AIPL1-Related Retinopathy

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Classifications

Harrison's Part

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Inheritance

2

Autosomal recessive HP:0000007

The great majority of AIPL1-related retinopathy is caused by biallelic (homozygous or compound heterozygous) pathogenic variants.

Autosomal recessive inheritance

Show evidence (1 reference)

PMID:10873396 SUPPORT Human Clinical

"LCA is usually inherited in an autosomal recessive fashion, although rare dominant cases have been reported."

Confirms autosomal recessive inheritance as the predominant mode, with rare dominant-acting variants also documented.

Autosomal dominant HP:0000006

A minority of heterozygous AIPL1 variants, most notably the 12-bp (c.1053_1064del) in-frame deletion, cause dominant-acting cone-rod dystrophy or juvenile RP rather than the classic recessive LCA/EOSRD phenotype.

Autosomal dominant inheritance

Show evidence (2 references)

PMID:10873396 SUPPORT Human Clinical

"We also identified affected individuals in two apparently dominant families, diagnosed with juvenile retinitis pigmentosa or dominant cone-rod dystrophy, respectively, who are heterozygous for a 12-bp AIPL1 deletion."

Establishes the founding dominant-family evidence for the heterozygous 12-bp AIPL1 deletion.

PMID:33067476 SUPPORT Human Clinical

"p.A352_P355del associated with autosomal dominant cone-rod dystrophy."

Independently confirms the same in-frame deletion as a cause of autosomal dominant cone-rod dystrophy in a separate cohort.

◆

Subtypes

2

Classic Leber Congenital Amaurosis (Null Alleles)

Biallelic null (nonsense, frameshift, or splice-disrupting) AIPL1 variants, including the recurrent c.421C>T (historically termed W278X) allele, abolish AIPL1 chaperone function and cause the classic severe LCA phenotype: severe visual impairment or blindness from birth, an extinguished electroretinogram, and frequent maculopathy, keratoconus, and cataract.

Show evidence (2 references)

PMID:38880373 SUPPORT Human Clinical

"Twenty-six patients with LCA harbored two null AIPL1 variants, while 18 were homozygous for c.421C>T and 6 were heterozygous for c.421C>T with another loss-of-function variant."

This 51-patient cohort study establishes biallelic null variants, dominated by the recurrent c.421C>T allele, as the genotype underlying the classic LCA phenotype.

PMID:15249368 SUPPORT Human Clinical

"The phenotype of LCA in patients with AIPL1 mutations is relatively severe, with a maculopathy in most patients and keratoconus and cataract in a large subset."

This 26-proband phenotype study characterizes the classic severe LCA presentation and its frequent ocular comorbidities.

Early-Onset Severe Retinal Dystrophy / Juvenile RP (Missense Alleles)

Patients carrying at least one missense or hypomorphic AIPL1 allele (e.g., c.152A>G, c.572T>C, or the rare hypomorphic p.Gly122Arg) that retains partial chaperone function present with a later-onset, milder disease course: a severe cone-rod (rather than fully extinguished) electroretinogram pattern, slower visual acuity decline, and in some families a juvenile retinitis pigmentosa or dominant cone-rod dystrophy phenotype rather than classic LCA.

Show evidence (3 references)

PMID:38880373 SUPPORT Human Clinical

"Patients harboring at least one nonnull mutation, especially c.152A>G and c.572T>C, were significantly more likely to have a milder EOSRD phenotype than those with two null mutations."

This directly establishes the genotype-phenotype correlation between missense allele burden and the milder EOSRD course.

PMID:33067476 SUPPORT Human Clinical

"the p.G122R variant is a rare hypomorphic allele with a later disease onset, amenable to therapeutic intervention"

This functional/clinical study confirms a specific hypomorphic missense allele associated with the milder end of the disease spectrum.

PMID:10873396 SUPPORT Human Clinical

"We also identified affected individuals in two apparently dominant families, diagnosed with juvenile retinitis pigmentosa or dominant cone-rod dystrophy, respectively, who are heterozygous for a 12-bp AIPL1 deletion."

This establishes that a subset of AIPL1 variants can cause a dominant, milder juvenile RP or cone-rod dystrophy phenotype distinct from classic recessive LCA.

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Pathophysiology

5

AIPL1 Chaperone Deficiency

Biallelic pathogenic AIPL1 variants disrupt the photoreceptor-specific co-chaperone function of AIPL1. Its N-terminal FKBP-like domain binds the farnesylated PDE6 alpha subunit, and its C-terminal TPR domain mediates interaction with the molecular chaperones HSP90 and HSP70; both domains and their relative organization are required together for AIPL1 to function.

photoreceptor cell CL:0000210

AIPL1 hgnc:359 ↓ DECREASED

protein-folding chaperone binding GO:0051087 ↓ DECREASED

Downstream

Impaired PDE6 Holoenzyme Folding and Assembly Loss of AIPL1's co-chaperone activity prevents correct folding and assembly of the PDE6 holoenzyme, the phototransduction effector enzyme.

Show evidence (2 references)

PMID:28973376 SUPPORT In Vitro

"Our data revealed that both the FK506 binding protein (FKBP)-like domain and the tetratricopeptide repeat (TPR) domain of AIPL1 are required for interaction with HSP90."

This functional domain-mapping study establishes that both AIPL1 domains are jointly required for HSP90 co-chaperone activity.

PMID:18408180 SUPPORT In Vitro

"LCA-causing mutations in AIPL1 also compromised these interactions, suggesting that the essential function of AIPL1 in photoreceptors may involve the interaction with Hsp90 and Hsp70."

This directly links disease-causing AIPL1 mutations to loss of chaperone interaction, supporting the causal mechanism.

Impaired PDE6 Holoenzyme Folding and Assembly

Without functional AIPL1 co-chaperone activity, the PDE6 holoenzyme (catalytic alpha/beta and regulatory gamma subunits) fails to fold and assemble correctly and is targeted for degradation, abolishing cGMP hydrolysis capacity in photoreceptor outer segments. AIPL1 variants that disrupt either the FKBP-like or TPR domain impair both HSP90 interaction and PDE6 activity together.

photoreceptor cell CL:0000210

3',5'-cyclic-GMP phosphodiesterase activity GO:0047555 ↓ DECREASED

Downstream

Rod PDE6 Loss and cGMP Accumulation In rods, loss of PDE6 activity removes the enzyme responsible for cGMP hydrolysis, causing cGMP to accumulate.

Cone PDE6 and RetGC1 Destabilization with Reduced cGMP Synthesis In cones, loss of AIPL1 destabilizes cone PDE6 assembly and also reduces RetGC1 (a cGMP-synthesizing guanylate cyclase), producing a mechanistically distinct outcome of reduced (not elevated) cGMP.

Show evidence (1 reference)

PMID:33067476 SUPPORT In Vitro

"We confirm that missense and nonsense variants in the FKBP-like and tetratricopeptide repeat domains of AIPL1 lead to the loss of both HSP90 interaction and PDE6 activity, confirming these variants cause LCA."

This functional study of patient-derived AIPL1 variants confirms that disruption of either domain jointly impairs HSP90 interaction and PDE6 activity.

Rod PDE6 Loss and cGMP Accumulation

Elevated cGMP in rods keeps cyclic-nucleotide-gated channels open, producing sustained depolarization and calcium influx that drives rapid rod photoreceptor cell death, confirmed directly in human iPSC-derived photoreceptors as well as mouse models.

retinal rod cell CL:0000604

Downstream

Rapid Photoreceptor Apoptosis and Congenital Retinal Dystrophy Sustained cGMP-driven depolarization and calcium influx in rods converges on rapid photoreceptor apoptosis.

