photoreceptor outer segments
      in the RPE.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:23139242
      reference_title: "iPS cell modeling of Best disease: insights into the pathophysiology of an inherited macular degeneration."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "stimulated calcium responses differed between BD and normal sibling hiPSC-RPE, as did oxidative stress levels after chronic POS feeding"
      explanation: >-
        Patient-derived RPE links mutant BEST1 to altered calcium responses and
        stress after photoreceptor-outer-segment exposure.
- name: RPE Dysfunction and Impaired Phagocytosis
  description: >-
    Bestrophin-1 CaCC dysfunction impairs multiple interdependent RPE functions:
    calcium homeostasis, transepithelial fluid transport, and phagocytic uptake of
    daily-shed photoreceptor outer segments (POS). Failure of RPE phagocytosis
    allows undigested POS to accumulate in the subretinal space. The pathognomonic
    reduction of the EOG Arden ratio (light-rise) is the electrophysiological
    readout of this RPE-level dysfunction, present even in asymptomatic BEST1
    carriers.
  cell_types:
  - preferred_term: retinal pigment epithelial cell
    term:
      id: CL:0002586
      label: retinal pigment epithelial cell
  biological_processes:
  - preferred_term: phagocytosis
    term:
      id: GO:0006909
      label: phagocytosis
    modifier: DECREASED
  - preferred_term: retina homeostasis
    term:
      id: GO:0001895
      label: retina homeostasis
    modifier: DECREASED
  evidence:
  - reference: DOI:10.3390/ijms23137432
    reference_title: "Impaired Bestrophin Channel Activity in an iPSC-RPE Model of Best Vitelliform Macular Dystrophy (BVMD) from an Early Onset Patient Carrying the P77S Dominant Mutation"
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "mutations in this gene induce functional problems in the RPE cell layer with an accumulation of lipofucsin that evolves into cell death and loss of sight"
    explanation: >-
      iPSC-RPE model of BVMD demonstrates that BEST1 mutations cause RPE
      dysfunction leading to lipofuscin accumulation and eventual cell death.
  - reference: DOI:10.1007/s10633-026-10093-y
    reference_title: "Review of the clinical electrooculogram - Part 2: the bestrophinopathies and modified protocols"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The light-rise of the electro-oculogram (EOG) is used as a clinical marker"
    explanation: >-
      The reduced EOG light-rise is the pathognomonic RPE electrophysiological
      signature of bestrophinopathy, reflecting the underlying bestrophin-1
      CaCC dysfunction in RPE.
  - reference: DOI:10.1111/aos.14958
    reference_title: "Disease expression caused by different variants in the <i>BEST1</i> gene: genotype and phenotype findings in bestrophinopathies"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The Arden ratio was significantly lower in ARB patients and in eyes with stage 5 of BVMD"
    explanation: >-
      Clinical cohort study confirms reduced EOG Arden ratio across BVMD stages,
      with the most severe reduction in end-stage (atrophic) disease.
  downstream:
  - target: Vitelliform Material Accumulation
    description: >-
      Impaired RPE phagocytosis and fluid transport lead to subretinal
      accumulation of lipofuscin-rich unphagocytosed outer-segment material,
      forming the characteristic vitelliform deposit.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:23139242
      reference_title: "iPS cell modeling of Best disease: insights into the pathophysiology of an inherited macular degeneration."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "RPE from mutant hiPSCs displayed disrupted fluid flux and increased accrual of autofluorescent material after long-term POS feeding when compared with hiPSC-RPE from unaffected siblings."
      explanation: >-
        The patient-derived model directly connects impaired RPE fluid/POS
        handling with accumulation of autofluorescent material.
  - target: Abnormal electrooculogram
    description: >-
      The reduced EOG light-rise is a functional clinical readout of RPE
      dysfunction in BEST1 disease.
    causal_link_type: DIRECT
    evidence:
    - reference: DOI:10.1007/s10633-026-10093-y
      reference_title: "Review of the clinical electrooculogram - Part 2: the bestrophinopathies and modified protocols"
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "test of the retinal pigment epithelium (RPE)"
      explanation: >-
        The clinical review explicitly identifies EOG as a functional test of
        the RPE, supporting this phenotype-to-mechanism connection.
- name: Vitelliform Material Accumulation
  description: >-
    Impaired RPE phagocytosis of shed photoreceptor outer segments and disrupted
    subretinal fluid homeostasis lead to progressive subretinal accumulation of
    lipofuscin-rich, hyperautofluorescent material beneath the macula. Quantitative
    autofluorescence studies indicate that lipofuscin accumulation is not a primary
    consequence of the genetic defect, but reflects secondary failure of
    RPE-photoreceptor apposition and POS clearance. The hallmark "egg-yolk"
    vitelliform lesion evolves through five classical stages over years to decades:
    previtelliform, vitelliform, pseudohypopyon, vitelliruptive ("scrambled-egg"),
    and atrophic/fibroatrophic.
  locations:
  - preferred_term: macula lutea
    term:
      id: UBERON:0000053
      label: macula lutea
  - preferred_term: fovea centralis
    term:
      id: UBERON:0001786
      label: fovea centralis
  cell_types:
  - preferred_term: retinal pigment epithelial cell
    term:
      id: CL:0002586
      label: retinal pigment epithelial cell
  biological_processes:
  - preferred_term: photoreceptor cell maintenance
    term:
      id: GO:0045494
      label: photoreceptor cell maintenance
    modifier: DECREASED
  evidence:
  - reference: DOI:10.1177/11206721231166434
    reference_title: "Multimodal imaging in Best Vitelliform Macular Dystrophy: Literature review and novel insights"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "lipofuscin accumulation, the hallmark of BVMD, is unlikely to be a primary effect of the genetic defect. It could be due to a lack of apposition between photoreceptors and retinal pigment epithelium in the macula with subsequent accumulation of shed outer segments over time"
    explanation: >-
      Quantitative FAF imaging review establishes that vitelliform material
      accumulates secondary to impaired RPE-photoreceptor apposition and POS
      phagocytosis, not as a direct primary effect of BEST1 dysfunction.
  downstream:
  - target: Progressive Photoreceptor Damage and Vision Loss
    description: >-
      Chronic subretinal lipofuscin-rich deposit disrupts photoreceptor-RPE
      apposition and causes progressive structural cone photoreceptor damage,
      outer-nuclear-layer thinning, and ellipsoid-zone disruption.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - subretinal lipofuscin-rich material disrupting photoreceptor-RPE apposition
    evidence:
    - reference: DOI:10.1177/11206721231166434
      reference_title: "Multimodal imaging in Best Vitelliform Macular Dystrophy: Literature review and novel insights"
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "vitelliform lesions are characterized by progressive changes in the cone mosaic corresponding to a thinning of the outer nuclear layer and then disruption of the ellipsoid zone"
      explanation: >-
        Human multimodal imaging connects the vitelliform lesion with
        progressive cone, outer-nuclear-layer, and ellipsoid-zone damage.
  - target: Vitelliform macular lesion
    description: >-
      Subretinal accumulation of autofluorescent material produces the
      clinically visible vitelliform lesion.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:23139242
      reference_title: "iPS cell modeling of Best disease: insights into the pathophysiology of an inherited macular degeneration."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "lead to the accumulation of subretinal fluid and autofluorescent waste products from shed photoreceptor outer segments (POSs)."
      explanation: >-
        Patient-derived modeling supports accumulation of the subretinal
        material that constitutes the vitelliform lesion.
- name: Progressive Photoreceptor Damage and Vision Loss
  description: >-
    The subretinal vitelliform deposit progressively disrupts photoreceptor-RPE
    apposition and causes structural damage to the cone-dominated macular
    photoreceptors. OCT and adaptive optics imaging demonstrate progressive
    disruption of the cone mosaic, followed by outer-nuclear-layer thinning and
    ellipsoid-zone disruption. In late stages, choroidal
    neovascularization (CNV) can develop beneath the damaged RPE, causing
    exudative complications and acute vision loss on a background of slow chronic
    progression.
  locations:
  - preferred_term: macula lutea
    term:
      id: UBERON:0000053
      label: macula lutea
  cell_types:
  - preferred_term: cone photoreceptor cell
    term:
      id: CL:0000573
      label: retinal cone cell
  biological_processes:
  - preferred_term: photoreceptor cell maintenance
    term:
      id: GO:0045494
      label: photoreceptor cell maintenance
    modifier: DECREASED
  - preferred_term: visual perception
    term:
      id: GO:0007601
      label: visual perception
    modifier: DECREASED
  evidence:
  - reference: DOI:10.1177/11206721231166434
    reference_title: "Multimodal imaging in Best Vitelliform Macular Dystrophy: Literature review and novel insights"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "vitelliform lesions are characterized by progressive changes in the cone mosaic corresponding to a thinning of the outer nuclear layer and then disruption of the ellipsoid zone, which are associated with a decreased sensitivity and visual acuity"
    explanation: >-
      OCT and adaptive optics imaging directly demonstrate progressive cone
      mosaic disruption and outer-nuclear-layer thinning as the structural
      basis of visual loss in BVMD.
  - reference: DOI:10.1177/11206721231166434
    reference_title: "Multimodal imaging in Best Vitelliform Macular Dystrophy: Literature review and novel insights"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "OCT Angiography proved a greater prevalence of macular neovascularization, the majority of which are non-exudative and develop in late disease stages"
    explanation: >-
      OCT angiography demonstrates that macular neovascularization is prevalent
      in late-stage BVMD, with most cases non-exudative; exudative CNV
      represents a serious complication requiring anti-VEGF treatment.
  downstream:
  - target: Reduced visual acuity
    description: Progressive outer-retinal and photoreceptor damage reduces central visual acuity.
    causal_link_type: DIRECT
    evidence:
    - reference: DOI:10.1177/11206721231166434
      reference_title: "Multimodal imaging in Best Vitelliform Macular Dystrophy: Literature review and novel insights"
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "disruption of the ellipsoid zone, which are associated with a decreased sensitivity and visual acuity"
      explanation: Imaging directly associates outer-retinal disruption with reduced visual function.
  - target: Metamorphopsia
    description: Macular structural distortion can manifest as distorted central vision.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - subfoveal structural distortion
    evidence:
    - reference: PMID:36281445
      reference_title: "Temporary Vitelliform Regression After Intravitreal Ranibizumab Injection for Macular Neovascularization Complicating Best Disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "A 12-year-old boy complaining of metamorphopsia presented with bilateral yellowish subfoveal deposits"
      explanation: A genetically confirmed BVMD presentation connects subfoveal lesions with metamorphopsia.
  - target: Macular atrophy
    description: Progressive RPE and photoreceptor injury culminates in macular atrophy.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:40086732
      reference_title: "Best Vitelliform Macular Dystrophy Natural History Study Report 2: Fundus Autofluorescence and OCT."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "the presence of intraretinal fluid and atrophy/fibrosis were correlated with a worse mean VA."
      explanation: The large imaging cohort ties atrophy/fibrosis to advanced structural and functional damage.
  - target: Choroidal neovascularization
    description: Late RPE/outer-retinal damage can be complicated by choroidal neovascularization.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - damaged RPE-Bruch membrane interface and pro-angiogenic signaling
    evidence:
    - reference: PMID:38278445
      reference_title: "Best Vitelliform Macular Dystrophy Natural History Study Report 1: Clinical Features and Genetic Findings."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Thirty-seven patients (17.3%) received a diagnosis of CNV over a mean follow-up of 8.0 years."
      explanation: The large natural-history cohort establishes CNV as a longitudinal complication of BVMD.
phenotypes:
- name: Vitelliform macular lesion
  category: Ophthalmological
  frequency: VERY_FREQUENT
  diagnostic: true
  description: >-
    The hallmark of BVMD: a bilateral, dome-shaped, yellow "egg-yolk" subfoveal
    lesion of vitelliform material visible on fundoscopy, confirmed by
    hyperautofluorescence on FAF imaging and subretinal hyperreflective material
    on OCT. Present in the classic vitelliform stage; may be absent or subtle in
    the previtelliform and atrophic stages.
  phenotype_term:
    preferred_term: Vitelliform macular lesion
    term:
      id: HP:0007677
      label: Vitelliform-like macular lesions
  evidence:
  - reference: DOI:10.1177/11206721231166434
    reference_title: "Multimodal imaging in Best Vitelliform Macular Dystrophy: Literature review and novel insights"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Best Vitelliform Macular Dystrophy (BVMD) is a dominantly inherited retinal disease caused by dominant variants in the BEST1 gene"
    explanation: >-
      Multimodal imaging review establishes the vitelliform macular lesion as
      the defining hallmark of BVMD, caused by dominant BEST1 variants.
  - reference: PMID:20301346
    reference_title: "Bestrophinopathies."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The four recognized phenotypes are the three autosomal dominant disorders: Best vitelliform macular dystrophy (BVMD), BEST1 adult-onset vitelliform macular dystrophy (AVMD), and autosomal dominant vitreoretinochoroidopathy (ADVIRC); and autosomal recessive bestrophinopathy (ARB)."
    explanation: >-
      GeneReviews identifies BVMD (with its vitelliform macular lesion) as the
      prototypic autosomal-dominant BEST1 phenotype, anchoring the cardinal
      diagnostic feature in the authoritative clinical reference.
- name: Abnormal electrooculogram
  category: Ophthalmological
  frequency: VERY_FREQUENT
  diagnostic: true
  description: >-
    Reduced or absent EOG light-rise (Arden ratio typically below 1.5) is the
    pathognomonic electrophysiological feature of BVMD. It reflects underlying
    RPE dysfunction and can be present in asymptomatic BEST1 carriers before any
    visible macular change.
  phenotype_term:
    preferred_term: Abnormal electrooculogram
    term:
      id: HP:0030453
      label: Abnormal visual electrophysiology
  reports_on:
  - target: RPE Dysfunction and Impaired Phagocytosis
    relationship: READOUT_OF
    endpoint_context: DIAGNOSTIC
    interpretation: EOG light-rise (Arden ratio) as the electrophysiological readout of RPE function
    evidence:
    - reference: DOI:10.1007/s10633-026-10093-y
      reference_title: "Review of the clinical electrooculogram - Part 2: the bestrophinopathies and modified protocols"
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "test of the retinal pigment epithelium (RPE)"
      explanation: The clinical EOG directly reports on RPE function.
  evidence:
  - reference: DOI:10.1007/s10633-026-10093-y
    reference_title: "Review of the clinical electrooculogram - Part 2: the bestrophinopathies and modified protocols"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The light-rise of the electro-oculogram (EOG) is used as a clinical marker"
    explanation: >-
      The EOG light-rise reduction is the pathognomonic functional RPE marker
      used clinically to diagnose and classify bestrophinopathies.
  - reference: DOI:10.1111/aos.14958
    reference_title: "Disease expression caused by different variants in the <i>BEST1</i> gene: genotype and phenotype findings in bestrophinopathies"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The Arden ratio was significantly lower in ARB patients and in eyes with stage 5 of BVMD"
    explanation: >-
