CNGB1-Related Retinopathy

Mendelian MONDO:0800403 Pathograph 25 Show in embeddings browser Ophthalmological Disease Retinal Dystrophy Inherited retinal dystrophy

CNGB1-related retinopathy is an autosomal recessive rod-cone dystrophy, historically retinitis pigmentosa 45. Biallelic pathogenic variants affect the beta subunit of the rod cyclic nucleotide-gated channel. Rod dysfunction commonly precedes extensive photoreceptor loss. Night blindness often begins in childhood, but reported symptom onset and disease severity vary, and one series reported onset between ages 4 and 49 years. Central visual acuity and foveal structure may remain useful into adulthood, while some patients develop severe visual loss. These observations suggest an opportunity for intervention but do not establish a universal treatment window or a human gene-therapy benefit. CNGB1 also encodes an olfactory-channel isoform. Formal testing has identified hyposmia or anosmia in selected patients, many of whom had not noticed impaired smell. Neither olfactory penetrance nor a reliable variant-specific retinal or olfactory prognosis has been established. Cystoid macular edema, epiretinal membranes and cataract can accompany the retinal disease and affect clinical measurements. Animal gene-augmentation studies provide preclinical evidence that restoring CNGB1 can improve rod function and preserve retinal structure.

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Classifications

Harrison's Part

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Inheritance

Autosomal recessive HP:0000007

CNGB1-related retinopathy is caused by biallelic (homozygous or compound heterozygous) loss-of-function variants in CNGB1.

Autosomal recessive inheritance

Show evidence (1 reference)

PMID:11379879 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"By performing full genome linkage analysis in a consanguineous French family affected with severe autosomal recessive RP, we have excluded linkage to known loci involved in RP and mapped a novel locus to chromosome 16q13-q21"

This original gene-discovery paper establishes autosomal recessive inheritance for CNGB1-related retinitis pigmentosa via linkage in a consanguineous family.

Discussions and Knowledge Gaps

Which structural and functional features identify a rescuable human CNGB1 retina?

HUMAN MODEL MISMATCH OPEN cngb1_rescue_stage_translation

Attached to

animal_models#Conditional Cngb1 rescue mouse treatments#AAV-Mediated CNGB1 Gene Augmentation Therapy

Conditional endogenous rescue bypasses vector transduction and expression variability. Late-treated mice retain some benefit but do not regain normal retinal output, and mice lack a macula. Human OCT preservation alone therefore does not establish an intervention window or justify transferring model-specific rod-loss thresholds into eligibility criteria.

Show evidence (1 reference)

PMID:38086857 SUPPORT DIRECT PRIMARY RESULT Model Organism

"Mouse retina lacks a cone-dense region and is (at best) more analogous to human peripheral retina"

The study explicitly limits translation of its rescue-stage results to human central retina.

Which intermediates link channel deficiency and cGMP accumulation to progressive rod death in CNGB1 disease?

KNOWLEDGE GAP OPEN cngb1_cgmp_death_intermediates

Attached to

pathophysiology#Rod cGMP Accumulation pathophysiology#Progressive Rod Photoreceptor Loss

Channel-deficient model rods accumulate cGMP, and CNGB1 restoration reduces the staining while improving function. Those rescue experiments correct multiple consequences simultaneously and do not isolate cGMP as the death effector. Calcium overload and a specific downstream death pathway should not be inferred from cGMP immunoreactivity alone.

Show evidence (1 reference)

PMID:37056049 SUPPORT DIRECT PRIMARY RESULT Model Organism

"A feature of lack of CNG channel function in rod outer segments is the abnormal accumulation of cGMP. IHC showed that this was reversed within the treated retinal regions"

In the cGMP-accumulation results section, immunohistochemistry showed reversal of abnormal cGMP staining in treated dog retina, with staining retained outside the treated regions. This is not a direct channel-current measurement.

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Pathophysiology

Biallelic CNGB1 Dysfunction

Mechanism confidence: Established

Biallelic pathogenic CNGB1 variants impair the rod channel beta subunit. Alleles include truncating, splice-site and missense changes, with effects that can differ in protein abundance, localization or gating. CNGB1a belongs to the rod CNGA1/CNGB1 channel; CNGB1b is an olfactory isoform. Not every reported variant is pathogenic and not every pathogenic allele eliminates the protein.

CNGB1 hgnc:2151 ↓ DECREASED

Downstream

Reduced Rod Outer-Segment CNG Channel Abundance Loss of CNGB1 in mouse and dog models depletes outer-segment partner CNGA1; rescue restores its localization. Allele-specific channel-gating defects need not share this abundance mechanism.

Impaired Olfactory Signal Transduction CNGB1 also encodes an olfactory channel subunit; impaired olfactory signaling is a plausible basis for the variable smell dysfunction observed in human cohorts.

Variant-Specific CNGB1 Protein Instability A specific splice-site allele produces an unstable mutant protein in a heterologous assay; the effect is not assigned to all CNGB1 alleles.

Show evidence (2 references)

PMID:33847019 SUPPORT DIRECT REVIEW SYNTHESIS Other

"According to the ACMG criteria, 59 variants were considered pathogenic or likely pathogenic and 25 variants were classified of uncertain significance"

Variant reclassification in the 2021 review distinguishes reported alleles from confirmed pathogenic or likely pathogenic variants.

PMID:20126465 SUPPORT DIRECT PRIMARY RESULT In Vitro

"Here, we investigated the splicing of c.3444+1G>A by exon trapping experiments and could demonstrate that instead of the proposed truncation of the last 28 aa this mutation leads to replacement of the last 170 aa of CNGB1a by 68 unrelated amino acids."

Exon trapping in HEK293T cells demonstrates exon-32 skipping for c.3444+1G>A, replacing the last 170 residues with 68 unrelated residues. This is a variant-specific assay, not patient-rod transcript analysis.

Variant-Specific CNGB1 Protein Instability

Mechanism confidence: Provisional

For c.3444+1G>A, exon-32 skipping replaces the terminal 170 amino acids with 68 unrelated residues. The engineered full-length mutant showed reduced abundance in HEK293T cells, reversible with proteasome inhibitors. This allele-specific instability may contribute to channel deficiency; NMD and altered targeting in patient rods were proposed rather than measured.

Downstream

Reduced Rod Outer-Segment CNG Channel Abundance Instability could reduce channel availability in rods; that tissue-level consequence was not directly measured in the HEK293T assay.

Show evidence (2 references)

PMID:20126465 SUPPORT DIRECT PRIMARY RESULT In Vitro

"When expressed in a heterologous expression system the corresponding mutant full-length CNGB1a subunit was more susceptible to proteosomal degradation compared to the wild-type counterpart."

The exon-32-skipped mutant is less stable in a heterologous expression system; the full-text experiment used HEK293T cells coexpressing CNGA1. This does not establish NMD or channel trafficking in patient rods.

PMID:20126465 SUPPORT DIRECT PRIMARY RESULT In Vitro

"Since this difference in expression could be reversed by the addition of proteasome inhibitors, we concluded that the mutant protein is partially degraded by the proteasome"

Proteasome inhibitor rescue supports a degradation contribution in the heterologous cell experiment.

Reduced Rod Outer-Segment CNG Channel Abundance

Mechanism confidence: Provisional

In CNGB1-deficient mouse rods, outer-segment CNGA1 is markedly depleted. CNGB1 augmentation restores CNGA1 abundance and outer-segment localization in mice and dogs. These findings support defective channel assembly/targeting or stability without assigning the same lesion to every human missense allele.

retinal rod cell CL:0000604

photoreceptor outer segment GO:0001750

Downstream

Impaired Rod Light Responses Loss of normal outer-segment channel abundance compromises rod phototransduction.

Show evidence (2 references)

PMID:15634774 SUPPORT DIRECT PRIMARY RESULT Model Organism

"In the absence of CNGB1, only trace amounts of the CNGA1 subunit were found on the rod outer segment."

CNGB1-deficient mouse rods have markedly depleted outer-segment CNGA1.

PMID:37056049 SUPPORT DIRECT PRIMARY RESULT Model Organism

"In the treated region, but not the untreated, CNGA1 protein was detectable in rod outer segments"

Human CNGB1 augmentation restores canine partner-subunit localization within the treated region.

Impaired Rod Light Responses

Mechanism confidence: Established

Rod CNG-channel deficiency markedly reduces light responses before extensive cell loss in knockout mice and affected dogs. Residual isolated-rod responses occur, and human ERG responses range from attenuated to undetectable. Severe functional impairment is therefore distinct from physical disappearance of rods.

retinal rod cell CL:0000604

phototransduction GO:0007602 ↓ DECREASED

Animal models

Cngb1-X26 knockout mouse Mouse partially recapitulates The X26 knockout has absent rod-mediated ERGs and predominantly unresponsive isolated rods.

Cngb1-X26 knockout mouse Mouse rescues Subretinal AAV8-mediated delivery of CNGB1a to Cngb1-/- mice restores full-length CNGB1a expression, rescues degraded CNGA1 to normal levels, and reconstitutes functional CNG channel complexes in rod outer segments.

Cngb1-X26 knockout mouse Mouse rescues AAV5-hRHO194-human CNGB1 given at four weeks improves rod ERGs and dim-light behavior most strongly at the intermediate dose. The highest dose had no clear ERG benefit, and structural thinning was slowed rather than stopped.

CNGB1-mutant dog (naturally occurring, Papillon/Phalene breeds) Dog rescues AAV5-hGRK1-canine CNGB1 in the 2018 proof-of-concept study yielded ERG rescue through 18 months in the longest ERG follow-up; 23 months referred to protein expression/structural follow-up. The distinct 2023 AAV5-RHO-human CNGB1 study treated ten three-month-old dogs and assessed functional rescue through 12 months in animals retained that long.

Downstream

Rod cGMP Accumulation Channel-deficient mouse and dog rods accumulate cGMP; restoring CNGB1 reduces staining. Reduced calcium-dependent feedback on guanylate cyclase is a mechanistic interpretation, not a calcium measurement in these rescue studies.

Progressive Rod Photoreceptor Loss Rod dysfunction precedes progressive rod loss in CNGB1-deficient models; the critical intermediates connecting channel loss to death are incompletely resolved.

Nyctalopia Reduced rod-mediated sensitivity impairs vision under dim illumination.

Show evidence (2 references)

PMID:15634774 SUPPORT DIRECT PRIMARY RESULT Model Organism

"the vast majority of isolated rod photoreceptors in mice lacking CNGB1 (CNGB1-/-) failed to respond to light. In electroretinograms (ERGs), CNGB1-/- mice showed no rod-mediated responses."

Most isolated knockout rods were unresponsive; the population ERG lacked rod-mediated responses. Neither observation proves that every rod is silent.

PMID:33465333 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"Electrophysiological testing in five patients showed an absence of the rod response. Cone responses ranged from normal to severely reduced."

Human ERGs establish rod-system impairment without directly measuring channel current.

Rod cGMP Accumulation

Mechanism confidence: Provisional

Abnormal cGMP immunoreactivity occurs in inner and outer segments of CNGB1-deficient mouse and dog photoreceptors and decreases in successfully treated retinal regions. Loss of calcium entry and its negative feedback on guanylate cyclase is proposed to explain accumulation. These observations do not establish calcium overload or directly identify the death-effector pathway.

retinal rod cell CL:0000604

Animal models

CNGB1-mutant dog (naturally occurring, Papillon/Phalene breeds) Dog rescues Abnormal cGMP immunoreactivity is reduced within human-CNGB1-treated canine retina.

Show evidence (1 reference)

PMID:37056049 SUPPORT DIRECT PRIMARY RESULT Model Organism

"A feature of lack of CNG channel function in rod outer segments is the abnormal accumulation of cGMP. IHC showed that this was reversed within the treated retinal regions"

Progressive Rod Photoreceptor Loss

Mechanism confidence: Established

Rod photoreceptors are progressively lost following early functional impairment. Apoptotic death was demonstrated in the X26 mouse; human imaging documents structural decline without identifying an identical death program for every allele. Disease tempo differs among models and patients.

retinal rod cell CL:0000604

Animal models

Cngb1-X26 knockout mouse Mouse partially recapitulates Progressive apoptotic rod loss occurs in the X26 mouse.

CNGB1-mutant dog (naturally occurring, Papillon/Phalene breeds) Dog partially recapitulates Progressive rod loss and later cone decline provide a large-eye model of the rod-first disease course; the cited dog histology does not itself establish apoptosis.

Downstream

Secondary Cone Dysfunction and Degeneration Cone dysfunction and loss occur later than rod loss in mouse and dog models; the non-cell-autonomous intermediates remain unresolved.

Reactive Retinal Gliosis Progressive retinal degeneration is accompanied by reactive glial labeling in mouse models.

Photoreceptor Synaptic Ribbon Loss Advanced degeneration in the conditional mouse is associated with loss of photoreceptor synaptic ribbon structures.

Constriction of peripheral visual field Progressive peripheral photoreceptor degeneration contributes to field constriction; symptom recognition can lag objective field loss.

Pigmentary retinopathy Photoreceptor degeneration is associated with progressive retinal pigment redistribution; this does not imply that rod apoptosis directly causes each pigment deposit.

Show evidence (2 references)

PMID:15634774 SUPPORT DIRECT PRIMARY RESULT Model Organism

"The rods also showed a slow-progressing degeneration caused by apoptotic death and concurred by retinal gliosis."

The X26 knockout shows progressive apoptotic rod loss and associated gliosis. This does not establish the same death pathway in every human allele.

PMID:35743231 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"The results support previous findings of CNGB1-related RP being a slowly progressive disease with patients maintaining visual acuity."

States the natural-history cohort's overall conclusion of slow, measurable progression with maintained visual acuity.

Secondary Cone Dysfunction and Degeneration

Mechanism confidence: Established

Cone function and structure decline after the primary rod defect. Normal early cone ERGs followed by later degeneration in X26 mice, and preservation of cone responses after rod-directed rescue in dogs, support a secondary process. The molecular intermediates are unresolved. Central vision can remain useful for years, but severity and timing vary and macular complications also affect acuity.

retinal cone cell CL:0000573

Downstream

Color vision defect Cone-system dysfunction contributes to impaired color discrimination; the clinical test does not distinguish cone loss from all other causes of reduced color performance.

Show evidence (2 references)

PMID:15634774 SUPPORT DIRECT PRIMARY RESULT Model Organism

"Cones were primarily unaffected and showed normal ERG responses up to 6 months, but they started to degenerate in later stages."

Direct evidence in the mouse model that cone dysfunction and degeneration are delayed relative to rod loss.

PMID:37056049 SUPPORT DIRECT PRIMARY RESULT Model Organism

"Taken together, this analysis of cone ERG responses provides evidence of the preservation of cone function when rod rescue is achieved by gene augmentation therapy."

Cone ERG modeling supports secondary preservation following rod-directed rescue in dogs; it does not prove normal cone physiology or human benefit.

Reactive Retinal Gliosis

Mechanism confidence: Provisional

Reactive Müller-cell gliosis accompanies CNGB1-deficient mouse retinal degeneration. GFAP labeling decreases after effective early AAV augmentation but persists after late conditional endogenous rescue. GFAP is a stress-response readout; these experiments do not establish that gliosis alone drives ongoing cell loss.

Mueller cell CL:0000636

Animal models

Conditional Cngb1 rescue mouse Mouse partially recapitulates GFAP labeling persists after late rescue.

Show evidence (1 reference)

PMID:38086857 SUPPORT DIRECT PRIMARY RESULT Model Organism

"we found that GFAP was present in both untreated and late-treated retinas at 7 M"

Persistent GFAP labeling after late endogenous rescue supports a sustained glial stress response in this conditional mouse model; it does not establish a causal inflammatory mediator.

Photoreceptor Synaptic Ribbon Loss

Mechanism confidence: Provisional

In the conditional Cngb1 mouse, late rescue leaves substantially reduced CtBP2-labeled photoreceptor ribbon structures despite surviving rods and cones. This identifies an anatomical limitation to recovery, without proving which circuit changes explain every functional deficit.

Animal models

Conditional Cngb1 rescue mouse Mouse partially recapitulates Late rescue leaves fewer intact CtBP2-labeled ribbon structures.

Downstream

Impaired Retinal Ganglion Cell Signaling Loss of ribbon structures is a proposed contributor to impaired retinal output; the study did not isolate synapse loss as the sole cause.

Show evidence (1 reference)

PMID:38086857 SUPPORT DIRECT PRIMARY RESULT Model Organism

"Following late treatment, CtBP2 horseshoe structures were substantially reduced"

CtBP2 immunolabeling showed loss of normal photoreceptor synaptic ribbon structures after late conditional rescue.

Impaired Retinal Ganglion Cell Signaling

Mechanism confidence: Provisional

After late conditional Cngb1 rescue, retinal ganglion cell responses have lower contrast gain and greater signal-dependent variability than after earlier rescue. Information transmission improves above untreated levels but fails to normalize and can decline over follow-up. These ex vivo mouse measurements are distinct from human visual acuity or an AAV clinical endpoint.