Show evidence (1 reference)

PMID:36084639 SUPPORT In Vitro

"iPSC-derived photoreceptors exhibited the molecular hallmarks of LCA4, including undetectable AIPL1 and rod cyclic guanosine monophosphate (cGMP) phosphodiesterase (PDE6) compared with control or CRISPR-corrected organoids. Increased levels of cGMP were detected."

This patient-derived retinal organoid model confirms the PDE6-loss and cGMP-elevation mechanism directly in human photoreceptor cells.

Cone PDE6 and RetGC1 Destabilization with Reduced cGMP Synthesis

In cones, AIPL1 loss impairs stability, assembly, and membrane association of cone PDE6 and reduces RetGC1, causing a light-independent cone death that proceeds via reduced cGMP synthesis rather than the excitotoxic cGMP-accumulation mechanism seen in rods.

retinal cone cell CL:0000573

Downstream

Rapid Photoreceptor Apoptosis and Congenital Retinal Dystrophy Cone PDE6/RetGC1 destabilization and reduced cGMP synthesis converges, alongside the rod branch, on rapid photoreceptor apoptosis.

Show evidence (1 reference)

PMID:24108108 SUPPORT Model Organism

"Aipl1 is needed for stability, assembly and membrane association of cone PDE6, an enzyme crucial for photoreceptor function and survival. Furthermore, RetGC1, a protein linked to LCA that is needed for cGMP synthesis, was dramatically reduced in cones lacking Aipl1."

This all-cone mouse model directly demonstrates the dual PDE6/RetGC1 destabilization mechanism specific to cones.

Rapid Photoreceptor Apoptosis and Congenital Retinal Dystrophy

Both the rod (cGMP-accumulation) and cone (reduced cGMP-synthesis) branches converge on rapid, light-independent photoreceptor apoptosis and disorganization of photoreceptor outer segments. In biallelic null alleles this produces the classic severe congenital LCA phenotype from birth; missense or hypomorphic alleles that retain partial chaperone function slow this process, producing the milder, later-onset EOSRD/juvenile RP end of the spectrum. Unlike the photoreceptor_degeneration module's rod-first apoptosis followed by non-cell-autonomous secondary cone loss, AIPL1 cone death is primary and cell-autonomous (PMID:24108108), arising from the same direct chaperone-loss mechanism as the rod branch rather than as a bystander effect of rod death, so this node does not declare conforms_to the module.

retinal rod cell CL:0000604 retinal cone cell CL:0000573

phototransduction GO:0007602 ↓ DECREASED

Show evidence (1 reference)

PMID:15365178 SUPPORT Model Organism

"In Aipl1(-/-) retinas, the outer nuclear layer develops normally, but rods and cones then quickly degenerate. Aipl1(-/-) mice have highly disorganized, short, fragmented photoreceptor outer segments and lack both rod and cone electroretinogram responses."

This establishes that photoreceptor development is initially normal, with rapid postnatal degeneration of both rods and cones once AIPL1 is lost -- the mechanistic basis for the severe congenital phenotype.

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Pathograph

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Phenotypes

8

Eye 5

Nystagmus VERY_FREQUENT HP:0000639

Show evidence (1 reference)

PMID:10615133 SUPPORT Human Clinical

"Individuals affected with LCA are diagnosed at birth or in the first few months of life with severely impaired vision or blindness, nystagmus and an abnormal or flat electroretinogram (ERG)."

Confirms nystagmus as a consistent early clinical feature alongside severe visual impairment.

Undetectable electroretinogram VERY_FREQUENT HP:0000550

Show evidence (1 reference)

PMID:38880373 SUPPORT Human Clinical

"classical extinguished pattern was documented in all patients with LCA available for the examination"

This 51-patient cohort study confirms the extinguished ERG pattern as a consistent finding across all examined classic LCA patients.

Keratoconus OCCASIONAL HP:0000563

Show evidence (1 reference)

PMID:15249368 SUPPORT Human Clinical

"Keratoconus and cataracts were identified in 5 (26%) of 19 patients, all of whom were homozygotes."

This documents keratoconus specifically among homozygous patients in the phenotype cohort.

Cataract OCCASIONAL HP:0000518

Show evidence (1 reference)

PMID:15249368 SUPPORT Human Clinical

"Keratoconus and cataracts were identified in 5 (26%) of 19 patients, all of whom were homozygotes."

This documents cataract as co-occurring with keratoconus in the homozygous patient subset.

Nyctalopia HP:0000662

Show evidence (1 reference)

PMID:33067476 SUPPORT Human Clinical

"The patient presented with nyctalopia since early childhood with a VA at 34 years old of 20/50 in the right eye and 20/100 in the left eye."

This case (homozygous for the hypomorphic p.G122R variant) documents childhood-onset night blindness with only mildly reduced adult visual acuity, illustrating the milder end of the AIPL1 disease spectrum.

Other 3

Congenital blindness VERY_FREQUENT HP:0007875

Show evidence (1 reference)

PMID:10615133 SUPPORT Human Clinical

"Individuals affected with LCA are diagnosed at birth or in the first few months of life with severely impaired vision or blindness, nystagmus and an abnormal or flat electroretinogram (ERG)."

This original gene-discovery paper establishes the classic congenital presentation of AIPL1-LCA.

Abnormal macular morphology VERY_FREQUENT HP:0001103

Show evidence (1 reference)

PMID:15249368 SUPPORT Human Clinical

"Atrophic and/or pigmentary macular changes were present in 16 (80%) of 20 probands."

This directly quantifies maculopathy as a frequent finding in the 26-proband AIPL1-LCA phenotype cohort.

Cone dystrophy FREQUENT HP:0008020

Show evidence (1 reference)

PMID:38880373 SUPPORT Human Clinical

"Electroretinography showed severe cone-rod patterns in 78.6% (11/14) of patients with EOSRD"

This quantifies the cone-rod ERG pattern as a frequent finding in the milder EOSRD subtype, distinct from classic LCA's full extinction.

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Genetic Associations

1

AIPL1 pathogenic variants (Causative)

Gene: AIPL1 hgnc:359

Autosomal recessive

Show evidence (2 references)

PMID:38880373 SUPPORT Human Clinical

"The most common mutation was the nonsense variants of c.421C>T, with an allele frequency of 53.9%."

This establishes c.421C>T as the most prevalent AIPL1 disease allele in this modern 51-patient cohort.

PMID:33067476 SUPPORT In Vitro

"the p.G122R variant is a rare hypomorphic allele with a later disease onset, amenable to therapeutic intervention"

This functional study confirms the hypomorphic mechanism of a specific rare missense allele at the mild end of the AIPL1 allelic spectrum.

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Medical Actions

4

rAAV8.hRKp.AIPL1 Gene Therapy

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

A recombinant AAV8 vector delivering the human AIPL1 coding sequence under a human rhodopsin-kinase promoter (rAAV8.hRKp.AIPL1), administered by subretinal injection. In a first-in-human, open-label study, four children (ages 1.0-2.8 years) with biallelic AIPL1 disease-causing variants and baseline binocular visual acuity limited to light perception showed substantial improvement in visual acuity and functional vision after treatment, with some structural preservation of the outer retina, and no serious adverse effects other than cystoid macular oedema in one treated eye.