      Clinical cohort data confirm that reduced Arden ratio (EOG light-rise)
      is present across BVMD stages, with severity correlating with disease stage.
- name: Reduced visual acuity
  category: Ophthalmological
  frequency: FREQUENT
  description: >-
    Progressive central visual impairment that correlates with structural
    macular damage; visual function is often relatively preserved in early
    vitelliform stages despite prominent lesion appearance.
  phenotype_term:
    preferred_term: Reduced visual acuity
    term:
      id: HP:0007663
      label: Reduced visual acuity
    clinical_course: PROGRESSIVE
  evidence:
  - reference: DOI:10.1177/11206721231166434
    reference_title: "Multimodal imaging in Best Vitelliform Macular Dystrophy: Literature review and novel insights"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "vitelliform lesions are characterized by progressive changes in the cone mosaic corresponding to a thinning of the outer nuclear layer and then disruption of the ellipsoid zone, which are associated with a decreased sensitivity and visual acuity"
    explanation: >-
      OCT studies demonstrate that progressive structural cone and
      outer-nuclear-layer damage directly correlates with reduced visual acuity
      in BVMD.
  - reference: DOI:10.1111/aos.14958
    reference_title: "Disease expression caused by different variants in the <i>BEST1</i> gene: genotype and phenotype findings in bestrophinopathies"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The genotype does not always predict the phenotype in patients with BVMD and ARB"
    explanation: >-
      Clinical cohort study confirms that disease course is not strictly
      determined by genotype, consistent with the variable expressivity and
      often slowly progressive character of BVMD with relatively preserved
      visual function in many patients over 5 years of follow-up.
  - reference: PMID:20301346
    reference_title: "Bestrophinopathies."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Slow visual deterioration is the usual course."
    explanation: >-
      GeneReviews confirms slowly progressive visual impairment as the typical
      clinical trajectory of bestrophinopathies, consistent with often-preserved
      VA in early stages and the long window of opportunity for intervention.
- name: Metamorphopsia
  category: Ophthalmological
  frequency: OCCASIONAL
  description: Distortion of central vision from the subfoveal vitelliform macular lesion.
  phenotype_term:
    preferred_term: Metamorphopsia
    term:
      id: HP:0012508
      label: Metamorphopsia
  evidence:
  - reference: PMID:36281445
    reference_title: "Temporary Vitelliform Regression After Intravitreal Ranibizumab Injection for Macular Neovascularization Complicating Best Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "A 12-year-old boy complaining of metamorphopsia presented with bilateral yellowish subfoveal deposits, suggestive of BVMD, which was confirmed by fundus autofluorescence and electrooculography"
    explanation: >-
      Case report of BVMD in which metamorphopsia was the presenting symptom,
      directly documenting metamorphopsia arising from the subfoveal vitelliform
      lesion.
- name: Macular atrophy
  category: Ophthalmological
  frequency: OCCASIONAL
  description: >-
    End-stage finding with RPE and outer retinal atrophy in the macular region,
    developing as the vitelliform lesion progresses through vitelliruptive to
    atrophic stage.
  phenotype_term:
    preferred_term: Macular atrophy
    term:
      id: HP:0007401
      label: Macular atrophy
  evidence:
  - reference: DOI:10.1111/aos.14958
    reference_title: "Disease expression caused by different variants in the <i>BEST1</i> gene: genotype and phenotype findings in bestrophinopathies"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "categorization of 52 eyes as Best vitelliform macular dystrophy (BVMD) with stages 1 to 5"
    explanation: >-
      Clinical staging in a 62-eye cohort demonstrates the full BVMD progression
      from stage 1 (previtelliform) through stage 5 (atrophic/cicatricial),
      confirming macular atrophy as a recognized end-stage phenotype.
  - reference: DOI:10.1111/aos.14958
    reference_title: "Disease expression caused by different variants in the <i>BEST1</i> gene: genotype and phenotype findings in bestrophinopathies"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the atrophic stage of BVMD"
    explanation: >-
      The same cohort study identifies the atrophic stage of BVMD as the disease
      end-stage with the worst visual function and EOG results, directly anchoring
      macular atrophy as the terminal BVMD phenotype.
- name: Choroidal neovascularization
  category: Ophthalmological
  frequency: OCCASIONAL
  description: >-
    Macular choroidal neovascularization develops as a late complication of RPE
    damage and atrophy, causing exudative complications and acute vision loss.
    Most CNV in BVMD is non-exudative on OCT-A.
  phenotype_term:
    preferred_term: Choroidal neovascularization
    term:
      id: HP:0011506
      label: Choroidal neovascularization
  evidence:
  - reference: DOI:10.1177/11206721231166434
    reference_title: "Multimodal imaging in Best Vitelliform Macular Dystrophy: Literature review and novel insights"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "OCT Angiography proved a greater prevalence of macular neovascularization, the majority of which are non-exudative and develop in late disease stages"
    explanation: >-
      OCT angiography studies demonstrate macular neovascularization as a
      frequent late-stage BVMD finding, with the majority non-exudative.
  - reference: PMID:20301346
    reference_title: "Bestrophinopathies."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Choroidal neovascularization can occur in rare cases."
    explanation: >-
      GeneReviews confirms choroidal neovascularization as a recognized, though
      uncommon, late complication of bestrophinopathies, warranting annual
      ophthalmologic surveillance for its detection.
genetic:
- name: BEST1 heterozygous pathogenic variant
  gene_term:
    preferred_term: BEST1
    term:
      id: hgnc:12703
      label: BEST1
  association: Causative
  features: >-
    Dominant BEST1-related retinopathy is caused by heterozygous pathogenic
    variants in BEST1 (bestrophin-1, HGNC:12703). Over 250 pathogenic BEST1
    variants are known; the vast majority are missense mutations, with a minority
    nonsense, frameshift, or splice-site variants. Three molecular mechanisms
    operate: dominant-negative (DN, most common), loss-of-function (LOF), and
    gain-of-function (GOF, minority). Both LOF and DN mutations may respond to
    gene augmentation therapy, while GOF mutations require gene silencing plus
    augmentation.
  evidence:
  - reference: DOI:10.1177/2515841421997191
    reference_title: "Bestrophinopathies: perspectives on clinical disease, Bestrophin-1 function and developing therapies"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "over 250 individual pathological mutations have been identified in the BEST1 gene, with many reported to have various clinical expressivity and incomplete penetrance"
    explanation: >-
      Establishes the genetic landscape: over 250 BEST1 pathogenic variants
      underlie the bestrophinopathies, with variable expressivity and incomplete
      penetrance characterizing the dominant forms.
  - reference: DOI:10.1002/mgg3.2095
    reference_title: "<i>BEST1</i> novel mutation causes Bestrophinopathies in six families with distinct phenotypic diversity"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "A total of 9 variants on the BEST1 gene were identified, containing 7 missense variants, 1 nonsense variant, and 1 frameshift variant"
    explanation: >-
      Family-based genetic study of bestrophinopathies demonstrates the variant
      type distribution: predominantly missense, with minority
      frameshift/nonsense variants.
  - reference: DOI:10.4103/sjopt.sjopt_175_23
    reference_title: "Gene therapy in bestrophinopathies: Insights from preclinical studies in preparation for clinical trials"
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "most BEST1 pathogenic variants have been shown to cause either loss of function (LOF) of the protein or a dominant-negative (DN) effect, with a smaller subset causing a toxic gain of function (GOF)"
    explanation: >-
      Categorizes BEST1 variant molecular mechanisms with important therapeutic
      implications: GOF variants require combined gene silencing + augmentation
      versus augmentation alone for LOF/DN.
inheritance:
- name: Autosomal dominant
  inheritance_term:
    preferred_term: Autosomal dominant inheritance
    term:
      id: HP:0000006
      label: Autosomal dominant inheritance
  description: >-
    BVMD follows autosomal dominant inheritance with incomplete penetrance and
    marked variable expressivity. Asymptomatic carriers with pathogenic BEST1
    variants may show only reduced EOG without visible macular lesions.
    Intrafamilial phenotypic diversity is pronounced, with some heterozygous
    carriers showing no visible fundus changes.
  evidence:
  - reference: DOI:10.1002/mgg3.2095
    reference_title: "<i>BEST1</i> novel mutation causes Bestrophinopathies in six families with distinct phenotypic diversity"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "patients carrying a pathogenic heterozygous variant of BEST1 to develop obvious intrafamilial phenotypic diversity"
    explanation: >-
      Family-based clinical genetic study demonstrates marked intrafamilial
      phenotypic diversity characteristic of dominant BEST1 disease with variable
      expressivity.
  - reference: DOI:10.1177/2515841421997191
    reference_title: "Bestrophinopathies: perspectives on clinical disease, Bestrophin-1 function and developing therapies"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "over 250 individual pathological mutations have been identified in the BEST1 gene, with many reported to have various clinical expressivity and incomplete penetrance"
    explanation: >-
      Documents incomplete penetrance and variable clinical expressivity as
      characteristic features of dominant BEST1 inheritance.
  - reference: PMID:20301346
    reference_title: "Bestrophinopathies."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "BVMD, AVMD, and ADVIRC are inherited in an autosomal dominant (AD) manner."
    explanation: >-
      GeneReviews explicitly confirms autosomal dominant inheritance as the mode
      for all three dominant BEST1 bestrophinopathy phenotypes.
  - reference: PMID:20301346
    reference_title: "Bestrophinopathies."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Each child of an affected individual has a 50% chance of inheriting the BEST1 pathogenic variant."
    explanation: >-
      GeneReviews documents the foundational AD transmission risk: each child of
      an affected parent has a 50% chance of inheriting the causative BEST1 variant,
      forming the basis of genetic counseling for this disorder.
diagnosis:
- name: Multimodal retinal examination
  description: >-
    Dilated examination and color fundus photography establish the lesion
    pattern, while spectral-domain OCT and fundus autofluorescence characterize
    subretinal material, fluid, outer-retinal integrity, fibrosis, and atrophy.
    OCT angiography is useful when macular neovascularization is suspected.
  diagnosis_term:
    preferred_term: eye examination
    term:
      id: NCIT:C38060
      label: Eye Examination
  evidence:
  - reference: PMID:40086732
    reference_title: "Best Vitelliform Macular Dystrophy Natural History Study Report 2: Fundus Autofluorescence and OCT."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Retinal imaging with OCT and fundus autofluorescence (FAF) was analyzed cross-sectionally and longitudinally."
    explanation: >-
      The large BVMD natural-history cohort establishes OCT and FAF as core
      structural modalities for diagnosis, staging, and longitudinal assessment.
  - reference: DOI:10.1177/11206721231166434
    reference_title: "Multimodal imaging in Best Vitelliform Macular Dystrophy: Literature review and novel insights"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "effective diagnosis, staging, and clinical management of BVMD will likely require a deep understanding of the multimodal imaging features of this disease"
    explanation: The imaging review supports a multimodal rather than single-test assessment.
- name: Electrooculography
  description: >-
    EOG measurement of the light-peak-to-dark-trough (Arden) ratio evaluates
    generalized RPE dysfunction. A reduced light-rise strongly supports a
    bestrophinopathy, including in some clinically unaffected heterozygotes, but
    it is not independently molecularly specific.
  diagnosis_term:
    preferred_term: diagnostic procedure
    term:
      id: NCIT:C18020
      label: Diagnostic Procedure
  evidence:
  - reference: DOI:10.1007/s10633-026-10093-y
    reference_title: "Review of the clinical electrooculogram - Part 2: the bestrophinopathies and modified protocols"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The light-rise of the electro-oculogram (EOG) is used as a clinical marker"
    explanation: The current clinical review identifies EOG light-rise as a bestrophinopathy marker.
- name: BEST1 molecular genetic testing
  description: >-
    Sequence and copy-number analysis of BEST1 confirms the gene-level diagnosis
    and determines whether the genotype is heterozygous (dominant disease) or
    biallelic (autosomal-recessive bestrophinopathy). Interpretation must combine
    the variant classification with the ocular phenotype because expressivity
    and penetrance are variable.
  diagnosis_term:
    preferred_term: genetic testing
    term:
      id: NCIT:C15709
      label: Genetic Testing
  evidence:
  - reference: PMID:20301346
    reference_title: "Bestrophinopathies."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The diagnosis of autosomal dominant bestrophinopathy is established in a proband with suggestive findings and a heterozygous BEST1 pathogenic (or likely pathogenic) variant identified by molecular genetic testing."
    explanation: GeneReviews requires a compatible phenotype plus a heterozygous pathogenic BEST1 variant.
treatments:
- name: Anti-VEGF Therapy for Choroidal Neovascularization
  description: >-
    Intravitreal anti-VEGF agents (e.g., bevacizumab, ranibizumab) are the
    current standard of care for exudative choroidal neovascularization
    complicating late-stage BVMD. No approved disease-modifying therapy exists
    for the underlying bestrophinopathy.
  therapeutic_modality: MONOCLONAL_ANTIBODY
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: angiogenesis inhibitor (anti-VEGF)
      term:
        id: NCIT:C1742
        label: Angiogenesis Inhibitor
  target_phenotypes:
  - preferred_term: Choroidal neovascularization
    term:
      id: HP:0011506
      label: Choroidal neovascularization
  evidence:
  - reference: DOI:10.1177/2515841421997191
    reference_title: "Bestrophinopathies: perspectives on clinical disease, Bestrophin-1 function and developing therapies"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "no current clinical treatments available for patients with bestrophinopathies"
    explanation: >-
      Confirms that no approved disease-modifying treatment exists for
      bestrophinopathies; anti-VEGF for CNV is the only currently available
      targeted intervention.
  - reference: PMID:36281445
    reference_title: "Temporary Vitelliform Regression After Intravitreal Ranibizumab Injection for Macular Neovascularization Complicating Best Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "suggest a favorable long-term prognosis for intravitreal anti-VEGF injections in eyes with BVMD presenting with early complicating MNVs"
    explanation: >-
      Case report with 2-year follow-up documents a favorable response to
      intravitreal anti-VEGF (ranibizumab) for macular neovascularization
      complicating BVMD, supporting anti-VEGF as standard of care for the
      exudative/neovascular complication.
  - reference: PMID:38278445
    reference_title: "Best Vitelliform Macular Dystrophy Natural History Study Report 1: Clinical Features and Genetic Findings."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Eyes with CNV that received treatment with an anti-vascular endothelial growth factor (VEGF) agent showed better mean BCVA compared with eyes that were not treated with an anti-VEGF agent"
    explanation: >-
      The 222-patient natural-history cohort found better mean visual acuity in
      treated than untreated eyes with CNV; the observational comparison does
      not establish randomized efficacy.
- name: OPGx-BEST1 Gene Augmentation Therapy (BIRD-1 Trial)
  description: >-
    OPGx-BEST1 (Opus Genetics) is a recombinant AAV vector delivering a