Animal models

Conditional Cngb1 rescue mouse Mouse rescues Tamoxifen activates Cre-mediated removal of the blocking cassette to restore endogenous Cngb1 at one, two or three months. Earlier rescue restores output closer to wild type; late rescue retains lower gain and greater variability.

Show evidence (2 references)

PMID:38086857 SUPPORT DIRECT PRIMARY RESULT Model Organism

"Early and mid-treatment brought the response variability back toward that of WT"

Multielectrode recordings show stage-dependent recovery of retinal ganglion cell response fidelity after conditional Cngb1 rescue.

PMID:38086857 SUPPORT DIRECT PRIMARY RESULT Model Organism

"Late treatment also improved the information rate of the rod-mediated RGC signaling above baseline"

Late rescue retains measurable benefit without normalizing retinal output.

Impaired Olfactory Signal Transduction

Mechanism confidence: Provisional

CNGB1 encodes a signal-transduction subunit expressed in olfactory sensory neurons as well as rods. Olfactory testing in affected patients supports variable impairment consistent with an olfactory channel defect. The clinical studies do not demonstrate progressive olfactory-neuron death, and the single non-targeted MRI with nonvisible bulbs does not establish bulb agenesis.

Downstream

Hyposmia A shared olfactory CNG-channel defect is a proposed explanation for psychophysically measured smell loss; direct human neuronal channel measurements are lacking.

Anosmia A shared olfactory CNG-channel defect is a proposed explanation for psychophysically measured smell loss; direct human neuronal channel measurements are lacking.

Show evidence (2 references)

PMID:29800053 SUPPORT INDIRECT BACKGROUND Other

"a gene coding for a signal transduction channel subunit expressed in rod photoreceptors and olfactory sensory neurons."

Background establishes the shared expression context; this clinical study does not directly measure olfactory channel currents.

PMID:29800053 SUPPORT INDIRECT PRIMARY RESULT Human Clinical

"Olfactory testing revealed reduced or absent olfactory function"

Patient testing establishes impaired smell; attribution to defective olfactory channel signaling is mechanistic interpretation.

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Pathograph

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

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Phenotypes

Cardiovascular 1

Attenuation of retinal blood vessels HP:0007843

Show evidence (1 reference)

PMID:33465333 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"Funduscopic images showed widespread retinal degeneration with pigment clumping, optic disk pallor, arteriole attenuation, and a peri-foveal ring of hyper autofluorescence."

Directly documents retinal arteriole attenuation on fundus imaging in a CNGB1-RP cohort.

Eye 11

Nyctalopia VERY_FREQUENT HP:0000662

Show evidence (4 references)

PMID:28056120 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"The first clinical presentation was with nyctalopia in childhood with visual field loss documented later at a mean (SD) age of 33.2 (8.0) years."

Documents childhood-onset nyctalopia as the first clinical presentation in a dedicated CNGB1-RP clinical characterization series.

PMID:35743231 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"The presenting complaint was nyctalopia in 88% (21/24) with symptom onset in childhood for the majority."

The denominator is the 24 patients with recorded presenting symptoms, not all 33 participants.

PMID:33465333 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"Age of onset ranged from 4 to 49 years"

This independent 11-patient series reports variable onset, including adulthood; retrospective symptom histories may differ between cohorts.

+ 1 more reference

Rod-cone dystrophy VERY_FREQUENT HP:0000510

Show evidence (1 reference)

PMID:28056120 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"Electrophysiologic testing in 6 patients confirmed a rod-cone dystrophy phenotype."

Direct electrophysiological confirmation of the rod-cone dystrophy pattern in a dedicated clinical characterization series.

Undetectable dark-adapted electroretinogram HP:0030474

Show evidence (1 reference)

PMID:33465333 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"Electrophysiological testing in five patients showed an absence of the rod response. Cone responses ranged from normal to severely reduced."

Directly documents absent rod ERG responses in a CNGB1 cohort, with variable cone involvement.

Pigmentary retinopathy HP:0000580

Show evidence (1 reference)

PMID:28056120 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"Fundus examination revealed midperipheral retinal pigment epithelial atrophy and intraretinal pigment migration."

Direct fundoscopic documentation of retinal pigment epithelial atrophy and pigment migration in a CNGB1-RP cohort.

Constriction of peripheral visual field VERY_FREQUENT HP:0001133

Show evidence (2 references)

PMID:28056120 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"The first clinical presentation was with nyctalopia in childhood with visual field loss documented later at a mean (SD) age of 33.2 (8.0) years."

Documents visual field loss as a distinct, later-documented feature of the CNGB1-RP clinical course, with a mean age at documentation of 33.2 years.

url:https://discovery.ucl.ac.uk/id/eprint/1535961/1/Hull_CNGB1%20accepted%20version.pdf SUPPORT DIRECT PRIMARY RESULT Human Clinical

"it was detectable on formal kinetic perimetry in patient 9 at age 12 years."

The full manuscript distinguishes objective field loss from later symptomatic recognition.

Cystoid macular edema FREQUENT HP:0011505

Show evidence (1 reference)

PMID:35743231 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"Cystoid macular oedema was present in 19.7% (13/65) of eyes in 7 patients (21.2%)."

The longitudinal cohort reported edema in 21.2% of patients and 19.7% of eyes; these are distinct denominators.

Posterior subcapsular cataract FREQUENT HP:0007787

Show evidence (2 references)

PMID:35743231 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"Thirteen patients had undergone cataract surgery in at least one eye, with a mean age of first eye cataract surgery of 52.7 years"

Thirteen patients had undergone surgery; the mean surgical age was based on six with available age data, not all thirteen.

url:https://discovery.ucl.ac.uk/id/eprint/1535961/1/Hull_CNGB1%20accepted%20version.pdf SUPPORT DIRECT PRIMARY RESULT Human Clinical

"Six of 10 patients ... developed visually significant posterior subcapsular lens opacities in both eyes during follow-up"

The recovered CNGB1-specific manuscript establishes the posterior subcapsular subtype in six of ten patients; the 33-patient surgical count is not treated as a subtype-specific denominator.

Epiretinal membrane FREQUENT HP:0100014

Show evidence (1 reference)

PMID:35743231 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"Epiretinal membrane was present in 47.0% (31/65) of the eyes in 17 patients (51.5%) in at least one scan over the mean 4.5 year follow-up period."

This is cumulative detection during the reported follow-up; patient and eye denominators differ.

Optic disc pallor HP:0000543

Show evidence (1 reference)

PMID:33847019 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"All subjects presented a classic form of RP with waxy optic disc pallor, attenuated retinal vessels, and peripheral bone spicules at fundus examination"

The 34-patient series documents the funduscopic finding.

Color vision defect FREQUENT HP:0000551

Show evidence (1 reference)

PMID:33847019 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"Color vision was abnormal in at least one eye of 9/17 patients (52.94%)"

The denominator is those assessed, not all 34 participants.

Reduced visual acuity HP:0007663

Show evidence (1 reference)

PMID:33847019 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"Visual acuity ranged from no light perception to 20/20 Snellen"

Acuity varied widely in the clinical series; most patients retained useful central vision in at least one eye.

Head and Neck 2

Hyposmia HP:0004409

Show evidence (3 references)

PMID:29800053 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"Olfactory testing revealed reduced or absent olfactory function, with all except one patient scoring in the lowest quartile in relation to age-related norms."

Most tested patients ranked low relative to age-related norms, but this encompasses different absolute categories, including anosmia and borderline normosmia.

PMID:29800053 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"Mutations in CNGB1 may cause an autosomal recessive RP-olfactory dysfunction syndrome characterized by a slow progression of retinal degeneration and variable anosmia or hyposmia."

The study supports an association with olfactory dysfunction, with variable severity; it does not establish universal olfactory involvement or a stable longitudinal course.

url:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6136054/ SUPPORT DIRECT PRIMARY RESULT Human Clinical

"anosmia was diagnosed in 2 patients, hyposmia was diagnosed in 5 patients, and normosmia (borderline low) was diagnosed in 1 patient"

These counts concern eight Sniffin’ Sticks tests classified against the stated absolute reference group.

Anosmia HP:0000458

Show evidence (1 reference)

url:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6136054/ SUPPORT DIRECT PRIMARY RESULT Human Clinical

"anosmia was diagnosed in 2 patients, hyposmia was diagnosed in 5 patients, and normosmia (borderline low) was diagnosed in 1 patient"

Two of eight Sniffin’ Sticks tests met the study’s anosmia criterion. The full text additionally reports an anosmic-range T&T result in patient 9.

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Genetic Associations

CNGB1 (Causative)

Gene: CNGB1 hgnc:2151

Autosomal recessive

Show evidence (3 references)

PMID:20126465 SUPPORT DIRECT PRIMARY RESULT In Vitro

Exon trapping demonstrates exon-32 skipping for this splice-site allele; the result replaces the original last-28-residue truncation prediction. Tissue transcript fate and channel function were not directly measured.

PMID:33847019 SUPPORT DIRECT REVIEW SYNTHESIS Other

"According to the ACMG criteria, 59 variants were considered pathogenic or likely pathogenic and 25 variants were classified of uncertain significance"

Variant reclassification in the 2021 review distinguishes reported alleles from confirmed pathogenic or likely pathogenic variants.

url:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6136054/ SUPPORT DIRECT PRIMARY RESULT Human Clinical

"evaluating the 3 missense variants as variants of uncertain significance"

The 2018 study classified p.Arg737His, p.Arg762Cys and p.Asn986Ile as VUS under its stated criteria; this is a dated study classification, not a current independent reinterpretation.

💊

Medical Actions

AAV-Mediated CNGB1 Gene Augmentation Therapy

Action: gene therapy Ontology label: Gene Therapy NCIT:C15238

Platform: Gene therapy

AAV-mediated delivery of CNGB1 has restored rod function and preserved retinal structure in preclinical mouse and dog experiments. The 2023 translational study additionally tested a promoter/capsid reporter in primates; this was a rod-targeting experiment, not a demonstration of retinal rescue in diseased primates. Construct, species, treatment age and follow-up differ between studies. These experiments do not establish human efficacy or a universal treatment window. The 2021 AAV5 mouse dose-ranging study found the strongest benefit at the intermediate dose and no clear ERG benefit at the highest dose; retinal thinning was slowed rather than arrested. In the 2023 dog study, one treated eye developed inflammation and focal retinal/choroidal degeneration. Conditional endogenous rescue in a separate mouse line shows incomplete recovery after advanced rod loss, without defining a human treatment cutoff.

Mechanism Target:

RESTORES Impaired Rod Light Responses — Restores rod light-response function in preclinical CNGB1-deficient animals; benefit depends on construct, dose and disease stage.

Show evidence (1 reference)

PMID:37056049 SUPPORT DIRECT PRIMARY RESULT Model Organism

"In conclusion, this study establishes the long-term efficacy of subretinal delivery of AAV5-RHO-CNGB1 to rescue the disease phenotype in a canine model of CNGB1-RP, confirming its suitability for future clinical development."

Directly supports gene augmentation as restoring the channel-loss mechanism this treatment targets.

INHIBITS Rod cGMP Accumulation — Reduces abnormal cGMP accumulation within effectively treated model retina.

Show evidence (1 reference)

PMID:37056049 SUPPORT DIRECT PRIMARY RESULT Model Organism

"A feature of lack of CNG channel function in rod outer segments is the abnormal accumulation of cGMP. IHC showed that this was reversed within the treated retinal regions"

Show evidence (7 references)

PMID:22802073 SUPPORT DIRECT PRIMARY RESULT Model Organism

"this work provides a proof-of-concept for the treatment of rod channelopathy-associated RP by AAV-mediated gene replacement"

Establishes preclinical proof-of-concept for AAV-mediated CNGB1 gene replacement in the mouse model.

PMID:29202463 SUPPORT DIRECT PRIMARY RESULT Model Organism

"gene augmentation using adeno-associated virus vectors robustly sustained the rescue of rod function and preserved retinal structure in the dog model"

Sustained preclinical canine functional and structural benefit; human efficacy is not established by this experiment.

PMID:37056049 SUPPORT DIRECT PRIMARY RESULT Model Organism

"The promoter/capsid combination drives efficient expression of a reporter gene (AAV5-RHO-eGFP) exclusively in rod photoreceptors in primate, dog, and mouse following subretinal delivery."

Reporter expression demonstrates rod targeting across species, including healthy primates, not therapeutic efficacy or full therapeutic-vector safety in primates.

+ 4 more references

Genetic counseling

Action: genetic counseling Ontology label: Genetic Counseling NCIT:C15240

Platform: Other

Counseling should interpret the familial pathogenic/likely pathogenic alleles and their phase, discuss testing of relatives and reproductive options, and explain autosomal recessive recurrence. When both parents carry the causal alleles, each pregnancy has a 25% chance of an affected child. Reported VUS do not establish a molecular diagnosis.

Show evidence (2 references)

url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1417/pdf/Bookshelf_NBK1417.pdf SUPPORT DIRECT REVIEW SYNTHESIS Other

"At conception, each sib has a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier."

General autosomal recessive RP counseling, applicable when both parents carry the established familial causal alleles.

url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1417/pdf/Bookshelf_NBK1417.pdf SUPPORT DIRECT REVIEW SYNTHESIS Other

"Carrier testing for at-risk relatives requires prior identification of the RP- related pathogenic variants in the family."

Family testing depends on the established molecular cause, rather than treating an uncertain variant as diagnostic.

Low-vision rehabilitation

Action: Low-vision rehabilitation Ontology label: Rehabilitation NCIT:C15315

Platform: Other

Low-vision aids and individualized mobility, vocational and independent-living support address visual disability. This is general RP supportive care and does not restore the CNGB1 channel.

Show evidence (2 references)

url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1417/pdf/Bookshelf_NBK1417.pdf SUPPORT DIRECT REVIEW SYNTHESIS Other

"Low vision aids such as magnifiers and closed circuit television may provide useful reading vision for individuals with reduced central acuity and constricted visual fields."

General RP guidance supports functional aids for central-acuity and field limitations.

url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1417/pdf/Bookshelf_NBK1417.pdf SUPPORT DIRECT REVIEW SYNTHESIS Other

"services include vocational training, mobility training, and skills for independent living."

General RP guidance supports rehabilitation services.

Carbonic anhydrase inhibition for cystoid macular edema

Action: Pharmacotherapy NCIT:C15986

Agent: acetazolamide CHEBI:27690 dorzolamide CHEBI:4702

Platform: Small molecule

Oral acetazolamide or topical dorzolamide may be considered by the treating ophthalmologist for RP-associated cystoid macular edema; response is variable and rebound can occur. This is complication-directed general RP care, not proven modification of CNGB1 retinal degeneration.

Show evidence (1 reference)

url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1417/pdf/Bookshelf_NBK1417.pdf SUPPORT DIRECT REVIEW SYNTHESIS Other

"Some therapeutic success has been reported with both systemic and topical carbonic anhydrase inhibitors ... however, rebound edema can occur with continued use"

General RP treatment synthesis; it is not a CNGB1-specific randomized trial.

Cataract surgery when visually significant

Action: Cataract Surgery NCIT:C157809

Platform: Surgery

Assess whether cataract contributes materially to visual impairment before considering extraction. Macular disease can limit visual improvement; RP increases the risk of postoperative inflammation and cystoid macular edema. Surgery treats the lens opacity, not the underlying channelopathy.

Show evidence (2 references)

url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1417/pdf/Bookshelf_NBK1417.pdf SUPPORT DIRECT REVIEW SYNTHESIS Other

"Individuals with retinitis pigmentosa are at a greater-than-average risk for postoperative inflammation and induced CME."

General RP perioperative considerations, not a CNGB1-specific comparative surgical trial.

url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1417/pdf/Bookshelf_NBK1417.pdf SUPPORT DIRECT REVIEW SYNTHESIS Other

"In the presence of macular disease, extraction of lenses when cataracts are in the early stage may not always improve the quality of vision"

General RP guidance emphasizes identifying the cause of visual impairment before intervention.

🔬

Diagnosis

Molecular genetic testing

An inherited-retinal-disease panel or genomic test can identify candidate CNGB1 variants. A molecular diagnosis requires biallelic pathogenic or likely pathogenic variants, with phase, segregation and copy-number assessment where needed. VUS findings or in-silico predictions alone do not establish the diagnosis. Apparent homozygosity may require evaluation for a deletion on the other allele.

diagnostic procedure NCIT:C18020

Results: Biallelic pathogenic or likely pathogenic CNGB1 variants consistent with recessive inheritance support molecular confirmation; uncertain variants require further assessment.

Show evidence (2 references)

PMID:28056120 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"10 patients from 9 families underwent full ophthalmologic examination. Molecular investigations included whole-exome analysis in 6 patients."