Show evidence (4 references)

PMID:39986747 SUPPORT Human Clinical

"Before intervention, the children's binocular visual acuities were limited to perception of light."

This establishes the severe baseline visual function of the treated cohort prior to gene therapy.

PMID:39986747 SUPPORT Human Clinical

"Our findings indicate that young children with AIPL1-related retinal dystrophy benefited substantially from subretinal administration of rAAV8.hRKp.AIPL1, with improved visual acuity and functional vision and evidence of some protection against progressive retinal degeneration, without serious..."

This is the trial's primary efficacy and safety conclusion.

PMID:39986747 SUPPORT Human Clinical

"The treated eye of one child developed cystoid macular oedema. No other safety concerns were identified."

This documents the single reported adverse event in the trial.

+ 1 more reference

PTC124 Translational Readthrough (Investigational)

Action: Pharmacotherapy NCIT:C15986

An investigational translational readthrough-inducing drug studied in patient-derived iPSC retinal organoids carrying AIPL1 nonsense mutations. PTC124 partially restored full-length AIPL1 protein, but this was insufficient to fully restore PDE6 expression or normalize cGMP levels, indicating this approach alone is not yet an effective therapy.

Show evidence (1 reference)

PMID:36084639 SUPPORT In Vitro

"LCA4 retinal organoids exhibited low levels of rescue of full-length AIPL1. However, this was insufficient to fully restore PDE6 in photoreceptors and reduce cGMP."

This patient-derived organoid study directly tested and quantified the limited efficacy of PTC124 readthrough therapy for AIPL1 nonsense alleles.

Supportive care and monitoring

Action: supportive care Ontology label: Supportive Care NCIT:C15747

In the absence of an approved disease-modifying therapy, management consists of low-vision support, early referral for gene-therapy consideration if biallelic AIPL1 variants are confirmed, and routine ophthalmological monitoring. Because AIPL1 is a phototransduction chaperone rather than a visual-cycle protein, vitamin A/retinoid supplementation strategies used for visual-cycle diseases have no mechanistic rationale here, consistent with the general lack of demonstrated benefit of such supplementation across LCA/EOSRD.

Show evidence (1 reference)

PMID:33712480 SUPPORT Other

"amino acids supplementation have failed to show"

This management review states that vitamin A, mineral, and amino acid supplementation have failed to demonstrate clear benefit and are not recommended for LCA/EOSRD as a class, which includes AIPL1-related disease.

Genetic counseling

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

Genetic counseling is indicated given the predominantly autosomal recessive inheritance pattern, and molecular allele classification (null versus missense/hypomorphic) is prognostically important and increasingly relevant to gene-therapy eligibility.

Show evidence (1 reference)

PMID:10873396 SUPPORT Human Clinical

"LCA is usually inherited in an autosomal recessive fashion, although rare dominant cases have been reported."

Confirms the inheritance pattern underlying genetic counseling recommendations for affected families.

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Diagnosis

3

Molecular genetic testing

Sequencing of AIPL1 confirms the diagnosis and classifies the allele burden as null, missense/nonnull, or hypomorphic -- a classification directly correlated with clinical severity and gene-therapy eligibility.

diagnostic procedure NCIT:C18020

Results: Two null alleles predict classic, severe congenital LCA. At least one nonnull (missense) allele, particularly c.152A>G or c.572T>C, predicts a significantly milder EOSRD phenotype. The rare hypomorphic p.Gly122Arg allele predicts the mildest, latest-onset retinitis pigmentosa phenotype.

Show evidence (1 reference)

PMID:38880373 SUPPORT Human Clinical

"This study reveals distinct clinical features and variation spectrum between AIPL1-associated LCA and EOSRD."

This cohort study establishes molecular genotyping as the basis for distinguishing the LCA and EOSRD clinical subtypes.

Electroretinography

Full-field ERG distinguishes the classic LCA subtype (fully extinguished responses) from the milder EOSRD subtype (severe but not fully extinguished cone-rod pattern).

diagnostic procedure NCIT:C18020

Results: A classical extinguished pattern is seen in essentially all classic LCA patients, while a severe cone-rod pattern (rather than full extinction) is seen in most EOSRD patients.

Show evidence (1 reference)

PMID:38880373 SUPPORT Human Clinical

"Electroretinography showed severe cone-rod patterns in 78.6% (11/14) of patients with EOSRD, while classical extinguished pattern was documented in all patients with LCA available for the examination."

This directly establishes the ERG pattern as a key diagnostic differentiator between the two clinical subtypes.

Multimodal retinal imaging

Optical coherence tomography (OCT) assesses residual foveal ellipsoid-zone structure, which is preserved only in the youngest patients and is important for identifying an early therapeutic window for gene therapy.

diagnostic procedure NCIT:C18020

Results: Foveal ellipsoid zone preservation is documented in the youngest EOSRD and LCA children; patients with a damaging AIPL1 variant generally lack residual outer retinal structure beyond about age 4 years.

Show evidence (2 references)

PMID:38880373 SUPPORT Human Clinical

"Optical coherence tomography imaging demonstrated preservation of foveal ellipsoid zone in the 5 youngest EOSRD patients and 9 LCA children."

This documents the age-dependent window of residual foveal structure relevant to gene-therapy candidacy.

PMID:33712480 SUPPORT Other

"AIPL1 generally do not have residual outer retinal structure"

This management review states that patients with damaging AIPL1 variants generally lose residual outer retinal structure beyond approximately age 4 years.

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Progression

2

Congenital severe visual impairment (classic LCA, null alleles)

Age: Birth to early infancy

Severe visual impairment or blindness, nystagmus, and an extinguished ERG are present from birth or the first few months of life in patients with biallelic null AIPL1 variants.

Show evidence (1 reference)

PMID:10615133 SUPPORT Human Clinical

"Individuals affected with LCA are diagnosed at birth or in the first few months of life with severely impaired vision or blindness, nystagmus and an abnormal or flat electroretinogram (ERG)."

This establishes the congenital onset and severity of the classic LCA presentation.

Slower progressive decline (milder EOSRD/RP, missense alleles)

Age: Childhood through adulthood

Patients with at least one nonnull allele show a measurable but gradual annual decline in visual acuity rather than congenital near-total vision loss, with foveal structure preserved longer than in classic LCA.

Show evidence (1 reference)

PMID:38880373 SUPPORT Human Clinical

"with an average annual decline of 0.03 logMAR"

This quantifies the gradual, measurable rate of visual acuity decline in the milder EOSRD subtype, in contrast to the congenital severe loss of the classic LCA subtype.

🌍

Epidemiology

1

Contribution to Leber congenital amaurosis

Estimates of the AIPL1 contribution to LCA vary substantially by cohort era and size: an early, small, non-representative screen suggested approximately 20%, while a later worldwide screen of 512 probands found approximately 7%. No single figure is treated as definitive across the literature.

Show evidence (2 references)

PMID:10873396 SUPPORT Human Clinical

"Our results suggest that AIPL1 mutations cause approximately 7% of LCA worldwide and may cause dominant retinopathy."

This larger, 512-proband worldwide screen is the most commonly cited prevalence estimate for AIPL1 among LCA cases.

PMID:10615133 SUPPORT Human Clinical

"AIPL1 mutations may cause approximately 20% of recessive LCA, as disease-causing mutations were identified in 3 of 14 LCA families not tested previously for linkage."