    codon-optimized full-length human BEST1 cDNA under an RPE-specific VMD2
    promoter, administered by subretinal injection. The Phase 1b/2a BIRD-1 trial
    (NCT07185256) opened for enrollment in 2025, exploring two doses (1.5E9 and
    4.5E9 vg/eye) with 5-year follow-up. Both LOF and DN mutations are potentially
    amenable to gene augmentation alone; GOF variants would require concurrent
    gene silencing.
  therapeutic_modality: GENE_THERAPY
  treatment_term:
    preferred_term: gene therapy
    term:
      id: NCIT:C15238
      label: Gene Therapy
  target_phenotypes:
  - preferred_term: Vitelliform macular lesion
    term:
      id: HP:0007677
      label: Vitelliform-like macular lesions
  evidence:
  - reference: clinicaltrials:NCT07185256
    reference_title: "A Phase 1b/2a, Open-Label, Dose-Exploration Basket Study to Investigate the Safety and Tolerability of Subretinally Injected OPGx-BEST1 Administered in Patients With Either Autosomal-Dominant BEST1 Disease (Best Vitelliform Macular Dystrophy [BVMD]) or Autosomal-Recessive Bestrophinopathy (ARB)"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Evaluate the safety and tolerability of drug OPGx-BEST1 in one eye (the treatment eye), for 5 years post-injection, in participants with BVMD or ARB"
    explanation: >-
      The first interventional gene therapy trial for bestrophinopathies is
      actively recruiting; OPGx-BEST1 subretinal gene delivery targets both
      BVMD (dominant) and ARB (recessive) patients.
  - reference: DOI:10.3390/ijms26199421
    reference_title: "Gene Therapy Strategies for the Treatment of Bestrophinopathies"
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "gene augmentation may be effective for a subset of bestrophinopathies, others require allele-specific silencing or correction of the disease-causing variant"
    explanation: >-
      Establishes that gene augmentation (the OPGx-BEST1 approach) is
      appropriate for LOF/DN variants but that GOF variants require additional
      silencing strategies, informing patient eligibility and future trial design.
  - reference: DOI:10.4103/sjopt.sjopt_175_23
    reference_title: "Gene therapy in bestrophinopathies: Insights from preclinical studies in preparation for clinical trials"
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "individuals harboring GOF variants would require a combination of gene silencing and gene augmentation, which has been shown to be effective in RPE cells derived from patients with Best disease"
    explanation: >-
      Demonstrates proof-of-concept for combined silencing + augmentation for
      GOF BEST1 variants in iPSC-RPE, supporting the therapeutic rationale for
      BEST1 gene therapy.
  - reference: PMID:42411064
    reference_title: Evaluation of the Toxicity and Efficacy of an Adeno-Associated Viral Vector Expressing BEST1 Delivered by Subretinal Injection in a Canine Model of Human Bestrophinopathy.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Subretinal injections were well tolerated and were not associated with any systemic or ocular toxicity."
    explanation: >-
      The 2026 IND-enabling canine study reports no systemic or ocular toxicity
      across the tested OPGx-BEST1 doses.
- name: Annual Ophthalmologic Surveillance
  description: >-
    Annual ophthalmologic examination including best-corrected visual acuity,
    visual fields, and spectral-domain OCT to monitor fundus lesion progression
    and detect the development of choroidal neovascularization. In children with
    BVMD, annual ophthalmologic examinations also help prevent amblyopia development.
  treatment_term:
    preferred_term: eye examination
    term:
      id: NCIT:C38060
      label: Eye Examination
  target_phenotypes:
  - preferred_term: Choroidal neovascularization
    term:
      id: HP:0011506
      label: Choroidal neovascularization
  - preferred_term: Reduced visual acuity
    term:
      id: HP:0007663
      label: Reduced visual acuity
  evidence:
  - reference: PMID:20301346
    reference_title: "Bestrophinopathies."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Annual ophthalmologic examination (including best corrected visual acuity, visual fields, and spectral domain optical coherence tomography) to monitor progression of fundus lesions and to evaluate for coincidental development of CNV; in childhood, perform annual ophthalmologic examinations to help prevent the development of amblyopia."
    explanation: >-
      GeneReviews recommends annual ophthalmologic surveillance including BCVA,
      visual fields, and SD-OCT as standard of care for bestrophinopathies,
      specifically to monitor disease progression and detect CNV.
- name: Genetic Counseling
  description: >-
    Genetic counseling is recommended for all affected individuals and their
    families, particularly given the autosomal dominant inheritance with
    incomplete penetrance and marked variable expressivity, and the availability
    of cascade genetic testing for at-risk family members.
  treatment_term:
    preferred_term: Genetic Counseling
    term:
      id: NCIT:C15240
      label: Genetic Counseling
  evidence:
  - reference: DOI:10.1177/2515841421997191
    reference_title: "Bestrophinopathies: perspectives on clinical disease, Bestrophin-1 function and developing therapies"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "over 250 individual pathological mutations have been identified in the BEST1 gene, with many reported to have various clinical expressivity and incomplete penetrance"
    explanation: >-
      The broad genetic heterogeneity and variable penetrance/expressivity of
      dominant BEST1 disease make genetic counseling essential for accurate
      risk assessment and family planning guidance.
  - reference: PMID:20301346
    reference_title: "Bestrophinopathies."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Once the BEST1 pathogenic variant(s) have been identified in an affected family member, prenatal testing for a pregnancy at increased risk and preimplantation genetic testing for a bestrophinopathy are possible."
    explanation: >-
      GeneReviews confirms that once a causative BEST1 variant is identified,
      prenatal diagnostic testing and preimplantation genetic testing are
      available options, which should be communicated during genetic counseling.
  - reference: PMID:20301346
    reference_title: "Bestrophinopathies."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Evaluation of relatives at risk: It is appropriate to clarify the genetic status of apparently asymptomatic older and younger at-risk relatives of an affected individual in order to identify as early as possible those who would benefit from prompt ophthalmologic evaluation and routine follow up."
    explanation: >-
      GeneReviews recommends cascade genetic testing for at-risk relatives,
      because asymptomatic carriers may have subclinical RPE dysfunction
      detectable only by EOG or molecular testing.
epidemiology:
- name: Prevalence
  description: >-
    BVMD is among the more prevalent inherited macular dystrophies. Over 250
    pathogenic BEST1 variants have been catalogued worldwide, with phenotypic
    and variant frequency differences across populations.
  evidence:
  - reference: DOI:10.1177/2515841421997191
    reference_title: "Bestrophinopathies: perspectives on clinical disease, Bestrophin-1 function and developing therapies"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Bestrophinopathies are a group of clinically distinct inherited retinal dystrophies that typically affect the macular region, an area synonymous with central high acuity vision."
    explanation: >-
      Characterizes bestrophinopathies as an important class of inherited macular
      dystrophies affecting the central high-acuity retina.
progression:
- phase: Five-stage macular evolution (BVMD)
  notes: >-
    BVMD evolves through five classical stages: (1) Previtelliform — subtle
    RPE irregularity or normal fundus, relatively normal VA; (2) Vitelliform —
    classic dome-shaped "egg-yolk" subfoveal yellow lesion, often preserved VA;
    (3) Pseudohypopyon — vitelliform material layers inferiorly within the lesion,
    variable VA; (4) Vitelliruptive/"scrambled-egg" — fragmented lesion with
    outer-nuclear-layer thinning and ellipsoid-zone disruption, declining VA;
    (5) Atrophic/fibroatrophic —
    macular atrophy or fibrosis with severe and often irreversible central vision
    loss. Visual acuity is characteristically preserved longer than structural
    appearance suggests, consistent with the slow disease progression.
  evidence:
  - reference: DOI:10.1111/aos.14958
    reference_title: "Disease expression caused by different variants in the <i>BEST1</i> gene: genotype and phenotype findings in bestrophinopathies"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "categorization of 52 eyes as Best vitelliform macular dystrophy (BVMD) with stages 1 to 5"
    explanation: >-
      Clinical cohort of 62 bestrophinopathy eyes demonstrates the five-stage
      BVMD classification system, including stage 5 (atrophic/cicatricial).
  - reference: DOI:10.1177/11206721231166434
    reference_title: "Multimodal imaging in Best Vitelliform Macular Dystrophy: Literature review and novel insights"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "effective diagnosis, staging, and clinical management of BVMD will likely require a deep understanding of the multimodal imaging features of this disease"
    explanation: >-
      Multimodal imaging review establishes that BVMD staging requires
      integration of fundoscopy, OCT, FAF, and OCT-A data across disease stages.
  - reference: PMID:20301346
    reference_title: "Bestrophinopathies."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Onset is usually in the first decade (except AVMD in which onset is age 30 to 50 years). Slow visual deterioration is the usual course."
    explanation: >-
      GeneReviews anchors onset (first decade for BVMD) and the characteristically
      slow clinical trajectory, underpinning the five-stage natural history model
      and the long therapeutic window for future interventions.
  - reference: PMID:38278445
    reference_title: "Best Vitelliform Macular Dystrophy Natural History Study Report 1: Clinical Features and Genetic Findings."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Mean age at presentation was 26.8 years (range, 1.3-84.8 years) and most patients (61.5%) demonstrated deterioration of central vision."
    explanation: >-
      The 222-patient cohort quantifies the broad presentation-age range and
      frequency of central-vision deterioration.
- phase: Slow structural and functional decline (BVMD)
  notes: >-
    Longitudinal cohorts show slow average visual-acuity and central retinal
    thickness loss, with substantial between-patient and between-variant
    variation. Atrophy, fibrosis, intraretinal fluid, and CNV identify more
    advanced disease, while lesion dimensions, outer-nuclear-layer thickness,
    and dark-adapted chromatic sensitivity are candidate trial outcomes.
  evidence:
  - reference: PMID:38278445
    reference_title: "Best Vitelliform Macular Dystrophy Natural History Study Report 1: Clinical Features and Genetic Findings."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "with a mean annual loss rate of 0.013 logMAR and 0.009 logMAR, respectively, over a mean follow-up of 9.7 years."
    explanation: The cohort quantifies slow mean annual visual-acuity decline.
  - reference: PMID:40086732
    reference_title: "Best Vitelliform Macular Dystrophy Natural History Study Report 2: Fundus Autofluorescence and OCT."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "with a mean annual thickness loss of 5.7 and 5.2 μm, respectively."
    explanation: The imaging cohort quantifies slow bilateral central-retinal-thickness loss.
differential_diagnoses:
- name: Autosomal recessive bestrophinopathy
  description: >-
    ARB shares RPE dysfunction, abnormal EOG, subretinal fluid, and vitelliform
    material with dominant BEST1 disease. Demonstration of biallelic pathogenic
    BEST1 variants rather than a single heterozygous variant is the defining
    molecular discriminator.
  distinguishing_features:
  - Biallelic pathogenic BEST1 variants support ARB; one heterozygous pathogenic variant supports dominant BEST1 disease.
  - ARB is often a more diffuse retinal disease than the BVMD-centered macular pattern modeled here.
  disease_term:
    preferred_term: autosomal recessive bestrophinopathy
    term:
      id: MONDO:0012733
      label: autosomal recessive bestrophinopathy
  evidence:
  - reference: PMID:20301346
    reference_title: "Bestrophinopathies."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The diagnosis of autosomal recessive bestrophinopathy is established in a proband with suggestive findings and biallelic BEST1 pathogenic variants."
    explanation: GeneReviews directly states the biallelic molecular discriminator for ARB.
- name: Genetically heterogeneous adult-onset vitelliform macular dystrophy
  description: >-
    Adult-onset vitelliform lesions can be caused by BEST1, PRPH2, IMPG1,
    IMPG2, HTRA1, CTNNA1, or non-genetic mimics. Multigene testing and the
    complete retinal phenotype are therefore needed before assigning a
    gene-level BEST1 diagnosis.
  distinguishing_features:
  - A heterozygous pathogenic BEST1 variant establishes the BEST1-defined subtype in a compatible phenotype.
  - PRPH2 and other macular-dystrophy genes should be assessed when BEST1 testing is negative or the phenotype is atypical.
  evidence:
  - reference: DOI:10.1007/s10633-026-10093-y
    reference_title: "Review of the clinical electrooculogram - Part 2: the bestrophinopathies and modified protocols"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "genetically heterogeneous, with PRPH2"
    explanation: >-
      The clinical review identifies adult-onset vitelliform presentations as
      genetically heterogeneous and lists multiple non-BEST1 genes.
clinical_trials:
- name: NCT07185256
  phase: PHASE_I
  status: RECRUITING
  description: >-
    BIRD-1 is a phase 1b/2a open-label dose-exploration basket study of a single
    subretinal OPGx-BEST1 injection in one eye of participants with BVMD or ARB.
    It evaluates safety, tolerability, dose selection, and exploratory efficacy
    over five years. The schema's PHASE_I value represents the combined early
    phase 1b/2a designation.
  target_phenotypes:
  - preferred_term: Vitelliform macular lesion
    term:
      id: HP:0007677
      label: Vitelliform-like macular lesions
  evidence:
  - reference: clinicaltrials:NCT07185256
    reference_title: "A Phase 1b/2a, Open-Label, Dose-Exploration Basket Study to Investigate the Safety and Tolerability of Subretinally Injected OPGx-BEST1 Administered in Patients With Either Autosomal-Dominant BEST1 Disease (Best Vitelliform Macular Dystrophy [BVMD]) or Autosomal-Recessive Bestrophinopathy (ARB)"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Evaluate the safety and tolerability of drug OPGx-BEST1 in one eye (the treatment eye), for 5 years post-injection, in participants with BVMD or ARB."
    explanation: The registry record directly states the population, treated eye, and five-year safety objective.
  notes: Recruitment status was verified against ClinicalTrials.gov on 2026-07-23.
- name: NCT05809635
  phase: NOT_APPLICABLE
  status: RECRUITING
  description: >-
    Prospective observational natural-history study of molecularly confirmed
    BEST1 vitelliform macular dystrophy. It follows structural and functional
    measures for up to three years to select outcomes, assess fellow-eye
    comparability, and define populations for later interventional trials.
  evidence:
  - reference: clinicaltrials:NCT05809635
    reference_title: Natural History Study in Retinitis Pigmentosa Caused by Mutations in the BEST1 Gene
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Identify sensitive structural and functional outcome measures to use for future multicenter clinical trials for the treatment of BESTROPHIN 1 VMD."
    explanation: The registry summary directly states the trial-readiness and outcome-measure objective.
  notes: >-
    Recruitment status was verified against ClinicalTrials.gov on 2026-07-23.
    The registry's official title says retinitis pigmentosa, while its brief
    title, conditions, intervention description, and summary specify BEST1
    vitelliform macular dystrophy.
animal_models:
- species: Dog
  genotype: Best1 loss-of-function (CMR1/2/3 — canine multifocal retinopathy)
  description: >-
    Canine multifocal retinopathy (CMR) is a naturally occurring bestrophinopathy
    in multiple dog breeds caused by autosomal-recessive BEST1 mutations
    (cmr1: p.Arg25Ter in Great Pyrenees/mastiff; cmr2: p.Gly161Asp in Coton de
    Tulear; cmr3: two variants in Swedish Lapponian Herder). Although CMR
    inheritance is recessive (unlike human BVMD), it recapitulates key features:
    multifocal retinal microdetachments, lipofuscin accumulation, and RPE