The clinical series used exome analysis in six patients. This documents a testing method, not a claim that every reported variant had definitive pathogenic classification.

url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1417/pdf/Bookshelf_NBK1417.pdf SUPPORT DIRECT REVIEW SYNTHESIS Other

"Methods used in a panel may include sequence analysis, deletion/duplication analysis, and/or other non- sequencing-based tests."

General RP molecular evaluation includes methods beyond coding SNV detection; coverage and diagnostic sensitivity vary between laboratories.

Full-field electroretinography

Dark- and light-adapted full-field ERG characterizes the severity of rod and cone dysfunction and typically shows non-recordable or severely attenuated scotopic responses even when visual acuity remains good.

diagnostic procedure NCIT:C18020

Results: Scotopic (rod) responses are absent or severely attenuated; photopic (cone) responses range from normal to severely reduced depending on patient age and disease stage.

Show evidence (1 reference)

PMID:33465333 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"Electrophysiological testing in five patients showed an absence of the rod response. Cone responses ranged from normal to severely reduced."

Directly quantifies the electrophysiological diagnostic pattern.

Multimodal retinal imaging

SD-OCT and fundus autofluorescence characterize preserved and diseased retinal regions. Ellipsoid-zone length and hyperautofluorescent ring area are candidate progression metrics for patients in whom those features can be measured. Their sensitivity, reproducibility and relationship to treatment benefit require prospective validation; neither is an established surrogate endpoint.

diagnostic procedure NCIT:C18020

Results: In the 33-patient retrospective cohort, EZ length was measurable in 23 patients and constricted by a mean 178 ± 161 micrometers per year. Eight of 14 patients in a two-year simulation changed by more than 250 micrometers, the cited approximate interobserver variability. Hyperautofluorescent ring area was measurable in 17 patients; some had no ring and others had rings beyond the image. These selection limits prevent transferring the rates or sensitivity to every patient or disease stage.

Show evidence (1 reference)

PMID:35743231 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"The ellipsoid zone (EZ) length was measurable in at least one eye of 23 patients"

Establishes ellipsoid zone length as a measured structural biomarker used as a candidate imaging endpoint.

Ophthalmic surveillance

General RP guidance recommends annual dilated examination and perimetry, with closer review for active complications such as cystoid macular edema. OCT/FAF and functional assessments can follow CNGB1 disease progression, with interpretation adapted to the measurable retinal area and macular comorbidity.

Eye Examination NCIT:C38060

Show evidence (1 reference)

url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1417/pdf/Bookshelf_NBK1417.pdf SUPPORT DIRECT REVIEW SYNTHESIS Other

"and a full ophthalmoscopic examination with dilation are performed on an annual basis, with more frequent follow up for active complications such as cystoid macular edema."

General RP surveillance guidance applied to CNGB1-related disease; frequency is individualized for active complications.

📈

Progression

Variable onset of rod dysfunction

Age: Childhood to adulthood

Night blindness commonly begins in childhood, but reported onset varied from ages 4 to 49 in one series. Retrospective symptom recognition, age at diagnosis and first measured field loss are different observations.

Show evidence (2 references)

PMID:28056120 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"The first clinical presentation was with nyctalopia in childhood with visual field loss documented later at a mean (SD) age of 33.2 (8.0) years."

Establishes the childhood-onset timing of the presenting symptom.

PMID:33465333 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"Age of onset ranged from 4 to 49 years"

Reported onset includes adults in this series.

Prolonged preservation of visual acuity and macular structure

Age: Childhood through the third and fourth decades

Several cohorts document prolonged preservation of central acuity and foveal structure, but other patients have substantial loss. Preservation suggests remaining therapeutic substrate; it does not establish individual treatment eligibility or guarantee benefit.

Show evidence (1 reference)

PMID:28056120 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"All patients had preserved best-corrected visual acuity into adulthood, with a mean of 0.1 logMAR (Snellen equivalent, 20/25) in each eye"

Directly quantifies preserved visual acuity into adulthood in a dedicated CNGB1-RP clinical series.

Slow progressive structural decline in adulthood

Age: Adulthood, over multi-year follow-up

Retrospective longitudinal imaging demonstrates progression in measurable subsets. The 2022 cohort had a mean follow-up of 4.5 years, but four patients had no follow-up visit. Acuity changes can be confounded by lens or macular disease. Prospective natural-history data are needed to define reliable functional and structural outcomes.

Show evidence (1 reference)

PMID:35743231 SUPPORT DIRECT PRIMARY RESULT Human Clinical

"The results support previous findings of CNGB1-related RP being a slowly progressive disease with patients maintaining visual acuity."

States the natural-history cohort's overall conclusion of slow, measurable progression with maintained visual acuity.

🔬

Clinical Trials

NCT04639635 NOT_APPLICABLE SUSPENDED

Prospective observational natural-history study of CNGB1 retinitis pigmentosa and allied disorders intended to develop outcome measures. It administers no gene-therapy intervention. The registry update posted 13 April 2026 lists suspension because IRB renewal lapsed; status verified from the registry on 2 October 2026.

Show evidence (2 references)

clinicaltrials:NCT04639635 SUPPORT DIRECT PRIMARY RESULT Other

"our objective is to better understand the disease process of CNGB1-RP and other allied inherited disorders so that we can develop clinical tests to measure the outcomes of treatment."

Registry summary describes natural-history and outcome-development objectives, not demonstrated therapeutic benefit.

url:https://clinicaltrials.gov/api/v2/studies/NCT04639635 SUPPORT DIRECT PRIMARY RESULT Other

""officialTitle":"Study of CNGB1 Retinitis Pigmentosa and Allied Hereditary Disorders" ... "overallStatus":"SUSPENDED","whyStopped":"IRB renewal lapsed""

Current registry metadata gives the status and stated reason; checked 2 October 2026.

🐁

Animal Models

Cngb1-X26 knockout mouse

Exon-26 knockout abolishing the full-length channel subunit while preserving soluble GARP isoforms. It models channel deficiency, not all human alleles or GARP-null phenotypes.

Species

Mouse

Genotype

Cngb1-/- (exon 26 deletion; Cngb1-X26)

Publication

PMID:15634774

Pathograph links

Impaired Rod Light Responses partially recapitulates fidelity: moderate observes: cellular The X26 knockout has absent rod-mediated ERGs and predominantly unresponsive isolated rods.

Limitations: Mice lack a macula; the knockout is not representative of every missense or GARP-region allele.

Readouts

Rod-mediated ERG

Direction: DECREASED

Interpretation: Rod-system functional impairment, not a direct assay of apoptosis.

Show evidence (1 reference)

PMID:15634774 SUPPORT DIRECT PRIMARY RESULT Model Organism

"the vast majority of isolated rod photoreceptors in mice lacking CNGB1 (CNGB1-/-) failed to respond to light. In electroretinograms (ERGs), CNGB1-/- mice showed no rod-mediated responses."

Most isolated knockout rods were unresponsive; the population ERG lacked rod-mediated responses. Neither observation proves that every rod is silent.

Show evidence (1 reference)

PMID:15634774 SUPPORT DIRECT PRIMARY RESULT Model Organism

"the vast majority of isolated rod photoreceptors in mice lacking CNGB1 (CNGB1-/-) failed to respond to light. In electroretinograms (ERGs), CNGB1-/- mice showed no rod-mediated responses."

Most isolated knockout rods were unresponsive; the population ERG lacked rod-mediated responses. Neither observation proves that every rod is silent.

Progressive Rod Photoreceptor Loss partially recapitulates fidelity: moderate observes: cellular Progressive apoptotic rod loss occurs in the X26 mouse.

Limitations: Mouse histology establishes apoptosis in this model; human structural imaging does not establish a shared death-effector pathway.

Show evidence (1 reference)

PMID:15634774 SUPPORT DIRECT PRIMARY RESULT Model Organism

"The rods also showed a slow-progressing degeneration caused by apoptotic death and concurred by retinal gliosis."

The X26 knockout shows progressive apoptotic rod loss and associated gliosis. This does not establish the same death pathway in every human allele.

Impaired Rod Light Responses rescues fidelity: moderate observes: cellular Subretinal AAV8-mediated delivery of CNGB1a to Cngb1-/- mice restores full-length CNGB1a expression, rescues degraded CNGA1 to normal levels, and reconstitutes functional CNG channel complexes in rod outer segments.

Limitations: AAV rescue in mice; treatment at two weeks and rodent retinal anatomy limit inference about older human patients.

Readouts

Scotopic ERG rod-driven light response

Direction: RESTORED

Interpretation: Restoration of rod-driven ERG light responses after gene therapy confirms reconstitution of a functional rod CNG channel.

Show evidence (1 reference)

PMID:22802073 SUPPORT DIRECT PRIMARY RESULT Model Organism

"In the electroretinographic analysis, we also observed restoration of rod-driven light responses."

Directly reports restored rod-driven ERG responses following AAV gene therapy in the mouse model.

Show evidence (1 reference)

PMID:22802073 SUPPORT DIRECT PRIMARY RESULT Model Organism

"We found that the treatment not only led to expression of full-length CNGB1a, but also restored normal levels of the previously degraded CNGA1 subunit of the rod CNG channel."

Establishes that gene augmentation not only supplies CNGB1a but also rescues the secondary CNGA1 degradation, restoring channel assembly.

Impaired Rod Light Responses rescues fidelity: moderate observes: cellular AAV5-hRHO194-human CNGB1 given at four weeks improves rod ERGs and dim-light behavior most strongly at the intermediate dose. The highest dose had no clear ERG benefit, and structural thinning was slowed rather than stopped.

Limitations: Human/mouse hybrid channels, ectopic human CNGB1 localization and a young knockout retina complicate dose translation. Doses are preclinical experimental values, not human recommendations.

Show evidence (2 references)

PMID:34376057 SUPPORT DIRECT PRIMARY RESULT Model Organism

"increasing doses of rAAV5.hCNGB1 were delivered through single subretinal injection in 4-week-old Cngb1"

The 2021 study tests a human CNGB1 AAV5 construct in young knockout mice, separately from the 2012 species-matched proof of concept.

+ 1 more reference

Show evidence (1 reference)

PMID:15634774 SUPPORT DIRECT PRIMARY RESULT Model Organism

"To investigate the importance of the CNGB subunits in vivo, we deleted the CNGB1 gene in mice."

Establishes this as the original targeted-knockout mouse model of CNGB1-related retinopathy.

CNGB1-mutant dog (naturally occurring, Papillon/Phalene breeds)

Naturally occurring Papillon/Phalène channel-deficiency model. The 2013 discovery paper predicted NMD without affected retinal tissue. The 2018 follow-up demonstrated exon skipping, approximately 40% residual transcript and inner-segment truncated protein; it is not a complete transcript-null model.

Species

Dog

Genotype

Biallelic complex CNGB1 indel (c.2387delA;2389_2390insAGCTAC in the later transcript annotation), causing exon-26 skipping

Publication

PMID:24015210

Pathograph links

Progressive Rod Photoreceptor Loss partially recapitulates fidelity: moderate observes: cellular Progressive rod loss and later cone decline provide a large-eye model of the rod-first disease course; the cited dog histology does not itself establish apoptosis.

Limitations: Dogs have an area centralis but differ from humans in early central outer nuclear layer thinning and autofluorescence patterns. One breed-associated allele does not model all human variants.

Show evidence (2 references)

PMID:29202463 SUPPORT DIRECT PRIMARY RESULT Model Organism

"Cngb1-/- dogs have slow photoreceptor loss and relative preservation of cones."

Reports the canine result alone: photoreceptor loss is slow and cones are relatively spared, the rod-first pattern of the human disease.

+ 1 more reference

Impaired Rod Light Responses rescues fidelity: moderate observes: cellular AAV5-hGRK1-canine CNGB1 in the 2018 proof-of-concept study yielded ERG rescue through 18 months in the longest ERG follow-up; 23 months referred to protein expression/structural follow-up. The distinct 2023 AAV5-RHO-human CNGB1 study treated ten three-month-old dogs and assessed functional rescue through 12 months in animals retained that long.

Readouts

Scotopic ERG b-wave and vision-guided behavior

Direction: RESTORED

Interpretation: Sustained improvement in rod-mediated ERG amplitude and scotopic vision-guided behavior over long-term follow-up confirms durable functional rescue.

Show evidence (1 reference)

PMID:29202463 SUPPORT DIRECT PRIMARY RESULT Model Organism

"gene augmentation using adeno-associated virus vectors robustly sustained the rescue of rod function and preserved retinal structure in the dog model"

Confirms sustained functional and structural rescue following gene augmentation in the canine model.

Show evidence (1 reference)

PMID:37056049 SUPPORT DIRECT PRIMARY RESULT Model Organism

"The therapeutic vector (AAV5-RHO-CNGB1) delivered to the subretinal space of CNGB1 mutant dogs restores rod-mediated retinal function (electroretinographic responses and vision)"

Establishes the canine model as the pharmacodynamic efficacy platform for a clinically translatable AAV construct.

Rod cGMP Accumulation rescues fidelity: moderate observes: molecular Abnormal cGMP immunoreactivity is reduced within human-CNGB1-treated canine retina.

Limitations: Immunoreactivity is not a direct ionic-current or intracellular-calcium measurement.

Readouts

Photoreceptor outer segment cGMP accumulation

Direction: RESTORED

Interpretation: Reduced abnormal cGMP staining in treated regions is an indirect pharmacodynamic marker of restored channel function.

Show evidence (1 reference)

PMID:37056049 SUPPORT DIRECT PRIMARY RESULT Model Organism

"A feature of lack of CNG channel function in rod outer segments is the abnormal accumulation of cGMP. IHC showed that this was reversed within the treated retinal regions"

Show evidence (1 reference)

PMID:37056049 SUPPORT DIRECT PRIMARY RESULT Model Organism

"A feature of lack of CNG channel function in rod outer segments is the abnormal accumulation of cGMP. IHC showed that this was reversed within the treated retinal regions"

Show evidence (2 references)

PMID:24015210 SUPPORT DIRECT PRIMARY RESULT Model Organism

"This mutation causes a frameshift and premature stop codon leading to probable nonsense mediated decay (NMD) of the CNGB1 mRNA."

Establishes this as a naturally occurring, large-eye CNGB1 loss-of-function animal model of the disease.

PMID:29202463 SUPPORT DIRECT PRIMARY RESULT Model Organism

"The truncated product partly escaped nonsense- mediated decay, leading to a relative expression level approximately 40% of that of WT tran- script levels in the controls"

Retinal RT-PCR and expression studies in the later paper revise the original NMD-only prediction; approximately 40% residual transcript and a truncated inner-segment protein were reported.

Conditional Cngb1 rescue mouse

Tamoxifen-inducible restoration of endogenous Cngb1 used to isolate the effect of disease stage on rescue; distinct from X26 knockout and viral augmentation.

Species

Mouse

Genotype

Cngb1neo/neo; UBC-cre/ERT2 (loxP-flanked neomycin cassette in intron 19)

Publication

PMID:38086857

Pathograph links

Impaired Retinal Ganglion Cell Signaling rescues fidelity: moderate observes: cellular Tamoxifen activates Cre-mediated removal of the blocking cassette to restore endogenous Cngb1 at one, two or three months. Earlier rescue restores output closer to wild type; late rescue retains lower gain and greater variability.

Limitations: Conditional endogenous restoration is an artificial best-case experiment, not AAV delivery. Approximate 25%, 50% and 70% rod-loss groups are model-specific and are not human eligibility thresholds.

Readouts

Ganglion-cell spike-response variability and information rate

Interpretation: Late rescue improves signaling above untreated levels but fails to normalize fidelity.

Show evidence (1 reference)

PMID:38086857 SUPPORT DIRECT PRIMARY RESULT Model Organism

"late treatment failed to reduce the signal-dependent noise"

Multielectrode recordings distinguish incomplete functional rescue from structural photoreceptor survival.

Show evidence (1 reference)

PMID:38086857 SUPPORT DIRECT PRIMARY RESULT Model Organism

"Early and mid-treatment brought the response variability back toward that of WT"

Multielectrode recordings show stage-dependent recovery of retinal ganglion cell response fidelity after conditional Cngb1 rescue.

Reactive Retinal Gliosis partially recapitulates fidelity: moderate observes: cellular GFAP labeling persists after late rescue.

Limitations: Qualitative GFAP staining; no quantitative causal test of inflammation.

Show evidence (1 reference)

PMID:38086857 SUPPORT DIRECT PRIMARY RESULT Model Organism

"we found that GFAP was present in both untreated and late-treated retinas at 7 M"

Persistent GFAP labeling after late endogenous rescue supports a sustained glial stress response in this conditional mouse model; it does not establish a causal inflammatory mediator.

Photoreceptor Synaptic Ribbon Loss partially recapitulates fidelity: moderate observes: cellular Late rescue leaves fewer intact CtBP2-labeled ribbon structures.

Limitations: Anatomical association with advanced degeneration; not a selective synapse-restoration experiment.

