Achromatopsia is an autosomal recessive cone photoreceptor disorder characterized by the absence or severe impairment of cone cell function from birth. Most affected individuals have complete achromatopsia with total loss of cone function, severely reduced visual acuity, absent or markedly impaired color discrimination, photophobia, and nystagmus. Rare incomplete achromatopsia retains partial cone function and can have milder acuity loss. The condition results from mutations in genes encoding components of the cone phototransduction cascade, most commonly CNGA3 and CNGB3 (encoding the alpha and beta subunits of the cone cyclic nucleotide-gated channel), and less frequently GNAT2 (cone transducin alpha), PDE6C (cone phosphodiesterase alpha), PDE6H (cone phosphodiesterase gamma), and ATF6 (activating transcription factor 6). The prevalence is approximately 1 in 30,000-50,000. Achromatopsia is a leading target for investigational retinal gene therapy, with completed and active-not-recruiting clinical trials for CNGA3 and CNGB3 gene augmentation but no approved achromatopsia gene therapy represented here.
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Conditions with similar clinical presentations that must be differentiated from Achromatopsia:
name: Achromatopsia
creation_date: '2026-04-22T00:00:00Z'
updated_date: '2026-04-22T00:00:00Z'
category: Mendelian
synonyms:
- Rod monochromatism
- Total color blindness
- Complete achromatopsia
- ACHM
description: >
Achromatopsia is an autosomal recessive cone photoreceptor disorder
characterized by the absence or severe impairment of cone cell function from
birth. Most affected individuals have complete achromatopsia with total loss
of cone function, severely reduced visual acuity, absent or markedly impaired
color discrimination, photophobia, and nystagmus. Rare incomplete
achromatopsia retains partial cone function and can have milder acuity loss.
The condition results from mutations in genes encoding components of the cone
phototransduction cascade, most commonly CNGA3 and CNGB3 (encoding the alpha
and beta subunits of the cone cyclic nucleotide-gated channel), and less
frequently GNAT2 (cone transducin alpha), PDE6C (cone phosphodiesterase
alpha), PDE6H (cone phosphodiesterase gamma), and ATF6 (activating
transcription factor 6). The prevalence is approximately 1 in 30,000-50,000.
Achromatopsia is a leading target for investigational retinal gene therapy,
with completed and active-not-recruiting clinical trials for CNGA3 and CNGB3
gene augmentation but no approved achromatopsia gene therapy represented here.
disease_term:
preferred_term: achromatopsia
term:
id: MONDO:0018852
label: achromatopsia
parents:
- Cone dystrophy
- Color vision disorder
- Retinal disorder
inheritance:
- name: Autosomal Recessive
inheritance_term:
preferred_term: Autosomal recessive inheritance
term:
id: HP:0000007
label: Autosomal recessive inheritance
evidence:
- reference: PMID:29257187
reference_title: "Diagnosis and Treatment Options for Achromatopsia: A Review of the Literature."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "It is usually an autosomal-recessive disease and is characterized by pendular nystagmus, poor visual acuity, lack of color vision, and marked photophobia."
explanation: Confirms autosomal recessive inheritance pattern of achromatopsia.
has_subtypes:
- name: ACHM2
display_name: Achromatopsia 2 (CNGA3)
description: >
Caused by biallelic mutations in CNGA3, encoding the alpha subunit of the
cone CNG channel. Accounts for approximately 25-28% of European/US cases.
- name: ACHM3
display_name: Achromatopsia 3 (CNGB3)
description: >
Caused by biallelic mutations in CNGB3, encoding the beta subunit of the
cone CNG channel. The most common form, accounting for approximately 50%
of cases. The c.1148delC founder mutation accounts for approximately 70%
of CNGB3 disease-causing alleles and approximately 40% of all
achromatopsia-associated alleles.
- name: ACHM4
display_name: Achromatopsia 4 (GNAT2)
description: >
Caused by biallelic mutations in GNAT2, encoding the alpha subunit of cone
transducin. A rare form accounting for less than 2% of cases.
- name: ACHM5
display_name: Achromatopsia 5 (PDE6C)
description: >
Caused by biallelic mutations in PDE6C, encoding the alpha prime subunit
of cone phosphodiesterase. Very rare.
- name: ACHM6
display_name: Achromatopsia 6 (PDE6H)
description: >
Caused by biallelic mutations in PDE6H, encoding the inhibitory gamma
subunit of cone phosphodiesterase. Extremely rare and associated with
incomplete achromatopsia.
- name: ACHM7
display_name: Achromatopsia 7 (ATF6)
description: >
Caused by biallelic mutations in ATF6, encoding activating transcription
factor 6 involved in the unfolded protein response. Distinct mechanism
from the phototransduction cascade defects.
prevalence:
- population: General population
percentage: 1 in 30,000-50,000
notes: >-
Estimated prevalence based on multiple population studies. Higher prevalence
in consanguineous populations and isolated communities such as Pingelap atoll
in Micronesia (approximately 5-10% of population) and among Arab-Muslims in
Jerusalem (approximately 1:5000).
evidence:
- reference: PMID:25616768
reference_title: "Genetics and Disease Expression in the CNGA3 Form of Achromatopsia: Steps on the Path to Gene Therapy."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "These mutations lead to a high ACHM prevalence of ∼1:5000 among Arab-Muslims residing in Jerusalem."
explanation: Documents high prevalence of CNGA3-achromatopsia in a consanguineous population.
pathophysiology:
- name: Cone CNG Channel Dysfunction
description: >
The cone cyclic nucleotide-gated (CNG) channel is a heterotetrameric complex
composed of CNGA3 and CNGB3 subunits. In darkness, high cGMP levels keep
CNG channels open, maintaining a depolarizing dark current. Light-driven
phototransduction reduces cGMP, closing channels and hyperpolarizing the
cone. Loss-of-function mutations in CNGA3 or CNGB3 abolish the cone CNG
channel, eliminating the dark current and rendering cones non-functional.
This is the most common mechanism, with up to 90% of patients carrying
mutations in CNGA3 or CNGB3.
cell_types:
- preferred_term: retinal cone cell
term:
id: CL:0000573
label: retinal cone cell
locations:
- preferred_term: retina
term:
id: UBERON:0000966
label: retina
- preferred_term: fovea centralis
term:
id: UBERON:0001786
label: fovea centralis
biological_processes:
- preferred_term: phototransduction, visible light
term:
id: GO:0007603
label: phototransduction, visible light
modifier: ABSENT
downstream:
- target: Cone Photoreceptor Degeneration
description: Non-functional cone photoreceptors undergo progressive structural degeneration.
evidence:
- reference: PMID:34860352
reference_title: "Achromatopsia: Genetics and Gene Therapy."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Up to 90% of patients with ACHM carry mutations in CNGA3 or CNGB3, which are the genes encoding the alpha and beta subunits of the cone cyclic nucleotide-gated (CNG) channel, respectively."
explanation: Confirms that CNG channel subunit mutations account for the vast majority of achromatopsia cases.
- reference: PMID:34860352
reference_title: "Achromatopsia: Genetics and Gene Therapy."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "These mutations result in a functional loss and a slow progressive degeneration of cone photoreceptors."
explanation: Establishes that CNG channel mutations cause both functional loss and progressive structural degeneration.
- name: Cone Transducin Deficiency
description: >
GNAT2 encodes the alpha subunit of cone transducin, a heterotrimeric G
protein that couples activated cone opsin to phosphodiesterase activation.
Loss of GNAT2 function prevents signal transduction from photoactivated
cone opsin to PDE6C, blocking the phototransduction cascade at the G-protein
coupling step. cGMP levels remain constitutively high, but without transducin
signaling the cone cannot generate a light response.
cell_types:
- preferred_term: retinal cone cell
term:
id: CL:0000573
label: retinal cone cell
biological_processes:
- preferred_term: phototransduction, visible light
term:
id: GO:0007603
label: phototransduction, visible light
modifier: ABSENT
downstream:
- target: Cone Photoreceptor Degeneration
description: Cones with non-functional transducin signaling undergo progressive structural degeneration.
evidence:
- reference: PMID:29257187
reference_title: "Diagnosis and Treatment Options for Achromatopsia: A Review of the Literature."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "CNGA3, CNGB3, GNAT2, PDE6C, PDE6H, and ATF6 gene mutations have been identified as associated with this disease."
explanation: Confirms GNAT2 as one of the six known achromatopsia genes.
- name: Cone Phosphodiesterase Deficiency
description: >
PDE6C and PDE6H encode the alpha prime and inhibitory gamma subunits of
cone cGMP phosphodiesterase (PDE6), respectively. In the phototransduction
cascade, activated transducin stimulates PDE6 to hydrolyze cGMP, reducing
its concentration and closing CNG channels. Loss of PDE6C or PDE6H function
prevents cGMP hydrolysis, so cGMP remains constitutively high and CNG
channels remain open regardless of light stimulation, eliminating the
normal cone light response. These are very rare causes of achromatopsia.
cell_types:
- preferred_term: retinal cone cell
term:
id: CL:0000573
label: retinal cone cell
biological_processes:
- preferred_term: phototransduction, visible light
term:
id: GO:0007603
label: phototransduction, visible light
modifier: ABSENT
downstream:
- target: Cone Photoreceptor Degeneration
description: Non-functional cones with constitutively open CNG channels undergo progressive degeneration.
evidence:
- reference: PMID:35332618
reference_title: "Comprehensive variant spectrum of the CNGA3 gene in patients affected by achromatopsia."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "To date, six genes have been associated with ACHM (CNGA3, CNGB3, GNAT2, PDE6C, PDE6H, and ATF6), the majority of these being implicated in the cone phototransduction cascade."
explanation: Confirms PDE6C and PDE6H as established achromatopsia genes in the cone phototransduction cascade.
- name: Cone Photoreceptor Degeneration
description: >
Although achromatopsia is classically considered a stationary disorder,
progressive foveal cone photoreceptor loss has been documented by optical
coherence tomography (OCT). Disruption of the IS/OS junction, outer
nuclear layer thinning, and hyporeflective zones in the fovea are
frequently observed and are age-dependent, suggesting that non-functional
cones undergo slow degeneration. This progressive structural deterioration
has implications for the therapeutic window of gene therapy interventions.
cell_types:
- preferred_term: retinal cone cell
term:
id: CL:0000573
label: retinal cone cell
locations:
- preferred_term: fovea centralis
term:
id: UBERON:0001786
label: fovea centralis
biological_processes:
- preferred_term: cone photoreceptor cell death
term:
id: GO:0008219
label: cell death
modifier: INCREASED
evidence:
- reference: PMID:21211844
reference_title: "High-resolution in vivo imaging in achromatopsia."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "The IS/OS junction and COST reflectivity disruption and presence of HRZ and ONL thinning are signs of cone photoreceptor degeneration. The latter 2 are age-dependent, which suggests that achromatopsia is a progressive disorder." # codespell:ignore-line
explanation: OCT imaging demonstrates age-dependent progressive cone photoreceptor loss in achromatopsia patients.
- reference: PMID:21211844
reference_title: "High-resolution in vivo imaging in achromatopsia."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "There was significant (P = 1.1×10(-6)) ONL thinning in the achromats compared with controls, which was age-dependent (P = 0.0002)." # codespell:ignore-line
explanation: Quantitative evidence of progressive outer nuclear layer thinning in achromatopsia.