    microvilli loss. Subretinal AAV2-mediated BEST1 gene augmentation therapy in
    CMR dogs reversed both clinically detectable subretinal lesions and the diffuse
    RPE-photoreceptor microdetachment and corrected the RPE-photoreceptor interface
    across three canine BEST1 genotypes, providing the key preclinical
    proof-of-concept for the OPGx-BEST1 gene therapy approach. A 2026
    dose-ranging study in 12 mutant dogs reported improved rod- and cone-mediated
    responses and retinal structure without systemic or ocular toxicity.
  evidence:
  - reference: PMID:29507198
    reference_title: "BEST1 gene therapy corrects a diffuse retina-wide microdetachment modulated by light exposure."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Subretinal BEST1 gene augmentation therapy using adeno-associated virus 2 reversed not only clinically detectable subretinal lesions but also the diffuse microdetachments"
    explanation: >-
      In the canine BEST1 (CMR) model, subretinal AAV2-BEST1 gene augmentation
      reversed both clinically visible subretinal lesions and the diffuse
      RPE-photoreceptor microdetachment, the pivotal preclinical proof-of-concept
      underpinning the OPGx-BEST1 clinical gene therapy program.
  - reference: DOI:10.3390/cells9040882
    reference_title: "Large Animal Models of Inherited Retinal Degenerations: A Review"
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Studies utilizing large animal models of inherited retinal degeneration (IRD) have proven important in not only the development of translational therapeutic approaches, but also in improving our understanding of disease mechanisms"
    explanation: >-
      Large animal model review establishes the critical translational role of
      canine IRD models for inherited retinal disease gene therapy development,
      including for bestrophinopathy.
  - reference: DOI:10.1007/s00335-024-10091-y
    reference_title: "Canine models of inherited retinal diseases: from neglect to well-recognized translational value"
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Large animal models of inherited retinal diseases, particularly dogs, have been extensively used over the past decades to study disease natural history and evaluate therapeutic interventions"
    explanation: >-
      Canine IRD model review highlights the central role of dog models in
      bestrophinopathy translational research, from natural history to gene
      therapy preclinical evaluation.
  - reference: PMID:42411064
    reference_title: Evaluation of the Toxicity and Efficacy of an Adeno-Associated Viral Vector Expressing BEST1 Delivered by Subretinal Injection in a Canine Model of Human Bestrophinopathy.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Electroretinography showed improved rod- and cone-mediated responses in eyes treated with OPGx-BEST1."
    explanation: The current dose-ranging study demonstrates functional rescue in treated mutant-dog eyes.
  - reference: PMID:42411064
    reference_title: Evaluation of the Toxicity and Efficacy of an Adeno-Associated Viral Vector Expressing BEST1 Delivered by Subretinal Injection in a Canine Model of Human Bestrophinopathy.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "showed improved structural integrity with a reduction or prevention of appearance of vitelliform lesions and reversal of microdetachments"
    explanation: OCT demonstrated structural benefit in treated retinal regions.
- species: Mouse
  genotype: Best1 W93C knock-in and Best1 knockout
  description: >-
    Best1 W93C knock-in mice (heterozygous and homozygous) exhibit an altered EOG
    light-peak luminance response reminiscent of BVMD patients, together with
    fluid- and debris-filled retinal detachments and enhanced RPE lipofuscin
    accumulation, yet retain normal chloride conductances — indicating that the
    dominant disease is not simply loss of bestrophin-1 chloride-channel function.
    The knock-in phenotype is distinct from that of Best1 knockout mice (with
    respect to lipofuscin accumulation and ATP-stimulated calcium responses), and
    the W93C knock-in is regarded as a valid model of BVMD. Overall, mouse models
    incompletely recapitulate human BVMD, limiting their translational utility
    relative to canine models and iPSC-RPE systems.
  evidence:
  - reference: PMID:20053664
    reference_title: "Suppression of Ca2+ signaling in a mouse model of Best disease."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Both Best1(+/W93C)and Best1(W93C/W93C) mice had normal ERG a- and b-waves, but exhibited an altered LP luminance response reminiscent of that observed in BVMD patients"
    explanation: >-
      Knock-in mouse study shows the dominant BVMD-causing W93C variant produces
      the hallmark altered EOG light-peak (LP) response with normal ERG, modeling
      the human electrophysiological phenotype of BVMD.
  - reference: PMID:20053664
    reference_title: "Suppression of Ca2+ signaling in a mouse model of Best disease."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "RPE cells from Best1(W93C) mice exhibited normal Cl(-) conductances"
    explanation: >-
      Despite reproducing the disease phenotype, W93C knock-in RPE retains normal
      chloride conductance, showing that dominant BVMD pathology is not simply
      loss of bestrophin-1 chloride-channel function.
experimental_models:
- name: Patient-derived Best disease iPSC-RPE model
  experimental_model_type: IPSC_DERIVED_MODEL
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  cell_types:
  - preferred_term: retinal pigment epithelial cell
    term:
      id: CL:0002586
      label: retinal pigment epithelial cell
  cell_source: >-
    RPE differentiated from induced pluripotent stem cells from individuals
    with Best disease and their unaffected siblings
  culture_system: Polarized hiPSC-RPE with chronic photoreceptor-outer-segment feeding
  publication: PMID:23139242
  conditions:
  - Best disease patient-derived RPE
  - Unaffected sibling-derived RPE
  - Long-term photoreceptor-outer-segment feeding
  description: >-
    Patient-derived RPE reproduces abnormal fluid flux, delayed rhodopsin
    degradation, autofluorescent-material accumulation, altered stimulated
    calcium responses, and oxidative stress. The matched unaffected-sibling
    comparison provides a human cellular bridge between BEST1 variation and RPE
    handling of photoreceptor outer segments.
  modeled_mechanisms:
  - target: RPE Dysfunction and Impaired Phagocytosis
    description: Models RPE fluid transport, calcium signaling, and photoreceptor-outer-segment handling.
    evidence:
    - reference: PMID:23139242
      reference_title: "iPS cell modeling of Best disease: insights into the pathophysiology of an inherited macular degeneration."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "RHODOPSIN degradation after POS feeding was delayed in BD hiPSC-RPE relative to unaffected sibling hiPSC-RPE, directly implicating impaired POS handling in the pathophysiology of the disease."
      explanation: The matched human model directly demonstrates impaired photoreceptor-outer-segment handling.
  - target: Vitelliform Material Accumulation
    description: Models accumulation of autofluorescent material after chronic outer-segment feeding.
    evidence:
    - reference: PMID:23139242
      reference_title: "iPS cell modeling of Best disease: insights into the pathophysiology of an inherited macular degeneration."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "RPE from mutant hiPSCs displayed disrupted fluid flux and increased accrual of autofluorescent material after long-term POS feeding when compared with hiPSC-RPE from unaffected siblings."
      explanation: The disease model reproduces the material-accumulation phenotype.
  evidence:
  - reference: PMID:23139242
    reference_title: "iPS cell modeling of Best disease: insights into the pathophysiology of an inherited macular degeneration."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "We employed human iPS cell (hiPSC) technology to generate RPE from BD patients and unaffected siblings"
    explanation: This establishes the patient-derived, sibling-controlled human RPE model.
discussions:
- discussion_id: best1_channel_versus_calcium_and_pos_handling
  prompt: >-
    To what extent does dominant BEST1 retinopathy result from altered chloride
    conductance versus calcium signaling, fluid transport, and handling of
    photoreceptor outer segments?
  kind: CONTROVERSY
  status: OPEN
  attaches_to:
  - pathophysiology#BEST1 Calcium-Activated Chloride Channel Dysfunction
  - pathophysiology#RPE Dysfunction and Impaired Phagocytosis
  rationale: >-
    BEST1 is a calcium-activated chloride channel, yet a dominant W93C mouse
    model reproduces the light-peak phenotype with normal RPE chloride
    conductance, while patient-derived RPE implicates calcium-store regulation
    and outer-segment processing. The entry therefore does not reduce every
    dominant variant to a single channel-loss mechanism.
  evidence:
  - reference: PMID:20053664
    reference_title: "Suppression of Ca2+ signaling in a mouse model of Best disease."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "RPE cells from Best1(W93C) mice exhibited normal Cl(-) conductances"
    explanation: The dominant mouse model separates a disease phenotype from simple chloride-conductance loss.
  - reference: PMID:23139242
    reference_title: "iPS cell modeling of Best disease: insights into the pathophysiology of an inherited macular degeneration."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "further linked BEST1 to the regulation and release of endoplasmic reticulum calcium stores."
    explanation: Patient-derived RPE provides an alternative calcium-regulatory mechanism.
- discussion_id: recessive_canine_model_for_dominant_human_disease
  prompt: >-
    How well does gene augmentation in recessive canine BEST1 disease predict
    efficacy across dominant-negative and gain-of-function human BVMD variants?
  kind: HUMAN_MODEL_MISMATCH
  status: OPEN
  attaches_to:
  - pathophysiology#BEST1 Calcium-Activated Chloride Channel Dysfunction
  rationale: >-
    The canine model supplies strong safety and structural-rescue evidence but
    uses homozygous or compound-heterozygous BEST1 genotypes. Dominant human
    alleles can interfere with wild-type subunits or increase channel activity,
    so rescue by augmentation may be variant-class dependent.
  evidence:
  - reference: PMID:42411064
    reference_title: Evaluation of the Toxicity and Efficacy of an Adeno-Associated Viral Vector Expressing BEST1 Delivered by Subretinal Injection in a Canine Model of Human Bestrophinopathy.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "dogs that were homozygous mutant or compound heterozygotes for 3 naturally occurring mutations in BEST1."
    explanation: The IND-enabling model uses recessive genotypes rather than heterozygous dominant human variants.
  - reference: DOI:10.4103/sjopt.sjopt_175_23
    reference_title: "Gene therapy in bestrophinopathies: Insights from preclinical studies in preparation for clinical trials"
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "individuals harboring GOF variants would require a combination of gene silencing and gene augmentation"
    explanation: Variant mechanism may limit direct extrapolation from recessive augmentation models.
- discussion_id: bvmd_trial_endpoints_for_slow_variable_progression
  prompt: >-
    Which structural or functional measures are sufficiently sensitive and
    reproducible for early-phase BVMD treatment trials?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - pathophysiology#Progressive Photoreceptor Damage and Vision Loss
  rationale: >-
    Visual acuity and retinal thickness decline slowly and variably, which can
    obscure treatment effects in small early-phase trials. Longitudinal lesion
    dimensions, outer-nuclear-layer thickness, and dark-adapted chromatic
    sensitivity are promising but remain to be qualified as endpoints.
  evidence:
  - reference: PMID:40086732
    reference_title: "Best Vitelliform Macular Dystrophy Natural History Study Report 2: Fundus Autofluorescence and OCT."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The slow and variable disease course may pose a challenge in identification of early end points for therapeutic trials aimed at altering kinetics of degeneration."
    explanation: The large natural-history imaging study explicitly identifies the endpoint problem.
  - reference: PMID:40688488
    reference_title: "Multimodal Imaging and Dark-Adapted Chromatic Perimetry in BEST1 Vitelliform Macular Dystrophy: Identification of Outcome Measurements."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "may serve as valuable outcome measurements for treatment trials for BVMD."
    explanation: The longitudinal study nominates imaging and dark-adapted sensitivity measures for trials.
datasets: []
computational_models: []
review_notes: >-
  The 2026 re-review kept the entry at the ClinGen/MONDO gene-level dominant
  umbrella but made the detailed graph explicitly BVMD-centered. It added the
  definitive ClinGen assertion, molecular definition, diagnostic workflow,
  current trial records, a patient-derived iPSC-RPE model, current natural
  history and canine gene-therapy evidence, and open translational questions.
  All phenotype nodes are now connected to the causal graph. The accession-level
  GEO review identified no disease-specific public omics dataset, so datasets
  remains explicitly empty.
references:
- reference: CGGV:assertion_487a42cc-7dd0-4991-ac9d-1346f59073c0-2023-08-03T160000.000Z
  title: BEST1 / BEST1-related dominant retinopathy (Definitive)
- reference: PMID:20301346
  title: "Bestrophinopathies."
  tags:
  - GeneReviews
- reference: PMID:38278445
  title: "Best Vitelliform Macular Dystrophy Natural History Study Report 1: Clinical Features and Genetic Findings."
- reference: PMID:40086732
  title: "Best Vitelliform Macular Dystrophy Natural History Study Report 2: Fundus Autofluorescence and OCT."
- reference: PMID:40688488
  title: "Multimodal Imaging and Dark-Adapted Chromatic Perimetry in BEST1 Vitelliform Macular Dystrophy: Identification of Outcome Measurements."
- reference: DOI:10.1177/2515841421997191
  title: "Bestrophinopathies: perspectives on clinical disease, Bestrophin-1 function and developing therapies"
- reference: DOI:10.4103/sjopt.sjopt_175_23
  title: "Gene therapy in bestrophinopathies: Insights from preclinical studies in preparation for clinical trials"
- reference: DOI:10.3390/ijms26199421
  title: "Gene Therapy Strategies for the Treatment of Bestrophinopathies"
- reference: DOI:10.1177/11206721231166434
  title: "Multimodal imaging in Best Vitelliform Macular Dystrophy: Literature review and novel insights"
- reference: DOI:10.3390/ijms23137432
  title: "Impaired Bestrophin Channel Activity in an iPSC-RPE Model of Best Vitelliform Macular Dystrophy (BVMD) from an Early Onset Patient Carrying the P77S Dominant Mutation"
- reference: DOI:10.1111/aos.14958
  title: "Disease expression caused by different variants in the <i>BEST1</i> gene: genotype and phenotype findings in bestrophinopathies"
- reference: DOI:10.1007/s10633-026-10093-y
  title: "Review of the clinical electrooculogram - Part 2: the bestrophinopathies and modified protocols"
- reference: DOI:10.1002/mgg3.2095
  title: "<i>BEST1</i> novel mutation causes Bestrophinopathies in six families with distinct phenotypic diversity"
- reference: DOI:10.3390/cells9040882
  title: "Large Animal Models of Inherited Retinal Degenerations: A Review"
- reference: DOI:10.1007/s00335-024-10091-y
  title: "Canine models of inherited retinal diseases: from neglect to well-recognized translational value"
- reference: PMID:20053664
  title: "Suppression of Ca2+ signaling in a mouse model of Best disease."
- reference: PMID:29507198
  title: "BEST1 gene therapy corrects a diffuse retina-wide microdetachment modulated by light exposure."
- reference: PMID:36281445
  title: "Temporary Vitelliform Regression After Intravitreal Ranibizumab Injection for Macular Neovascularization Complicating Best Disease."
- reference: PMID:23139242
  title: "iPS cell modeling of Best disease: insights into the pathophysiology of an inherited macular degeneration."
- reference: PMID:42411064
  title: Evaluation of the Toxicity and Efficacy of an Adeno-Associated Viral Vector Expressing BEST1 Delivered by Subretinal Injection in a Canine Model of Human Bestrophinopathy.
- reference: clinicaltrials:NCT05809635
  title: Natural History Study in Retinitis Pigmentosa Caused by Mutations in the BEST1 Gene
- reference: clinicaltrials:NCT07185256
  title: "A Phase 1b/2a, Open-Label, Dose-Exploration Basket Study to Investigate the Safety and Tolerability of Subretinally Injected OPGx-BEST1 Administered in Patients With Either Autosomal-Dominant BEST1 Disease (Best Vitelliform Macular Dystrophy [BVMD]) or Autosomal-Recessive Bestrophinopathy (ARB)"
📚