Show evidence (1 reference)

PMID:38086857 SUPPORT DIRECT PRIMARY RESULT Model Organism

"Following late treatment, CtBP2 horseshoe structures were substantially reduced"

CtBP2 immunolabeling showed loss of normal photoreceptor synaptic ribbon structures after late conditional rescue.

Show evidence (1 reference)

PMID:38086857 SUPPORT DIRECT PRIMARY RESULT Model Organism

"By delivering tamoxifen, activated cre removes the neomycin insert to enable endogenous CNGB1 expression across all rods"

Defines the conditional endogenous rescue system.

{ }

Source YAML

click to show

name: CNGB1-Related Retinopathy
creation_date: "2026-08-25T00:00:00Z"
category: Mendelian
description: >-
  CNGB1-related retinopathy is an autosomal recessive rod-cone dystrophy, historically retinitis pigmentosa 45. Biallelic pathogenic variants affect the beta subunit of the rod cyclic nucleotide-gated channel. Rod dysfunction commonly precedes extensive photoreceptor loss. Night blindness often begins in childhood, but reported symptom onset and disease severity vary, and one series reported onset between ages 4 and 49 years. Central visual acuity and foveal structure may remain useful into adulthood, while some patients develop severe visual loss. These observations suggest an opportunity for intervention but do not establish a universal treatment window or a human gene-therapy benefit.

  CNGB1 also encodes an olfactory-channel isoform. Formal testing has identified hyposmia or anosmia in selected patients, many of whom had not noticed impaired smell. Neither olfactory penetrance nor a reliable variant-specific retinal or olfactory prognosis has been established. Cystoid macular edema, epiretinal membranes and cataract can accompany the retinal disease and affect clinical measurements. Animal gene-augmentation studies provide preclinical evidence that restoring CNGB1 can improve rod function and preserve retinal structure.
disease_term:
  preferred_term: CNGB1-related retinopathy
  term:
    id: MONDO:0800403
    label: CNGB1-related retinopathy
synonyms:
- Retinitis pigmentosa 45
- RP45
- CNGB1-related autosomal recessive retinitis pigmentosa
- CNGB1-associated retinitis pigmentosa
parents:
- Ophthalmological Disease
- Retinal Dystrophy
- Inherited retinal dystrophy
notes: >-
  CNGB1 is distinct from CNGA1-associated rod-cone dystrophy and CNGA3/CNGB3-associated achromatopsia. Findings from those genes must not be treated as direct CNGB1 variant evidence. Primary CNGB1 cohorts supply the disease-specific phenotype baseline; the general Nonsyndromic Retinitis Pigmentosa Overview can support broader diagnostic and management guidance.
inheritance:
- name: Autosomal recessive
  inheritance_term:
    preferred_term: Autosomal recessive inheritance
    term:
      id: HP:0000007
      label: Autosomal recessive inheritance
  description: >-
    CNGB1-related retinopathy is caused by biallelic (homozygous or compound
    heterozygous) loss-of-function variants in CNGB1.
  evidence:
  - reference: PMID:11379879
    reference_title: Segregation of a mutation in CNGB1 encoding the beta-subunit of the rod cGMP-gated channel in a family with autosomal recessive retinitis pigmentosa.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "By performing full genome linkage analysis in a consanguineous French family affected with severe autosomal recessive RP, we have excluded linkage to known loci involved in RP and mapped a novel locus to chromosome 16q13-q21"
    explanation: >-
      This original gene-discovery paper establishes autosomal recessive
      inheritance for CNGB1-related retinitis pigmentosa via linkage in a
      consanguineous family.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
pathophysiology:
- name: Biallelic CNGB1 Dysfunction
  description: Biallelic pathogenic CNGB1 variants impair the rod channel beta subunit. Alleles include truncating, splice-site and missense changes, with effects that can differ in protein abundance, localization or gating. CNGB1a belongs to the rod CNGA1/CNGB1 channel; CNGB1b is an olfactory isoform. Not every reported variant is pathogenic and not every pathogenic allele eliminates the protein.
  biological_scale: MOLECULAR
  mechanism_confidence: ESTABLISHED
  evidence:
  - reference: PMID:33847019
    reference_title: 'CNGB1-related rod-cone dystrophy: A mutation review and update.'
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
    snippet: According to the ACMG criteria, 59 variants were considered pathogenic or likely pathogenic and 25 variants were classified of uncertain significance
    explanation: Variant reclassification in the 2021 review distinguishes reported alleles from confirmed pathogenic or likely pathogenic variants.
  - reference: PMID:20126465
    reference_title: "The retinitis pigmentosa mutation c.3444+1G>A in CNGB1 results in skipping of exon 32."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Here, we investigated the splicing of c.3444+1G>A by exon trapping experiments and could demonstrate that instead of the proposed truncation of the last 28 aa this mutation leads to replacement of the last 170 aa of CNGB1a by 68 unrelated amino acids."
    explanation: >-
      Exon trapping in HEK293T cells demonstrates exon-32 skipping for c.3444+1G>A, replacing the last 170 residues with 68 unrelated residues. This is a variant-specific assay, not patient-rod transcript analysis.