- name: Unfolded Protein Response Defect (ATF6)
description: >
ATF6 is a key ER stress sensor and transcription factor in the unfolded
protein response (UPR). Biallelic ATF6 mutations cause achromatopsia through
a mechanism distinct from phototransduction cascade defects. ATF6 is
required for cone photoreceptor development and maintenance, and its loss
leads to foveal hypoplasia and cone dysfunction. This subtype may present
with foveal structural abnormalities visible on OCT.
cell_types:
- preferred_term: retinal cone cell
term:
id: CL:0000573
label: retinal cone cell
biological_processes:
- preferred_term: endoplasmic reticulum unfolded protein response
term:
id: GO:0030968
label: endoplasmic reticulum unfolded protein response
modifier: ABSENT
downstream:
- target: Cone Photoreceptor Degeneration
description: Impaired UPR leads to ER stress-mediated cone photoreceptor dysfunction and foveal hypoplasia.
evidence:
- reference: PMID:28795510
reference_title: "CNGB3 mutation spectrum including copy number variations in 552 achromatopsia patients."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "The disease is caused by mutations in genes encoding crucial components of the cone phototransduction cascade (CNGA3, CNGB3, GNAT2, PDE6C, and PDE6H) or in ATF6, involved in the unfolded protein response."
explanation: Distinguishes ATF6 from the other five achromatopsia genes as having a distinct unfolded protein response mechanism.
- reference: PMID:31237654
reference_title: "Characterization of Retinal Structure in ATF6-Associated Achromatopsia."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Foveal hypoplasia was observed in all subjects with ATF6 mutations."
explanation: Confirms foveal hypoplasia as a consistent structural finding in ATF6-associated achromatopsia.
- reference: PMID:31237654
reference_title: "Characterization of Retinal Structure in ATF6-Associated Achromatopsia."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Our data demonstrate a near absence of cone structure in subjects harboring ATF6 mutations. This implicates ATF6 as having a major role in cone development"
explanation: Demonstrates that ATF6 is essential for cone photoreceptor development and maintenance.
phenotypes:
- category: Ophthalmologic
name: Achromatopsia
description: >
Complete absence of color vision and failure to discriminate chromatic
contrasts. Affected individuals perceive the world in shades of gray.
This results from non-functional cone photoreceptors while rod
photoreceptors remain intact.
frequency: OBLIGATE
phenotype_term:
preferred_term: Achromatopsia
term:
id: HP:0011516
label: Achromatopsia
evidence:
- reference: PMID:34860352
reference_title: "Achromatopsia: Genetics and Gene Therapy."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "The loss of cone photoreceptor function manifests at birth or early in childhood and results in decreased visual acuity, lack of color discrimination, abnormal intolerance to light (photophobia), and rapid involuntary eye movement (nystagmus)."
explanation: Comprehensive description of the cardinal features including absent color discrimination.
- category: Ophthalmologic
name: Severely Reduced Visual Acuity
description: >
Visual acuity is often 20/200 or worse in complete achromatopsia, as central
vision depends primarily on cone-rich foveal photoreceptors. Incomplete
achromatopsia can be milder, with residual cone function and acuity as good
as 20/80 in some individuals. Rod-mediated vision provides only peripheral
and low-resolution input.
frequency: OBLIGATE
phenotype_term:
preferred_term: Severely reduced visual acuity
term:
id: HP:0001141
label: Severely reduced visual acuity
evidence:
- reference: PMID:32352493
reference_title: "Safety and Vision Outcomes of Subretinal Gene Therapy Targeting Cone Photoreceptors in Achromatopsia: A Nonrandomized Controlled Trial."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Baseline visual acuity letter score (approximate Snellen equivalent) ranged from 34 (20/200) to 49 (20/100)"
explanation: Clinical trial baseline data confirms severely reduced visual acuity in CNGA3-achromatopsia patients.
- reference: url:https://www.ncbi.nlm.nih.gov/books/NBK1418/
reference_title: Achromatopsia - GeneReviews - NCBI Bookshelf
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Best visual acuity varies with severity of the disease
explanation: >-
GeneReviews distinguishes severe complete achromatopsia from milder
incomplete achromatopsia with residual cone function.
- category: Ophthalmologic
name: Hyperopia
description: >
Hyperopic refractive error is common and should be assessed during
ophthalmologic evaluation because refractive correction can improve
functional vision even though it does not restore cone photoreceptor
function.
frequency: FREQUENT
phenotype_term:
preferred_term: Hypermetropia
term:
id: HP:0000540
label: Hypermetropia
evidence:
- reference: url:https://www.ncbi.nlm.nih.gov/books/NBK1418/
reference_title: Achromatopsia - GeneReviews - NCBI Bookshelf
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Hyperopia is common in achromatopsia."
explanation: GeneReviews identifies hyperopia as a common associated refractive finding.
- category: Ophthalmologic
name: Photophobia
description: >
Marked light sensitivity and photoaversion. In photopic conditions,
dysfunctional cones cannot modulate signaling appropriately, and excessive
rod stimulation causes glare and discomfort. Patients often squint or use
tinted lenses.
frequency: OBLIGATE
phenotype_term:
preferred_term: Photophobia
term:
id: HP:0000613
label: Photophobia
evidence:
- reference: PMID:25616768
reference_title: "Genetics and Disease Expression in the CNGA3 Form of Achromatopsia: Steps on the Path to Gene Therapy."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Achromatopsia (ACHM) is a congenital, autosomal recessive retinal disease that manifests cone dysfunction, reduced visual acuity and color vision, nystagmus, and photoaversion."
explanation: Photoaversion is listed as a cardinal feature of achromatopsia.
- category: Ophthalmologic
name: Congenital Nystagmus
description: >
Involuntary rhythmic eye movements present from infancy. Results from
the lack of stable foveal fixation due to absent cone function.
frequency: FREQUENT
phenotype_term:
preferred_term: Congenital nystagmus
term:
id: HP:0006934
label: Congenital nystagmus
evidence:
- reference: PMID:29257187
reference_title: "Diagnosis and Treatment Options for Achromatopsia: A Review of the Literature."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "It is usually an autosomal-recessive disease and is characterized by pendular nystagmus, poor visual acuity, lack of color vision, and marked photophobia."
explanation: Pendular nystagmus is identified as a characteristic feature of achromatopsia.
- category: Ophthalmologic
name: Abnormal Foveal Morphology
description: >
OCT imaging reveals a range of foveal structural abnormalities including
disruption of the IS/OS junction, outer nuclear layer thinning, foveal
hyporeflective zones, and foveal maldevelopment. Progressive cone
photoreceptor loss is documented in longitudinal studies.
frequency: FREQUENT
phenotype_term:
preferred_term: Abnormal foveal morphology
term:
id: HP:0000493
label: Abnormal foveal morphology
evidence:
- reference: PMID:21211844
reference_title: "High-resolution in vivo imaging in achromatopsia."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "A characteristic so-called punched out hyporeflective zone (HRZ) was noted in 7 of 13 patients; this was age-dependent (P = 0.001)."
explanation: OCT demonstrates characteristic foveal structural abnormalities in achromatopsia patients.
- reference: PMID:21211844
reference_title: "High-resolution in vivo imaging in achromatopsia."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Foveal maldevelopment was seen in 9 of 13 patients."
explanation: Foveal maldevelopment is a common structural finding in achromatopsia.
- reference: PMID:25616768
reference_title: "Genetics and Disease Expression in the CNGA3 Form of Achromatopsia: Steps on the Path to Gene Therapy."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Retinal structure in CNGA3 ACHM patients revealed persistent but abnormal foveal cones."
explanation: Confirms the presence of structurally abnormal but persistent foveal cones in CNGA3-achromatopsia.
genetic:
- name: CNGA3 Mutations
association: Causative
subtype: ACHM2
gene_term:
preferred_term: CNGA3
term:
id: hgnc:2150
label: CNGA3
features: >
Biallelic loss-of-function mutations in CNGA3 encoding the alpha subunit
of the cone cyclic nucleotide-gated channel. A total of 244 likely
disease-causing variants have been identified, with missense substitutions
being the predominant mutation class. Accounts for approximately 25-28%
of European and US achromatopsia cases.
evidence:
- reference: PMID:35332618
reference_title: "Comprehensive variant spectrum of the CNGA3 gene in patients affected by achromatopsia."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "we provide a comprehensive overview of the CNGA3 variant spectrum in a cohort of 1060 genetically confirmed ACHM patients, 385 (36.3%) of these carrying \"likely disease-causing\" variants in CNGA3."
explanation: Largest CNGA3 variant spectrum study documenting 385 patients with CNGA3 mutations out of 1060 ACHM cases.
- reference: PMID:35332618
reference_title: "Comprehensive variant spectrum of the CNGA3 gene in patients affected by achromatopsia."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "we further extend the CNGA3 variant spectrum to a total of 316 variants, 244 of which we interpreted as \"likely disease-causing\" according to ACMG/AMP criteria."
explanation: Comprehensive cataloging of 244 likely pathogenic CNGA3 variants.
- name: CNGB3 Mutations
association: Causative
subtype: ACHM3
gene_term:
preferred_term: CNGB3
term:
id: hgnc:2153
label: CNGB3
features: >
Biallelic mutations in CNGB3 encoding the beta subunit of the cone CNG
channel. CNGB3 is the major achromatopsia gene, with mutations found in
approximately 45% of families. A total of 98 different potentially
disease-causing variants have been identified. Copy number variations
encompassing one to ten exons have also been reported.
evidence:
- reference: PMID:28795510
reference_title: "CNGB3 mutation spectrum including copy number variations in 552 achromatopsia patients."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "CNGB3 encoding the beta subunit of the cyclic nucleotide-gated ion channel in cone photoreceptors is the major achromatopsia gene. Here, we present a comprehensive spectrum of CNGB3 mutations and their prevalence in a cohort of 1074 independent families clinically diagnosed with achromatopsia. Of these, 485 (45.2%) carried mutations in CNGB3."
explanation: Largest CNGB3 mutation study confirming it as the most common achromatopsia gene.
- reference: PMID:28795510
reference_title: "CNGB3 mutation spectrum including copy number variations in 552 achromatopsia patients."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "We identified a total of 98 different potentially disease-causing CNGB3 variants, 58 of which are novel."
explanation: Comprehensive cataloging of 98 different CNGB3 variants including copy number variations.
- name: GNAT2 Mutations
association: Causative
subtype: ACHM4
gene_term:
preferred_term: GNAT2
term:
id: hgnc:4394
label: GNAT2
features: >
Biallelic mutations in GNAT2 encoding the alpha subunit of cone transducin.
Rare, accounting for less than 2% of cases.
evidence:
- reference: PMID:35332618
reference_title: "Comprehensive variant spectrum of the CNGA3 gene in patients affected by achromatopsia."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "To date, six genes have been associated with ACHM (CNGA3, CNGB3, GNAT2, PDE6C, PDE6H, and ATF6), the majority of these being implicated in the cone phototransduction cascade."
explanation: Confirms GNAT2 as one of the six established achromatopsia genes involved in the cone phototransduction cascade.