References & Deep Research

References

22
CGGV:assertion_487a42cc-7dd0-4991-ac9d-1346f59073c0-2023-08-03T160000.000Z
BEST1 / BEST1-related dominant retinopathy (Definitive)
No top-level findings curated for this source.
PMID:20301346
Bestrophinopathies.
No top-level findings curated for this source.
PMID:38278445
Best Vitelliform Macular Dystrophy Natural History Study Report 1: Clinical Features and Genetic Findings.
No top-level findings curated for this source.
PMID:40086732
Best Vitelliform Macular Dystrophy Natural History Study Report 2: Fundus Autofluorescence and OCT.
No top-level findings curated for this source.
PMID:40688488
Multimodal Imaging and Dark-Adapted Chromatic Perimetry in BEST1 Vitelliform Macular Dystrophy: Identification of Outcome Measurements.
No top-level findings curated for this source.
DOI:10.1177/2515841421997191
Bestrophinopathies: perspectives on clinical disease, Bestrophin-1 function and developing therapies
No top-level findings curated for this source.
DOI:10.4103/sjopt.sjopt_175_23
Gene therapy in bestrophinopathies: Insights from preclinical studies in preparation for clinical trials
No top-level findings curated for this source.
DOI:10.3390/ijms26199421
Gene Therapy Strategies for the Treatment of Bestrophinopathies
No top-level findings curated for this source.
DOI:10.1177/11206721231166434
Multimodal imaging in Best Vitelliform Macular Dystrophy: Literature review and novel insights
No top-level findings curated for this source.
DOI:10.3390/ijms23137432
Impaired Bestrophin Channel Activity in an iPSC-RPE Model of Best Vitelliform Macular Dystrophy (BVMD) from an Early Onset Patient Carrying the P77S Dominant Mutation
No top-level findings curated for this source.
DOI:10.1111/aos.14958
Disease expression caused by different variants in the <i>BEST1</i> gene: genotype and phenotype findings in bestrophinopathies
No top-level findings curated for this source.
DOI:10.1007/s10633-026-10093-y
Review of the clinical electrooculogram - Part 2: the bestrophinopathies and modified protocols
No top-level findings curated for this source.
DOI:10.1002/mgg3.2095
<i>BEST1</i> novel mutation causes Bestrophinopathies in six families with distinct phenotypic diversity
No top-level findings curated for this source.
DOI:10.3390/cells9040882
Large Animal Models of Inherited Retinal Degenerations: A Review
No top-level findings curated for this source.
DOI:10.1007/s00335-024-10091-y
Canine models of inherited retinal diseases: from neglect to well-recognized translational value
No top-level findings curated for this source.
PMID:20053664
Suppression of Ca2+ signaling in a mouse model of Best disease.
No top-level findings curated for this source.
PMID:29507198
BEST1 gene therapy corrects a diffuse retina-wide microdetachment modulated by light exposure.
No top-level findings curated for this source.
PMID:36281445
Temporary Vitelliform Regression After Intravitreal Ranibizumab Injection for Macular Neovascularization Complicating Best Disease.
No top-level findings curated for this source.
PMID:23139242
iPS cell modeling of Best disease: insights into the pathophysiology of an inherited macular degeneration.
No top-level findings curated for this source.
PMID:42411064
Evaluation of the Toxicity and Efficacy of an Adeno-Associated Viral Vector Expressing BEST1 Delivered by Subretinal Injection in a Canine Model of Human Bestrophinopathy.
No top-level findings curated for this source.
clinicaltrials:NCT05809635
Natural History Study in Retinitis Pigmentosa Caused by Mutations in the BEST1 Gene
No top-level findings curated for this source.
clinicaltrials:NCT07185256
A Phase 1b/2a, Open-Label, Dose-Exploration Basket Study to Investigate the Safety and Tolerability of Subretinally Injected OPGx-BEST1 Administered in Patients With Either Autosomal-Dominant BEST1 Disease (Best Vitelliform Macular Dystrophy [BVMD]) or Autosomal-Recessive Bestrophinopathy (ARB)
No top-level findings curated for this source.

Deep Research

1
Falcon ▸
1. Disease Information
Edison Scientific Literature 40 citations 2026-06-23T15:56:31.141446

1. Disease Information

Overview

BEST1-related dominant retinopathy encompasses a group of inherited retinal dystrophies caused by heterozygous pathogenic variants in the BEST1 gene (formerly VMD2), which encodes bestrophin-1, a calcium-activated chloride channel expressed exclusively in the retinal pigment epithelium (RPE) (amato2023genetherapyin pages 2-3, navinesferrer2022impairedbestrophinchannel pages 1-2). The most common dominant phenotype is Best vitelliform macular dystrophy (BVMD, or Best disease), first described by Dr. Friedrich Best in 1905 (haldrup2025genetherapystrategies pages 3-5). BVMD is characterized by the bilateral accumulation of yellow, lipofuscin-rich vitelliform material beneath the neurosensory retina in the macular region, leading to progressive central visual impairment (beryozkin2024bestdiseaseglobal pages 1-2, bianco2024multimodalimagingin pages 1-2).

Other BEST1-associated dominant retinopathies include adult-onset foveomacular vitelliform dystrophy (AOFVD/AVMD) and autosomal dominant vitreoretinochoroidopathy (ADVIRC) (yang2023best1novelmutation pages 1-2, amato2023genetherapyin pages 1-2). While biallelic BEST1 variants cause autosomal recessive bestrophinopathy (ARB), this report focuses on the dominantly inherited forms.

Disease Identifiers and Synonyms

The following table summarizes the key identifiers, synonyms, and related phenotypes for BEST1-related dominant retinopathy:

Identifier Type Value/ID Notes
Preferred disease name BEST1-related dominant retinopathy Umbrella term for autosomal-dominant BEST1-associated retinal disease, most commonly Best vitelliform macular dystrophy (BVMD/Best disease); other dominant phenotypes include adult-onset foveomacular vitelliform dystrophy (AOFVD/AVMD) and autosomal dominant vitreoretinochoroidopathy (ADVIRC) (amato2023genetherapyin pages 2-3, yang2023best1novelmutation pages 1-2, beryozkin2024bestdiseaseglobal pages 1-2, amato2023genetherapyin pages 1-2)
OMIM disease 153700 Best vitelliform macular dystrophy / Best disease; the common dominant BEST1 phenotype (yang2023best1novelmutation pages 1-2, beryozkin2024bestdiseaseglobal pages 1-2)
MONDO disease MONDO_0007931 Vitelliform macular dystrophy 2; Open Targets links this disease to BEST1 as the top associated target (OpenTargets Search: -BEST1)
Orphanet disease Orphanet_1243 Best vitelliform macular dystrophy (OpenTargets Search: -BEST1)
MeSH D057826 Vitelliform Macular Dystrophy; used in the ClinicalTrials.gov natural-history record for BEST1 VMD (NCT05809635 chunk 1)
ICD-10 Not uniquely established from retrieved evidence BEST1-related dominant retinopathy/BVMD is generally grouped under hereditary retinal dystrophy/macular degeneration coding in practice; a disease-specific ICD-10 code was not confirmed in the retrieved sources
Gene symbol BEST1 HGNC-approved symbol for bestrophin 1; causative gene for dominant and recessive bestrophinopathies (OpenTargets Search: -BEST1, amato2023genetherapyin pages 2-3, yang2023best1novelmutation pages 1-2)
Gene OMIM 607854 BEST1 gene entry (formerly VMD2) (yang2023best1novelmutation pages 1-2)
Ensembl gene ENSG00000167995 Open Targets identifier for BEST1 (OpenTargets Search: -BEST1)
Protein Bestrophin-1 585-amino-acid, homopentameric calcium-activated chloride channel expressed in retinal pigment epithelium (RPE) (amato2023genetherapyin pages 2-3, navinesferrer2022impairedbestrophinchannel pages 1-2, amato2023genetherapyin pages 1-2)
Chromosomal locus 11q13 / 11q12-q13.1 BEST1 is reported at chromosome 11q13 in clinical literature; the interventional trial requires genetic confirmation on chromosome 11q12-q13.1 (nowomiejska2022diseaseexpressioncaused pages 1-2, NCT07185256 chunk 1)
Related dominant phenotype ADVIRC; OMIM 193220; MONDO_0008662 Autosomal dominant vitreoretinochoroidopathy is another dominant BEST1-associated phenotype (yang2023best1novelmutation pages 1-2, OpenTargets Search: -BEST1)
Related dominant phenotype Adult-onset vitelliform macular dystrophy / AOFVD / AVMD Adult-onset dominant vitelliform phenotype associated in some cases with BEST1 variants; typically presents after age 40 (yang2023best1novelmutation pages 1-2, amato2023genetherapyin pages 1-2)
Related recessive phenotype ARB; OMIM 611809; MONDO_0012733 Autosomal recessive bestrophinopathy is part of the BEST1 disease spectrum but is not the dominant form (yang2023best1novelmutation pages 1-2, OpenTargets Search: -BEST1)
Related phenotype Retinitis pigmentosa 50; MONDO_0013175 BEST1 is also associated with RP50 in curated disease-target resources (OpenTargets Search: -BEST1)
Common synonym Best disease Widely used synonym for BVMD (yang2023best1novelmutation pages 1-2, beryozkin2024bestdiseaseglobal pages 1-2)
Common synonym BVMD Standard abbreviation for Best vitelliform macular dystrophy (amato2023genetherapyin pages 2-3, beryozkin2024bestdiseaseglobal pages 1-2)
Common synonym VMD / VMD2-associated disease Historical nomenclature linked to vitelliform macular dystrophy and the former BEST1 name VMD2 (yang2023best1novelmutation pages 1-2, NCT07185256 chunk 1)
Common synonym Bestrophinopathy / BEST1-related bestrophinopathy Collective term for the phenotypic spectrum caused by BEST1 variants (amato2023genetherapyin pages 2-3, amato2023genetherapyin pages 1-2)
Inheritance Autosomal dominant with variable expressivity and incomplete/reduced penetrance Characteristic for BVMD and several other dominant BEST1 phenotypes (grewal2021bestrophinopathiesperspectiveson pages 1-2, beryozkin2024bestdiseaseglobal pages 1-2, nowomiejska2022diseaseexpressioncaused pages 1-2)