    quote_role: PRIMARY_RESULT
    directness: DIRECT
  role: trigger
  gene:
    preferred_term: CNGB1
    term:
      id: hgnc:2151
      label: CNGB1
    modifier: DECREASED
  conforms_to: phototransduction_cascade_dysfunction#Phototransduction Cascade Component Defect
  downstream:
  - target: Reduced Rod Outer-Segment CNG Channel Abundance
    description: Loss of CNGB1 in mouse and dog models depletes outer-segment partner CNGA1; rescue restores its localization. Allele-specific channel-gating defects need not share this abundance mechanism.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Impaired Olfactory Signal Transduction
    description: CNGB1 also encodes an olfactory channel subunit; impaired olfactory signaling is a plausible basis for the variable smell dysfunction observed in human cohorts.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Variant-Specific CNGB1 Protein Instability
    description: A specific splice-site allele produces an unstable mutant protein in a heterologous assay; the effect is not assigned to all CNGB1 alleles.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
- name: Variant-Specific CNGB1 Protein Instability
  description: For c.3444+1G>A, exon-32 skipping replaces the terminal 170 amino acids with 68 unrelated residues. The engineered full-length mutant showed reduced abundance in HEK293T cells, reversible with proteasome inhibitors. This allele-specific instability may contribute to channel deficiency; NMD and altered targeting in patient rods were proposed rather than measured.
  biological_scale: MOLECULAR
  mechanism_confidence: PROVISIONAL
  evidence:
  - reference: PMID:20126465
    reference_title: The retinitis pigmentosa mutation c.3444+1G>A in CNGB1 results in skipping of exon 32.
    supports: SUPPORT
    evidence_source: IN_VITRO
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: When expressed in a heterologous expression system the corresponding mutant full-length CNGB1a subunit was more susceptible to proteosomal degradation compared to the wild-type counterpart.
    explanation: The exon-32-skipped mutant is less stable in a heterologous expression system; the full-text experiment used HEK293T cells coexpressing CNGA1. This does not establish NMD or channel trafficking in patient rods.
  - reference: PMID:20126465
    reference_title: The retinitis pigmentosa mutation c.3444+1G>A in CNGB1 results in skipping of exon 32.
    supports: SUPPORT
    evidence_source: IN_VITRO
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: Since this difference in expression could be reversed by the addition of proteasome inhibitors, we concluded that the mutant protein is partially degraded by the proteasome
    explanation: Proteasome inhibitor rescue supports a degradation contribution in the heterologous cell experiment.
  downstream:
  - target: Reduced Rod Outer-Segment CNG Channel Abundance
    description: Instability could reduce channel availability in rods; that tissue-level consequence was not directly measured in the HEK293T assay.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
- name: Reduced Rod Outer-Segment CNG Channel Abundance
  description: In CNGB1-deficient mouse rods, outer-segment CNGA1 is markedly depleted. CNGB1 augmentation restores CNGA1 abundance and outer-segment localization in mice and dogs. These findings support defective channel assembly/targeting or stability without assigning the same lesion to every human missense allele.
  biological_scale: MOLECULAR
  mechanism_confidence: PROVISIONAL
  evidence:
  - reference: PMID:15634774
    reference_title: Impaired channel targeting and retinal degeneration in mice lacking the cyclic nucleotide-gated channel subunit CNGB1.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: In the absence of CNGB1, only trace amounts of the CNGA1 subunit were found on the rod outer segment.
    explanation: CNGB1-deficient mouse rods have markedly depleted outer-segment CNGA1.
  - reference: PMID:37056049
    reference_title: Development of a translatable gene augmentation therapy for CNGB1-retinitis pigmentosa.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: In the treated region, but not the untreated, CNGA1 protein was detectable in rod outer segments
    explanation: Human CNGB1 augmentation restores canine partner-subunit localization within the treated region.
  cell_types:
  - preferred_term: retinal rod cell
    term:
      id: CL:0000604
      label: retinal rod cell
  cellular_components:
  - preferred_term: photoreceptor outer segment
    term:
      id: GO:0001750
      label: photoreceptor outer segment
  downstream:
  - target: Impaired Rod Light Responses
    description: Loss of normal outer-segment channel abundance compromises rod phototransduction.
    causal_link_type: DIRECT
- name: Impaired Rod Light Responses
  description: Rod CNG-channel deficiency markedly reduces light responses before extensive cell loss in knockout mice and affected dogs. Residual isolated-rod responses occur, and human ERG responses range from attenuated to undetectable. Severe functional impairment is therefore distinct from physical disappearance of rods.
  biological_scale: CELLULAR
  mechanism_confidence: ESTABLISHED
  evidence:
  - reference: PMID:15634774
    reference_title: Impaired channel targeting and retinal degeneration in mice lacking the cyclic nucleotide-gated channel subunit CNGB1.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: the vast majority of isolated rod photoreceptors in mice lacking CNGB1 (CNGB1-/-) failed to respond to light. In electroretinograms (ERGs), CNGB1-/- mice showed no rod-mediated responses.
    explanation: Most isolated knockout rods were unresponsive; the population ERG lacked rod-mediated responses. Neither observation proves that every rod is silent.
  - reference: PMID:33465333
    reference_title: Variable expressivity in patients with autosomal recessive retinitis pigmentosa associated with the gene CNGB1.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: Electrophysiological testing in five patients showed an absence of the rod response. Cone responses ranged from normal to severely reduced.
    explanation: Human ERGs establish rod-system impairment without directly measuring channel current.
  cell_types:
  - preferred_term: retinal rod cell
    term:
      id: CL:0000604
      label: retinal rod cell
  biological_processes:
  - preferred_term: phototransduction
    term:
      id: GO:0007602
      label: phototransduction
    modifier: DECREASED
  conforms_to: phototransduction_cascade_dysfunction#Failure of Photoreceptor Light-Response Generation or Timely Recovery
  downstream:
  - target: Rod cGMP Accumulation
    description: Channel-deficient mouse and dog rods accumulate cGMP; restoring CNGB1 reduces staining. Reduced calcium-dependent feedback on guanylate cyclase is a mechanistic interpretation, not a calcium measurement in these rescue studies.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Progressive Rod Photoreceptor Loss
    description: Rod dysfunction precedes progressive rod loss in CNGB1-deficient models; the critical intermediates connecting channel loss to death are incompletely resolved.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Nyctalopia
    description: Reduced rod-mediated sensitivity impairs vision under dim illumination.
    causal_link_type: DIRECT
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1417/pdf/Bookshelf_NBK1417.pdf
      reference_title: https://www.ncbi.nlm.nih.gov/sites/books/NBK1417/pdf/Bookshelf_NBK1417.pdf
      supports: SUPPORT
      evidence_source: OTHER
      quote_role: REVIEW_SYNTHESIS
      directness: DIRECT
      snippet: In RP , loss of rod function predominates early in the clinical course. The initial symptom of RP is usually defective dark adaptation
      explanation: General RP physiology connects early rod dysfunction with night blindness; disease-specific cohorts establish the CNGB1 manifestation.
- name: Rod cGMP Accumulation
  description: Abnormal cGMP immunoreactivity occurs in inner and outer segments of CNGB1-deficient mouse and dog photoreceptors and decreases in successfully treated retinal regions. Loss of calcium entry and its negative feedback on guanylate cyclase is proposed to explain accumulation. These observations do not establish calcium overload or directly identify the death-effector pathway.
  biological_scale: MOLECULAR
  mechanism_confidence: PROVISIONAL
  evidence:
  - reference: PMID:37056049
    reference_title: Development of a translatable gene augmentation therapy for CNGB1-retinitis pigmentosa.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: A feature of lack of CNG channel function in rod outer segments is the abnormal accumulation of cGMP. IHC showed that this was reversed within the treated retinal regions
    explanation: In the cGMP-accumulation results section, immunohistochemistry showed reversal of abnormal cGMP staining in treated dog retina, with staining retained outside the treated regions. This is not a direct channel-current measurement.
  cell_types:
  - preferred_term: retinal rod cell
    term:
      id: CL:0000604
      label: retinal rod cell
- name: Progressive Rod Photoreceptor Loss
  description: Rod photoreceptors are progressively lost following early functional impairment. Apoptotic death was demonstrated in the X26 mouse; human imaging documents structural decline without identifying an identical death program for every allele. Disease tempo differs among models and patients.
  biological_scale: CELLULAR
  mechanism_confidence: ESTABLISHED
  evidence:
  - reference: PMID:15634774
    reference_title: Impaired channel targeting and retinal degeneration in mice lacking the cyclic nucleotide-gated channel subunit CNGB1.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: The rods also showed a slow-progressing degeneration caused by apoptotic death and concurred by retinal gliosis.
    explanation: The X26 knockout shows progressive apoptotic rod loss and associated gliosis. This does not establish the same death pathway in every human allele.
  - reference: PMID:35743231
    reference_title: "The Natural History of CNGB1-Related Retinopathy: A Longitudinal Phenotypic Analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The results support previous findings of CNGB1-related RP being a slowly progressive disease with patients maintaining visual acuity."
    explanation: >-
      States the natural-history cohort's overall conclusion of slow,
      measurable progression with maintained visual acuity.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  cell_types:
  - preferred_term: retinal rod cell
    term:
      id: CL:0000604
      label: retinal rod cell
  downstream:
  - target: Secondary Cone Dysfunction and Degeneration
    description: Cone dysfunction and loss occur later than rod loss in mouse and dog models; the non-cell-autonomous intermediates remain unresolved.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Reactive Retinal Gliosis
    description: Progressive retinal degeneration is accompanied by reactive glial labeling in mouse models.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Photoreceptor Synaptic Ribbon Loss
    description: Advanced degeneration in the conditional mouse is associated with loss of photoreceptor synaptic ribbon structures.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Constriction of peripheral visual field
    description: Progressive peripheral photoreceptor degeneration contributes to field constriction; symptom recognition can lag objective field loss.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:28056120
      reference_title: Clinical Characterization of CNGB1-Related Autosomal Recessive Retinitis Pigmentosa.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "The first clinical presentation was with nyctalopia in childhood with visual field loss documented later at a mean (SD) age of 33.2 (8.0) years."
      explanation: >-
        The clinical course includes later recognized field constriction; attributing it to progressive peripheral photoreceptor loss is a mechanistic interpretation, not an experimental causal test.
      quote_role: PRIMARY_RESULT
      directness: INDIRECT
  - target: Pigmentary retinopathy
    description: Photoreceptor degeneration is associated with progressive retinal pigment redistribution; this does not imply that rod apoptosis directly causes each pigment deposit.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1417/pdf/Bookshelf_NBK1417.pdf
      reference_title: https://www.ncbi.nlm.nih.gov/sites/books/NBK1417/pdf/Bookshelf_NBK1417.pdf
      supports: SUPPORT
      evidence_source: OTHER
      quote_role: REVIEW_SYNTHESIS
      directness: DIRECT
      snippet: As photoreceptor deterioration progresses, there is increasing loss of pigment from the pigment epithelium with intraretinal clumping of melanin
      explanation: General RP pathology links progressive photoreceptor deterioration with pigment migration/clumping; molecular intermediates are not identified.
- name: Secondary Cone Dysfunction and Degeneration
  description: Cone function and structure decline after the primary rod defect. Normal early cone ERGs followed by later degeneration in X26 mice, and preservation of cone responses after rod-directed rescue in dogs, support a secondary process. The molecular intermediates are unresolved. Central vision can remain useful for years, but severity and timing vary and macular complications also affect acuity.
  biological_scale: TISSUE
  mechanism_confidence: ESTABLISHED
  evidence:
  - reference: PMID:15634774
    reference_title: Impaired channel targeting and retinal degeneration in mice lacking the cyclic nucleotide-gated channel subunit CNGB1.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Cones were primarily unaffected and showed normal ERG responses up to 6 months, but they started to degenerate in later stages."
    explanation: >-
      Direct evidence in the mouse model that cone dysfunction and degeneration
      are delayed relative to rod loss.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: PMID:37056049
    reference_title: Development of a translatable gene augmentation therapy for CNGB1-retinitis pigmentosa.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: Taken together, this analysis of cone ERG responses provides evidence of the preservation of cone function when rod rescue is achieved by gene augmentation therapy.
    explanation: Cone ERG modeling supports secondary preservation following rod-directed rescue in dogs; it does not prove normal cone physiology or human benefit.
  cell_types:
  - preferred_term: retinal cone cell
    term:
      id: CL:0000573
      label: retinal cone cell
  conforms_to: photoreceptor_degeneration#Secondary Cone Degeneration and Outer Retinal Thinning
  downstream:
  - target: Color vision defect
    description: Cone-system dysfunction contributes to impaired color discrimination; the clinical test does not distinguish cone loss from all other causes of reduced color performance.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:33847019
      reference_title: 'CNGB1-related rod-cone dystrophy: A mutation review and update.'
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      quote_role: PRIMARY_RESULT
      directness: DIRECT
      snippet: Color vision was abnormal in at least one eye of 9/17 patients (52.94%)
      explanation: The denominator is those assessed, not all 34 participants.
- name: Reactive Retinal Gliosis
  description: Reactive Müller-cell gliosis accompanies CNGB1-deficient mouse retinal degeneration. GFAP labeling decreases after effective early AAV augmentation but persists after late conditional endogenous rescue. GFAP is a stress-response readout; these experiments do not establish that gliosis alone drives ongoing cell loss.
  biological_scale: CELLULAR
  mechanism_confidence: PROVISIONAL
  evidence:
  - reference: PMID:38086857
    reference_title: Late gene therapy limits the restoration of retinal function in a mouse model of retinitis pigmentosa.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: we found that GFAP was present in both untreated and late-treated retinas at 7 M
    explanation: Persistent GFAP labeling after late endogenous rescue supports a sustained glial stress response in this conditional mouse model; it does not establish a causal inflammatory mediator.
  cell_types:
  - preferred_term: Mueller cell
    term:
      id: CL:0000636
      label: Mueller cell
- name: Photoreceptor Synaptic Ribbon Loss
  description: In the conditional Cngb1 mouse, late rescue leaves substantially reduced CtBP2-labeled photoreceptor ribbon structures despite surviving rods and cones. This identifies an anatomical limitation to recovery, without proving which circuit changes explain every functional deficit.
  biological_scale: CELLULAR
  mechanism_confidence: PROVISIONAL
  evidence:
  - reference: PMID:38086857
    reference_title: Late gene therapy limits the restoration of retinal function in a mouse model of retinitis pigmentosa.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: Following late treatment, CtBP2 horseshoe structures were substantially reduced
    explanation: CtBP2 immunolabeling showed loss of normal photoreceptor synaptic ribbon structures after late conditional rescue.
  downstream:
  - target: Impaired Retinal Ganglion Cell Signaling
    description: Loss of ribbon structures is a proposed contributor to impaired retinal output; the study did not isolate synapse loss as the sole cause.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
- name: Impaired Retinal Ganglion Cell Signaling
  description: After late conditional Cngb1 rescue, retinal ganglion cell responses have lower contrast gain and greater signal-dependent variability than after earlier rescue. Information transmission improves above untreated levels but fails to normalize and can decline over follow-up. These ex vivo mouse measurements are distinct from human visual acuity or an AAV clinical endpoint.
  biological_scale: CELLULAR
  mechanism_confidence: PROVISIONAL
  evidence:
  - reference: PMID:38086857
    reference_title: Late gene therapy limits the restoration of retinal function in a mouse model of retinitis pigmentosa.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: Early and mid-treatment brought the response variability back toward that of WT
    explanation: Multielectrode recordings show stage-dependent recovery of retinal ganglion cell response fidelity after conditional Cngb1 rescue.
  - reference: PMID:38086857
    reference_title: Late gene therapy limits the restoration of retinal function in a mouse model of retinitis pigmentosa.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: Late treatment also improved the information rate of the rod-mediated RGC signaling above baseline
    explanation: Late rescue retains measurable benefit without normalizing retinal output.
- name: Impaired Olfactory Signal Transduction
  description: CNGB1 encodes a signal-transduction subunit expressed in olfactory sensory neurons as well as rods. Olfactory testing in affected patients supports variable impairment consistent with an olfactory channel defect. The clinical studies do not demonstrate progressive olfactory-neuron death, and the single non-targeted MRI with nonvisible bulbs does not establish bulb agenesis.
  biological_scale: CELLULAR
  mechanism_confidence: PROVISIONAL
  evidence:
  - reference: PMID:29800053
    reference_title: Olfactory Dysfunction in Patients With CNGB1-Associated Retinitis Pigmentosa.
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: BACKGROUND
    directness: INDIRECT
    snippet: a gene coding for a signal transduction channel subunit expressed in rod photoreceptors and olfactory sensory neurons.
    explanation: Background establishes the shared expression context; this clinical study does not directly measure olfactory channel currents.
  - reference: PMID:29800053
    reference_title: Olfactory Dysfunction in Patients With CNGB1-Associated Retinitis Pigmentosa.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: INDIRECT
    snippet: Olfactory testing revealed reduced or absent olfactory function
    explanation: Patient testing establishes impaired smell; attribution to defective olfactory channel signaling is mechanistic interpretation.
  downstream:
  - target: Hyposmia
    description: A shared olfactory CNG-channel defect is a proposed explanation for psychophysically measured smell loss; direct human neuronal channel measurements are lacking.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:29800053
      reference_title: Olfactory Dysfunction in Patients With CNGB1-Associated Retinitis Pigmentosa.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      quote_role: PRIMARY_RESULT
      directness: INDIRECT
      snippet: Mutations in CNGB1 may cause an autosomal recessive RP-olfactory dysfunction syndrome characterized by a slow progression of retinal degeneration and variable anosmia or hyposmia.
      explanation: The clinical authors propose the connection; this does not prove olfactory-neuron loss.
  - target: Anosmia
    description: A shared olfactory CNG-channel defect is a proposed explanation for psychophysically measured smell loss; direct human neuronal channel measurements are lacking.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:29800053
      reference_title: Olfactory Dysfunction in Patients With CNGB1-Associated Retinitis Pigmentosa.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      quote_role: PRIMARY_RESULT
      directness: INDIRECT
      snippet: Mutations in CNGB1 may cause an autosomal recessive RP-olfactory dysfunction syndrome characterized by a slow progression of retinal degeneration and variable anosmia or hyposmia.
      explanation: The clinical authors propose the connection; this does not prove olfactory-neuron loss.
phenotypes:
- category: Ophthalmological
  name: Nyctalopia
  frequency: VERY_FREQUENT
  description: >-
    Night blindness was reported as the presenting complaint in 21 of 24 patients with available symptom data in the 33-patient longitudinal cohort, usually beginning in childhood. Other series document variable reported onset, including adulthood. The age at diagnosis or at recognition of visual-field loss should not be substituted for the onset of rod dysfunction.
  phenotype_term:
    preferred_term: Nyctalopia
    term:
      id: HP:0000662
      label: Nyctalopia
  reports_on:
  - target: Impaired Rod Light Responses
    relationship: READOUT_OF
    endpoint_context: DIAGNOSTIC
    interpretation: >-
      Night blindness is the direct clinical readout of loss of rod CNG
      channel-mediated phototransduction.
  evidence:
  - reference: PMID:28056120
    reference_title: Clinical Characterization of CNGB1-Related Autosomal Recessive Retinitis Pigmentosa.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The first clinical presentation was with nyctalopia in childhood with visual field loss documented later at a mean (SD) age of 33.2 (8.0) years."
    explanation: >-
      Documents childhood-onset nyctalopia as the first clinical presentation
      in a dedicated CNGB1-RP clinical characterization series.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: PMID:35743231
    reference_title: 'The Natural History of CNGB1-Related Retinopathy: A Longitudinal Phenotypic Analysis.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: The presenting complaint was nyctalopia in 88% (21/24) with symptom onset in childhood for the majority.
    explanation: The denominator is the 24 patients with recorded presenting symptoms, not all 33 participants.
  - reference: PMID:33465333
    reference_title: Variable expressivity in patients with autosomal recessive retinitis pigmentosa associated with the gene CNGB1.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: Age of onset ranged from 4 to 49 years
    explanation: This independent 11-patient series reports variable onset, including adulthood; retrospective symptom histories may differ between cohorts.
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1417/pdf/Bookshelf_NBK1417.pdf
    reference_title: https://www.ncbi.nlm.nih.gov/sites/books/NBK1417/pdf/Bookshelf_NBK1417.pdf
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
    snippet: The initial symptom of RP is usually defective dark adaptation
    explanation: General RP clinical baseline, consistent with the disease-specific cohorts. The overview does not supply a CNGB1-specific frequency or onset distribution.
- category: Ophthalmological
  name: Rod-cone dystrophy
  frequency: VERY_FREQUENT
  description: >-
    Electrophysiological testing confirms a generalized rod-cone dystrophy
    pattern, with rod dysfunction preceding and exceeding cone involvement.
  phenotype_term:
    preferred_term: Rod-cone dystrophy
    term:
      id: HP:0000510
      label: Rod-cone dystrophy
  reports_on:
  - target: Secondary Cone Dysfunction and Degeneration
    relationship: READOUT_OF
    endpoint_context: DIAGNOSTIC
    interpretation: >-
      The rod-cone pattern is what secondary cone involvement looks like on
      electrophysiology: cone loss following, and staying behind, the primary
      rod degeneration.
  evidence:
  - reference: PMID:28056120
    reference_title: Clinical Characterization of CNGB1-Related Autosomal Recessive Retinitis Pigmentosa.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Electrophysiologic testing in 6 patients confirmed a rod-cone dystrophy phenotype."
    explanation: >-
      Direct electrophysiological confirmation of the rod-cone dystrophy
      pattern in a dedicated clinical characterization series.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
- category: Ophthalmological
  name: Undetectable dark-adapted electroretinogram
  description: >-
    Rod-specific full-field ERG responses were absent in the five tested patients in the 2021 variable-expressivity series and in eight tested patients in the 2018 olfactory series. Other reports include attenuated responses. This characterizes rod-system dysfunction without proving that every surviving rod lacks a light response or distinguishing all possible cellular causes.
  phenotype_term:
    preferred_term: Undetectable dark-adapted electroretinogram
    term:
      id: HP:0030474
      label: Undetectable dark-adapted electroretinogram
  reports_on:
  - target: Impaired Rod Light Responses
    relationship: READOUT_OF
    endpoint_context: DIAGNOSTIC
    interpretation: >-
      Non-recordable rod-specific ERGs indicate severe rod-system dysfunction. They do not directly measure channel abundance or prove that every surviving rod is electrically silent.
  evidence:
  - reference: PMID:33465333
    reference_title: Variable expressivity in patients with autosomal recessive retinitis pigmentosa associated with the gene CNGB1.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Electrophysiological testing in five patients showed an absence of the rod response. Cone responses ranged from normal to severely reduced."
    explanation: >-
      Directly documents absent rod ERG responses in a CNGB1 cohort, with
      variable cone involvement.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
- category: Ophthalmological
  name: Attenuation of retinal blood vessels
  description: >-
    Attenuation of the retinal vasculature is a common fundoscopic finding,
    part of the classic triad of RP fundus changes.
  phenotype_term:
    preferred_term: Attenuation of retinal blood vessels
    term:
      id: HP:0007843
      label: Attenuation of retinal blood vessels
  evidence:
  - reference: PMID:33465333
    reference_title: Variable expressivity in patients with autosomal recessive retinitis pigmentosa associated with the gene CNGB1.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Funduscopic images showed widespread retinal degeneration with pigment clumping, optic disk pallor, arteriole attenuation, and a peri-foveal ring of hyper autofluorescence."
    explanation: >-
      Directly documents retinal arteriole attenuation on fundus imaging in a
      CNGB1-RP cohort.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
- category: Ophthalmological
  name: Pigmentary retinopathy
  description: >-
    Midperipheral retinal pigment epithelial atrophy and intraretinal pigment
    migration, the classic pigmentary finding of retinitis pigmentosa.
  phenotype_term:
    preferred_term: Pigmentary retinopathy
    term:
      id: HP:0000580
      label: Pigmentary retinopathy
  reports_on:
  - target: Progressive Rod Photoreceptor Loss
    relationship: READOUT_OF
    endpoint_context: DIAGNOSTIC
    interpretation: >-
      Pigment migration and RPE atrophy are the fundoscopic trace left by
      midperipheral rod photoreceptor loss.
  evidence:
  - reference: PMID:28056120
    reference_title: Clinical Characterization of CNGB1-Related Autosomal Recessive Retinitis Pigmentosa.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Fundus examination revealed midperipheral retinal pigment epithelial atrophy and intraretinal pigment migration."
    explanation: >-
      Direct fundoscopic documentation of retinal pigment epithelial atrophy
      and pigment migration in a CNGB1-RP cohort.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
- category: Ophthalmological
  name: Constriction of peripheral visual field
  frequency: VERY_FREQUENT
  description: >-
    Peripheral visual-field constriction is common and may be recognized substantially later than night blindness. One 10-patient series reported a mean age of documented field loss of 33.2 years; that is a cohort observation, not a universal onset threshold. Testing method, preserved retinal area and disease stage affect the measured field. Formal kinetic perimetry detected field loss at age 12 in one patient in the Hull series; the cohort mean for symptomatic onset does not imply exclusively adult onset.
  phenotype_term:
    preferred_term: Constriction of peripheral visual field
    term:
      id: HP:0001133
      label: Constriction of peripheral visual field
  reports_on:
  - target: Progressive Rod Photoreceptor Loss
    relationship: READOUT_OF
    endpoint_context: DIAGNOSTIC
    interpretation: >-
      Perimetric field constriction is the direct clinical measurement of the
      progressive field loss this node describes.
  evidence:
  - reference: PMID:28056120
    reference_title: Clinical Characterization of CNGB1-Related Autosomal Recessive Retinitis Pigmentosa.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The first clinical presentation was with nyctalopia in childhood with visual field loss documented later at a mean (SD) age of 33.2 (8.0) years."
    explanation: >-
      Documents visual field loss as a distinct, later-documented feature of
      the CNGB1-RP clinical course, with a mean age at documentation of 33.2
      years.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: url:https://discovery.ucl.ac.uk/id/eprint/1535961/1/Hull_CNGB1%20accepted%20version.pdf
    reference_title: https://discovery.ucl.ac.uk/id/eprint/1535961/1/Hull_CNGB1%20accepted%20version.pdf
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: it was detectable on formal kinetic perimetry in patient 9 at age 12 years.
    explanation: The full manuscript distinguishes objective field loss from later symptomatic recognition.
- category: Ophthalmological
  name: Cystoid macular edema
  frequency: FREQUENT
  description: >-
    Cystoid macular edema was present in 13 of 65 eyes belonging to seven of 33 patients in the 2022 longitudinal cohort. Edema can affect visual function and confound retinal-thickness measurements. This limits unadjusted thickness as a progression metric in affected eyes, rather than establishing that no thickness-based endpoint can ever be informative.
  phenotype_term:
    preferred_term: Cystoid macular oedema
    term:
      id: HP:0011505
      label: Cystoid macular edema
  evidence:
  - reference: PMID:35743231
    reference_title: "The Natural History of CNGB1-Related Retinopathy: A Longitudinal Phenotypic Analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Cystoid macular oedema was present in 19.7% (13/65) of eyes in 7 patients (21.2%)."
    explanation: >-
      The longitudinal cohort reported edema in 21.2% of patients and 19.7% of eyes; these are distinct denominators.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
- category: Ophthalmological
  name: Posterior subcapsular cataract
  frequency: FREQUENT
  description: >-
    Six of ten patients in the Hull series developed visually significant bilateral posterior subcapsular lens opacities during follow-up and underwent cataract surgery. In the separate 33-patient longitudinal cohort, 13 underwent surgery, but that report does not establish the subtype in every operated eye. Age at first surgery was available for only six of those 13, with a mean of 52.7 years (range 37–69). Lens disease can confound visual-acuity trajectories.
  phenotype_term:
    preferred_term: Posterior subcapsular cataract
    term:
      id: HP:0007787
      label: Posterior subcapsular cataract
  evidence:
  - reference: PMID:35743231
    reference_title: "The Natural History of CNGB1-Related Retinopathy: A Longitudinal Phenotypic Analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Thirteen patients had undergone cataract surgery in at least one eye, with a mean age of first eye cataract surgery of 52.7 years"
    explanation: >-
      Thirteen patients had undergone surgery; the mean surgical age was based on six with available age data, not all thirteen.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: url:https://discovery.ucl.ac.uk/id/eprint/1535961/1/Hull_CNGB1%20accepted%20version.pdf
    reference_title: https://discovery.ucl.ac.uk/id/eprint/1535961/1/Hull_CNGB1%20accepted%20version.pdf
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: Six of 10 patients ... developed visually significant posterior subcapsular lens opacities in both eyes during follow-up
    explanation: The recovered CNGB1-specific manuscript establishes the posterior subcapsular subtype in six of ten patients; the 33-patient surgical count is not treated as a subtype-specific denominator.
- category: Neurological
  name: Hyposmia
  description: >-
    In the 2018 nine-patient series, five of eight patients tested with Sniffin’ Sticks met the study’s absolute-norm definition of hyposmia; two had anosmia and one borderline-low normosmia. A ninth patient tested with a different method had anosmia. Age-adjusted rankings and these absolute categories are not interchangeable. Six of the nine patients were unaware of reduced smell. This selected series does not provide population penetrance.
  phenotype_term:
    preferred_term: Hyposmia
    term:
      id: HP:0004409
      label: Hyposmia
  evidence:
  - reference: PMID:29800053
    reference_title: Olfactory Dysfunction in Patients With CNGB1-Associated Retinitis Pigmentosa.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Olfactory testing revealed reduced or absent olfactory function, with all except one patient scoring in the lowest quartile in relation to age-related norms."
    explanation: >-
      Most tested patients ranked low relative to age-related norms, but this encompasses different absolute categories, including anosmia and borderline normosmia.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: PMID:29800053
    reference_title: Olfactory Dysfunction in Patients With CNGB1-Associated Retinitis Pigmentosa.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Mutations in CNGB1 may cause an autosomal recessive RP-olfactory dysfunction syndrome characterized by a slow progression of retinal degeneration and variable anosmia or hyposmia."
    explanation: >-
      The study supports an association with olfactory dysfunction, with variable severity; it does not establish universal olfactory involvement or a stable longitudinal course.