- name: PDE6C Mutations
association: Causative
subtype: ACHM5
gene_term:
preferred_term: PDE6C
term:
id: hgnc:8787
label: PDE6C
features: >
Biallelic mutations in PDE6C encoding the alpha prime subunit of cone
cGMP phosphodiesterase. Very rare cause of achromatopsia.
evidence:
- reference: PMID:35332618
reference_title: "Comprehensive variant spectrum of the CNGA3 gene in patients affected by achromatopsia."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "To date, six genes have been associated with ACHM (CNGA3, CNGB3, GNAT2, PDE6C, PDE6H, and ATF6), the majority of these being implicated in the cone phototransduction cascade."
explanation: Confirms PDE6C as one of the six established achromatopsia genes.
- name: PDE6H Mutations
association: Causative
subtype: ACHM6
gene_term:
preferred_term: PDE6H
term:
id: hgnc:8790
label: PDE6H
features: >
Biallelic mutations in PDE6H encoding the inhibitory gamma subunit of
cone phosphodiesterase. Extremely rare.
evidence:
- reference: PMID:35332618
reference_title: "Comprehensive variant spectrum of the CNGA3 gene in patients affected by achromatopsia."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "To date, six genes have been associated with ACHM (CNGA3, CNGB3, GNAT2, PDE6C, PDE6H, and ATF6), the majority of these being implicated in the cone phototransduction cascade."
explanation: Confirms PDE6H as one of the six established achromatopsia genes.
- name: ATF6 Mutations
association: Causative
subtype: ACHM7
gene_term:
preferred_term: ATF6
term:
id: hgnc:791
label: ATF6
features: >
Biallelic mutations in ATF6 encoding activating transcription factor 6,
a key UPR sensor. Distinct pathomechanism from phototransduction defects.
Associated with foveal hypoplasia.
evidence:
- reference: PMID:28795510
reference_title: "CNGB3 mutation spectrum including copy number variations in 552 achromatopsia patients."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "The disease is caused by mutations in genes encoding crucial components of the cone phototransduction cascade (CNGA3, CNGB3, GNAT2, PDE6C, and PDE6H) or in ATF6, involved in the unfolded protein response."
explanation: Distinguishes ATF6 from phototransduction cascade genes as having a distinct UPR-related mechanism.
diagnosis:
- name: Electroretinography (ERG)
description: >
Full-field electroretinography is the cornerstone diagnostic test for
achromatopsia. Cone-mediated (photopic) ERG responses are absent or
severely reduced, including absent or markedly diminished 30-Hz flicker
responses, while rod-mediated (scotopic) responses are preserved or only
mildly abnormal. A 15-Hz flicker ERG can demonstrate absence of the
cone-driven fast pathway at high flash intensities.
diagnosis_term:
preferred_term: electroretinogram procedure
term:
id: MAXO:0035099
label: electroretinogram procedure
evidence:
- reference: PMID:25616768
reference_title: "Genetics and Disease Expression in the CNGA3 Form of Achromatopsia: Steps on the Path to Gene Therapy."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Rod ERG abnormalities (in addition to cone dysfunction) were detected in 59% of patients."
explanation: ERG-based phenotyping in CNGA3-achromatopsia patients, with cone dysfunction universally detected and unexpected rod abnormalities in a subset.
- reference: url:https://www.ncbi.nlm.nih.gov/books/NBK1418/
reference_title: Achromatopsia - GeneReviews - NCBI Bookshelf
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
The photopic response (including the 30-Hz flicker response) is absent or markedly diminished
explanation: >-
GeneReviews defines the characteristic ERG pattern used to support the
clinical diagnosis of achromatopsia.
- name: Ophthalmologic Examination and Retinal Imaging
description: >
Clinical diagnosis includes visual acuity, nystagmus assessment,
fundoscopic examination, and multimodal retinal imaging. Optical coherence
tomography may show foveal hypoplasia, inner/outer segment junction
disruption, attenuation of the retinal pigment epithelium in the macula, or
other macular changes; fundus autofluorescence and visual fields can further
characterize the phenotype and help distinguish progressive retinal
dystrophies.
diagnosis_term:
preferred_term: ophthalmologist evaluation
term:
id: MAXO:0000703
label: ophthalmologist evaluation
results: Visual acuity, nystagmus, fundus findings, OCT, fundus autofluorescence, and visual field results.
evidence:
- reference: url:https://www.ncbi.nlm.nih.gov/books/NBK1418/
reference_title: Achromatopsia - GeneReviews - NCBI Bookshelf
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
additional testing may include optical coherence tomography, fundus autofluorescence, visual fields, and electroretinogram
explanation: >-
GeneReviews supports adding OCT, fundus autofluorescence, visual fields,
and fundus examination to the diagnostic workup.
- name: Optical Coherence Tomography
description: >
OCT specifically documents foveal hypoplasia, disruption or loss of the
photoreceptor inner/outer segment junction, foveal hyporeflective zones,
outer nuclear layer thinning, and macular retinal pigment epithelium
attenuation. These findings support diagnosis and help stage the residual
retinal structure relevant to gene-therapy trial eligibility.
diagnosis_term:
preferred_term: optical coherence tomography
term:
id: MAXO:0000969
label: optical coherence tomography
results: Foveal hypoplasia, photoreceptor junction disruption, foveal hyporeflective zones, outer nuclear layer thinning, and RPE attenuation.
evidence:
- reference: url:https://www.ncbi.nlm.nih.gov/books/NBK1418/
reference_title: Achromatopsia - GeneReviews - NCBI Bookshelf
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
A variable degree of foveal hypoplasia
explanation: >-
GeneReviews describes OCT-visible foveal and outer retinal abnormalities
as early structural findings in achromatopsia.
- name: Color Vision Assessment
description: >
Formal color vision testing is part of the diagnostic assessment. Testing
should evaluate red-green and broader chromatic discrimination because
achromatopsia impairs color discrimination along all three cone axes, while
differential diagnoses can have restricted color-axis defects.
diagnosis_term:
preferred_term: ophthalmologist evaluation
term:
id: MAXO:0000703
label: ophthalmologist evaluation
results: Abnormal color discrimination along protan, deutan, and tritan axes supports achromatopsia.
evidence:
- reference: url:https://www.ncbi.nlm.nih.gov/books/NBK1418/
reference_title: Achromatopsia - GeneReviews - NCBI Bookshelf
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
all achromats have anomalous (impaired) color discrimination along all three axes
explanation: >-
GeneReviews supports formal color vision testing as a core diagnostic
feature and differential-diagnosis tool.
- name: Genetic Testing
description: >
Molecular genetic testing by targeted gene panel or whole-exome sequencing
identifies biallelic pathogenic variants in one of six genes (CNGA3, CNGB3,
GNAT2, PDE6C, PDE6H, ATF6). Required for definitive genetic diagnosis and
eligibility for gene therapy clinical trials.
diagnosis_term:
preferred_term: genetic testing
term:
id: MAXO:0000127
label: genetic testing
evidence:
- reference: PMID:35332618
reference_title: "Comprehensive variant spectrum of the CNGA3 gene in patients affected by achromatopsia."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "we provide a comprehensive overview of the CNGA3 variant spectrum in a cohort of 1060 genetically confirmed ACHM patients"
explanation: Demonstrates the role of genetic testing in confirming achromatopsia diagnosis across a large patient cohort.
- reference: url:https://www.ncbi.nlm.nih.gov/books/NBK1418/
reference_title: Achromatopsia - GeneReviews - NCBI Bookshelf
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
establishes the molecular diagnosis
explanation: >-
GeneReviews confirms that biallelic pathogenic or likely pathogenic
variants in ATF6, CNGA3, CNGB3, GNAT2, PDE6C, or PDE6H establish the
molecular diagnosis.
differential_diagnoses:
- name: Blue-cone monochromatism
description: >-
Blue-cone monochromatism overlaps through congenital severe visual acuity
reduction, infantile nystagmus, photophobia, normal-appearing fundus, and
poor color discrimination.
distinguishing_features:
- >-
X-linked inheritance and predominant male affection favor blue-cone
monochromatism over autosomal recessive achromatopsia.
- >-
Blue-cone monochromatism preserves S-cone function, so blue flashes on a
yellow background can elicit cone ERG responses.
- >-
Special four-color plate or two-color filter testing can distinguish
blue-cone monochromats from rod monochromats.
evidence:
- reference: url:https://www.ncbi.nlm.nih.gov/books/NBK1418/
reference_title: Achromatopsia - GeneReviews - NCBI Bookshelf
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Blue-cone monochromatism
explanation: >-
GeneReviews lists blue-cone monochromatism among inherited retinal
dystrophies to consider in the differential diagnosis of achromatopsia.
- name: Cone and cone-rod dystrophies
description: >-
Cone and cone-rod dystrophies overlap with achromatopsia through reduced
visual acuity, photophobia, glare sensitivity, and abnormal color vision.
distinguishing_features:
- >-
Disease progression over time favors cone or cone-rod dystrophy, whereas
achromatopsia is typically congenital and relatively stable.
- >-
Later onset and elevated dark-adapted rod thresholds support cone-rod
dystrophy rather than isolated congenital cone dysfunction.
evidence:
- reference: url:https://www.ncbi.nlm.nih.gov/books/NBK1418/
reference_title: Achromatopsia - GeneReviews - NCBI Bookshelf
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Best clinical discriminator is disease progression."
explanation: >-
GeneReviews identifies progression as a key discriminator between
achromatopsia and cone/cone-rod dystrophies.
- name: Cerebral achromatopsia or dyschromatopsia
description: >-
Acquired cortical color vision disorders can mimic severe color
discrimination loss but reflect post-chiasmal brain injury rather than
congenital cone photoreceptor dysfunction.
distinguishing_features:
- >-
Acute or acquired onset after cortical trauma, cerebral infarction, or other
neurologic injury favors cerebral achromatopsia or dyschromatopsia.
- >-
Normal retinal structure and retinal ERG responses favor cerebral rather
than retinal achromatopsia.
evidence:
- reference: url:https://www.ncbi.nlm.nih.gov/books/NBK1418/
reference_title: Achromatopsia - GeneReviews - NCBI Bookshelf
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
cerebral achromatopsia or dyschromatopsia
explanation: >-
GeneReviews includes acquired cerebral color-vision disorders in the
differential diagnosis of achromatopsia.
treatments:
- name: Gene Augmentation Therapy (CNGA3)
description: >
Subretinal delivery of AAV8 vectors carrying wild-type CNGA3 cDNA under
a cone-specific promoter (human cone arrestin ARR3 promoter). Published
phase I data and an active-not-recruiting phase 1/2 trial support continued
clinical study of CNGA3 gene augmentation, but this remains investigational
rather than an approved achromatopsia therapy.
treatment_term:
preferred_term: gene therapy
term:
id: MAXO:0001001
label: gene therapy
evidence:
- reference: PMID:32352493
reference_title: "Safety and Vision Outcomes of Subretinal Gene Therapy Targeting Cone Photoreceptors in Achromatopsia: A Nonrandomized Controlled Trial."
supports: PARTIAL
evidence_source: HUMAN_CLINICAL
snippet: "all 9 treated eyes demonstrated some level of improvement in secondary end points regarding cone function, including mean change in visual acuity of 2.9 letters (95% CI, 1.65-4.13; P = .006, 2-sided t test paired samples). Contrast sensitivity improved by a mean of 0.33 log (95% CI, 0.14-0.51 log; P = .003, 2-sided t test paired samples)."
explanation: >-
Phase I trial of AAV8.CNGA3 in nine adults showed safety and secondary
outcome signals, but the nonrandomized early-phase design keeps this
treatment investigational.