Table: This table compiles the main disease and gene identifiers used for BEST1-related dominant retinopathy, centered on Best vitelliform macular dystrophy. It also summarizes key synonyms, related BEST1 phenotypes, and inheritance details useful for database curation.

Common Synonyms: Best disease, Best vitelliform macular dystrophy (BVMD), VMD2-associated macular dystrophy, bestrophinopathy, BEST1-related bestrophinopathy.

Information Sources: This report synthesizes data from aggregated disease-level resources including OMIM, Orphanet, OpenTargets (OpenTargets Search: -BEST1), ClinicalTrials.gov (NCT05809635 chunk 1, NCT07185256 chunk 1), and primary peer-reviewed literature.

2. Etiology

Disease Causal Factors

BEST1-related dominant retinopathy is a Mendelian genetic disorder caused by heterozygous pathogenic variants in the BEST1 gene located on chromosome 11q12-q13.1 (nowomiejska2022diseaseexpressioncaused pages 1-2, NCT07185256 chunk 1). The disease is exclusively genetic in origin, with no known environmental or infectious causes.

Genetic Risk Factors

  • Causal Gene: BEST1 (HGNC symbol; Ensembl: ENSG00000167995; OMIM gene: 607854) (OpenTargets Search: -BEST1, yang2023best1novelmutation pages 1-2).
  • Variant Spectrum: Over 250–300 individual pathogenic mutations have been identified in BEST1, with the majority being missense variants in functional domains of the protein (grewal2021bestrophinopathiesperspectiveson pages 1-2, nowomiejska2022diseaseexpressioncaused pages 1-2). In an 18-year single-center DNA diagnostics study of over 7,000 inherited retinal dystrophy patients, BEST1 accounted for 7.8% of all disease-causing variants, making it the second most frequently implicated gene after ABCA4 (nowomiejska2022diseaseexpressioncaused pages 1-2).
  • Critical Conserved Domains: Disease-causing dominant missense mutations cluster in transmembrane domains and the intracellular Ca²⁺-binding domain of the BEST1 protein (beryozkin2024bestdiseaseglobal pages 1-2). Dominant variants specifically cluster around the Ca²⁺-clasp and gating apparatus regions of the ion pore (haldrup2025genetherapystrategies pages 1-3).
  • Inheritance Pattern: Autosomal dominant with variable expressivity and incomplete penetrance (grewal2021bestrophinopathiesperspectiveson pages 1-2, beryozkin2024bestdiseaseglobal pages 1-2, haldrup2025genetherapystrategies pages 3-5).

Protective and Environmental Factors

No specific genetic protective factors, modifier genes, or environmental factors that influence disease risk or expression have been conclusively identified for BEST1-related dominant retinopathy in the current literature. The phenotypic variability observed is attributed primarily to the specific pathogenic variant and stochastic biological factors rather than known gene-environment interactions (grewal2021bestrophinopathiesperspectiveson pages 1-2, nowomiejska2022diseaseexpressioncaused pages 1-2).

3. Phenotypes

Clinical Features and Staging

BVMD progresses through five classic clinical stages, originally described by Gass and subsequently refined with modern imaging:

Stage Number Stage Name Fundus Appearance OCT Findings FAF Findings Visual Acuity Clinical Description
1 Previtelliform / Subclinical Fundus may appear normal or show only subtle RPE irregularity; early macular change without classic yellow lesion (bianco2024multimodalimagingin pages 1-2, padhy2026reviewofthe pages 2-4, amato2023genetherapyin pages 2-3, haldrup2025genetherapystrategies pages 3-5) Subtle OCT abnormalities; early disturbance at the photoreceptor–RPE interdigitation zone; heightened RPE–outer segment reflectance may be present (padhy2026reviewofthe pages 2-4, amato2023genetherapyin pages 2-3) Near-infrared autofluorescence may help identify early disease; FAF can be minimal or only subtly abnormal before obvious vitelliform deposition (padhy2026reviewofthe pages 2-4, amato2023genetherapyin pages 2-3) Usually normal or near-normal vision (haldrup2025genetherapystrategies pages 3-5) Earliest clinically recognized stage; RPE-photoreceptor interaction is already abnormal, but overt lesion formation may not yet be visible on ophthalmoscopy (padhy2026reviewofthe pages 2-4, amato2023genetherapyin pages 2-3)
2 Vitelliform Classic yellow, dome-shaped “egg-yolk” lesion in the macula; central vitelliform material beneath the neurosensory retina (bianco2024multimodalimagingin pages 1-2, nowomiejska2022diseaseexpressioncaused pages 1-2, amato2023genetherapyin pages 2-3, haldrup2025genetherapystrategies pages 3-5) Dome-shaped subretinal hyperreflective material/elevation; raised ellipsoid/interdigitation zones; subretinal deposit corresponding to vitelliform lesion (amato2023genetherapyin pages 2-3, yang2023best1novelmutation pages 4-5) Marked hyperautofluorescence corresponding to vitelliform material (padhy2026reviewofthe pages 2-4, yang2023best1novelmutation pages 4-5) Mild visual loss, though many patients still retain good central acuity; symptoms may include photophobia, metamorphopsia, or nyctalopia (haldrup2025genetherapystrategies pages 3-5) Hallmark stage of BVMD with lipofuscin-rich/unphagocytosed outer segment material accumulation in the macula (bianco2024multimodalimagingin pages 1-2, padhy2026reviewofthe pages 2-4)
3 Pseudohypopyon Yellow material gravitates inferiorly within the lesion, creating a fluid level / layered appearance (padhy2026reviewofthe pages 2-4, amato2023genetherapyin pages 2-3, haldrup2025genetherapystrategies pages 3-5) Layering of vitelliform material within subretinal space; inferior pooling of hyperreflective material (amato2023genetherapyin pages 2-3) Persistent hyperautofluorescence, often redistributed according to layered material (amato2023genetherapyin pages 2-3, haldrup2025genetherapystrategies pages 3-5) Variable; often still relatively preserved but may begin to decline (padhy2026reviewofthe pages 2-4, haldrup2025genetherapystrategies pages 3-5) Transitional stage in which accumulated material separates and settles inferiorly, producing the “pseudohypopyon” appearance (padhy2026reviewofthe pages 2-4, amato2023genetherapyin pages 2-3)
4 Vitelliruptive / “Scrambled-egg” Fragmented, irregular, clumped yellow deposits with “scrambled-egg” appearance; lesion disintegration (padhy2026reviewofthe pages 2-4, nowomiejska2022diseaseexpressioncaused pages 1-2, haldrup2025genetherapystrategies pages 3-5, grewal2021bestrophinopathiesperspectiveson pages 1-2) Clumped/disrupted hyperreflective material; increasing outer retinal disorganization, ONL thinning, and ellipsoid zone disruption (bianco2024multimodalimagingin pages 1-2, amato2023genetherapyin pages 2-3) Mixed or irregular autofluorescence as material fragments and redistributes (amato2023genetherapyin pages 2-3) Visual acuity often declines substantially compared with earlier stages (haldrup2025genetherapystrategies pages 3-5) Represents breakdown/resorption of the vitelliform lesion with increasing photoreceptor dysfunction and structural damage (bianco2024multimodalimagingin pages 1-2, haldrup2025genetherapystrategies pages 3-5)
5 Atrophic / Fibroatrophic (Atrophic/Fibrotic) Macular atrophy, fibrosis, or scar-like end-stage lesion; may be complicated by choroidal neovascularization (bianco2024multimodalimagingin pages 1-2, padhy2026reviewofthe pages 2-4, amato2023genetherapyin pages 2-3, haldrup2025genetherapystrategies pages 3-5) Loss of outer retinal layers with photoreceptor loss, RPE atrophy, and advanced structural collapse; possible fibroatrophic change (padhy2026reviewofthe pages 2-4, amato2023genetherapyin pages 2-3) Reduced/heterogeneous autofluorescence in atrophic areas; prior hyperautofluorescent material may be lost as atrophy advances (bianco2024multimodalimagingin pages 1-2, amato2023genetherapyin pages 2-3) Severe, often irreversible visual loss in advanced disease (haldrup2025genetherapystrategies pages 3-5) End stage characterized by RPE death, photoreceptor loss, and possible CNV or fibrosis; central vision impairment becomes most pronounced (padhy2026reviewofthe pages 2-4, haldrup2025genetherapystrategies pages 3-5)

Table: This table summarizes the five classic clinical stages of Best vitelliform macular dystrophy, integrating fundus, OCT, FAF, and functional features. It is useful for disease characterization, differential diagnosis, and structuring natural history or trial-readiness annotations.

Key Phenotypic Features

  • Vitelliform macular lesion: Bilateral, yellow, "egg-yolk" appearance at the macula; the hallmark of BVMD (navinesferrer2022impairedbestrophinchannel pages 1-2, bianco2024multimodalimagingin pages 1-2). HPO: HP:0007754 (Macular dystrophy).
  • Reduced visual acuity: Progressive central vision loss, particularly in advanced stages (haldrup2025genetherapystrategies pages 3-5). HPO: HP:0000572 (Visual loss).
  • Metamorphopsia: Distortion of central vision reported in some patients (haldrup2025genetherapystrategies pages 3-5, shi2023comprehensivegeneticanalysis pages 5-8). HPO: HP:0012508 (Metamorphopsia).
  • Photophobia: Reported in vitelliform stage (haldrup2025genetherapystrategies pages 3-5). HPO: HP:0000613 (Photophobia).
  • Nyctalopia (night blindness): Reported variably (haldrup2025genetherapystrategies pages 3-5, shi2023comprehensivegeneticanalysis pages 5-8). HPO: HP:0000662 (Nyctalopia).
  • Abnormal EOG: Markedly reduced Arden ratio (≤1.5); pathognomonic (bianco2024multimodalimagingin pages 1-2, haldrup2025genetherapystrategies pages 3-5). HPO: HP:0000495 (Abnormality of the electrooculogram).
  • Lipofuscin accumulation: Subretinal deposition of lipofuscin and unphagocytosed photoreceptor outer segments (bianco2024multimodalimagingin pages 1-2). HPO: HP:0007807 (Vitelliform (egg-yolk) macular lesion).
  • Choroidal neovascularization (CNV): May complicate late-stage disease (bianco2024multimodalimagingin pages 1-2, padhy2026reviewofthe pages 2-4). HPO: HP:0011506 (Choroidal neovascularization).
  • Hyperopia and astigmatism: Associated refractive errors have been reported (haldrup2025genetherapystrategies pages 3-5).

Phenotype Characteristics

  • Age of onset: Typically childhood to early adulthood (ages 3–15 years for BVMD); AVMD presents after age 40 (yang2023best1novelmutation pages 1-2, navinesferrer2022impairedbestrophinchannel pages 1-2).
  • Severity: Highly variable, even among family members carrying the same mutation (grewal2021bestrophinopathiesperspectiveson pages 1-2, yang2023best1novelmutation pages 4-5).
  • Progression: Slow and unpredictable; not all patients progress through all stages sequentially (amato2023genetherapyin pages 2-3, bianco2024multimodalimagingin pages 1-2).
  • Quality of life: Central vision loss affects reading, driving, and fine visual tasks; 75% of patients under age 40 maintain visual acuity of 6/12 (20/40) or better in at least one eye (haldrup2025genetherapystrategies pages 3-5).

4. Genetic/Molecular Information

Causal Gene

BEST1 (bestrophin 1): Located on chromosome 11q12-q13.1, comprising 11 exons (of which 10 encode the protein), the gene encodes bestrophin-1, a 585-amino acid, 68 kDa protein that forms a homopentameric calcium-activated chloride channel (CaCC) (amato2023genetherapyin pages 2-3, navinesferrer2022impairedbestrophinchannel pages 1-2, amato2023genetherapyin pages 1-2).