This original gene-discovery paper's estimate came from a small, non-representative sub-cohort and is higher than later, larger screens.

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Clinical Trials

1

NCT-pending (Specials Licence compassionate program) PHASE_I COMPLETED

Open-label, first-in-human, non-randomised, single-arm study of subretinal rAAV8.hRKp.AIPL1 gene therapy in four children (ages 1.0-2.8 years) with biallelic AIPL1 disease-causing variants and severe retinal dystrophy, conducted at Moorfields Eye Hospital/Great Ormond Street Hospital (UK) under a Specials Licence from the UK Medicines and Healthcare products Regulatory Agency rather than as a formally registered trial at study outset. Results published as PMID:39986747.

Target Phenotypes: Congenital blindness HP:0007875 Undetectable electroretinogram HP:0000550

Show evidence (1 reference)

PMID:39986747 SUPPORT Human Clinical

"This non-randomised, single-arm, clinical study conducted in the UK"

This describes the study design of the first-in-human AIPL1 gene therapy program (four children, ages 1.0-2.8 years, treated between July 2019 and March 2020). Note this study was conducted under a Specials Licence rather than a standard registered clinical trial, so no independently verifiable NCT identifier is cited here (see notes on avoiding citation of mismatched trial identifiers).

{ }

Source YAML

click to show

name: AIPL1-Related Retinopathy
creation_date: "2026-07-22T16:30:00Z"
category: Mendelian
description: >-
  AIPL1-related retinopathy is an autosomal recessive inherited retinal disease
  caused by biallelic pathogenic variants in AIPL1, encoding aryl-hydrocarbon
  receptor interacting protein-like 1, a photoreceptor-specific molecular
  co-chaperone. Unlike the visual-cycle genes RDH5 and RLBP1, AIPL1 has no role in
  chromophore regeneration: its N-terminal FKBP-like domain binds the farnesylated
  PDE6 alpha subunit while its C-terminal tetratricopeptide repeat (TPR) domain
  mediates interaction with the chaperones HSP90 and HSP70, together enabling
  correct folding and assembly of the rod and cone phosphodiesterase-6 (PDE6)
  holoenzyme, the effector that hydrolyzes cGMP during phototransduction. Loss of
  AIPL1 function causes PDE6 misassembly and degradation, with divergent
  downstream consequences in rods (cGMP accumulation driving rapid degeneration)
  versus cones (reduced cGMP synthesis via RetGC1 loss). Biallelic null alleles
  cause classic Leber congenital amaurosis (LCA4), among the most severe forms of
  congenital blindness, while missense or hypomorphic alleles that retain partial
  chaperone function can cause a milder, later-onset early-onset severe retinal
  dystrophy (EOSRD), juvenile retinitis pigmentosa, or dominant cone-rod dystrophy
  phenotype. A first-in-human AAV gene therapy trial in young children with
  classic AIPL1-LCA has reported substantial visual improvement.
disease_term:
  preferred_term: AIPL1-related retinopathy
  term:
    id: MONDO:0100438
    label: AIPL1-related retinopathy
synonyms:
- Leber congenital amaurosis 4
- LCA4
- AIPL1-related cone-rod dystrophy
- AIPL1-related juvenile retinitis pigmentosa
- AIPL1 retinopathy
parents:
- Ophthalmological Disease
- Retinal Dystrophy
- Inherited retinal dystrophy
notes: >-
  AIPL1 mechanistically diverges from RDH5-Related_Retinopathy and
  RLBP1-Related_Retinopathy (both visual-cycle/chromophore-regeneration genes):
  AIPL1 is a phototransduction-effector chaperone, not a visual-cycle protein, so
  vitamin A/retinoid supplementation strategies used or investigated for those
  diseases have no mechanistic rationale here and are not recommended for LCA as a
  class. Two AIPL1 gene-therapy papers from 2009 share superficially similar
  titles; PMID:19299492 (AAV2/2 and AAV2/8 rescue of Aipl1-deficient mice) carries
  three published corrections (2010, 2023, 2024) but is not retracted and remains
  citable, while a separate 2009 Gene Therapy paper on a dual rod/cone promoter
  was formally retracted in 2024 for image-duplication concerns and is
  deliberately not cited in this entry. Reported
  AIPL1 contribution to LCA varies widely by cohort era (from ~20% in an early,
  small, non-representative screen to ~7% in a later 512-proband worldwide
  screen), so no single percentage is treated as definitive.
has_subtypes:
- name: Classic LCA
  display_name: Classic Leber Congenital Amaurosis (Null Alleles)
  description: >-
    Biallelic null (nonsense, frameshift, or splice-disrupting) AIPL1 variants,
    including the recurrent c.421C>T (historically termed W278X) allele, abolish
    AIPL1 chaperone function and cause the classic severe LCA phenotype: severe
    visual impairment or blindness from birth, an extinguished electroretinogram,
    and frequent maculopathy, keratoconus, and cataract.
  evidence:
  - reference: PMID:38880373
    reference_title: Clinical and Molecular Characterization of AIPL1-Associated Leber Congenital Amaurosis/Early-Onset Severe Retinal Dystrophy.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Twenty-six patients with LCA harbored two null AIPL1 variants, while 18 were homozygous for c.421C>T and 6 were heterozygous for c.421C>T with another loss-of-function variant."
    explanation: >-
      This 51-patient cohort study establishes biallelic null variants,
      dominated by the recurrent c.421C>T allele, as the genotype underlying
      the classic LCA phenotype.
  - reference: PMID:15249368
    reference_title: The phenotype of Leber congenital amaurosis in patients with AIPL1 mutations.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The phenotype of LCA in patients with AIPL1 mutations is relatively severe, with a maculopathy in most patients and keratoconus and cataract in a large subset."
    explanation: >-
      This 26-proband phenotype study characterizes the classic severe LCA
      presentation and its frequent ocular comorbidities.
- name: Milder EOSRD
  display_name: Early-Onset Severe Retinal Dystrophy / Juvenile RP (Missense Alleles)
  description: >-
    Patients carrying at least one missense or hypomorphic AIPL1 allele (e.g.,
    c.152A>G, c.572T>C, or the rare hypomorphic p.Gly122Arg) that retains partial
    chaperone function present with a later-onset, milder disease course: a
    severe cone-rod (rather than fully extinguished) electroretinogram pattern,
    slower visual acuity decline, and in some families a juvenile retinitis
    pigmentosa or dominant cone-rod dystrophy phenotype rather than classic LCA.
  evidence:
  - reference: PMID:38880373
    reference_title: Clinical and Molecular Characterization of AIPL1-Associated Leber Congenital Amaurosis/Early-Onset Severe Retinal Dystrophy.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Patients harboring at least one nonnull mutation, especially c.152A>G and c.572T>C, were significantly more likely to have a milder EOSRD phenotype than those with two null mutations."
    explanation: >-
      This directly establishes the genotype-phenotype correlation between
      missense allele burden and the milder EOSRD course.
  - reference: PMID:33067476
    reference_title: Clinical and functional analyses of AIPL1 variants reveal mechanisms of pathogenicity linked to different forms of retinal degeneration.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the p.G122R variant is a rare hypomorphic allele with a later disease onset, amenable to therapeutic intervention"
    explanation: >-
      This functional/clinical study confirms a specific hypomorphic missense
      allele associated with the milder end of the disease spectrum.
  - reference: PMID:10873396
    reference_title: Prevalence of AIPL1 mutations in inherited retinal degenerative disease.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We also identified affected individuals in two apparently dominant families, diagnosed with juvenile retinitis pigmentosa or dominant cone-rod dystrophy, respectively, who are heterozygous for a 12-bp AIPL1 deletion."