- reference: PMID:34006508
reference_title: "Three-year results of phase I retinal gene therapy trial for CNGA3-mutated achromatopsia."
supports: PARTIAL
evidence_source: HUMAN_CLINICAL
snippet: "The functional benefits that were noted in the treated eye at year 1 were persistent throughout the following visits at years 2 and 3."
explanation: >-
Three-year follow-up supports durable outcome signals after phase I
treatment, while remaining early-phase investigational evidence.
- reference: PMID:34006508
reference_title: "Three-year results of phase I retinal gene therapy trial for CNGA3-mutated achromatopsia."
supports: PARTIAL
evidence_source: HUMAN_CLINICAL
snippet: "No adverse or serious adverse events deemed related to the study drug occurred after year 1. Safety of the therapy, as the primary endpoint of this trial, can, therefore, be confirmed."
explanation: >-
Supports longer-term safety within a phase I cohort but does not establish
approval-level efficacy.
- reference: clinicaltrials:NCT02610582
reference_title: >-
Safety and Efficacy of a Bilateral Single Subretinal Injection of
rAAV.hCNGA3 in Adult and Minor Patients With CNGA3-linked Achromatopsia
Investigated in a Randomized, Wait List Controlled, Observer-masked Trial
supports: PARTIAL
evidence_source: HUMAN_CLINICAL
snippet: >-
The purpose of this study is to proof the safety and efficacy of a single
bilateral subretinal injection of rAAV.hCNGA3 in adult and minor patients
with CNGA3-linked achromatopsia.
explanation: >-
ClinicalTrials.gov documents a phase 1/2 rAAV.hCNGA3 trial; this supports
investigational clinical evaluation rather than approved use.
- name: Gene Augmentation Therapy (CNGB3)
description: >
Subretinal AAV-mediated delivery of CNGB3 aims to restore cone CNG channel
function. Preclinical studies in CNGB3-mutant dogs demonstrated stable
restoration of cone function for at least 33 months. Human phase 1/2 trials
NCT02599922 and NCT03001310 document active-not-recruiting and completed
investigational programs, respectively; efficacy remains under evaluation.
treatment_term:
preferred_term: gene therapy
term:
id: MAXO:0001001
label: gene therapy
evidence:
- reference: PMID:20378608
reference_title: "Gene therapy rescues cone function in congenital achromatopsia."
supports: SUPPORT
evidence_source: MODEL_ORGANISM
snippet: "rAAV-mediated gene replacement therapy with different forms of the human red cone opsin promoter led to the restoration of cone function and day vision in two canine models of CNGB3 achromatopsia"
explanation: Demonstrates successful restoration of cone function through CNGB3 gene therapy in the naturally occurring dog model.
- reference: PMID:20378608
reference_title: "Gene therapy rescues cone function in congenital achromatopsia."
supports: SUPPORT
evidence_source: MODEL_ORGANISM
snippet: "Subretinal administration of rAAV5-hCNGB3 with a long version of the red cone opsin promoter in younger animals led to a stable therapeutic effect for at least 33 months."
explanation: Demonstrates long-term durability of CNGB3 gene therapy effect in dogs.
- reference: clinicaltrials:NCT02599922
reference_title: >-
A Multiple-Site, Phase 1/2, Safety and Efficacy Trial of a Recombinant
Adeno-associated Virus Vector Expressing CNGB3 in Patients With
Congenital Achromatopsia Caused by Mutations in the CNGB3 Gene
supports: PARTIAL
evidence_source: HUMAN_CLINICAL
snippet: >-
This will be a non-randomized, open-label, Phase 1/2 study of the safety
and efficacy of AGTC-401 administered to one eye by subretinal injection
in individuals with achromatopsia caused by mutations in the CNGB3 gene.
explanation: >-
Supports investigational human evaluation of CNGB3 gene augmentation, with
a primary safety endpoint and secondary efficacy endpoint.
- reference: clinicaltrials:NCT03001310
reference_title: >-
An Open Label, Multi-centre, Phase I/II Dose Escalation Trial of a
Recombinant Adeno-associated Virus Vector (AAV2/8-hCARp.hCNGB3) for Gene
Therapy of Adults and Children With Achromatopsia Owing to Defects in
CNGB3
supports: PARTIAL
evidence_source: HUMAN_CLINICAL
snippet: "A clinical trial of AAV - CNGB3 retinal gene therapy for patients with achromatopsia"
explanation: >-
Documents a completed CNGB3 AAV trial, supporting trial activity without
implying established clinical efficacy.
- name: Tinted Contact Lenses and Filters
description: >
Dark glasses, special filter glasses, red or magenta-tinted contact lenses,
and sun-protection strategies reduce photophobia and may improve visual
comfort and contrast sensitivity by limiting glare and rod saturation in
photopic conditions.
treatment_term:
preferred_term: supportive care
term:
id: MAXO:0000950
label: supportive care
target_phenotypes:
- preferred_term: Photophobia
term:
id: HP:0000613
label: Photophobia
evidence:
- reference: url:https://www.ncbi.nlm.nih.gov/books/NBK1418/
reference_title: Achromatopsia - GeneReviews - NCBI Bookshelf
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Dark or special filter glasses or red-tinted contact lenses
explanation: >-
GeneReviews recommends tinted lenses or filter glasses to reduce
photophobia and improve functional comfort.
- name: Low Vision Aids
description: >
Magnification devices, high-contrast displays, preferential classroom
seating, adaptive educational or occupational technologies, and other
low-vision accommodations help patients manage reduced visual acuity in
school, work, and daily activities.
treatment_term:
preferred_term: supportive care
term:
id: MAXO:0000950
label: supportive care
target_phenotypes:
- preferred_term: Severely reduced visual acuity
term:
id: HP:0001141
label: Severely reduced visual acuity
evidence:
- reference: url:https://www.ncbi.nlm.nih.gov/books/NBK1418/
reference_title: Achromatopsia - GeneReviews - NCBI Bookshelf
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
low vision aids; preferential classroom seating for children; occupational aids
explanation: >-
GeneReviews supports low-vision, classroom, and occupational
accommodations as practical management.
- name: Ophthalmologic Surveillance
description: >
Regular ophthalmologic follow-up monitors acuity, refractive error, fundus
and OCT changes, photophobia management, and low-vision needs. Children
should be followed more frequently because visual development, refractive
correction, and educational accommodations change rapidly.
treatment_term:
preferred_term: eye examination
term:
id: MAXO:0001155
label: eye examination
evidence:
- reference: url:https://www.ncbi.nlm.nih.gov/books/NBK1418/
reference_title: Achromatopsia - GeneReviews - NCBI Bookshelf
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Ophthalmologic examination every six to 12 months for children
explanation: >-
GeneReviews recommends ophthalmologic surveillance every six to 12 months
for children and every two to three years for adults.
- name: Genetic Counseling
description: >
Genetic counseling explains autosomal recessive inheritance, carrier testing
for at-risk relatives, recurrence risk, and reproductive options once the
familial pathogenic variants are known.
treatment_term:
preferred_term: genetic counseling
term:
id: MAXO:0000079
label: genetic counseling
evidence:
- reference: url:https://www.ncbi.nlm.nih.gov/books/NBK1418/
reference_title: Achromatopsia - GeneReviews - NCBI Bookshelf
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
each sib of an affected individual has a 25% chance of being affected
explanation: >-
GeneReviews supports counseling around autosomal recessive recurrence risk
and available carrier, prenatal, and preimplantation testing.
clinical_trials:
- name: NCT02610582
phase: PHASE_I
status: ACTIVE_NOT_RECRUITING
description: >-
Combined phase 1/2 rAAV.hCNGA3 subretinal gene-augmentation trial for adult
and minor patients with CNGA3-linked achromatopsia, listed as active but
not recruiting by ClinicalTrials.gov.
target_phenotypes:
- preferred_term: Achromatopsia
term:
id: HP:0011516
label: Achromatopsia
evidence:
- reference: clinicaltrials:NCT02610582
reference_title: >-
Safety and Efficacy of a Bilateral Single Subretinal Injection of
rAAV.hCNGA3 in Adult and Minor Patients With CNGA3-linked Achromatopsia
Investigated in a Randomized, Wait List Controlled, Observer-masked Trial
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
The purpose of this study is to proof the safety and efficacy of a single
bilateral subretinal injection of rAAV.hCNGA3 in adult and minor patients
with CNGA3-linked achromatopsia.
explanation: >-
ClinicalTrials.gov documents the CNGA3-linked achromatopsia gene-therapy
trial and its safety/efficacy purpose.
notes: >-
ClinicalTrials.gov lists phases PHASE1 and PHASE2; this schema stores
PHASE_I as the nearest single early-phase value. Status checked against the
ClinicalTrials.gov API on 2026-05-31.
- name: NCT02599922
phase: PHASE_I
status: ACTIVE_NOT_RECRUITING
description: >-
Combined phase 1/2 AGTC-401 AAV-CNGB3 trial administering subretinal gene
therapy to one eye in individuals with CNGB3-related achromatopsia, listed
as active but not recruiting by ClinicalTrials.gov.
target_phenotypes:
- preferred_term: Achromatopsia
term:
id: HP:0011516
label: Achromatopsia
evidence:
- reference: clinicaltrials:NCT02599922
reference_title: >-
A Multiple-Site, Phase 1/2, Safety and Efficacy Trial of a Recombinant
Adeno-associated Virus Vector Expressing CNGB3 in Patients With
Congenital Achromatopsia Caused by Mutations in the CNGB3 Gene
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
This will be a non-randomized, open-label, Phase 1/2 study of the safety
and efficacy of AGTC-401 administered to one eye by subretinal injection
in individuals with achromatopsia caused by mutations in the CNGB3 gene.
explanation: >-
ClinicalTrials.gov documents the AGTC-401 CNGB3 trial design and
endpoints.
notes: >-
ClinicalTrials.gov lists phases PHASE1 and PHASE2; this schema stores
PHASE_I as the nearest single early-phase value. Status checked against the
ClinicalTrials.gov API on 2026-05-31.