Pathogenic Variants

  • Variant types: Predominantly missense variants for dominant forms; nonsense, frameshift, splice-site, and structural variants are more common in recessive disease (haldrup2025genetherapystrategies pages 1-3, nowomiejska2022diseaseexpressioncaused pages 1-2).
  • Variant classification: Pathogenic and likely pathogenic per ACMG/AMP guidelines; the BIRD-1 clinical trial (NCT07185256) requires ACMG/AMP-classified pathogenic or likely pathogenic variants for enrollment (NCT07185256 chunk 1).
  • Functional consequences: Three major categories have been identified (amato2023genetherapyin pages 1-2, haldrup2025genetherapystrategies pages 5-7):
  • Loss of function (LOF): Destabilized protein, non-functional channels, or reduced function; can occur throughout the gene.
  • Dominant negative (DN): Mutant subunits incorporate into pentameric channels and impair overall channel function; since BEST1 forms pentamers containing both wild-type and mutant subunits, even a 4:1 WT:mutant ratio can cause substantial dysfunction (navinesferrer2022impairedbestrophinchannel pages 10-11). This is the most common mechanism in dominant BVMD.
  • Gain of function (GOF): Increased or aberrant channel activity; a smaller subset of variants, exemplified by p.Pro77Ser which increases anion permeability (navinesferrer2022impairedbestrophinchannel pages 10-11).
  • Allelic expression imbalance: At the BEST1 locus, mutant alleles may be transcribed at higher levels than wildtype alleles in human RPE cells, promoting dominant negative effects (haldrup2025genetherapystrategies pages 5-7).
  • Somatic vs. germline: All described BEST1 pathogenic variants are germline in origin.

Specific Variant Examples

Multiple specific pathogenic variants have been characterized functionally: R218C shows correct basolateral localization but impaired function; W93C and V9M show intracellular mislocalization; Y85H, Q96R, L100R, Y227N, T6P, L21V, W24C, L224M, T237R, F305S, and V311G show trafficking errors on the cytoplasmic face; S79C, F80L, L82V, and A243T affect membrane domain function (padhy2026reviewofthe pages 2-4).

Modifier Genes and Epigenetics

No confirmed modifier genes or disease-associated epigenetic changes have been identified specifically for BEST1-related dominant retinopathy in the current literature.

5. Environmental Information

No environmental factors, lifestyle factors, or infectious agents have been identified as contributing to BEST1-related dominant retinopathy. This is a purely genetic, Mendelian disorder.

6. Mechanism / Pathophysiology

Molecular Pathways

Bestrophin-1 functions as a calcium-dependent chloride channel (CaCC) that controls chloride-ion current across the RPE basolateral membrane (haldrup2025genetherapystrategies pages 1-3). The protein's Ca²⁺-clasps regulate calcium-dependent opening and closing through conformational changes. Additionally, bestrophin-1 regulates intracellular calcium signaling, calcium release from endoplasmic reticulum stores, and cell volume homeostasis in RPE cells (haldrup2025genetherapystrategies pages 3-5, amato2023genetherapyin pages 2-3).

Relevant GO Biological Process terms: - GO:0005229 (intracellular calcium activated chloride channel activity) - GO:0006821 (chloride transport) - GO:0007601 (visual perception) - GO:0055085 (transmembrane transport)

Causal Chain from Initial Trigger to Clinical Manifestation

  1. Initial trigger: Heterozygous pathogenic variant in BEST1 leads to production of mutant bestrophin-1 subunits (amato2023genetherapyin pages 1-2).
  2. Protein dysfunction: Mutant subunits incorporate into pentameric channel complexes, causing dominant negative effects (most commonly), loss of function, or gain of function depending on the specific variant (navinesferrer2022impairedbestrophinchannel pages 10-11, haldrup2025genetherapystrategies pages 5-7). Some variants cause protein mislocalization from the basolateral membrane to intracellular compartments (padhy2026reviewofthe pages 2-4).
  3. RPE dysfunction: Impaired chloride transport disrupts RPE transepithelial potential (measured as reduced EOG light rise), fluid transport, and calcium homeostasis (padhy2026reviewofthe pages 2-4, haldrup2025genetherapystrategies pages 1-3).
  4. RPE-photoreceptor interaction failure: Loss of normal apposition between RPE apical microvilli and photoreceptor outer segments leads to impaired phagocytosis of shed outer segments (navinesferrer2022impairedbestrophinchannel pages 11-13, bianco2024multimodalimagingin pages 1-2).
  5. Vitelliform material accumulation: Unphagocytosed photoreceptor outer segments and lipofuscin accumulate in the subretinal space, forming the characteristic vitelliform lesion (bianco2024multimodalimagingin pages 1-2).
  6. Progressive photoreceptor damage: Cone mosaic changes, outer nuclear layer thinning, and ellipsoid zone disruption develop over time (bianco2024multimodalimagingin pages 1-2).
  7. End-stage disease: RPE death, photoreceptor loss, geographic atrophy, and potential choroidal neovascularization result in irreversible central vision loss (padhy2026reviewofthe pages 2-4, grewal2021bestrophinopathiesperspectiveson pages 1-2).

Cell Types Involved

  • Retinal pigment epithelium (RPE): Primary cell type expressing BEST1 and site of initial pathology. CL:0002586 (retinal pigment epithelial cell).
  • Cone photoreceptors: Secondary damage from RPE dysfunction, particularly in the macula. CL:0000573 (cone photoreceptor cell).
  • Rod photoreceptors: May also be affected in later stages. CL:0000604 (rod photoreceptor cell).

Biochemical Abnormalities

  • Ion channel defect: Impaired calcium-activated chloride channel activity at the RPE basolateral membrane (amato2023genetherapyin pages 2-3, navinesferrer2022impairedbestrophinchannel pages 10-11).
  • Calcium signaling disruption: Altered intracellular calcium dynamics in RPE cells (amato2023genetherapyin pages 2-3).
  • Phagocytosis defect: Impaired photoreceptor outer segment phagocytosis by RPE (navinesferrer2022impairedbestrophinchannel pages 11-13, xu2024ionchannelsresearch pages 4-5).
  • Transepithelial fluid transport deficiency: Reduced subretinal fluid clearance (xu2024ionchannelsresearch pages 4-5).

7. Anatomical Structures Affected

Organ Level

  • Primary organ: Eye (UBERON:0000970)
  • Primary structure: Retina (UBERON:0000966), specifically the macula (UBERON:0000053)
  • Body system: Visual/nervous system

Tissue and Cell Level

  • Retinal pigment epithelium (RPE): Primary tissue directly affected; site of bestrophin-1 expression and initial pathology (UBERON:0001782) (amato2023genetherapyin pages 2-3, padhy2026reviewofthe pages 2-4).
  • Photoreceptor layer: Secondary damage to cone and rod photoreceptors (UBERON:0001789) (bianco2024multimodalimagingin pages 1-2).
  • Subretinal space: Site of vitelliform material accumulation (bianco2024multimodalimagingin pages 1-2).

Subcellular Level

  • Basolateral plasma membrane: Primary localization of bestrophin-1 (GO:0016323) (amato2023genetherapyin pages 2-3, padhy2026reviewofthe pages 2-4).
  • Endoplasmic reticulum: Secondary localization of bestrophin-1; involved in calcium release regulation (GO:0005783) (amato2023genetherapyin pages 2-3, padhy2026reviewofthe pages 2-4).

Localization

  • Bilateral involvement: Typically bilateral and symmetrical, though asymmetric presentation occurs (haldrup2025genetherapystrategies pages 3-5).
  • Macular predominance: Vitelliform lesions primarily affect the central macula, with some patients showing extramacular deposits (yang2023best1novelmutation pages 1-2, bianco2024multimodalimagingin pages 1-2).

8. Temporal Development

Onset

  • Typical age of onset: Childhood to early adulthood for BVMD (ages 3–15 years); AVMD presents after age 40 (yang2023best1novelmutation pages 1-2, navinesferrer2022impairedbestrophinchannel pages 1-2, nowomiejska2022diseaseexpressioncaused pages 1-2).
  • Onset pattern: Insidious; pre-vitelliform stage may be detected on imaging before symptoms develop (padhy2026reviewofthe pages 2-4, amato2023genetherapyin pages 2-3).

Progression

  • Disease course: Slowly progressive over decades; photoreceptors can remain viable for extended periods despite subretinal material accumulation (amato2023genetherapyin pages 2-3, amato2023genetherapyin pages 6-7).
  • Progression rate: Highly variable and unpredictable; not all patients progress through all five stages sequentially (bianco2024multimodalimagingin pages 1-2, amato2023genetherapyin pages 2-3).
  • Duration: Chronic, lifelong condition.
  • Critical periods: The slow progression provides a wide therapeutic window for gene therapy intervention, as central photoreceptors usually remain viable for decades (amato2023genetherapyin pages 2-3, amato2023genetherapyin pages 6-7).

9. Inheritance and Population

Inheritance Pattern

  • Mode: Autosomal dominant with variable expressivity and incomplete/reduced penetrance (grewal2021bestrophinopathiesperspectiveson pages 1-2, beryozkin2024bestdiseaseglobal pages 1-2, haldrup2025genetherapystrategies pages 3-5).
  • Penetrance: Incomplete; many BEST1 pathogenic variants show reduced penetrance, meaning not all carriers develop clinical disease (grewal2021bestrophinopathiesperspectiveson pages 1-2).
  • Expressivity: Highly variable, even within families carrying the same mutation; intrafamilial phenotypic diversity is a hallmark (grewal2021bestrophinopathiesperspectiveson pages 1-2, yang2023best1novelmutation pages 4-5).

Epidemiology

  • Prevalence estimates: Widely variable across studies:
  • General estimates range from 1:5,000 to 1:67,000 (grewal2021bestrophinopathiesperspectiveson pages 1-2, navinesferrer2022impairedbestrophinchannel pages 1-2, haldrup2025genetherapystrategies pages 3-5).
  • Israel: 1 in 127,000 overall; 1 in 76,000 among Arab Muslims; 1 in 145,000 among Jews (beryozkin2024bestdiseaseglobal pages 2-3, beryozkin2024bestdiseaseglobal pages 1-2).
  • Denmark: 0.8–1.5 per 100,000 (beryozkin2024bestdiseaseglobal pages 4-7).
  • Northern Sweden: 2 per 10,000 (beryozkin2024bestdiseaseglobal pages 4-7).
  • Minnesota (USA): 1:16,500 to 1:21,000 (beryozkin2024bestdiseaseglobal pages 4-7).
  • BVMD prevalence of approximately 1:50,000 has been cited (nowomiejska2022diseaseexpressioncaused pages 1-2).
  • Population variation: Higher prevalence in populations with higher consanguinity rates (for recessive forms); Arab Muslim populations in Israel showed higher prevalence than Jewish populations (42% vs. ≤13.6% consanguinity rates) (beryozkin2024bestdiseaseglobal pages 7-8).
  • Founder effects: Population-specific founder variants have been identified, including a founder variant c.867+97G>A in Chinese patients with ARB (allele frequency 16%) (shi2023comprehensivegeneticanalysis pages 5-8) and a founder variant p.Arg122Pro in Egyptian families (from Elbagoury et al. 2025).

Sex Ratio

No significant sex predilection has been established for BEST1-related dominant retinopathy; the clinical trials include participants of all sexes (NCT05809635 chunk 1, NCT07185256 chunk 1).

10. Diagnostics

Clinical Tests

  • Electrooculogram (EOG): The hallmark diagnostic test; markedly reduced Arden ratio (typically ≤1.5, pathognomonic) reflecting impaired RPE function (bianco2024multimodalimagingin pages 1-2, nowomiejska2022diseaseexpressioncaused pages 1-2, haldrup2025genetherapystrategies pages 3-5). MAXO: MAXO:0000930 (electrooculography).
  • Full-field electroretinogram (ERG): Usually normal in BVMD, distinguishing it from other retinal dystrophies; may show progressive amplitude reductions in advanced stages (bianco2024multimodalimagingin pages 1-2, padhy2026reviewofthe pages 2-4).
  • Multifocal ERG (mfERG): Reduced central ring amplitudes correlating with subretinal fluid (padhy2026reviewofthe pages 2-4).
  • Optical coherence tomography (OCT): Reveals subretinal hyperreflective material, dome-shaped lesions, outer retinal layer disruption, and cystoid changes; an OCT-based staging system has been developed (bianco2024multimodalimagingin pages 1-2, amato2023genetherapyin pages 2-3). MAXO: MAXO:0010034 (optical coherence tomography).
  • Fundus autofluorescence (FAF): Intense hyperautofluorescence corresponding to vitelliform deposits; useful for disease monitoring (bianco2024multimodalimagingin pages 1-2, padhy2026reviewofthe pages 2-4, amato2023genetherapyin pages 2-3).
  • Near-infrared fundus autofluorescence (NIR-AF): Helps identify pre-vitelliform stage changes (padhy2026reviewofthe pages 2-4).
  • Color fundus photography: Classic "egg-yolk" yellow macular lesion appearance (bianco2024multimodalimagingin pages 1-2, yang2023best1novelmutation pages 4-5).
  • OCT angiography (OCTA): Emerging role in detecting macular neovascularization, with a higher prevalence of non-exudative CNV in late stages (bianco2024multimodalimagingin pages 1-2).