    explanation: >-
      This establishes that a subset of AIPL1 variants can cause a dominant,
      milder juvenile RP or cone-rod dystrophy phenotype distinct from
      classic recessive LCA.
inheritance:
- name: Autosomal recessive
  inheritance_term:
    preferred_term: Autosomal recessive inheritance
    term:
      id: HP:0000007
      label: Autosomal recessive inheritance
  description: >-
    The great majority of AIPL1-related retinopathy is caused by biallelic
    (homozygous or compound heterozygous) pathogenic variants.
  evidence:
  - reference: PMID:10873396
    reference_title: Prevalence of AIPL1 mutations in inherited retinal degenerative disease.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "LCA is usually inherited in an autosomal recessive fashion, although rare dominant cases have been reported."
    explanation: >-
      Confirms autosomal recessive inheritance as the predominant mode, with
      rare dominant-acting variants also documented.
- name: Autosomal dominant
  inheritance_term:
    preferred_term: Autosomal dominant inheritance
    term:
      id: HP:0000006
      label: Autosomal dominant inheritance
  description: >-
    A minority of heterozygous AIPL1 variants, most notably the 12-bp
    (c.1053_1064del) in-frame deletion, cause dominant-acting cone-rod
    dystrophy or juvenile RP rather than the classic recessive LCA/EOSRD
    phenotype.
  evidence:
  - reference: PMID:10873396
    reference_title: Prevalence of AIPL1 mutations in inherited retinal degenerative disease.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We also identified affected individuals in two apparently dominant families, diagnosed with juvenile retinitis pigmentosa or dominant cone-rod dystrophy, respectively, who are heterozygous for a 12-bp AIPL1 deletion."
    explanation: >-
      Establishes the founding dominant-family evidence for the heterozygous
      12-bp AIPL1 deletion.
  - reference: PMID:33067476
    reference_title: Clinical and functional analyses of AIPL1 variants reveal mechanisms of pathogenicity linked to different forms of retinal degeneration.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "p.A352_P355del associated with autosomal dominant cone-rod dystrophy."
    explanation: >-
      Independently confirms the same in-frame deletion as a cause of
      autosomal dominant cone-rod dystrophy in a separate cohort.
pathophysiology:
- name: AIPL1 Chaperone Deficiency
  biological_scale: MOLECULAR
  description: >-
    Biallelic pathogenic AIPL1 variants disrupt the photoreceptor-specific
    co-chaperone function of AIPL1. Its N-terminal FKBP-like domain binds the
    farnesylated PDE6 alpha subunit, and its C-terminal TPR domain mediates
    interaction with the molecular chaperones HSP90 and HSP70; both domains and
    their relative organization are required together for AIPL1 to function.
  gene:
    preferred_term: AIPL1
    modifier: DECREASED
    term:
      id: hgnc:359
      label: AIPL1
  cell_types:
  - preferred_term: photoreceptor cell
    term:
      id: CL:0000210
      label: photoreceptor cell
  molecular_functions:
  - preferred_term: protein-folding chaperone binding
    modifier: DECREASED
    term:
      id: GO:0051087
      label: protein-folding chaperone binding
  downstream:
  - target: Impaired PDE6 Holoenzyme Folding and Assembly
    description: >-
      Loss of AIPL1's co-chaperone activity prevents correct folding and
      assembly of the PDE6 holoenzyme, the phototransduction effector enzyme.
    evidence:
    - reference: PMID:18408180
      reference_title: The Leber congenital amaurosis protein AIPL1 functions as part of a chaperone heterocomplex.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "AIPL1 interacts with the molecular chaperones Hsp90 and Hsp70."
      explanation: >-
        This establishes AIPL1's direct interaction with both major
        chaperones, the structural basis for its co-chaperone role.
  evidence:
  - reference: PMID:28973376
    reference_title: The integrity and organization of the human AIPL1 functional domains is critical for its role as a HSP90-dependent co-chaperone for rod PDE6.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Our data revealed that both the FK506 binding protein (FKBP)-like domain and the tetratricopeptide repeat (TPR) domain of AIPL1 are required for interaction with HSP90."
    explanation: >-
      This functional domain-mapping study establishes that both AIPL1
      domains are jointly required for HSP90 co-chaperone activity.
  - reference: PMID:18408180
    reference_title: The Leber congenital amaurosis protein AIPL1 functions as part of a chaperone heterocomplex.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "LCA-causing mutations in AIPL1 also compromised these interactions, suggesting that the essential function of AIPL1 in photoreceptors may involve the interaction with Hsp90 and Hsp70."
    explanation: >-
      This directly links disease-causing AIPL1 mutations to loss of
      chaperone interaction, supporting the causal mechanism.
- name: Impaired PDE6 Holoenzyme Folding and Assembly
  biological_scale: MOLECULAR
  description: >-
    Without functional AIPL1 co-chaperone activity, the PDE6 holoenzyme
    (catalytic alpha/beta and regulatory gamma subunits) fails to fold and
    assemble correctly and is targeted for degradation, abolishing cGMP
    hydrolysis capacity in photoreceptor outer segments. AIPL1 variants that
    disrupt either the FKBP-like or TPR domain impair both HSP90 interaction and
    PDE6 activity together.
  cell_types:
  - preferred_term: photoreceptor cell
    term:
      id: CL:0000210
      label: photoreceptor cell
  molecular_functions:
  - preferred_term: 3',5'-cyclic-GMP phosphodiesterase activity
    modifier: DECREASED
    term:
      id: GO:0047555
      label: 3',5'-cyclic-GMP phosphodiesterase activity
  downstream:
  - target: Rod PDE6 Loss and cGMP Accumulation
    description: >-
      In rods, loss of PDE6 activity removes the enzyme responsible for cGMP
      hydrolysis, causing cGMP to accumulate.
    evidence:
    - reference: PMID:15365178
      reference_title: "Leber congenital amaurosis linked to AIPL1: a mouse model reveals destabilization of cGMP phosphodiesterase."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "rod cGMP phosphodiesterase, a farnesylated protein, is absent and cGMP levels are elevated in AIPL1(-/-) retinas before the onset of degeneration"
      explanation: >-
        This Aipl1-knockout mouse study directly demonstrates PDE6 loss and
        antecedent cGMP elevation as the proximate rod mechanism.
  - target: Cone PDE6 and RetGC1 Destabilization with Reduced cGMP Synthesis
    description: >-
      In cones, loss of AIPL1 destabilizes cone PDE6 assembly and also reduces
      RetGC1 (a cGMP-synthesizing guanylate cyclase), producing a mechanistically
      distinct outcome of reduced (not elevated) cGMP.
    evidence:
    - reference: PMID:24108108
      reference_title: "AIPL1, A protein linked to blindness, is essential for the stability of enzymes mediating cGMP metabolism in cone photoreceptor cells."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "These findings are in contrast to the role of Aipl1 in rods, where destabilization of rod PDE6 results in an increase in cGMP levels, which drives rapid rod degeneration. Our results illustrate mechanistic differences behind the death of rods and cones in retinal degenerative disease caused by deficiencies in AIPL1."
      explanation: >-
        This all-cone mouse model study establishes that the rod and cone
        degeneration mechanisms downstream of AIPL1 loss are biochemically
        distinct.
  evidence:
  - reference: PMID:33067476