- name: NCT03001310
phase: PHASE_I
status: COMPLETED
description: >-
Completed phase 1/2 open-label dose-escalation AAV2/8-CNGB3 trial for
adults and children with CNGB3-related achromatopsia.
target_phenotypes:
- preferred_term: Achromatopsia
term:
id: HP:0011516
label: Achromatopsia
evidence:
- reference: clinicaltrials:NCT03001310
reference_title: >-
An Open Label, Multi-centre, Phase I/II Dose Escalation Trial of a
Recombinant Adeno-associated Virus Vector (AAV2/8-hCARp.hCNGB3) for Gene
Therapy of Adults and Children With Achromatopsia Owing to Defects in
CNGB3
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "A clinical trial of AAV - CNGB3 retinal gene therapy for patients with achromatopsia"
explanation: >-
ClinicalTrials.gov documents a completed CNGB3 retinal gene-therapy trial.
notes: >-
ClinicalTrials.gov lists phases PHASE1 and PHASE2; this schema stores
PHASE_I as the nearest single early-phase value. Status checked against the
ClinicalTrials.gov API on 2026-05-31.
animal_models:
- species: Mouse
genotype: Cnga3 knockout (Cnga3-/-)
description: >
The Cnga3 knockout mouse recapitulates cone dysfunction with absent cone
ERG responses. Used extensively for preclinical gene therapy studies.
AAV-mediated CNGA3 gene delivery restores cone function in these mice.
evidence:
- reference: PMID:34860352
reference_title: "Achromatopsia: Genetics and Gene Therapy."
supports: SUPPORT
evidence_source: MODEL_ORGANISM
snippet: "research activities have intensified over the past decade and have led to several preclinical gene therapy studies that have shown functional and morphological improvements in animal models of ACHM."
explanation: Summarizes preclinical gene therapy success in animal models including Cnga3-deficient mice.
- species: Mouse
genotype: Cpfl5 (Cngb3 mutant)
description: >
The cpfl5 mouse carries a spontaneous Cngb3 mutation causing cone
photoreceptor function loss. Preclinical gene therapy studies in this
model demonstrated restoration of cone-mediated vision.
evidence:
- reference: PMID:34860352
reference_title: "Achromatopsia: Genetics and Gene Therapy."
supports: SUPPORT
evidence_source: MODEL_ORGANISM
snippet: "research activities have intensified over the past decade and have led to several preclinical gene therapy studies that have shown functional and morphological improvements in animal models of ACHM."
explanation: Summarizes preclinical gene therapy success in animal models including Cngb3-mutant mice.
- species: Dog
genotype: CNGB3 mutant (Alaskan Malamute)
description: >
Naturally occurring CNGB3 mutation in Alaskan Malamute dogs causes
day blindness (hemeralopia). This large animal model has been critical
for preclinical gene therapy development, demonstrating long-term
restoration of cone function after AAV-CNGB3 gene therapy.
evidence:
- reference: PMID:20378608
reference_title: "Gene therapy rescues cone function in congenital achromatopsia."
supports: SUPPORT
evidence_source: MODEL_ORGANISM
snippet: "the primary cone photoreceptor disorder achromatopsia served as the ideal translational model to develop gene therapy directed to cone photoreceptors."
explanation: CNGB3-mutant dogs are the key translational model for achromatopsia gene therapy.
- reference: PMID:29020838
reference_title: "Safety and Efficacy of AAV5 Vectors Expressing Human or Canine CNGB3 in CNGB3-Mutant Dogs."
supports: SUPPORT
evidence_source: MODEL_ORGANISM
snippet: "Studies in CNGB3-mutant dogs showed that subretinal injection of an AAV vector expressing human CNGB3, which has 76% amino acid identity with canine CNGB3, driven by a 2.1 kb human red cone opsin promoter (PR2.1) and packaged in AAV5 capsids (AAV5-PR2.1-hCNGB3) rescued cone photoreceptor function"
explanation: Demonstrates successful cone function rescue with AAV5-CNGB3 in the dog model.
- species: Dog
genotype: CNGA3 mutant (German Shepherd)
description: >
Naturally occurring CNGA3 mutation in German Shepherd dogs causes
achromatopsia. Used for CNGA3 gene therapy preclinical studies.
evidence:
- reference: PMID:34860352
reference_title: "Achromatopsia: Genetics and Gene Therapy."
supports: SUPPORT
evidence_source: MODEL_ORGANISM
snippet: "These encouraging preclinical data helped advance multiple gene therapy programs for CNGA3- and CNGB3-linked ACHM into the clinical phase."
explanation: Confirms the role of CNGA3-mutant dogs in advancing gene therapy programs to clinical trials.
datasets: []
references:
- reference: url:https://www.ncbi.nlm.nih.gov/books/NBK1418/
title: Achromatopsia - GeneReviews - NCBI Bookshelf
tags:
- GeneReviews
findings:
- statement: >-
GeneReviews provides baseline diagnosis, subtype scope, management,
surveillance, genetic counseling, and differential diagnosis for
achromatopsia.
supporting_text: >-
The diagnosis of achromatopsia is established in a proband through
clinical and family history, examination for nystagmus, visual acuity
testing, color vision assessment, and fundoscopic examination.
evidence:
- reference: url:https://www.ncbi.nlm.nih.gov/books/NBK1418/
reference_title: Achromatopsia - GeneReviews - NCBI Bookshelf
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
visual acuity testing, color vision assessment, and fundoscopic examination
explanation: >-
GeneReviews anchors the diagnostic and management updates added for the
review issue.
This report is retrieval-only and is generated directly from Asta results.
search_papers_by_relevance with snippet_search.Question: You are an expert researcher providing comprehensive, well-cited information.
Provide detailed information focusing on: 1. Key concepts and definitions with current understanding 2. Recent developments and latest research (prioritize 2023-2024 sources) 3. Current applications and real-world implementations 4. Expert opinions and analysis from authoritative sources 5. Relevant statistics and data from recent studies
Format as a comprehensive research report with proper citations. Include URLs and publication dates where available. Always prioritize recent, authoritative sources and provide specific citations for all major claims.
Please provide a comprehensive research report on Achromatopsia covering all of the disease characteristics listed below. This report will be used to populate a disease knowledge base entry. Be thorough and cite primary literature (PMID preferred) for all claims.
For each section, suggested databases/resources are listed. These are the first places you should search for information on each topic.
Search first: OMIM, Orphanet, ICD-10/ICD-11, MeSH, PubMed
Search first: PubMed, Cochrane Library, UpToDate, clinical guidelines, ClinVar, ClinGen, GWAS Catalog, PheGenI, CTD, CDC, WHO, epidemiological databases
Search first: PubMed, Cochrane Library, clinical trial databases, GWAS Catalog, gnomAD, WHO, CDC, nutrition databases
Search first: CTD, PubMed, PheGenI, GxE databases
Search first: HPO (Human Phenotype Ontology), OMIM, Orphanet, PubMed, clinicaltrials.gov, MedDRA, SNOMED CT, DECIPHER, LOINC
For each phenotype, provide: - Phenotype type: symptoms, clinical signs, physical manifestations, behavioral changes, or laboratory abnormalities
For symptoms/signs: HPO, OMIM, Orphanet, PubMed For behavioral changes: HPO, DSM, RDoC (Research Domain Criteria), PubMed For laboratory abnormalities: LOINC, SNOMED CT, LabTests Online, PubMed - Phenotype characteristics: Search first: OMIM, Orphanet, HPO, PubMed - Age of symptom onset (neonatal, childhood, adult-onset, late-onset) - Symptom severity (mild, moderate, severe, variable) - Symptom progression (stable, progressive, episodic, fluctuating) - Frequency among affected individuals (percentage or qualitative) - Quality of life impact: Effects on daily functioning and well-being (per-phenotype when possible) Search first: EQ-5D database, SF-36, WHO QOL databases, PubMed - Suggest HPO (Human Phenotype Ontology) terms for each phenotype
Search first: OMIM, ClinVar, HGMD, Ensembl, NCBI Gene
Search first: ENCODE, Roadmap Epigenomics, MethBase, DiseaseMeth
Search first: DECIPHER, ClinVar, ECARUCA, UCSC Genome Browser
Search first: CTD (Comparative Toxicogenomics Database), TOXNET, PubMed, EPA databases
Search first: CDC databases, WHO, PubMed, NHANES
Search first: NCBI Taxonomy, ViPR, BV-BRC, MicrobeDB, GIDEON
Search first: KEGG, Reactome, WikiPathways, PathBank, BioCyc
Search first: Gene Ontology (GO), Reactome, KEGG, PubMed
Search first: UniProt, PDB (Protein Data Bank), InterPro, Pfam, AlphaFold
Search first: KEGG, BioCyc, HMDB (Human Metabolome Database), BRENDA
Search first: ImmPort, Immunome Database, IEDB, Gene Ontology
Search first: PubMed, Gene Ontology, Reactome
Search first: BRENDA, UniProt, KEGG, OMIM, PubMed
Search first: ENCODE, Roadmap Epigenomics, MethBase, DiseaseMeth
For each mechanism, describe: - The causal chain from initial trigger to clinical manifestation - Which mechanisms are upstream vs downstream - What cell types and biological processes are involved - Suggest GO terms for biological processes and CL terms for cell types
Search first: Uberon, FMA (Foundational Model of Anatomy), OMIM, HPO, ICD-11, MeSH, SNOMED CT
Search first: Uberon, Human Protein Atlas, Cell Ontology, Human Cell Atlas, CellMarker, PanglaoDB
Search first: Gene Ontology (Cellular Component), UniProt, Human Protein Atlas
Search first: OMIM, Orphanet, HPO, PubMed
Search first: Disease registries, longitudinal cohort databases, natural history studies, PubMed, Orphanet, OMIM
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Structure your response as a comprehensive narrative organized by the sections above. For each section, provide: - Factual content with specific details (numbers, percentages, gene names, variant nomenclature) - Ontology term suggestions (HPO, GO, CL, UBERON, CHEBI, MAXO, MONDO) where applicable - Evidence citations with PMIDs - Direct quotes from abstracts to support key claims - Clear indication when information is not available or not applicable for this disease
This report will be used to populate a disease knowledge base entry with: - Pathophysiology descriptions with causal chains - Gene/protein annotations (HGNC, GO terms) - Phenotype associations (HP terms) with frequencies - Cell type involvement (CL terms) - Anatomical locations (UBERON terms) - Chemical entities (CHEBI terms) - Treatment annotations (MAXO terms) - Evidence items with PMIDs and exact abstract quotes - Epidemiology, prognosis, diagnostic, and prevention information - Animal model descriptions with phenotype recapitulation details
Achromatopsia (ACHM) is a rare congenital cone photoreceptor disorder (cone dysfunction syndrome) with onset at birth/early infancy and a characteristic triad of markedly reduced visual acuity, photophobia/photoaversion, and absent/markedly impaired color discrimination, often accompanied by infantile nystagmus. It is most commonly autosomal recessive and caused by biallelic loss-of-function variants in cone phototransduction genes—especially CNGA3 and CNGB3—with additional rarer causes including GNAT2, PDE6C, PDE6H, and ATF6. The best-supported disease mechanism is failure of cone phototransduction/cGMP-gated ion channel signaling (CNGA3/CNGB3/PDE6/GNAT2) and, for ATF6-ACHM, a developmental cone deficit linked to ER/UPR biology. Clinical management today is largely supportive (filters, low-vision rehabilitation), but multiple AAV subretinal gene-replacement trials* are in late phase I/II stages for CNGA3- and CNGB3-ACHM, with early signals of safety and functional benefit in subsets of participants.