    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: url:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6136054/
    reference_title: Olfactory Dysfunction in Patients With CNGB1-Associated Retinitis Pigmentosa - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: anosmia was diagnosed in 2 patients, hyposmia was diagnosed in 5 patients, and normosmia (borderline low) was diagnosed in 1 patient
    explanation: These counts concern eight Sniffin’ Sticks tests classified against the stated absolute reference group.
  reports_on:
  - target: Impaired Olfactory Signal Transduction
    relationship: READOUT_OF
    interpretation: Psychophysical testing measures olfactory impairment; it does not directly quantify channel activity or olfactory neuron survival.
- name: Anosmia
  category: Neurological
  description: Two of eight patients tested with Sniffin’ Sticks in the 2018 series met the study’s anosmia criterion, and the ninth patient scored in the anosmic range using the T&T olfactometer. These selected observations do not establish population frequency or prove olfactory-neuron degeneration.
  phenotype_term:
    preferred_term: Anosmia
    term:
      id: HP:0000458
      label: Anosmia
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6136054/
    reference_title: Olfactory Dysfunction in Patients With CNGB1-Associated Retinitis Pigmentosa - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: anosmia was diagnosed in 2 patients, hyposmia was diagnosed in 5 patients, and normosmia (borderline low) was diagnosed in 1 patient
    explanation: Two of eight Sniffin’ Sticks tests met the study’s anosmia criterion. The full text additionally reports an anosmic-range T&T result in patient 9.
  reports_on:
  - target: Impaired Olfactory Signal Transduction
    relationship: READOUT_OF
    interpretation: Psychophysical testing measures olfactory impairment; it does not directly quantify channel activity or olfactory neuron survival.
- name: Epiretinal membrane
  category: Ophthalmological
  frequency: FREQUENT
  description: Epiretinal membranes were detected in 17 of 33 patients during longitudinal imaging in the 2022 cohort. A separate 34-patient series reported membranes in 10 of 29 patients with OCT data, usually without central involvement. These cohorts should not be pooled without establishing participant independence. Membranes can affect retinal-thickness measurements.
  phenotype_term:
    preferred_term: Epiretinal membrane
    term:
      id: HP:0100014
      label: Epiretinal membrane
  evidence:
  - reference: PMID:35743231
    reference_title: 'The Natural History of CNGB1-Related Retinopathy: A Longitudinal Phenotypic Analysis.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: Epiretinal membrane was present in 47.0% (31/65) of the eyes in 17 patients (51.5%) in at least one scan over the mean 4.5 year follow-up period.
    explanation: This is cumulative detection during the reported follow-up; patient and eye denominators differ.
- name: Optic disc pallor
  category: Ophthalmological
  description: Pale or waxy optic discs were observed with vessel attenuation and peripheral pigmentary change in CNGB1 cohorts. Disc pallor alone does not establish an independent primary optic neuropathy.
  phenotype_term:
    preferred_term: Optic disc pallor
    term:
      id: HP:0000543
      label: Optic disc pallor
  evidence:
  - reference: PMID:33847019
    reference_title: 'CNGB1-related rod-cone dystrophy: A mutation review and update.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: All subjects presented a classic form of RP with waxy optic disc pallor, attenuated retinal vessels, and peripheral bone spicules at fundus examination
    explanation: The 34-patient series documents the funduscopic finding.
- name: Color vision defect
  category: Ophthalmological
  frequency: FREQUENT
  description: Color vision was abnormal in at least one eye in nine of 17 assessed patients in the 34-patient series. Tritan, deutan and tetartan defects were reported; this selected assessment does not establish a single characteristic color-confusion pattern.
  phenotype_term:
    preferred_term: Color vision defect
    term:
      id: HP:0000551
      label: Color vision defect
  reports_on:
  - target: Secondary Cone Dysfunction and Degeneration
    relationship: READOUT_OF
    endpoint_context: DIAGNOSTIC
    interpretation: Color testing can reflect cone-system impairment, but is not specific for a particular cellular mechanism.
  evidence:
  - reference: PMID:33847019
    reference_title: 'CNGB1-related rod-cone dystrophy: A mutation review and update.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: Color vision was abnormal in at least one eye of 9/17 patients (52.94%)
    explanation: The denominator is those assessed, not all 34 participants.
- name: Reduced visual acuity
  category: Ophthalmological
  description: Central acuity is often relatively preserved into adulthood but may decline substantially. In the 34-patient series, 24 of 32 patients with acuity data retained at least 20/40 in one eye, while measured acuity ranged from no light perception to 20/20. Cataract, macular edema and other ocular disease can contribute to poor acuity, so it is not a pure measure of cone loss.
  phenotype_term:
    preferred_term: Reduced visual acuity
    term:
      id: HP:0007663
      label: Reduced visual acuity
  reports_on:
  - target: Secondary Cone Dysfunction and Degeneration
    relationship: READOUT_OF
    endpoint_context: DIAGNOSTIC
    interpretation: Acuity can reflect central retinal impairment, but lens and macular comorbidities confound attribution specifically to cone degeneration.
  evidence:
  - reference: PMID:33847019
    reference_title: 'CNGB1-related rod-cone dystrophy: A mutation review and update.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: Visual acuity ranged from no light perception to 20/20 Snellen
    explanation: Acuity varied widely in the clinical series; most patients retained useful central vision in at least one eye.
genetic:
- name: CNGB1
  gene_term:
    preferred_term: CNGB1
    term:
      id: hgnc:2151
      label: CNGB1
  association: Causative
  features: >-
    The 2021 mutation review catalogued 84 reported CNGB1 variants, of which 59 were classified pathogenic or likely pathogenic and 25 as uncertain significance. These are dated literature counts, not a current inventory of 84 proven causal alleles. Variants span GARP and channel regions; the review noted concentrations of reported channel-domain missense variants. Individual alleles can affect abundance, splicing, trafficking or gating differently. No reliable genotype-based prediction of retinal severity or olfactory involvement was established in the reviewed clinical cohorts.
  case_fractions:
  - population: Autosomal recessive retinitis pigmentosa cohorts summarized in the 2021 mutation review
    case_fraction_low: 1.0
    case_fraction_high: 4.0
    notes: The review summarizes approximately 1–4% of autosomal recessive RP across earlier cohorts. This is not a population prevalence estimate or a measured constant across ancestries. Its separately reported 0.42–0.78% estimates use all inherited retinal disease index cases as denominator.
    evidence:
    - reference: PMID:33847019
      reference_title: 'CNGB1-related rod-cone dystrophy: A mutation review and update.'
      supports: SUPPORT
      evidence_source: OTHER
      quote_role: REVIEW_SYNTHESIS
      directness: DIRECT
      snippet: accounting for approximately 1%–4% of autosomal recessive RP cases
      explanation: Literature synthesis of case fractions in arRP cohorts; not a new population-frequency measurement.
  inheritance:
  - name: Autosomal recessive
    evidence:
    - reference: PMID:11379879
      reference_title: Segregation of a mutation in CNGB1 encoding the beta-subunit of the rod cGMP-gated channel in a family with autosomal recessive retinitis pigmentosa.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "The CNGB1 gene, which encodes the beta-subunit of the rod cGMP-gated channel, is mutated in the family presented in this study."
      explanation: >-
        Confirms autosomal recessive inheritance for CNGB1-related RP in the
        original gene-discovery family.
      quote_role: PRIMARY_RESULT
      directness: DIRECT
  evidence:
  - reference: PMID:20126465
    reference_title: "The retinitis pigmentosa mutation c.3444+1G>A in CNGB1 results in skipping of exon 32."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Here, we investigated the splicing of c.3444+1G>A by exon trapping experiments and could demonstrate that instead of the proposed truncation of the last 28 aa this mutation leads to replacement of the last 170 aa of CNGB1a by 68 unrelated amino acids."
    explanation: >-
      Exon trapping demonstrates exon-32 skipping for this splice-site allele; the result replaces the original last-28-residue truncation prediction. Tissue transcript fate and channel function were not directly measured.

    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: PMID:33847019
    reference_title: 'CNGB1-related rod-cone dystrophy: A mutation review and update.'
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
    snippet: According to the ACMG criteria, 59 variants were considered pathogenic or likely pathogenic and 25 variants were classified of uncertain significance
    explanation: Variant reclassification in the 2021 review distinguishes reported alleles from confirmed pathogenic or likely pathogenic variants.
  - reference: url:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6136054/
    reference_title: Olfactory Dysfunction in Patients With CNGB1-Associated Retinitis Pigmentosa - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: evaluating the 3 missense variants as variants of uncertain significance
    explanation: The 2018 study classified p.Arg737His, p.Arg762Cys and p.Asn986Ile as VUS under its stated criteria; this is a dated study classification, not a current independent reinterpretation.
animal_models:
- name: Cngb1-X26 knockout mouse
  species: Mouse
  genotype: "Cngb1-/- (exon 26 deletion; Cngb1-X26)"
  publication: PMID:15634774
  evidence:
  - reference: PMID:15634774
    reference_title: Impaired channel targeting and retinal degeneration in mice lacking the cyclic nucleotide-gated channel subunit CNGB1.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "To investigate the importance of the CNGB subunits in vivo, we deleted the CNGB1 gene in mice."
    explanation: >-
      Establishes this as the original targeted-knockout mouse model of
      CNGB1-related retinopathy.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  modeled_mechanisms:
  - target: Impaired Rod Light Responses
    description: The X26 knockout has absent rod-mediated ERGs and predominantly unresponsive isolated rods.
    evidence:
    - reference: PMID:15634774
      reference_title: Impaired channel targeting and retinal degeneration in mice lacking the cyclic nucleotide-gated channel subunit CNGB1.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      quote_role: PRIMARY_RESULT
      directness: DIRECT
      snippet: the vast majority of isolated rod photoreceptors in mice lacking CNGB1 (CNGB1-/-) failed to respond to light. In electroretinograms (ERGs), CNGB1-/- mice showed no rod-mediated responses.
      explanation: Most isolated knockout rods were unresponsive; the population ERG lacked rod-mediated responses. Neither observation proves that every rod is silent.
    relationship: PARTIALLY_RECAPITULATES
    model_scale: CELLULAR
    limitations: Mice lack a macula; the knockout is not representative of every missense or GARP-region allele.
    fidelity: MODERATE
    readouts:
    - name: Rod-mediated ERG
      target: Impaired Rod Light Responses
      direction: DECREASED
      interpretation: Rod-system functional impairment, not a direct assay of apoptosis.
      evidence:
      - reference: PMID:15634774
        reference_title: Impaired channel targeting and retinal degeneration in mice lacking the cyclic nucleotide-gated channel subunit CNGB1.
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        quote_role: PRIMARY_RESULT
        directness: DIRECT
        snippet: the vast majority of isolated rod photoreceptors in mice lacking CNGB1 (CNGB1-/-) failed to respond to light. In electroretinograms (ERGs), CNGB1-/- mice showed no rod-mediated responses.
        explanation: Most isolated knockout rods were unresponsive; the population ERG lacked rod-mediated responses. Neither observation proves that every rod is silent.
  - target: Progressive Rod Photoreceptor Loss
    description: Progressive apoptotic rod loss occurs in the X26 mouse.
    evidence:
    - reference: PMID:15634774
      reference_title: Impaired channel targeting and retinal degeneration in mice lacking the cyclic nucleotide-gated channel subunit CNGB1.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      quote_role: PRIMARY_RESULT
      directness: DIRECT
      snippet: The rods also showed a slow-progressing degeneration caused by apoptotic death and concurred by retinal gliosis.
      explanation: The X26 knockout shows progressive apoptotic rod loss and associated gliosis. This does not establish the same death pathway in every human allele.
    relationship: PARTIALLY_RECAPITULATES
    model_scale: CELLULAR
    limitations: Mouse histology establishes apoptosis in this model; human structural imaging does not establish a shared death-effector pathway.
    fidelity: MODERATE
  - target: Impaired Rod Light Responses
    relationship: RESCUES
    fidelity: MODERATE
    description: >-
      Subretinal AAV8-mediated delivery of CNGB1a to Cngb1-/- mice restores
      full-length CNGB1a expression, rescues degraded CNGA1 to normal levels,
      and reconstitutes functional CNG channel complexes in rod outer segments.
    readouts:
    - name: Scotopic ERG rod-driven light response
      target: Impaired Rod Light Responses
      direction: RESTORED
      interpretation: >-
        Restoration of rod-driven ERG light responses after gene therapy
        confirms reconstitution of a functional rod CNG channel.
      evidence:
      - reference: PMID:22802073
        reference_title: Gene therapy restores vision and delays degeneration in the CNGB1(-/-) mouse model of retinitis pigmentosa.
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: "In the electroretinographic analysis, we also observed restoration of rod-driven light responses."
        explanation: >-
          Directly reports restored rod-driven ERG responses following AAV
          gene therapy in the mouse model.
        quote_role: PRIMARY_RESULT
        directness: DIRECT
    evidence:
    - reference: PMID:22802073
      reference_title: Gene therapy restores vision and delays degeneration in the CNGB1(-/-) mouse model of retinitis pigmentosa.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "We found that the treatment not only led to expression of full-length CNGB1a, but also restored normal levels of the previously degraded CNGA1 subunit of the rod CNG channel."
      explanation: >-
        Establishes that gene augmentation not only supplies CNGB1a but also
        rescues the secondary CNGA1 degradation, restoring channel assembly.
      quote_role: PRIMARY_RESULT
      directness: DIRECT
    model_scale: CELLULAR
    limitations: AAV rescue in mice; treatment at two weeks and rodent retinal anatomy limit inference about older human patients.
  - target: Impaired Rod Light Responses
    description: AAV5-hRHO194-human CNGB1 given at four weeks improves rod ERGs and dim-light behavior most strongly at the intermediate dose. The highest dose had no clear ERG benefit, and structural thinning was slowed rather than stopped.
    evidence:
    - reference: PMID:34376057
      reference_title: In Vivo Potency Testing of Subretinal rAAV5.hCNGB1 Gene Therapy in the Cngb1 Knockout Mouse Model of Retinitis Pigmentosa.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      quote_role: PRIMARY_RESULT
      directness: DIRECT
      snippet: increasing doses of rAAV5.hCNGB1 were delivered through single subretinal injection in 4-week-old Cngb1
      explanation: The 2021 study tests a human CNGB1 AAV5 construct in young knockout mice, separately from the 2012 species-matched proof of concept.
    - reference: url:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8819509/
      reference_title: In Vivo Potency Testing of Subretinal rAAV5.hCNGB1 Gene Therapy in the Cngb1 Knockout Mouse Model of Retinitis Pigmentosa - PMC
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      quote_role: PRIMARY_RESULT
      directness: DIRECT
      snippet: no differences in b-wave amplitudes were seen between the high-dose treatment and the control group
      explanation: The full-text dose-ranging results report no obvious functional improvement at the highest dose; this is not a monotonic dose-response.
    relationship: RESCUES
    model_scale: CELLULAR
    limitations: Human/mouse hybrid channels, ectopic human CNGB1 localization and a young knockout retina complicate dose translation. Doses are preclinical experimental values, not human recommendations.
    fidelity: MODERATE
  description: Exon-26 knockout abolishing the full-length channel subunit while preserving soluble GARP isoforms. It models channel deficiency, not all human alleles or GARP-null phenotypes.
- name: CNGB1-mutant dog (naturally occurring, Papillon/Phalene breeds)
  species: Dog
  genotype: "Biallelic complex CNGB1 indel (c.2387delA;2389_2390insAGCTAC in the later transcript annotation), causing exon-26 skipping"
  publication: PMID:24015210
  evidence:
  - reference: PMID:24015210
    reference_title: A CNGB1 frameshift mutation in Papillon and Phalène dogs with progressive retinal atrophy.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "This mutation causes a frameshift and premature stop codon leading to probable nonsense mediated decay (NMD) of the CNGB1 mRNA."
    explanation: >-
      Establishes this as a naturally occurring, large-eye CNGB1
      loss-of-function animal model of the disease.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: PMID:29202463
    reference_title: Patients and animal models of CNGβ1-deficient retinitis pigmentosa support gene augmentation approach.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: The truncated product partly escaped nonsense- mediated decay, leading to a relative expression level approximately 40% of that of WT tran- script levels in the controls
    explanation: Retinal RT-PCR and expression studies in the later paper revise the original NMD-only prediction; approximately 40% residual transcript and a truncated inner-segment protein were reported.
  modeled_mechanisms:
  - target: Progressive Rod Photoreceptor Loss
    relationship: PARTIALLY_RECAPITULATES
    fidelity: MODERATE
    description: >-
      Progressive rod loss and later cone decline provide a large-eye model of the rod-first disease course; the cited dog histology does not itself establish apoptosis.
    evidence:
    - reference: PMID:29202463
      reference_title: Patients and animal models of CNGβ1-deficient retinitis pigmentosa support gene augmentation approach.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "Cngb1-/- dogs have slow photoreceptor loss and relative preservation of cones."
      explanation: >-
        Reports the canine result alone: photoreceptor loss is slow and cones
        are relatively spared, the rod-first pattern of the human disease.
      quote_role: PRIMARY_RESULT
      directness: DIRECT
    - reference: PMID:29202463
      reference_title: Patients and animal models of CNGβ1-deficient retinitis pigmentosa support gene augmentation approach.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "Cone function slowly declines with age in the Cngb1-/- dog."
      explanation: >-
        Reports the secondary, slow decline of cone function in the canine
        model, matching the cone-secondary course seen in patients.
      quote_role: PRIMARY_RESULT
      directness: DIRECT
    model_scale: CELLULAR
    limitations: Dogs have an area centralis but differ from humans in early central outer nuclear layer thinning and autofluorescence patterns. One breed-associated allele does not model all human variants.
  - target: Impaired Rod Light Responses
    relationship: RESCUES
    fidelity: MODERATE
    description: >-
      AAV5-hGRK1-canine CNGB1 in the 2018 proof-of-concept study yielded ERG rescue through 18 months in the longest ERG follow-up; 23 months referred to protein expression/structural follow-up. The distinct 2023 AAV5-RHO-human CNGB1 study treated ten three-month-old dogs and assessed functional rescue through 12 months in animals retained that long.
    readouts:
    - name: Scotopic ERG b-wave and vision-guided behavior
      target: Impaired Rod Light Responses
      direction: RESTORED
      interpretation: >-
        Sustained improvement in rod-mediated ERG amplitude and scotopic
        vision-guided behavior over long-term follow-up confirms durable
        functional rescue.
      evidence:
      - reference: PMID:29202463
        reference_title: Patients and animal models of CNGβ1-deficient retinitis pigmentosa support gene augmentation approach.
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: "gene augmentation using adeno-associated virus vectors robustly sustained the rescue of rod function and preserved retinal structure in the dog model"
        explanation: >-
          Confirms sustained functional and structural rescue following gene
          augmentation in the canine model.
        quote_role: PRIMARY_RESULT
        directness: DIRECT
    evidence:
    - reference: PMID:37056049
      reference_title: Development of a translatable gene augmentation therapy for CNGB1-retinitis pigmentosa.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "The therapeutic vector (AAV5-RHO-CNGB1) delivered to the subretinal space of CNGB1 mutant dogs restores rod-mediated retinal function (electroretinographic responses and vision)"
      explanation: >-
        Establishes the canine model as the pharmacodynamic efficacy platform
        for a clinically translatable AAV construct.