    reference_title: Clinical and functional analyses of AIPL1 variants reveal mechanisms of pathogenicity linked to different forms of retinal degeneration.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "We confirm that missense and nonsense variants in the FKBP-like and tetratricopeptide repeat domains of AIPL1 lead to the loss of both HSP90 interaction and PDE6 activity, confirming these variants cause LCA."
    explanation: >-
      This functional study of patient-derived AIPL1 variants confirms that
      disruption of either domain jointly impairs HSP90 interaction and PDE6
      activity.
- name: Rod PDE6 Loss and cGMP Accumulation
  biological_scale: CELLULAR
  description: >-
    Elevated cGMP in rods keeps cyclic-nucleotide-gated channels open,
    producing sustained depolarization and calcium influx that drives rapid
    rod photoreceptor cell death, confirmed directly in human iPSC-derived
    photoreceptors as well as mouse models.
  cell_types:
  - preferred_term: retinal rod cell
    term:
      id: CL:0000604
      label: retinal rod cell
  downstream:
  - target: Rapid Photoreceptor Apoptosis and Congenital Retinal Dystrophy
    description: >-
      Sustained cGMP-driven depolarization and calcium influx in rods
      converges on rapid photoreceptor apoptosis.
    evidence:
    - reference: PMID:15365178
      reference_title: "Leber congenital amaurosis linked to AIPL1: a mouse model reveals destabilization of cGMP phosphodiesterase."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "Aipl1(-/-) retinas, the outer nuclear layer develops normally, but rods and cones then quickly degenerate."
      explanation: >-
        Confirms rapid rod (and cone) degeneration follows the initial
        molecular lesion in the Aipl1-null mouse model.
  evidence:
  - reference: PMID:36084639
    reference_title: Investigation of PTC124-mediated translational readthrough in a retinal organoid model of AIPL1-associated Leber congenital amaurosis.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "iPSC-derived photoreceptors exhibited the molecular hallmarks of LCA4, including undetectable AIPL1 and rod cyclic guanosine monophosphate (cGMP) phosphodiesterase (PDE6) compared with control or CRISPR-corrected organoids. Increased levels of cGMP were detected."
    explanation: >-
      This patient-derived retinal organoid model confirms the PDE6-loss and
      cGMP-elevation mechanism directly in human photoreceptor cells.
- name: Cone PDE6 and RetGC1 Destabilization with Reduced cGMP Synthesis
  biological_scale: CELLULAR
  description: >-
    In cones, AIPL1 loss impairs stability, assembly, and membrane association
    of cone PDE6 and reduces RetGC1, causing a light-independent cone death
    that proceeds via reduced cGMP synthesis rather than the excitotoxic
    cGMP-accumulation mechanism seen in rods.
  cell_types:
  - preferred_term: retinal cone cell
    term:
      id: CL:0000573
      label: retinal cone cell
  downstream:
  - target: Rapid Photoreceptor Apoptosis and Congenital Retinal Dystrophy
    description: >-
      Cone PDE6/RetGC1 destabilization and reduced cGMP synthesis converges,
      alongside the rod branch, on rapid photoreceptor apoptosis.
    evidence:
    - reference: PMID:24108108
      reference_title: "AIPL1, A protein linked to blindness, is essential for the stability of enzymes mediating cGMP metabolism in cone photoreceptor cells."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "Aipl1 is needed for stability, assembly and membrane association of cone PDE6, an enzyme crucial for photoreceptor function and survival."
      explanation: >-
        Establishes that loss of cone PDE6/RetGC1 stability is the proximate
        cause of cone photoreceptor loss in the all-cone Aipl1-null model.
  evidence:
  - reference: PMID:24108108
    reference_title: "AIPL1, A protein linked to blindness, is essential for the stability of enzymes mediating cGMP metabolism in cone photoreceptor cells."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Aipl1 is needed for stability, assembly and membrane association of cone PDE6, an enzyme crucial for photoreceptor function and survival. Furthermore, RetGC1, a protein linked to LCA that is needed for cGMP synthesis, was dramatically reduced in cones lacking Aipl1."
    explanation: >-
      This all-cone mouse model directly demonstrates the dual PDE6/RetGC1
      destabilization mechanism specific to cones.
- name: Rapid Photoreceptor Apoptosis and Congenital Retinal Dystrophy
  biological_scale: TISSUE
  description: >-
    Both the rod (cGMP-accumulation) and cone (reduced cGMP-synthesis) branches
    converge on rapid, light-independent photoreceptor apoptosis and
    disorganization of photoreceptor outer segments. In biallelic null alleles
    this produces the classic severe congenital LCA phenotype from birth;
    missense or hypomorphic alleles that retain partial chaperone function slow
    this process, producing the milder, later-onset EOSRD/juvenile RP end of
    the spectrum. Unlike the photoreceptor_degeneration module's rod-first
    apoptosis followed by non-cell-autonomous secondary cone loss, AIPL1 cone
    death is primary and cell-autonomous (PMID:24108108), arising from the
    same direct chaperone-loss mechanism as the rod branch rather than as a
    bystander effect of rod death, so this node does not declare conforms_to
    the module.
  cell_types:
  - preferred_term: retinal rod cell
    term:
      id: CL:0000604
      label: retinal rod cell
  - preferred_term: retinal cone cell
    term:
      id: CL:0000573
      label: retinal cone cell
  biological_processes:
  - preferred_term: phototransduction
    modifier: DECREASED
    term:
      id: GO:0007602
      label: phototransduction
  evidence:
  - reference: PMID:15365178
    reference_title: "Leber congenital amaurosis linked to AIPL1: a mouse model reveals destabilization of cGMP phosphodiesterase."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "In Aipl1(-/-) retinas, the outer nuclear layer develops normally, but rods and cones then quickly degenerate. Aipl1(-/-) mice have highly disorganized, short, fragmented photoreceptor outer segments and lack both rod and cone electroretinogram responses."
    explanation: >-
      This establishes that photoreceptor development is initially normal,
      with rapid postnatal degeneration of both rods and cones once AIPL1 is
      lost -- the mechanistic basis for the severe congenital phenotype.
phenotypes:
- category: Ophthalmological
  name: Congenital blindness
  subtype: Classic LCA
  frequency: VERY_FREQUENT
  description: >-
    Severe visual impairment or blindness from birth or the first few months of
    life is the presenting feature of classic AIPL1-LCA.
  phenotype_term:
    preferred_term: Congenital blindness
    term:
      id: HP:0007875
      label: Congenital blindness
  evidence:
  - reference: PMID:10615133
    reference_title: Mutations in a new photoreceptor-pineal gene on 17p cause Leber congenital amaurosis.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Individuals affected with LCA are diagnosed at birth or in the first few months of life with severely impaired vision or blindness, nystagmus and an abnormal or flat electroretinogram (ERG)."
    explanation: >-
      This original gene-discovery paper establishes the classic congenital
      presentation of AIPL1-LCA.
- category: Ophthalmological
  name: Nystagmus
  subtype: Classic LCA
  frequency: VERY_FREQUENT
  description: >-
    Nystagmus is a consistent early feature of classic congenital AIPL1-LCA.
  phenotype_term:
    preferred_term: Nystagmus
    term:
      id: HP:0000639
      label: Nystagmus
  evidence:
  - reference: PMID:10615133
    reference_title: Mutations in a new photoreceptor-pineal gene on 17p cause Leber congenital amaurosis.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Individuals affected with LCA are diagnosed at birth or in the first few months of life with severely impaired vision or blindness, nystagmus and an abnormal or flat electroretinogram (ERG)."
    explanation: >-
      Confirms nystagmus as a consistent early clinical feature alongside