Note (identifier coverage limitation): OMIM/Orphanet/ICD-10/ICD-11/MeSH identifiers were not retrieved in the available evidence chunks in this run; they should be added from OMIM/Orphanet/ICD/MeSH primary sources in a follow-on extraction.
| Identifier system | ID/value | Notes | Source (include URL/publication year if present) |
|---|---|---|---|
| Disease name | Achromatopsia | Rare congenital cone photoreceptor disorder; commonly presents at birth or early infancy with poor visual acuity, nystagmus, photophobia, and loss of color vision; autosomal recessive | Baxter & Borchert 2024, Int J Mol Sci, https://doi.org/10.3390/ijms25179739 (2024) (baxter2024genetherapyfor pages 1-2) |
| MONDO | MONDO:0018852 | OpenTargets lists achromatopsia under MONDO_0018852 | OpenTargets disease-target association context (OpenTargets Search: Achromatopsia) |
| Synonym | Rod monochromacy | Explicitly listed as an alternative name for achromatopsia | Andersen et al. 2023, Genes, https://doi.org/10.3390/genes14030690 (2023); Michalakis et al. 2022, Mol Diagn Ther, https://doi.org/10.1007/s40291-021-00565-z (2022) (andersen2023geneticandclinical pages 1-2, michalakis2022achromatopsiageneticsand pages 1-2) |
| Synonym | Total color blindness | Used as an alternative disease name/descriptor | Michalakis et al. 2022, Mol Diagn Ther, https://doi.org/10.1007/s40291-021-00565-z (2022) (michalakis2022achromatopsiageneticsand pages 1-2) |
| Inheritance | Autosomal recessive | Consistently reported across reviews and clinical studies | Baxter & Borchert 2024, https://doi.org/10.3390/ijms25179739 (2024); Michalakis et al. 2022, https://doi.org/10.1007/s40291-021-00565-z (2022) (baxter2024genetherapyfor pages 1-2, michalakis2022achromatopsiageneticsand pages 1-2) |
| Prevalence estimate | ~1 in 30,000 | Commonly cited point estimate | Baxter & Borchert 2024, https://doi.org/10.3390/ijms25179739 (2024); Michalakis et al. 2022, https://doi.org/10.1007/s40291-021-00565-z (2022) (baxter2024genetherapyfor pages 1-2, michalakis2022achromatopsiageneticsand pages 1-2) |
| Prevalence estimate | 1 in 30,000–50,000 | Range reported in natural-history/clinical review sources | Andersen et al. 2023, https://doi.org/10.3390/genes14030690 (2023); Asensio-Sánchez 2020 (andersen2023geneticandclinical pages 1-2, asensiosanchez2020genetherapyfor pages 1-2) |
| Major causal genes | CNGA3; CNGB3 | Together account for up to ~90% of cases in recent reviews | Baxter & Borchert 2024, https://doi.org/10.3390/ijms25179739 (2024); Michalakis et al. 2022, https://doi.org/10.1007/s40291-021-00565-z (2022) (baxter2024genetherapyfor pages 1-2, michalakis2022achromatopsiageneticsand pages 1-2) |
| Other established causal genes | GNAT2; PDE6C; PDE6H; ATF6 | Recurrently listed as rarer achromatopsia genes | Baxter & Borchert 2024, https://doi.org/10.3390/ijms25179739 (2024); Michalakis et al. 2022, https://doi.org/10.1007/s40291-021-00565-z (2022) (baxter2024genetherapyfor pages 1-2, michalakis2022achromatopsiageneticsand pages 1-2) |
| OpenTargets associated targets | CNGA3; CNGB3; PDE6C; GNAT2; ATF6; PDE6H | Disease-target evidence also lists OPN1MW, OPN1LW, and CABP4, but the core Mendelian achromatopsia genes in retrieved review/clinical sources are CNGA3, CNGB3, GNAT2, PDE6C, PDE6H, and ATF6 | OpenTargets disease-target association context; corroborated by recent reviews (OpenTargets Search: Achromatopsia, baxter2024genetherapyfor pages 1-2, michalakis2022achromatopsiageneticsand pages 1-2) |
Table: This table summarizes key disease identifiers, synonyms, inheritance, prevalence, and causal genes for achromatopsia using only retrieved evidence. It is useful as a compact normalization reference for a disease knowledge base entry.
No specific environmental exposures or protective factors are established as causal for congenital achromatopsia in the retrieved evidence; ACHM is primarily genetic (baxter2024genetherapyfor pages 1-2, michalakis2022achromatopsiageneticsand pages 1-2).
No gene–environment interaction evidence specific to ACHM was present in the retrieved sources.
| Gene (HGNC symbol) | Protein/function in cone | Pathway step (phototransduction/CNG/UPR) | Typical inheritance | Relative contribution/proportion if stated in evidence | Notes on phenotype (complete vs incomplete; progression) | Key sources (with URL/year) |
|---|---|---|---|---|---|---|
| CNGA3 | Alpha subunit of the cone cyclic nucleotide-gated (CNG) channel; part of the final step converting cGMP changes into cone electrical responses (baxter2024genetherapyfor pages 1-2, baxter2024genetherapyfor pages 2-3, gerhardt2023biologypathobiologyand pages 1-2) | CNG / cone phototransduction | Autosomal recessive (baxter2024genetherapyfor pages 1-2, michalakis2022achromatopsiageneticsand pages 1-2) | Together with CNGB3, accounts for up to ~90% of ACHM; older review gives CNGA3 alone ~25% (baxter2024genetherapyfor pages 1-2, michalakis2022achromatopsiageneticsand pages 1-2, asensiosanchez2020genetherapyfor pages 1-2) | Can cause complete or incomplete ACHM; incomplete forms reported particularly with some missense variants in CNGA3; no strong genotype-phenotype correlation overall; progression less commonly documented than for CNGB3/PDE6C in Danish cohort (moussawi2021genetherapyin pages 1-3, andersen2023geneticandclinical pages 1-2, baxter2024genetherapyfor pages 1-2, andersen2023geneticandclinical pages 7-9) | Baxter & Borchert 2024, https://doi.org/10.3390/ijms25179739 (2024); Michalakis et al. 2022, https://doi.org/10.1007/s40291-021-00565-z (2022); Gerhardt et al. 2023, https://doi.org/10.3390/biomedicines11020269 (2023) (baxter2024genetherapyfor pages 1-2, michalakis2022achromatopsiageneticsand pages 1-2, gerhardt2023biologypathobiologyand pages 2-5) |
| CNGB3 | Beta subunit of the cone CNG channel; required with CNGA3 for functional cone CNG channel assembly and normal cone responses (baxter2024genetherapyfor pages 1-2, michalakis2022achromatopsiageneticsand pages 1-2, brotherton2024molecularmechanismsgoverning pages 3-5) | CNG / cone phototransduction | Autosomal recessive (baxter2024genetherapyfor pages 1-2, michalakis2022achromatopsiageneticsand pages 1-2) | Together with CNGA3, up to ~90% of ACHM; older review gives CNGB3 alone ~50% of autosomal recessive ACHM (baxter2024genetherapyfor pages 1-2, michalakis2022achromatopsiageneticsand pages 1-2, asensiosanchez2020genetherapyfor pages 7-10) | Often associated with complete achromatopsia in review evidence; progressive BCVA deterioration attributable to ACHM was observed in some CNGB3 patients in long-term Danish follow-up (moussawi2021genetherapyin pages 1-3, andersen2023geneticandclinical pages 1-2, andersen2023geneticandclinical pages 7-9) | Baxter & Borchert 2024, https://doi.org/10.3390/ijms25179739 (2024); Michalakis et al. 2022, https://doi.org/10.1007/s40291-021-00565-z (2022); Asensio-Sánchez 2020 (baxter2024genetherapyfor pages 1-2, michalakis2022achromatopsiageneticsand pages 1-2, asensiosanchez2020genetherapyfor pages 7-10) |
| GNAT2 | Cone transducin alpha subunit; couples activated cone opsin to PDE activation in phototransduction (baxter2024genetherapyfor pages 1-2, yang2024dyschromatopsiaacomprehensive pages 4-5, baxter2024genetherapyfor pages 2-3) | Phototransduction | Autosomal recessive (disease-level ACHM inheritance) (baxter2024genetherapyfor pages 1-2, michalakis2022achromatopsiageneticsand pages 1-2) | Rare; older review states <2% (asensiosanchez2020genetherapyfor pages 1-2) | Missense GNAT2 variants have been associated with incomplete achromatopsia and relative preservation of cone structure/function in some reports; Danish cohort suggested myopia may be more frequent with GNAT2 and no BCVA deterioration was reported in that cohort subset (moussawi2021genetherapyin pages 1-3, andersen2023geneticandclinical pages 7-9, yang2024dyschromatopsiaacomprehensive pages 4-5) | Baxter & Borchert 2024, https://doi.org/10.3390/ijms25179739 (2024); Yang et al. 2024, https://doi.org/10.3389/fnins.2024.1265630 (2024); Asensio-Sánchez 2020 (baxter2024genetherapyfor pages 1-2, yang2024dyschromatopsiaacomprehensive pages 4-5, asensiosanchez2020genetherapyfor pages 1-2) |
| PDE6C | Cone phosphodiesterase catalytic subunit; hydrolyzes cGMP in response to transducin activation (baxter2024genetherapyfor pages 1-2, yang2024dyschromatopsiaacomprehensive pages 6-8, baxter2024genetherapyfor pages 2-3) | Phototransduction / cGMP metabolism | Autosomal recessive (disease-level ACHM inheritance) (baxter2024genetherapyfor pages 1-2, michalakis2022achromatopsiageneticsand pages 1-2) | Rare; older review states <2% (asensiosanchez2020genetherapyfor pages 1-2) | Missense PDE6C variants can be associated with incomplete ACHM in review evidence, but PDE6C is also linked to more progressive cone disease in some reports; Danish cohort found progression attributable to ACHM in PDE6C and more frequent myopia/severe myopia (moussawi2021genetherapyin pages 1-3, andersen2023geneticandclinical pages 1-2, andersen2023geneticandclinical pages 7-9, yang2024dyschromatopsiaacomprehensive pages 4-5) | Baxter & Borchert 2024, https://doi.org/10.3390/ijms25179739 (2024); Yang et al. 2024, https://doi.org/10.3389/fnins.2024.1265630 (2024); Nouri et al. 2024, https://doi.org/10.1186/s12920-024-01942-3 (2024) (baxter2024genetherapyfor pages 1-2, yang2024dyschromatopsiaacomprehensive pages 6-8) |
| PDE6H | Cone phosphodiesterase gamma/inhibitory subunit; regulates cone PDE activity and therefore cGMP levels (baxter2024genetherapyfor pages 1-2, yang2024dyschromatopsiaacomprehensive pages 6-8, yang2024dyschromatopsiaacomprehensive pages 4-5) | Phototransduction / cGMP metabolism | Autosomal recessive (disease-level ACHM inheritance) (baxter2024genetherapyfor pages 1-2, michalakis2022achromatopsiageneticsand pages 1-2) | Very rare; older review states <1% (asensiosanchez2020genetherapyfor pages 1-2) | Missense PDE6H variants have been associated with incomplete achromatopsia in review evidence; Danish cohort found no BCVA deterioration in PDE6H subset but a high proportion with myopia/severe myopia (moussawi2021genetherapyin pages 1-3, andersen2023geneticandclinical pages 7-9, yang2024dyschromatopsiaacomprehensive pages 6-8) | Baxter & Borchert 2024, https://doi.org/10.3390/ijms25179739 (2024); Yang et al. 2024, https://doi.org/10.3389/fnins.2024.1265630 (2024); Asensio-Sánchez 2020 (baxter2024genetherapyfor pages 1-2, yang2024dyschromatopsiaacomprehensive pages 6-8, asensiosanchez2020genetherapyfor pages 1-2) |
| ATF6 | Activating transcription factor 6; ER membrane transcription factor regulating unfolded protein response and essential for human cone photoreceptor development (michalakis2022achromatopsiageneticsand pages 1-2, yang2024dyschromatopsiaacomprehensive pages 6-8) | UPR / ER homeostasis / cone development | Autosomal recessive (disease-level ACHM inheritance) (baxter2024genetherapyfor pages 1-2, michalakis2022achromatopsiageneticsand pages 1-2) | Rare; older review states ~1–2% (asensiosanchez2020genetherapyfor pages 1-2) | Mechanistically distinct from phototransduction genes; associated with developmental cone defects and foveal hypoplasia/absence of cone structures rather than only signaling failure; may provide fewer residual cone targets for classic gene replacement; pharmacologic ATF6 activation has shown rescue of cone growth/gene expression in patient organoids (yang2024dyschromatopsiaacomprehensive pages 6-8, yang2024dyschromatopsiaacomprehensive pages 4-5) | Kroeger et al. 2021, https://doi.org/10.1073/pnas.2103196118 (2021); Michalakis et al. 2022, https://doi.org/10.1007/s40291-021-00565-z (2022); Yang et al. 2024, https://doi.org/10.3389/fnins.2024.1265630 (2024) (michalakis2022achromatopsiageneticsand pages 1-2, yang2024dyschromatopsiaacomprehensive pages 6-8) |
Table: This table summarizes the established achromatopsia genes, their functional roles in cone biology, and evidence-based phenotype notes. It is useful for linking genotype to mechanism, inheritance, and expected clinical presentation.