Genetic Testing

  • Recommended approach: Molecular genetic confirmation is considered the gold standard for Best disease diagnosis due to variable clinical presentation (beryozkin2024bestdiseaseglobal pages 1-2).
  • Gene panels: IRD panels including BEST1 variant testing are routinely used (NCT07185256 chunk 1).
  • Single gene testing: Sanger sequencing of BEST1 coding exons (nowomiejska2022diseaseexpressioncaused pages 1-2, shi2023comprehensivegeneticanalysis pages 5-8).
  • Whole exome sequencing (WES): Used for comprehensive diagnostic screening (beryozkin2024bestdiseaseglobal pages 1-2).
  • Whole genome sequencing (WGS): Can detect deep intronic variants missed by standard approaches; three deep intronic variants (c.1101-491A>G, c.867+97G>A, c.867+97G>T) were identified through WGS in a Chinese cohort (shi2023comprehensivegeneticanalysis pages 5-8).

Differential Diagnosis

Conditions to distinguish from BEST1-related dominant retinopathy include: - Age-related macular degeneration (AMD) - Adult-onset foveomacular vitelliform dystrophy (pattern dystrophy without BEST1 mutation) - Central serous chorioretinopathy - Stargardt disease (ABCA4-related) - PRPH2-related vitelliform macular dystrophy - IMPG1/IMPG2-related vitelliform macular dystrophy (OpenTargets Search: -BEST1)

11. Outcome/Prognosis

Visual Prognosis

  • Most patients experience slow visual decline over decades (amato2023genetherapyin pages 2-3, amato2023genetherapyin pages 6-7).
  • Approximately 75% of patients under age 40 maintain best-corrected visual acuity of 6/12 (20/40) or better in at least one eye (haldrup2025genetherapystrategies pages 3-5).
  • Visual acuity can range from near-normal to severe impairment depending on disease stage (haldrup2025genetherapystrategies pages 3-5).
  • Central photoreceptors usually remain viable for decades despite subretinal material accumulation, providing a wide therapeutic window (amato2023genetherapyin pages 2-3, amato2023genetherapyin pages 6-7).

Complications

  • Choroidal neovascularization (CNV) may develop in late-stage disease, with OCTA studies showing a greater prevalence of non-exudative CNV than previously recognized (bianco2024multimodalimagingin pages 1-2).
  • Macular atrophy and fibrosis represent end-stage disease (padhy2026reviewofthe pages 2-4, haldrup2025genetherapystrategies pages 3-5).
  • Angle-closure glaucoma is primarily associated with recessive BEST1 disease rather than dominant forms (yang2023best1novelmutation pages 1-2).

Life Expectancy

BEST1-related dominant retinopathy is not associated with reduced life expectancy; morbidity is limited to progressive visual impairment.

12. Treatment

Current Treatments

Currently, no approved curative or disease-modifying treatments exist for any bestrophinopathy (haldrup2025genetherapystrategies pages 7-8, haldrup2025genetherapystrategies pages 1-3). Management is limited to: - Supportive care: Low-vision aids, adaptive technologies, and occupational therapy. - Anti-VEGF therapy: For secondary choroidal neovascularization (CNV) when present. - Monitoring: Regular multimodal imaging follow-up.

Experimental/Investigational Treatments

Gene Therapy

The following clinical trials are currently investigating or characterizing BEST1-related retinopathy for therapeutic development:

NCT Number Trial Name/Acronym Phase Sponsor Status Intervention Enrollment Key Details
NCT07185256 Safety and Tolerability of Subretinally Injected OPGx-BEST1 in Patients With BVMD or ARB / BIRD-1 Phase 1b/2a Opus Genetics, Inc Recruiting One-time subretinal injection of OPGx-BEST1 (codon-optimized full-length hBEST1 under an RPE-specific/VMD2 promoter); dose exploration at 1.5E9 vg/eye and 4.5E9 vg/eye 10 First interventional gene-therapy trial identified here for BEST1 bestrophinopathies; open-label basket study in adults with autosomal-dominant BVMD or ARB; vitrectomy plus subretinal delivery; 5-year follow-up; primary focus on dose-limiting toxicity, procedure/drug-related adverse events; secondary outcomes include OCT, FAF, OCT-A, microperimetry, ETDRS BCVA, low-luminance VA, and PROs. (NCT07185256 chunk 1, NCT07185256 chunk 2)
NCT05809635 Study of BEST1 Vitelliform Macular Dystrophy Not applicable (Observational natural history study) Columbia University Recruiting Natural history longitudinal assessment; no therapeutic intervention 52 Prospective cohort study to define the natural history of BEST1-associated vitelliform macular dystrophy and identify structural/functional endpoints for future trials; includes ERG, EOG, OCT, FAF, NIR-AF, qAF, BCVA, MAIA microperimetry, Goldman visual fields, and dark-adapted chromatic perimetry; includes children and adults; multicenter sites in the US, France, and Germany. (NCT05809635 chunk 1)
NCT02162953 Stem Cell Models of Best Disease and Other Retinal Degenerative Diseases Not applicable (Observational) Mayo Clinic Completed Collection of participant samples to generate stem-cell disease models (iPSC-based modeling) 48 Completed observational study designed to develop stem-cell models of Best disease and related retinal degeneration for mechanistic and translational research; useful for mutation-specific modeling rather than direct treatment efficacy testing. (OpenTargets Search: -BEST1)

Table: This table summarizes the main clinical studies currently identified for BEST1-related retinopathy, including the ongoing OPGx-BEST1 interventional gene therapy trial and key observational natural history/modeling studies. It is useful for quickly comparing trial purpose, status, intervention type, and outcome focus.

OPGx-BEST1 (BIRD-1 trial, NCT07185256): This is the first interventional gene therapy trial for bestrophinopathies, sponsored by Opus Genetics. OPGx-BEST1 is a codon-optimized full-length human BEST1 transgene under an RPE-specific VMD2 promoter, delivered via subretinal injection. Two dose levels (1.5E9 vg/eye and 4.5E9 vg/eye) are being explored in adults with BVMD or ARB. The trial began enrolling in September 2025 with 5-year follow-up planned (NCT07185256 chunk 1, NCT07185256 chunk 2). MAXO: MAXO:0001001 (gene therapy).

Preclinical gene augmentation: AAV-mediated gene augmentation therapy has demonstrated reversal of retinal microdetachments in canine bestrophinopathy models within 4–12 weeks post-injection, with sustained effects up to 245 weeks without inflammatory responses (amato2023genetherapyin pages 6-7, padhy2026reviewofthe pages 6-9). In iPSC-RPE cells, baculovirus and AAV2 vector-delivered wildtype BEST1 rescues calcium-dependent chloride channel function (grewal2021bestrophinopathiesperspectiveson pages 9-11).

CRISPR/Cas9 Gene Editing

  • Allele-specific CRISPR/Cas9 genome editing has shown proof-of-concept for silencing mutant BEST1 transcripts in hiPSC-RPE cells, with one study demonstrating 96% frameshift efficiency via NHEJ (grewal2021bestrophinopathiesperspectiveson pages 9-11).
  • Allele-specific silencing combined with gene augmentation has been proposed as a universal strategy, particularly for gain-of-function variants where gene augmentation alone is insufficient (amato2023genetherapyin pages 4-6).
  • Recent work (Milenkovic & Weber 2026) demonstrated that eliminating the mutant BEST1 transcript via allele-specific CRISPR editing led to enhanced BEST1 localization, improved protein stability, and restoration of anion transport function in clonal hiPSC-RPE lines (from milenkovic2026 abstract).

Small Molecule Approaches

Small molecule drugs showing promise in preclinical models include: bafilomycin-A1 (slowing POS degradation), valproic acid (accelerating POS degradation), curcumin (enhancing ZO-1 and bestrophin-1 expression and improving phagocytosis), and sodium phenylbutyrate (4PBA) (xu2024ionchannelsresearch pages 4-5).

Treatment Strategy by Mutation Type

  • LOF and DN mutations: Amenable to gene augmentation alone, potentially requiring higher doses for stronger dominant negative effects (amato2023genetherapyin pages 1-2, haldrup2025genetherapystrategies pages 8-10).
  • GOF mutations: Require combination approach: gene silencing (CRISPR or ASO) plus gene augmentation (amato2023genetherapyin pages 4-6).

13. Prevention

Primary Prevention

No primary prevention is available, as the disease is caused by germline genetic variants.

Secondary Prevention (Early Detection)

  • Genetic screening: Cascade genetic testing of family members of affected individuals is recommended to identify asymptomatic carriers (beryozkin2024bestdiseaseglobal pages 1-2).
  • Carrier screening/preimplantation genetic diagnosis (PGD): Available for families with known BEST1 mutations for family planning purposes.
  • Genetic counseling: Essential for affected families given the autosomal dominant inheritance, variable expressivity, and incomplete penetrance (grewal2021bestrophinopathiesperspectiveson pages 1-2). MAXO: MAXO:0000127 (genetic counseling).

Tertiary Prevention

  • Regular ophthalmological monitoring with multimodal imaging (OCT, FAF, EOG) to detect disease progression and complications such as CNV (bianco2024multimodalimagingin pages 1-2, amato2023genetherapyin pages 2-3).
  • Prompt anti-VEGF treatment for secondary choroidal neovascularization.

Natural History Studies

The NCT05809635 natural history study (Columbia University, PI: Stephen Tsang) is currently recruiting to establish the natural course of BEST1 vitelliform macular dystrophy and identify sensitive structural and functional outcome measures for future clinical trials (NCT05809635 chunk 1).

14. Other Species / Natural Disease

Canine Bestrophinopathy

Canine multifocal retinopathy (CMR) is a naturally occurring bestrophinopathy identified in multiple dog breeds, representing the most important large animal model for BEST1-related disease (dufour2025caninemodelsof pages 4-5, winkler2020largeanimalmodels pages 11-12):

  • cmr1: p.Arg25Ter mutation in Great Pyrenees and mastiff breeds (winkler2020largeanimalmodels pages 11-12).
  • cmr2: p.Gly161Asp mutation in Coton de Tulear (dufour2025caninemodelsof pages 4-5, winkler2020largeanimalmodels pages 11-12).
  • cmr3: Two mutations in Swedish Lapponian Herder (dufour2025caninemodelsof pages 4-5, winkler2020largeanimalmodels pages 11-12).

Species: Canis lupus familiaris (NCBI Taxon: 9615).

Key differences from human disease: Canine CMR follows autosomal recessive inheritance (unlike the dominant human BVMD), but recapitulates clinical, histological, and molecular features of human bestrophinopathy including multifocal retinal detachments, lipofuscin accumulation, and RPE apical microvilli loss (dufour2025caninemodelsof pages 4-5, winkler2020largeanimalmodels pages 11-12). The retina-wide microdetachment is light-modulated, making it useful as an outcome measure for gene therapy studies (dufour2025caninemodelsof pages 4-5).

Translational value: Gene therapy using rAAV2 vectors delivering wildtype BEST1 successfully resolved detachments and restored RPE microvilli for over 207 weeks (approximately 4 years) post-injection in dogs, independent of age or mutation type (winkler2020largeanimalmodels pages 11-12).

15. Model Organisms

Mouse Models

  • Best1 knockout mice: Do not exhibit bestrophinopathy phenotypes or significant chloride current abnormalities, limiting their utility (amato2023genetherapyin pages 6-7, xu2024ionchannelsresearch pages 4-5).
  • Best1 p.W93C knock-in mice: Display disease features with dominant inheritance, including reduced EOG light-rise and serous retinal detachments, but unexpectedly maintain normal chloride currents (padhy2026reviewofthe pages 6-9, xu2024ionchannelsresearch pages 4-5).
  • Best1 p.Y227N knock-in mice: Show no ocular abnormalities up to 2 years of age (xu2024ionchannelsresearch pages 4-5).

iPSC-RPE Models

Patient-derived induced pluripotent stem cell (iPSC)-RPE models represent the most flexible and disease-relevant in vitro system for studying BEST1-related dominant retinopathy (amato2023genetherapyin pages 6-7, xu2024ionchannelsresearch pages 4-5, xu2024ionchannelsresearch pages 14-14): - Successfully reproduce disease features including BEST1 protein mislocalization, defective chloride conductance, impaired phagocytosis, lipofuscin accumulation, and reduced transepithelial fluid transport (xu2024ionchannelsresearch pages 4-5). - Particularly valuable for studying dominant BEST1 mutations, since canine models lack dominant genotypes and mouse knockouts show no phenotype (amato2023genetherapyin pages 6-7). - Used for gene therapy preclinical testing and CRISPR/Cas9 proof-of-concept studies (grewal2021bestrophinopathiesperspectiveson pages 9-11, xu2024ionchannelsresearch pages 14-14).

Model Limitations

  • Canine models: Recessive inheritance limits applicability to dominant human disease (xu2024ionchannelsresearch pages 4-5).
  • Mouse models: Generally poor recapitulation of human phenotype; species-specific differences in RPE physiology limit translational value (amato2023genetherapyin pages 6-7, xu2024ionchannelsresearch pages 4-5).
  • iPSC-RPE: Two-dimensional cell culture lacks the complex retinal architecture and three-dimensional tissue interactions present in vivo (xu2024ionchannelsresearch pages 4-5).

Summary

BEST1-related dominant retinopathy, most commonly manifesting as Best vitelliform macular dystrophy, is a Mendelian inherited retinal dystrophy caused by heterozygous mutations in BEST1 encoding the bestrophin-1 calcium-activated chloride channel in the RPE. The disease is characterized by progressive vitelliform macular lesions, reduced EOG light rise, and variable visual impairment. With over 250 known pathogenic variants and three distinct molecular mechanisms (loss-of-function, dominant negative, and gain-of-function), the condition shows remarkable genetic and phenotypic heterogeneity. While no approved treatments currently exist, the first gene therapy clinical trial (BIRD-1/NCT07185256) began recruiting in 2025, and multiple preclinical gene therapy and gene editing strategies show considerable promise. The slow disease progression and prolonged photoreceptor viability provide a wide therapeutic window, positioning bestrophinopathies as a particularly attractive target for emerging genetic therapies.

References

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