      severe visual impairment.
- category: Ophthalmological
  name: Undetectable electroretinogram
  subtype: Classic LCA
  frequency: VERY_FREQUENT
  description: >-
    A non-recordable (extinguished) electroretinogram is the diagnostic
    electrophysiological hallmark of classic AIPL1-LCA, distinct from the
    severe cone-rod (but not fully extinguished) pattern seen in the milder
    EOSRD subtype.
  phenotype_term:
    preferred_term: Undetectable electroretinogram
    term:
      id: HP:0000550
      label: Undetectable electroretinogram
  reports_on:
  - target: Rapid Photoreceptor Apoptosis and Congenital Retinal Dystrophy
    relationship: READOUT_OF
    endpoint_context: DIAGNOSTIC
    interpretation: >-
      The extinguished ERG directly measures the rapid, near-complete loss of
      functional rod and cone photoreceptors in classic AIPL1-LCA.
  evidence:
  - reference: PMID:38880373
    reference_title: Clinical and Molecular Characterization of AIPL1-Associated Leber Congenital Amaurosis/Early-Onset Severe Retinal Dystrophy.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "classical extinguished pattern was documented in all patients with LCA available for the examination"
    explanation: >-
      This 51-patient cohort study confirms the extinguished ERG pattern as
      a consistent finding across all examined classic LCA patients.
- category: Ophthalmological
  name: Abnormal macular morphology
  subtype: Classic LCA
  frequency: VERY_FREQUENT
  description: >-
    Atrophic or pigmentary macular changes (maculopathy) are present in the
    majority of classic AIPL1-LCA patients.
  phenotype_term:
    preferred_term: Maculopathy
    term:
      id: HP:0001103
      label: Abnormal macular morphology
  evidence:
  - reference: PMID:15249368
    reference_title: The phenotype of Leber congenital amaurosis in patients with AIPL1 mutations.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Atrophic and/or pigmentary macular changes were present in 16 (80%) of 20 probands."
    explanation: >-
      This directly quantifies maculopathy as a frequent finding in the
      26-proband AIPL1-LCA phenotype cohort.
- category: Ophthalmological
  name: Keratoconus
  subtype: Classic LCA
  frequency: OCCASIONAL
  description: >-
    Keratoconus occurs in a subset of AIPL1-LCA patients, exclusively among
    those homozygous for their disease-causing variant.
  phenotype_term:
    preferred_term: Keratoconus
    term:
      id: HP:0000563
      label: Keratoconus
  evidence:
  - reference: PMID:15249368
    reference_title: The phenotype of Leber congenital amaurosis in patients with AIPL1 mutations.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Keratoconus and cataracts were identified in 5 (26%) of 19 patients, all of whom were homozygotes."
    explanation: >-
      This documents keratoconus specifically among homozygous patients in
      the phenotype cohort.
- category: Ophthalmological
  name: Cataract
  subtype: Classic LCA
  frequency: OCCASIONAL
  description: >-
    Cataract co-occurs with keratoconus in the same homozygous patient subset.
  phenotype_term:
    preferred_term: Cataract
    term:
      id: HP:0000518
      label: Cataract
  evidence:
  - reference: PMID:15249368
    reference_title: The phenotype of Leber congenital amaurosis in patients with AIPL1 mutations.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Keratoconus and cataracts were identified in 5 (26%) of 19 patients, all of whom were homozygotes."
    explanation: >-
      This documents cataract as co-occurring with keratoconus in the
      homozygous patient subset.
- category: Ophthalmological
  name: Cone dystrophy
  subtype: Milder EOSRD
  frequency: FREQUENT
  description: >-
    A severe cone-rod (rather than fully extinguished) electroretinogram
    pattern is characteristic of the milder EOSRD subtype associated with
    nonnull AIPL1 alleles.
  phenotype_term:
    preferred_term: Cone dystrophy
    term:
      id: HP:0008020
      label: Cone dystrophy
  evidence:
  - reference: PMID:38880373
    reference_title: Clinical and Molecular Characterization of AIPL1-Associated Leber Congenital Amaurosis/Early-Onset Severe Retinal Dystrophy.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Electroretinography showed severe cone-rod patterns in 78.6% (11/14) of patients with EOSRD"
    explanation: >-
      This quantifies the cone-rod ERG pattern as a frequent finding in the
      milder EOSRD subtype, distinct from classic LCA's full extinction.
- category: Ophthalmological
  name: Nyctalopia
  subtype: Milder EOSRD
  description: >-
    Night blindness since early childhood, rather than congenital blindness,
    is reported in patients with milder, later-onset AIPL1 phenotypes
    including retinitis pigmentosa.
  phenotype_term:
    preferred_term: Night blindness
    term:
      id: HP:0000662
      label: Nyctalopia
  evidence:
  - reference: PMID:33067476
    reference_title: Clinical and functional analyses of AIPL1 variants reveal mechanisms of pathogenicity linked to different forms of retinal degeneration.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The patient presented with nyctalopia since early childhood with a VA at 34 years old of 20/50 in the right eye and 20/100 in the left eye."
    explanation: >-
      This case (homozygous for the hypomorphic p.G122R variant) documents
      childhood-onset night blindness with only mildly reduced adult visual
      acuity, illustrating the milder end of the AIPL1 disease spectrum.
genetic:
- name: AIPL1 pathogenic variants
  gene_term:
    preferred_term: AIPL1
    term:
      id: hgnc:359
      label: AIPL1
  association: Causative
  features: >-
    Biallelic AIPL1 variants form an allelic severity gradient. Null alleles
    (nonsense, frameshift, or splice-disrupting), including the recurrent
    c.421C>T (historically W278X) variant, abolish AIPL1 function and cause
    classic LCA. Nonnull (missense) alleles, especially c.152A>G and c.572T>C,
    predict a significantly milder EOSRD phenotype. A rare hypomorphic missense
    variant, p.Gly122Arg, retains HSP90 binding but has impaired PDE6/cGMP
    modulation, producing a later-onset, milder retinitis pigmentosa phenotype.
    Rare heterozygous variants have also been reported in dominant families
    with juvenile retinitis pigmentosa or dominant cone-rod dystrophy.
  inheritance:
  - name: Autosomal recessive
    evidence:
    - reference: PMID:10873396
      reference_title: Prevalence of AIPL1 mutations in inherited retinal degenerative disease.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "LCA is usually inherited in an autosomal recessive fashion, although rare dominant cases have been reported."
      explanation: >-
        Confirms the predominant autosomal recessive inheritance mode with
        rare dominant exceptions.
  evidence:
  - reference: PMID:38880373
    reference_title: Clinical and Molecular Characterization of AIPL1-Associated Leber Congenital Amaurosis/Early-Onset Severe Retinal Dystrophy.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The most common mutation was the nonsense variants of c.421C>T, with an allele frequency of 53.9%."
    explanation: >-
      This establishes c.421C>T as the most prevalent AIPL1 disease allele in
      this modern 51-patient cohort.
  - reference: PMID:33067476
    reference_title: Clinical and functional analyses of AIPL1 variants reveal mechanisms of pathogenicity linked to different forms of retinal degeneration.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "the p.G122R variant is a rare hypomorphic allele with a later disease onset, amenable to therapeutic intervention"
    explanation: >-
      This functional study confirms the hypomorphic mechanism of a specific
      rare missense allele at the mild end of the AIPL1 allelic spectrum.
treatments:
- name: rAAV8.hRKp.AIPL1 Gene Therapy
  therapeutic_modality: GENE_THERAPY
  description: >-