      quote_role: PRIMARY_RESULT
      directness: DIRECT
    model_scale: CELLULAR
    limitations: Dogs have an area centralis but differ from humans in early central outer nuclear layer thinning and autofluorescence patterns. One breed-associated allele does not model all human variants.
  - target: Rod cGMP Accumulation
    description: Abnormal cGMP immunoreactivity is reduced within human-CNGB1-treated canine retina.
    evidence:
    - reference: PMID:37056049
      reference_title: Development of a translatable gene augmentation therapy for CNGB1-retinitis pigmentosa.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      quote_role: PRIMARY_RESULT
      directness: DIRECT
      snippet: A feature of lack of CNG channel function in rod outer segments is the abnormal accumulation of cGMP. IHC showed that this was reversed within the treated retinal regions
      explanation: In the cGMP-accumulation results section, immunohistochemistry showed reversal of abnormal cGMP staining in treated dog retina, with staining retained outside the treated regions. This is not a direct channel-current measurement.
    relationship: RESCUES
    model_scale: MOLECULAR
    limitations: Immunoreactivity is not a direct ionic-current or intracellular-calcium measurement.
    fidelity: MODERATE
    readouts:
    - name: Photoreceptor outer segment cGMP accumulation
      target: Rod cGMP Accumulation
      direction: RESTORED
      interpretation: >-
        Reduced abnormal cGMP staining in treated regions is an indirect pharmacodynamic marker of restored channel function.
      evidence:
      - reference: PMID:37056049
        reference_title: Development of a translatable gene augmentation therapy for CNGB1-retinitis pigmentosa.
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        quote_role: PRIMARY_RESULT
        directness: DIRECT
        snippet: A feature of lack of CNG channel function in rod outer segments is the abnormal accumulation of cGMP. IHC showed that this was reversed within the treated retinal regions
        explanation: In the cGMP-accumulation results section, immunohistochemistry showed reversal of abnormal cGMP staining in treated dog retina, with staining retained outside the treated regions. This is not a direct channel-current measurement.
  description: Naturally occurring Papillon/Phalène channel-deficiency model. The 2013 discovery paper predicted NMD without affected retinal tissue. The 2018 follow-up demonstrated exon skipping, approximately 40% residual transcript and inner-segment truncated protein; it is not a complete transcript-null model.
- name: Conditional Cngb1 rescue mouse
  species: Mouse
  genotype: Cngb1neo/neo; UBC-cre/ERT2 (loxP-flanked neomycin cassette in intron 19)
  publication: PMID:38086857
  description: Tamoxifen-inducible restoration of endogenous Cngb1 used to isolate the effect of disease stage on rescue; distinct from X26 knockout and viral augmentation.
  evidence:
  - reference: PMID:38086857
    reference_title: Late gene therapy limits the restoration of retinal function in a mouse model of retinitis pigmentosa.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: By delivering tamoxifen, activated cre removes the neomycin insert to enable endogenous CNGB1 expression across all rods
    explanation: Defines the conditional endogenous rescue system.
  modeled_mechanisms:
  - target: Impaired Retinal Ganglion Cell Signaling
    description: Tamoxifen activates Cre-mediated removal of the blocking cassette to restore endogenous Cngb1 at one, two or three months. Earlier rescue restores output closer to wild type; late rescue retains lower gain and greater variability.
    evidence:
    - reference: PMID:38086857
      reference_title: Late gene therapy limits the restoration of retinal function in a mouse model of retinitis pigmentosa.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      quote_role: PRIMARY_RESULT
      directness: DIRECT
      snippet: Early and mid-treatment brought the response variability back toward that of WT
      explanation: Multielectrode recordings show stage-dependent recovery of retinal ganglion cell response fidelity after conditional Cngb1 rescue.
    relationship: RESCUES
    model_scale: CELLULAR
    limitations: Conditional endogenous restoration is an artificial best-case experiment, not AAV delivery. Approximate 25%, 50% and 70% rod-loss groups are model-specific and are not human eligibility thresholds.
    fidelity: MODERATE
    readouts:
    - name: Ganglion-cell spike-response variability and information rate
      target: Impaired Retinal Ganglion Cell Signaling
      interpretation: Late rescue improves signaling above untreated levels but fails to normalize fidelity.
      evidence:
      - reference: PMID:38086857
        reference_title: Late gene therapy limits the restoration of retinal function in a mouse model of retinitis pigmentosa.
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        quote_role: PRIMARY_RESULT
        directness: DIRECT
        snippet: late treatment failed to reduce the signal-dependent noise
        explanation: Multielectrode recordings distinguish incomplete functional rescue from structural photoreceptor survival.
  - target: Reactive Retinal Gliosis
    description: GFAP labeling persists after late rescue.
    evidence:
    - reference: PMID:38086857
      reference_title: Late gene therapy limits the restoration of retinal function in a mouse model of retinitis pigmentosa.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      quote_role: PRIMARY_RESULT
      directness: DIRECT
      snippet: we found that GFAP was present in both untreated and late-treated retinas at 7 M
      explanation: Persistent GFAP labeling after late endogenous rescue supports a sustained glial stress response in this conditional mouse model; it does not establish a causal inflammatory mediator.
    relationship: PARTIALLY_RECAPITULATES
    model_scale: CELLULAR
    limitations: Qualitative GFAP staining; no quantitative causal test of inflammation.
    fidelity: MODERATE
  - target: Photoreceptor Synaptic Ribbon Loss
    description: Late rescue leaves fewer intact CtBP2-labeled ribbon structures.
    evidence:
    - reference: PMID:38086857
      reference_title: Late gene therapy limits the restoration of retinal function in a mouse model of retinitis pigmentosa.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      quote_role: PRIMARY_RESULT
      directness: DIRECT
      snippet: Following late treatment, CtBP2 horseshoe structures were substantially reduced
      explanation: CtBP2 immunolabeling showed loss of normal photoreceptor synaptic ribbon structures after late conditional rescue.
    relationship: PARTIALLY_RECAPITULATES
    model_scale: CELLULAR
    limitations: Anatomical association with advanced degeneration; not a selective synapse-restoration experiment.
    fidelity: MODERATE
treatments:
- name: AAV-Mediated CNGB1 Gene Augmentation Therapy
  therapeutic_modality: GENE_THERAPY
  description: >-
    AAV-mediated delivery of CNGB1 has restored rod function and preserved retinal structure in preclinical mouse and dog experiments. The 2023 translational study additionally tested a promoter/capsid reporter in primates; this was a rod-targeting experiment, not a demonstration of retinal rescue in diseased primates. Construct, species, treatment age and follow-up differ between studies. These experiments do not establish human efficacy or a universal treatment window. The 2021 AAV5 mouse dose-ranging study found the strongest benefit at the intermediate dose and no clear ERG benefit at the highest dose; retinal thinning was slowed rather than arrested. In the 2023 dog study, one treated eye developed inflammation and focal retinal/choroidal degeneration. Conditional endogenous rescue in a separate mouse line shows incomplete recovery after advanced rod loss, without defining a human treatment cutoff.
  treatment_term:
    preferred_term: gene therapy
    term:
      id: NCIT:C15238
      label: Gene Therapy
  target_mechanisms:
  - target: Impaired Rod Light Responses
    treatment_effect: RESTORES
    description: >-
      Restores rod light-response function in preclinical CNGB1-deficient animals; benefit depends on construct, dose and disease stage.
    evidence:
    - reference: PMID:37056049
      reference_title: Development of a translatable gene augmentation therapy for CNGB1-retinitis pigmentosa.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "In conclusion, this study establishes the long-term efficacy of subretinal delivery of AAV5-RHO-CNGB1 to rescue the disease phenotype in a canine model of CNGB1-RP, confirming its suitability for future clinical development."
      explanation: >-
        Directly supports gene augmentation as restoring the channel-loss
        mechanism this treatment targets.
      quote_role: PRIMARY_RESULT
      directness: DIRECT
  - target: Rod cGMP Accumulation
    treatment_effect: INHIBITS
    description: Reduces abnormal cGMP accumulation within effectively treated model retina.
    evidence:
    - reference: PMID:37056049
      reference_title: Development of a translatable gene augmentation therapy for CNGB1-retinitis pigmentosa.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      quote_role: PRIMARY_RESULT
      directness: DIRECT
      snippet: A feature of lack of CNG channel function in rod outer segments is the abnormal accumulation of cGMP. IHC showed that this was reversed within the treated retinal regions
      explanation: In the cGMP-accumulation results section, immunohistochemistry showed reversal of abnormal cGMP staining in treated dog retina, with staining retained outside the treated regions. This is not a direct channel-current measurement.
  evidence:
  - reference: PMID:22802073
    reference_title: Gene therapy restores vision and delays degeneration in the CNGB1(-/-) mouse model of retinitis pigmentosa.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "this work provides a proof-of-concept for the treatment of rod channelopathy-associated RP by AAV-mediated gene replacement"
    explanation: >-
      Establishes preclinical proof-of-concept for AAV-mediated CNGB1 gene
      replacement in the mouse model.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: PMID:29202463
    reference_title: Patients and animal models of CNGβ1-deficient retinitis pigmentosa support gene augmentation approach.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "gene augmentation using adeno-associated virus vectors robustly sustained the rescue of rod function and preserved retinal structure in the dog model"
    explanation: >-
      Sustained preclinical canine functional and structural benefit; human efficacy is not established by this experiment.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: PMID:37056049
    reference_title: Development of a translatable gene augmentation therapy for CNGB1-retinitis pigmentosa.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "The promoter/capsid combination drives efficient expression of a reporter gene (AAV5-RHO-eGFP) exclusively in rod photoreceptors in primate, dog, and mouse following subretinal delivery."
    explanation: >-
      Reporter expression demonstrates rod targeting across species, including healthy primates, not therapeutic efficacy or full therapeutic-vector safety in primates.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: PMID:34376057
    reference_title: In Vivo Potency Testing of Subretinal rAAV5.hCNGB1 Gene Therapy in the Cngb1 Knockout Mouse Model of Retinitis Pigmentosa.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: increasing doses of rAAV5.hCNGB1 were delivered through single subretinal injection in 4-week-old Cngb1
    explanation: The 2021 study tests a human CNGB1 AAV5 construct in young knockout mice, separately from the 2012 species-matched proof of concept.
  - reference: PMID:37056049
    reference_title: Development of a translatable gene augmentation therapy for CNGB1-retinitis pigmentosa.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: The subretinal injections were generally well tolerated, and no adverse events noted in injected eyes except for one group 3 eye (17-010 OD).
    explanation: The exception developed inflammation and focal retinal/choroidal thinning; the efficacy findings do not establish uniformly safe treatment.
  - reference: PMID:38086857
    reference_title: Late gene therapy limits the restoration of retinal function in a mouse model of retinitis pigmentosa.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: Late treatment retinas exhibit continued, albeit slowed, loss of sensitivity and signal fidelity among retinal ganglion cells, as well as persistent gliosis.
    explanation: A conditional endogenous rescue experiment demonstrates disease-stage limitations, not adverse effects or efficacy of an AAV vector.
  - reference: PMID:37056049
    reference_title: Development of a translatable gene augmentation therapy for CNGB1-retinitis pigmentosa.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: However, circular patches of retinal and choroidal thinning developed at the lower region of the ventral bleb
    explanation: The adverse-event results paragraph explicitly includes choroidal as well as retinal thinning in the inflamed dog eye.
- name: Genetic counseling
  therapeutic_modality: OTHER
  description: >-
    Counseling should interpret the familial pathogenic/likely pathogenic alleles and their phase, discuss testing of relatives and reproductive options, and explain autosomal recessive recurrence. When both parents carry the causal alleles, each pregnancy has a 25% chance of an affected child. Reported VUS do not establish a molecular diagnosis.
  treatment_term:
    preferred_term: genetic counseling
    term:
      id: NCIT:C15240
      label: Genetic Counseling
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1417/pdf/Bookshelf_NBK1417.pdf
    reference_title: https://www.ncbi.nlm.nih.gov/sites/books/NBK1417/pdf/Bookshelf_NBK1417.pdf
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
    snippet: At conception, each sib has a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier.
    explanation: General autosomal recessive RP counseling, applicable when both parents carry the established familial causal alleles.
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1417/pdf/Bookshelf_NBK1417.pdf
    reference_title: https://www.ncbi.nlm.nih.gov/sites/books/NBK1417/pdf/Bookshelf_NBK1417.pdf
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
    snippet: Carrier testing for at-risk relatives requires prior identification of the RP- related pathogenic variants in the family.
    explanation: Family testing depends on the established molecular cause, rather than treating an uncertain variant as diagnostic.
- name: Low-vision rehabilitation
  therapeutic_modality: OTHER
  treatment_term:
    preferred_term: Low-vision rehabilitation
    term:
      id: NCIT:C15315
      label: Rehabilitation
  description: Low-vision aids and individualized mobility, vocational and independent-living support address visual disability. This is general RP supportive care and does not restore the CNGB1 channel.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1417/pdf/Bookshelf_NBK1417.pdf
    reference_title: https://www.ncbi.nlm.nih.gov/sites/books/NBK1417/pdf/Bookshelf_NBK1417.pdf
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
    snippet: Low vision aids such as magnifiers and closed circuit television may provide useful reading vision for individuals with reduced central acuity and constricted visual fields.
    explanation: General RP guidance supports functional aids for central-acuity and field limitations.
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1417/pdf/Bookshelf_NBK1417.pdf
    reference_title: https://www.ncbi.nlm.nih.gov/sites/books/NBK1417/pdf/Bookshelf_NBK1417.pdf
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
    snippet: services include vocational training, mobility training, and skills for independent living.
    explanation: General RP guidance supports rehabilitation services.
- name: Carbonic anhydrase inhibition for cystoid macular edema
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: acetazolamide
      term:
        id: CHEBI:27690
        label: acetazolamide
    - preferred_term: dorzolamide
      term:
        id: CHEBI:4702
        label: dorzolamide
  description: Oral acetazolamide or topical dorzolamide may be considered by the treating ophthalmologist for RP-associated cystoid macular edema; response is variable and rebound can occur. This is complication-directed general RP care, not proven modification of CNGB1 retinal degeneration.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1417/pdf/Bookshelf_NBK1417.pdf
    reference_title: https://www.ncbi.nlm.nih.gov/sites/books/NBK1417/pdf/Bookshelf_NBK1417.pdf
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
    snippet: Some therapeutic success has been reported with both systemic and topical carbonic anhydrase inhibitors ... however, rebound edema can occur with continued use
    explanation: General RP treatment synthesis; it is not a CNGB1-specific randomized trial.
- name: Cataract surgery when visually significant
  therapeutic_modality: SURGERY
  treatment_term:
    preferred_term: Cataract Surgery
    term:
      id: NCIT:C157809
      label: Cataract Surgery
  description: Assess whether cataract contributes materially to visual impairment before considering extraction. Macular disease can limit visual improvement; RP increases the risk of postoperative inflammation and cystoid macular edema. Surgery treats the lens opacity, not the underlying channelopathy.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1417/pdf/Bookshelf_NBK1417.pdf
    reference_title: https://www.ncbi.nlm.nih.gov/sites/books/NBK1417/pdf/Bookshelf_NBK1417.pdf
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
    snippet: Individuals with retinitis pigmentosa are at a greater-than-average risk for postoperative inflammation and induced CME.
    explanation: General RP perioperative considerations, not a CNGB1-specific comparative surgical trial.
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1417/pdf/Bookshelf_NBK1417.pdf
    reference_title: https://www.ncbi.nlm.nih.gov/sites/books/NBK1417/pdf/Bookshelf_NBK1417.pdf
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
    snippet: In the presence of macular disease, extraction of lenses when cataracts are in the early stage may not always improve the quality of vision
    explanation: General RP guidance emphasizes identifying the cause of visual impairment before intervention.
classifications:
  harrisons_chapter:
  - classification_value: GENETICS_ENVIRONMENT_DISEASE
  - classification_value: NEUROLOGIC
diagnosis:
- name: Molecular genetic testing
  diagnosis_term:
    preferred_term: diagnostic procedure
    term:
      id: NCIT:C18020
      label: Diagnostic Procedure
  description: >-
    An inherited-retinal-disease panel or genomic test can identify candidate CNGB1 variants. A molecular diagnosis requires biallelic pathogenic or likely pathogenic variants, with phase, segregation and copy-number assessment where needed. VUS findings or in-silico predictions alone do not establish the diagnosis. Apparent homozygosity may require evaluation for a deletion on the other allele.
  results: >-
    Biallelic pathogenic or likely pathogenic CNGB1 variants consistent with recessive inheritance support molecular confirmation; uncertain variants require further assessment.
  evidence:
  - reference: PMID:28056120
    reference_title: Clinical Characterization of CNGB1-Related Autosomal Recessive Retinitis Pigmentosa.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "10 patients from 9 families underwent full ophthalmologic examination. Molecular investigations included whole-exome analysis in 6 patients."
    explanation: >-
      The clinical series used exome analysis in six patients. This documents a testing method, not a claim that every reported variant had definitive pathogenic classification.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1417/pdf/Bookshelf_NBK1417.pdf
    reference_title: https://www.ncbi.nlm.nih.gov/sites/books/NBK1417/pdf/Bookshelf_NBK1417.pdf
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
    snippet: Methods used in a panel may include sequence analysis, deletion/duplication analysis, and/or other non- sequencing-based tests.
    explanation: General RP molecular evaluation includes methods beyond coding SNV detection; coverage and diagnostic sensitivity vary between laboratories.
- name: Full-field electroretinography
  diagnosis_term:
    preferred_term: diagnostic procedure
    term:
      id: NCIT:C18020
      label: Diagnostic Procedure
  description: >-
    Dark- and light-adapted full-field ERG characterizes the severity of rod
    and cone dysfunction and typically shows non-recordable or severely
    attenuated scotopic responses even when visual acuity remains good.
  results: >-
    Scotopic (rod) responses are absent or severely attenuated; photopic
    (cone) responses range from normal to severely reduced depending on
    patient age and disease stage.
  evidence:
  - reference: PMID:33465333
    reference_title: Variable expressivity in patients with autosomal recessive retinitis pigmentosa associated with the gene CNGB1.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Electrophysiological testing in five patients showed an absence of the rod response. Cone responses ranged from normal to severely reduced."
    explanation: >-
      Directly quantifies the electrophysiological diagnostic pattern.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
- name: Multimodal retinal imaging
  diagnosis_term:
    preferred_term: diagnostic procedure
    term:
      id: NCIT:C18020
      label: Diagnostic Procedure
  description: >-
    SD-OCT and fundus autofluorescence characterize preserved and diseased retinal regions. Ellipsoid-zone length and hyperautofluorescent ring area are candidate progression metrics for patients in whom those features can be measured. Their sensitivity, reproducibility and relationship to treatment benefit require prospective validation; neither is an established surrogate endpoint.
  results: >-
    In the 33-patient retrospective cohort, EZ length was measurable in 23 patients and constricted by a mean 178 ± 161 micrometers per year. Eight of 14 patients in a two-year simulation changed by more than 250 micrometers, the cited approximate interobserver variability. Hyperautofluorescent ring area was measurable in 17 patients; some had no ring and others had rings beyond the image. These selection limits prevent transferring the rates or sensitivity to every patient or disease stage.
  evidence:
  - reference: PMID:35743231
    reference_title: "The Natural History of CNGB1-Related Retinopathy: A Longitudinal Phenotypic Analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The ellipsoid zone (EZ) length was measurable in at least one eye of 23 patients"
    explanation: >-
      Establishes ellipsoid zone length as a measured structural biomarker
      used as a candidate imaging endpoint.