Across reviews and cohort studies, ACHM is consistently characterized by: - Reduced visual acuity (HPO suggestion: HP:0007663 Decreased visual acuity). Andersen et al. report VA “around 20/200” in typical cases (andersen2023geneticandclinical pages 1-2), and Baxter & Borchert note similar typical VA and that incomplete forms can have better acuity (20/40–20/120) (baxter2024genetherapyfor pages 1-2). - Color vision loss (HPO: HP:0000551 Abnormal color vision; for complete ACHM, HP:0000618 Achromatopsia). In a Danish cohort, “49” of 57 tested had complete color blindness and “eight had residual color vision” (andersen2023geneticandclinical pages 5-7). - Photophobia/photoaversion (HPO: HP:0000613 Photophobia). Chan et al. emphasize: “photoaversion has been described to be one of the more debilitating symptoms of achromatopsia” (chan2023morphologicalandfunctional pages 1-2). - Infantile/childhood nystagmus (HPO: HP:0000639 Nystagmus). In the Danish cohort, “Most patients (89%, n = 72) had a history of childhood nystagmus” (andersen2023geneticandclinical pages 5-7). Chan et al. report nystagmus in 88.5% among 61 patients (chan2023morphologicalandfunctional pages 4-6). - Refractive error (myopia/hyperopia) (HPO: HP:0000545 Myopia, HP:0000540 Hyperopia). In Andersen et al., myopia was more frequent in GNAT2/PDE6C/PDE6H subsets (75–80%) (andersen2023geneticandclinical pages 7-9).
Established ACHM genes in the retrieved evidence: CNGA3, CNGB3, GNAT2, PDE6C, PDE6H, ATF6 (baxter2024genetherapyfor pages 1-2, michalakis2022achromatopsiageneticsand pages 1-2). OpenTargets also links ACHM to these targets and provides supporting PubMed ID lists (e.g., CNGA3/CNGB3 evidence) and the MONDO mapping (OpenTargets Search: Achromatopsia).
The retrieved evidence primarily provides gene-level rather than variant-level detail. Variant class patterns inferred from the evidence include: - Loss-of-function variants are common drivers (recessive) in CNGA3/CNGB3-related ACHM (gong2024infantilenystagmussyndrome—associated pages 12-13). - Some reviews note incomplete ACHM may be associated with specific missense changes in GNAT2/CNGA3/PDE6C/PDE6H (moussawi2021genetherapyin pages 1-3).
Note (variant-level limitation): ClinVar/HGMD/gnomAD allele frequencies, ACMG classifications, and recurrent founder variants were not retrieved in the evidence chunks and thus cannot be reliably populated here.
No infectious, toxic, occupational, or lifestyle exposures were identified as causal contributors for congenital ACHM in the retrieved evidence.
Mechanistically, ACHM (for the phototransduction-gene forms) arises from disruption of the cone phototransduction cascade and/or the CNG channel that converts cGMP signaling into an electrical response: - Yang et al. (2024) explicitly summarize the cascade: “Activated PDE begins to hydrolyze cGMP efficiently. As the cGMP concentration decreases, the CNG channel closed” (yang2024dyschromatopsiaacomprehensive pages 6-8). They further describe a PDE6H mechanism: “cGMP gated channels are permanently closed” in a way “similar to permanent light stimulation” (yang2024dyschromatopsiaacomprehensive pages 6-8). - Michalakis et al. (2022) describe the core dark/light physiology: in darkness high cGMP keeps CNG channels open producing Na+/Ca2+ current and depolarization; in light, opsin→transducin→PDE reduces cGMP, closes channels, and hyperpolarizes the cone (michalakis2022achromatopsiageneticsand pages 1-2). - Downstream consequences include absent cone-mediated ERG components with preserved rod function (diagnostic hallmark) and cone degeneration; Michalakis et al. note early cone degeneration features including cGMP accumulation (michalakis2022achromatopsiageneticsand pages 4-5).
GO term suggestions (biological process): phototransduction (GO:0007602), cyclic nucleotide-mediated signaling (GO:0019935), cGMP metabolic process (GO:0046068), ion transmembrane transport (GO:0034220).
ATF6-associated ACHM is mechanistically distinct, involving ER homeostasis/UPR signaling and cone development: - Yang et al. (2024) state: “ATF6 ... plays a key role in unfolded protein response (UPR) and endoplasmic reticulum homeostasis” (yang2024dyschromatopsiaacomprehensive pages 6-8). - Michalakis et al. (2022) likewise describe ATF6 as an ER-localized transcription factor capable of activating the unfolded protein response (michalakis2022achromatopsiageneticsand pages 1-2).
Therapeutic implication (conceptual): Phototransduction-gene ACHM is amenable to gene supplementation (recessive loss-of-function), whereas ATF6-associated disease may have fewer intact cone structures to target and may require pathway modulation (yang2024dyschromatopsiaacomprehensive pages 4-5).
Note (population genetics limitation): No carrier frequencies, founder variants, or geographic variant distributions were retrievable from the evidence in this run.
A practical diagnostic workflow supported by the retrieved sources is: 1) Clinical phenotype (infantile onset, photophobia, nystagmus, color vision deficit), 2) ERG documenting absent cone responses with preserved rod responses, 3) OCT/FAF characterization of foveal/outer retinal structure, 4) genetic testing to identify causal gene(s) and determine eligibility for gene therapy trials (baxter2024genetherapyfor pages 1-2, andersen2023geneticandclinical pages 1-2, gong2024infantilenystagmussyndrome—associated pages 12-13).
Differential diagnosis (limited in retrieved evidence): The retrieved evidence does not provide a systematic differential diagnosis list; however, the context of inherited retinal diseases presenting with infantile nystagmus includes multiple entities (review context) (gong2024infantilenystagmussyndrome—associated pages 12-13). A dedicated differential diagnosis extraction would require additional sources.
MAXO suggestions: low vision rehabilitation (MAXO:0000787), prescription of optical filters (filter-lens intervention; MAXO term may need confirmation), assistive device use.
Key trials and implementation details (ClinicalTrials.gov plus 2024 expert synthesis): - CNGA3 AAV subretinal trials: NCT02610582 and NCT02935517 (NCT02610582 chunk 1, NCT02935517 chunk 1). - NCT02610582 includes subretinal administration and multiple functional endpoints including microperimetry and patient-reported outcomes (NCT02610582 chunk 1). - Gong & Hertle (2024) summarize a first CNGA3 trial: treatment “well tolerated, with no serious adverse events” and visual acuity/contrast sensitivity improvements persisting “for at least three years” (gong2024infantilenystagmussyndrome—associated pages 12-13). - CNGB3 AAV subretinal trials: NCT03001310 and NCT02599922 (NCT03001310 chunk 1, gong2024infantilenystagmussyndrome—associated pages 12-13). - NCT03001310 is a completed phase I/II dose-escalation trial using AAV2/8-hCARp.hCNGB3 with BCVA and retinal sensitivity endpoints at 24 weeks and QoL EQ-VAS measures (NCT03001310 chunk 1). - Gong & Hertle (2024) report that in one CNGB3 program, “rAAV2tYF-PR1.7-hCNGB3 treatment has improved photosensitivity in some patients” (gong2024infantilenystagmussyndrome—associated pages 12-13).
| NCT ID | Gene | Sponsor | Vector / promoter | Route | Phase | Age eligibility | Enrollment | Status | Primary endpoint(s) | Key secondary endpoints | Reported outcomes / development notes |
|---|---|---|---|---|---|---|---|---|---|---|---|
| NCT02610582 | CNGA3 | STZ eyetrial | rAAV.hCNGA3; AAV8.hCNGA3 reported in review; promoter not specified in ClinicalTrials.gov chunk | Subretinal injection after pars plana vitrectomy | Phase I/II | 6–12 years and >=18 years; pediatric cohort C n=6 | 13 | Active, not recruiting | Safety at 12 months; adverse events/abnormal labs related to treatment (NCT02610582 chunk 2, NCT02610582 chunk 1) | Contrast sensitivity (Pelli Robson) at 6 months; BCVA (ETDRS), microperimetry (MAIA), chromatic pupil campimetry, VFQ25/CVFQ, A3-PRO; broader efficacy measures of improved visual function (NCT02610582 chunk 2, NCT02610582 chunk 1) | Review reports 9 CNGA3-ACHM patients treated; well tolerated with no serious adverse events; increases in visual acuity and contrast sensitivity persisted for at least 3 years; phase IIb follow-up planned for second eye and children 6–12 years (gong2024infantilenystagmussyndrome—associated pages 12-13) |
| NCT02935517 | CNGA3 | Beacon Therapeutics | AGTC-402 / rAAV2tYF-PR1.7-hCNGA3 | Subretinal, one eye | Phase I/II | Adults >=18 years in groups 1–5; 6–17 years in group 3a; 4–8 years in groups 4a and 6 | 24 | Active, not recruiting | Safety: proportion with grade 3 or greater adverse events over 1 year (NCT02935517 chunk 1) | Change in visual acuity, light discomfort/light aversion, and color vision vs pretreatment over 1 year (NCT02935517 chunk 1) | Gong 2024 describes this as an open-label dose-escalation subretinal AAV2-variant trial using engineered cone opsin promoter; participants assigned to 4 dose groups in review summary; outcomes for CNGA3 arm described as less encouraging than CNGB3 in available review commentary (gong2024infantilenystagmussyndrome—associated pages 12-13, NCT02935517 chunk 1) |
| NCT02599922 | CNGB3 | Beacon Therapeutics | rAAV2tYF-PR1.7-hCNGB3 | Subretinal | Phase I/II | Not stated in retrieved ClinicalTrials.gov chunks; review describes adults and children across achromatopsia programs | 32 | Active, not recruiting | Not fully detailed in retrieved ClinicalTrials.gov chunks; review characterizes trial as phase I/II open-label dose-escalation (gong2024infantilenystagmussyndrome—associated pages 12-13) | Not fully detailed in retrieved ClinicalTrials.gov chunks; review notes visual-function secondary outcomes (gong2024infantilenystagmussyndrome—associated pages 12-13) | Gong 2024 reports sequential assignment to 4 dose groups and that rAAV2tYF-PR1.7-hCNGB3 improved photosensitivity in some patients (gong2024infantilenystagmussyndrome—associated pages 12-13) |
| NCT03758404 | CNGA3 | MeiraGTx UK II Ltd | AAV2/8-hG1.7p.coCNGA3 (review) | Not stated in retrieved ClinicalTrials.gov chunk; review groups these with similar subretinal phase I/II trials | Phase I/II | Adults and children (review) | 11 | Completed | Incidence of treatment-related adverse events at 6 months (review) (gong2024infantilenystagmussyndrome—associated pages 12-13) | Improvements in visual function (review) (gong2024infantilenystagmussyndrome—associated pages 12-13) | Gong 2024 describes this as similar to NCT03001310, evaluating AAV2/8-hG1.7p.coCNGA3 in adults and children (gong2024infantilenystagmussyndrome—associated pages 12-13) |
| NCT03001310 | CNGB3 | MeiraGTx UK II Ltd | AAV2/8-hCARp.hCNGB3 | Subretinal, single administration; low/intermediate/high dose escalation | Phase I/II | >=3 years | 23 | Completed | Composite safety over 6 weeks post administration, including serious ocular/non-ocular events possibly related to ATIMP (NCT03001310 chunk 1) | Week-24 change in BCVA (ETDRS), mean retinal sensitivity by static perimetry, and QoL (EQ-VAS) for children/adults (NCT03001310 chunk 1) | Gong 2024 also describes a similar phase I/II open-label dose-escalation trial in adults and children; primary outcome framed as treatment-related adverse events at 6 months and secondary outcomes as visual-function improvements (gong2024infantilenystagmussyndrome—associated pages 12-13, NCT03001310 chunk 1) |
Table: This table summarizes the key human CNGA3- and CNGB3-targeted gene therapy trials for achromatopsia using only retrieved ClinicalTrials.gov records and the 2024 Gong review. It is useful for comparing sponsors, vectors, eligibility, endpoints, and the current state of clinical development.
Expert opinion / analysis (authoritative source): Gong & Hertle (2024) frame molecular diagnosis as crucial for access to gene-based therapies and highlight that AAV-based subretinal gene therapy is actively being studied in CNGA3/CNGB3 ACHM with evolving outcome measures (gong2024infantilenystagmussyndrome—associated pages 12-13).
The retrieved evidence describes naturally occurring large-animal ACHM models used translationally (dogs, sheep) and engineered models (mice), which serve as comparative biology for disease mechanisms and therapies (gerhardt2023biologypathobiologyand pages 10-12, asensiosanchez2020genetherapyfor pages 7-10).
These components require additional targeted retrieval from OMIM/Orphanet/ClinVar/gnomAD/GeneReviews and guideline databases.
References
(andersen2023geneticandclinical pages 1-2): Mette Kjøbæk Gundestrup Andersen, Mette Bertelsen, Karen Grønskov, Susanne Kohl, and Line Kessel. Genetic and clinical characterization of danish achromatopsia patients. Genes, 14:690, Mar 2023. URL: https://doi.org/10.3390/genes14030690, doi:10.3390/genes14030690. This article has 19 citations.
(baxter2024genetherapyfor pages 1-2): Megan F. Baxter and Grace A. Borchert. Gene therapy for achromatopsia. International Journal of Molecular Sciences, 25:9739, Sep 2024. URL: https://doi.org/10.3390/ijms25179739, doi:10.3390/ijms25179739. This article has 17 citations.
(michalakis2022achromatopsiageneticsand pages 1-2): Stylianos Michalakis, Maximilian Gerhardt, Günther Rudolph, Siegfried Priglinger, and Claudia Priglinger. Achromatopsia: genetics and gene therapy. Molecular Diagnosis & Therapy, 26:51-59, Dec 2022. URL: https://doi.org/10.1007/s40291-021-00565-z, doi:10.1007/s40291-021-00565-z. This article has 74 citations and is from a peer-reviewed journal.
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(baxter2024genetherapyfor pages 2-3): Megan F. Baxter and Grace A. Borchert. Gene therapy for achromatopsia. International Journal of Molecular Sciences, 25:9739, Sep 2024. URL: https://doi.org/10.3390/ijms25179739, doi:10.3390/ijms25179739. This article has 17 citations.
(gerhardt2023biologypathobiologyand pages 1-2): Maximilian J. Gerhardt, Siegfried G. Priglinger, Martin Biel, and Stylianos Michalakis. Biology, pathobiology and gene therapy of cng channel-related retinopathies. Biomedicines, 11:269, Jan 2023. URL: https://doi.org/10.3390/biomedicines11020269, doi:10.3390/biomedicines11020269. This article has 20 citations.
(andersen2023geneticandclinical pages 7-9): Mette Kjøbæk Gundestrup Andersen, Mette Bertelsen, Karen Grønskov, Susanne Kohl, and Line Kessel. Genetic and clinical characterization of danish achromatopsia patients. Genes, 14:690, Mar 2023. URL: https://doi.org/10.3390/genes14030690, doi:10.3390/genes14030690. This article has 19 citations.
(gerhardt2023biologypathobiologyand pages 2-5): Maximilian J. Gerhardt, Siegfried G. Priglinger, Martin Biel, and Stylianos Michalakis. Biology, pathobiology and gene therapy of cng channel-related retinopathies. Biomedicines, 11:269, Jan 2023. URL: https://doi.org/10.3390/biomedicines11020269, doi:10.3390/biomedicines11020269. This article has 20 citations.
(brotherton2024molecularmechanismsgoverning pages 3-5): Chloe Brotherton and Roly Megaw. Molecular mechanisms governing sight loss in inherited cone disorders. Genes, 15:727, Jun 2024. URL: https://doi.org/10.3390/genes15060727, doi:10.3390/genes15060727. This article has 8 citations.
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(yang2024dyschromatopsiaacomprehensive pages 6-8): Zihao Yang, Lin Yan, Wenliang Zhang, Jia Qi, Wenjing An, and Kai Yao. Dyschromatopsia: a comprehensive analysis of mechanisms and cutting-edge treatments for color vision deficiency. Frontiers in Neuroscience, Jan 2024. URL: https://doi.org/10.3389/fnins.2024.1265630, doi:10.3389/fnins.2024.1265630. This article has 26 citations and is from a peer-reviewed journal.
(andersen2023geneticandclinical pages 5-7): Mette Kjøbæk Gundestrup Andersen, Mette Bertelsen, Karen Grønskov, Susanne Kohl, and Line Kessel. Genetic and clinical characterization of danish achromatopsia patients. Genes, 14:690, Mar 2023. URL: https://doi.org/10.3390/genes14030690, doi:10.3390/genes14030690. This article has 19 citations.
(chan2023morphologicalandfunctional pages 4-6): Caroline Chan, Berthold Seitz, and Barbara Käsmann-Kellner. Morphological and functional aspects and quality of life in patients with achromatopsia. Journal of Personalized Medicine, 13:1106, Jul 2023. URL: https://doi.org/10.3390/jpm13071106, doi:10.3390/jpm13071106. This article has 0 citations.
(gong2024infantilenystagmussyndrome—associated pages 12-13): Xiaoming Gong and Richard W. Hertle. Infantile nystagmus syndrome—associated inherited retinal diseases: perspectives from gene therapy clinical trials. Life, 14:1356, Oct 2024. URL: https://doi.org/10.3390/life14111356, doi:10.3390/life14111356. This article has 2 citations.
(michalakis2022achromatopsiageneticsand pages 4-5): Stylianos Michalakis, Maximilian Gerhardt, Günther Rudolph, Siegfried Priglinger, and Claudia Priglinger. Achromatopsia: genetics and gene therapy. Molecular Diagnosis & Therapy, 26:51-59, Dec 2022. URL: https://doi.org/10.1007/s40291-021-00565-z, doi:10.1007/s40291-021-00565-z. This article has 74 citations and is from a peer-reviewed journal.
(cosmo2024microperimetrysensitivitycorrelates pages 1-2): Eleonora Cosmo, Elisabetta Pilotto, Enrica Convento, Federico Parolini, and Edoardo Midena. Microperimetry sensitivity correlates to structural macular changes in adolescents with achromatopsia unlike other visual function tests. Journal of Clinical Medicine, 13:5968, Oct 2024. URL: https://doi.org/10.3390/jcm13195968, doi:10.3390/jcm13195968. This article has 0 citations.
(cosmo2024microperimetrysensitivitycorrelates pages 4-6): Eleonora Cosmo, Elisabetta Pilotto, Enrica Convento, Federico Parolini, and Edoardo Midena. Microperimetry sensitivity correlates to structural macular changes in adolescents with achromatopsia unlike other visual function tests. Journal of Clinical Medicine, 13:5968, Oct 2024. URL: https://doi.org/10.3390/jcm13195968, doi:10.3390/jcm13195968. This article has 0 citations.
(chan2023morphologicalandfunctional pages 6-8): Caroline Chan, Berthold Seitz, and Barbara Käsmann-Kellner. Morphological and functional aspects and quality of life in patients with achromatopsia. Journal of Personalized Medicine, 13:1106, Jul 2023. URL: https://doi.org/10.3390/jpm13071106, doi:10.3390/jpm13071106. This article has 0 citations.
(NCT02610582 chunk 1): Safety and Efficacy of rAAV.hCNGA3 Gene Therapy in Patients With CNGA3-linked Achromatopsia. STZ eyetrial. 2015. ClinicalTrials.gov Identifier: NCT02610582
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(NCT02610582 chunk 2): Safety and Efficacy of rAAV.hCNGA3 Gene Therapy in Patients With CNGA3-linked Achromatopsia. STZ eyetrial. 2015. ClinicalTrials.gov Identifier: NCT02610582
(gerhardt2023biologypathobiologyand pages 10-12): Maximilian J. Gerhardt, Siegfried G. Priglinger, Martin Biel, and Stylianos Michalakis. Biology, pathobiology and gene therapy of cng channel-related retinopathies. Biomedicines, 11:269, Jan 2023. URL: https://doi.org/10.3390/biomedicines11020269, doi:10.3390/biomedicines11020269. This article has 20 citations.