    quote_role: PRIMARY_RESULT
    directness: DIRECT
- name: Ophthalmic surveillance
  diagnosis_term:
    preferred_term: Eye Examination
    term:
      id: NCIT:C38060
      label: Eye Examination
  description: General RP guidance recommends annual dilated examination and perimetry, with closer review for active complications such as cystoid macular edema. OCT/FAF and functional assessments can follow CNGB1 disease progression, with interpretation adapted to the measurable retinal area and macular comorbidity.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1417/pdf/Bookshelf_NBK1417.pdf
    reference_title: https://www.ncbi.nlm.nih.gov/sites/books/NBK1417/pdf/Bookshelf_NBK1417.pdf
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
    snippet: and a full ophthalmoscopic examination with dilation are performed on an annual basis, with more frequent follow up for active complications such as cystoid macular edema.
    explanation: General RP surveillance guidance applied to CNGB1-related disease; frequency is individualized for active complications.
progression:
- phase: Variable onset of rod dysfunction
  age_range: Childhood to adulthood
  notes: >-
    Night blindness commonly begins in childhood, but reported onset varied from ages 4 to 49 in one series. Retrospective symptom recognition, age at diagnosis and first measured field loss are different observations.
  evidence:
  - reference: PMID:28056120
    reference_title: Clinical Characterization of CNGB1-Related Autosomal Recessive Retinitis Pigmentosa.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The first clinical presentation was with nyctalopia in childhood with visual field loss documented later at a mean (SD) age of 33.2 (8.0) years."
    explanation: >-
      Establishes the childhood-onset timing of the presenting symptom.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: PMID:33465333
    reference_title: Variable expressivity in patients with autosomal recessive retinitis pigmentosa associated with the gene CNGB1.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: Age of onset ranged from 4 to 49 years
    explanation: Reported onset includes adults in this series.
- phase: Prolonged preservation of visual acuity and macular structure
  age_range: Childhood through the third and fourth decades
  notes: >-
    Several cohorts document prolonged preservation of central acuity and foveal structure, but other patients have substantial loss. Preservation suggests remaining therapeutic substrate; it does not establish individual treatment eligibility or guarantee benefit.
  evidence:
  - reference: PMID:28056120
    reference_title: Clinical Characterization of CNGB1-Related Autosomal Recessive Retinitis Pigmentosa.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All patients had preserved best-corrected visual acuity into adulthood, with a mean of 0.1 logMAR (Snellen equivalent, 20/25) in each eye"
    explanation: >-
      Directly quantifies preserved visual acuity into adulthood in a
      dedicated CNGB1-RP clinical series.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
- phase: Slow progressive structural decline in adulthood
  age_range: Adulthood, over multi-year follow-up
  notes: >-
    Retrospective longitudinal imaging demonstrates progression in measurable subsets. The 2022 cohort had a mean follow-up of 4.5 years, but four patients had no follow-up visit. Acuity changes can be confounded by lens or macular disease. Prospective natural-history data are needed to define reliable functional and structural outcomes.
  evidence:
  - reference: PMID:35743231
    reference_title: "The Natural History of CNGB1-Related Retinopathy: A Longitudinal Phenotypic Analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The results support previous findings of CNGB1-related RP being a slowly progressive disease with patients maintaining visual acuity."
    explanation: >-
      States the natural-history cohort's overall conclusion of slow,
      measurable progression with maintained visual acuity.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
references:
- reference: PMID:11379879
  title: Segregation of a mutation in CNGB1 encoding the beta-subunit of the rod cGMP-gated channel in a family with autosomal recessive retinitis pigmentosa.
- reference: PMID:15634774
  title: Impaired channel targeting and retinal degeneration in mice lacking the cyclic nucleotide-gated channel subunit CNGB1.
- reference: PMID:20126465
  title: The retinitis pigmentosa mutation c.3444+1G>A in CNGB1 results in skipping of exon 32.
- reference: PMID:20301590
  title: Nonsyndromic Retinitis Pigmentosa Overview.
  tags:
  - GeneReviews
- reference: PMID:22802073
  title: Gene therapy restores vision and delays degeneration in the CNGB1(-/-) mouse model of retinitis pigmentosa.
- reference: PMID:24015210
  title: A CNGB1 frameshift mutation in Papillon and Phalène dogs with progressive retinal atrophy.
- reference: PMID:28056120
  title: Clinical Characterization of CNGB1-Related Autosomal Recessive Retinitis Pigmentosa.
- reference: PMID:29202463
  title: Patients and animal models of CNGβ1-deficient retinitis pigmentosa support gene augmentation approach.
- reference: PMID:29800053
  title: Olfactory Dysfunction in Patients With CNGB1-Associated Retinitis Pigmentosa.
- reference: PMID:33465333
  title: Variable expressivity in patients with autosomal recessive retinitis pigmentosa associated with the gene CNGB1.
- reference: PMID:33847019
  title: 'CNGB1-related rod-cone dystrophy: A mutation review and update.'
- reference: PMID:34376057
  title: In Vivo Potency Testing of Subretinal rAAV5.hCNGB1 Gene Therapy in the Cngb1 Knockout Mouse Model of Retinitis Pigmentosa.
- reference: PMID:35743231
  title: 'The Natural History of CNGB1-Related Retinopathy: A Longitudinal Phenotypic Analysis.'
- reference: PMID:37056049
  title: Development of a translatable gene augmentation therapy for CNGB1-retinitis pigmentosa.
- reference: PMID:38086857
  title: Late gene therapy limits the restoration of retinal function in a mouse model of retinitis pigmentosa.
- reference: clinicaltrials:NCT04639635
  title: Study of CNGB1 Retinitis Pigmentosa and Allied Hereditary Disorders
- reference: url:https://clinicaltrials.gov/api/v2/studies/NCT04639635
  title: https://clinicaltrials.gov/api/v2/studies/NCT04639635
- reference: url:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6136054/
  title: Olfactory Dysfunction in Patients With CNGB1-Associated Retinitis Pigmentosa - PMC
- reference: url:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8819509/
  title: In Vivo Potency Testing of Subretinal rAAV5.hCNGB1 Gene Therapy in the Cngb1 Knockout Mouse Model of Retinitis Pigmentosa - PMC
- reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1417/pdf/Bookshelf_NBK1417.pdf
  title: https://www.ncbi.nlm.nih.gov/sites/books/NBK1417/pdf/Bookshelf_NBK1417.pdf
  tags:
  - GeneReviews
- reference: url:https://discovery.ucl.ac.uk/id/eprint/1535961/1/Hull_CNGB1%20accepted%20version.pdf
  title: https://discovery.ucl.ac.uk/id/eprint/1535961/1/Hull_CNGB1%20accepted%20version.pdf
clinical_trials:
- name: NCT04639635
  phase: NOT_APPLICABLE
  status: SUSPENDED
  description: Prospective observational natural-history study of CNGB1 retinitis pigmentosa and allied disorders intended to develop outcome measures. It administers no gene-therapy intervention. The registry update posted 13 April 2026 lists suspension because IRB renewal lapsed; status verified from the registry on 2 October 2026.
  evidence:
  - reference: clinicaltrials:NCT04639635
    reference_title: Study of CNGB1 Retinitis Pigmentosa and Allied Hereditary Disorders
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: our objective is to better understand the disease process of CNGB1-RP and other allied inherited disorders so that we can develop clinical tests to measure the outcomes of treatment.
    explanation: Registry summary describes natural-history and outcome-development objectives, not demonstrated therapeutic benefit.
  - reference: url:https://clinicaltrials.gov/api/v2/studies/NCT04639635
    reference_title: https://clinicaltrials.gov/api/v2/studies/NCT04639635
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: '"officialTitle":"Study of CNGB1 Retinitis Pigmentosa and Allied Hereditary Disorders" ... "overallStatus":"SUSPENDED","whyStopped":"IRB renewal lapsed"'
    explanation: Current registry metadata gives the status and stated reason; checked 2 October 2026.
discussions:
- discussion_id: cngb1_rescue_stage_translation
  kind: HUMAN_MODEL_MISMATCH
  status: OPEN
  prompt: Which structural and functional features identify a rescuable human CNGB1 retina?
  attaches_to:
  - animal_models#Conditional Cngb1 rescue mouse
  - treatments#AAV-Mediated CNGB1 Gene Augmentation Therapy
  rationale: Conditional endogenous rescue bypasses vector transduction and expression variability. Late-treated mice retain some benefit but do not regain normal retinal output, and mice lack a macula. Human OCT preservation alone therefore does not establish an intervention window or justify transferring model-specific rod-loss thresholds into eligibility criteria.
  evidence:
  - reference: PMID:38086857
    reference_title: Late gene therapy limits the restoration of retinal function in a mouse model of retinitis pigmentosa.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: Mouse retina lacks a cone-dense region and is (at best) more analogous to human peripheral retina
    explanation: The study explicitly limits translation of its rescue-stage results to human central retina.
- discussion_id: cngb1_cgmp_death_intermediates
  kind: KNOWLEDGE_GAP
  status: OPEN
  prompt: Which intermediates link channel deficiency and cGMP accumulation to progressive rod death in CNGB1 disease?
  attaches_to:
  - pathophysiology#Rod cGMP Accumulation
  - pathophysiology#Progressive Rod Photoreceptor Loss
  rationale: Channel-deficient model rods accumulate cGMP, and CNGB1 restoration reduces the staining while improving function. Those rescue experiments correct multiple consequences simultaneously and do not isolate cGMP as the death effector. Calcium overload and a specific downstream death pathway should not be inferred from cGMP immunoreactivity alone.
  evidence:
  - reference: PMID:37056049
    reference_title: Development of a translatable gene augmentation therapy for CNGB1-retinitis pigmentosa.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: A feature of lack of CNG channel function in rod outer segments is the abnormal accumulation of cGMP. IHC showed that this was reversed within the treated retinal regions
    explanation: In the cGMP-accumulation results section, immunohistochemistry showed reversal of abnormal cGMP staining in treated dog retina, with staining retained outside the treated regions. This is not a direct channel-current measurement.

📚

References & Deep Research

References

PMID:11379879

Segregation of a mutation in CNGB1 encoding the beta-subunit of the rod cGMP-gated channel in a family with autosomal recessive retinitis pigmentosa.