    A recombinant AAV8 vector delivering the human AIPL1 coding sequence under
    a human rhodopsin-kinase promoter (rAAV8.hRKp.AIPL1), administered by
    subretinal injection. In a first-in-human, open-label study, four children
    (ages 1.0-2.8 years) with biallelic AIPL1 disease-causing variants and
    baseline binocular visual acuity limited to light perception showed
    substantial improvement in visual acuity and functional vision after
    treatment, with some structural preservation of the outer retina, and no
    serious adverse effects other than cystoid macular oedema in one treated
    eye.
  treatment_term:
    preferred_term: gene therapy
    term:
      id: NCIT:C15238
      label: Gene Therapy
  evidence:
  - reference: PMID:39986747
    reference_title: "Gene therapy in children with AIPL1-associated severe retinal dystrophy: an open-label, first-in-human interventional study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Before intervention, the children's binocular visual acuities were limited to perception of light."
    explanation: >-
      This establishes the severe baseline visual function of the treated
      cohort prior to gene therapy.
  - reference: PMID:39986747
    reference_title: "Gene therapy in children with AIPL1-associated severe retinal dystrophy: an open-label, first-in-human interventional study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Our findings indicate that young children with AIPL1-related retinal dystrophy benefited substantially from subretinal administration of rAAV8.hRKp.AIPL1, with improved visual acuity and functional vision and evidence of some protection against progressive retinal degeneration, without serious adverse effects."
    explanation: >-
      This is the trial's primary efficacy and safety conclusion.
  - reference: PMID:39986747
    reference_title: "Gene therapy in children with AIPL1-associated severe retinal dystrophy: an open-label, first-in-human interventional study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The treated eye of one child developed cystoid macular oedema. No other safety concerns were identified."
    explanation: >-
      This documents the single reported adverse event in the trial.
  - reference: PMID:19299492
    reference_title: "Gene therapy for retinitis pigmentosa and Leber congenital amaurosis caused by defects in AIPL1: effective rescue of mouse models of partial and complete Aipl1 deficiency using AAV2/2 and AAV2/8 vectors."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "This is the first gene replacement study to report long-term rescue of a photoreceptor-specific defect and to demonstrate effective rescue of a rapid photoreceptor degeneration."
    explanation: >-
      This earlier mouse-model study established proof-of-concept for AAV
      gene replacement therapy across both partial and complete Aipl1
      deficiency, preceding the human trial.
- name: PTC124 Translational Readthrough (Investigational)
  therapeutic_modality: SMALL_MOLECULE
  description: >-
    An investigational translational readthrough-inducing drug studied in
    patient-derived iPSC retinal organoids carrying AIPL1 nonsense mutations.
    PTC124 partially restored full-length AIPL1 protein, but this was
    insufficient to fully restore PDE6 expression or normalize cGMP levels,
    indicating this approach alone is not yet an effective therapy.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
  evidence:
  - reference: PMID:36084639
    reference_title: Investigation of PTC124-mediated translational readthrough in a retinal organoid model of AIPL1-associated Leber congenital amaurosis.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "LCA4 retinal organoids exhibited low levels of rescue of full-length AIPL1. However, this was insufficient to fully restore PDE6 in photoreceptors and reduce cGMP."
    explanation: >-
      This patient-derived organoid study directly tested and quantified
      the limited efficacy of PTC124 readthrough therapy for AIPL1 nonsense
      alleles.
- name: Supportive care and monitoring
  therapeutic_modality: OTHER
  description: >-
    In the absence of an approved disease-modifying therapy, management
    consists of low-vision support, early referral for gene-therapy
    consideration if biallelic AIPL1 variants are confirmed, and routine
    ophthalmological monitoring. Because AIPL1 is a phototransduction chaperone
    rather than a visual-cycle protein, vitamin A/retinoid supplementation
    strategies used for visual-cycle diseases have no mechanistic rationale
    here, consistent with the general lack of demonstrated benefit of such
    supplementation across LCA/EOSRD.
  treatment_term:
    preferred_term: supportive care
    term:
      id: NCIT:C15747
      label: Supportive Care
  evidence:
  - reference: PMID:33712480
    reference_title: "Leber congenital amaurosis/early-onset severe retinal dystrophy: current management and clinical trials."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "amino acids supplementation have failed to show"
    explanation: >-
      This management review states that vitamin A, mineral, and amino acid
      supplementation have failed to demonstrate clear benefit and are not
      recommended for LCA/EOSRD as a class, which includes AIPL1-related
      disease.
- name: Genetic counseling
  therapeutic_modality: OTHER
  description: >-
    Genetic counseling is indicated given the predominantly autosomal
    recessive inheritance pattern, and molecular allele classification (null
    versus missense/hypomorphic) is prognostically important and increasingly
    relevant to gene-therapy eligibility.
  treatment_term:
    preferred_term: genetic counseling
    term:
      id: NCIT:C15240
      label: Genetic Counseling
  evidence:
  - reference: PMID:10873396
    reference_title: Prevalence of AIPL1 mutations in inherited retinal degenerative disease.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "LCA is usually inherited in an autosomal recessive fashion, although rare dominant cases have been reported."
    explanation: >-
      Confirms the inheritance pattern underlying genetic counseling
      recommendations for affected families.
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: >-
    Sequencing of AIPL1 confirms the diagnosis and classifies the allele
    burden as null, missense/nonnull, or hypomorphic -- a classification
    directly correlated with clinical severity and gene-therapy eligibility.
  results: >-
    Two null alleles predict classic, severe congenital LCA. At least one
    nonnull (missense) allele, particularly c.152A>G or c.572T>C, predicts a
    significantly milder EOSRD phenotype. The rare hypomorphic p.Gly122Arg
    allele predicts the mildest, latest-onset retinitis pigmentosa phenotype.
  evidence:
  - reference: PMID:38880373
    reference_title: Clinical and Molecular Characterization of AIPL1-Associated Leber Congenital Amaurosis/Early-Onset Severe Retinal Dystrophy.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "This study reveals distinct clinical features and variation spectrum between AIPL1-associated LCA and EOSRD."
    explanation: >-
      This cohort study establishes molecular genotyping as the basis for
      distinguishing the LCA and EOSRD clinical subtypes.
- name: Electroretinography
  diagnosis_term:
    preferred_term: diagnostic procedure
    term:
      id: NCIT:C18020
      label: Diagnostic Procedure
  description: >-
    Full-field ERG distinguishes the classic LCA subtype (fully extinguished
    responses) from the milder EOSRD subtype (severe but not fully
    extinguished cone-rod pattern).
  results: >-
    A classical extinguished pattern is seen in essentially all classic LCA
    patients, while a severe cone-rod pattern (rather than full extinction) is
    seen in most EOSRD patients.
  evidence:
  - reference: PMID:38880373
    reference_title: Clinical and Molecular Characterization of AIPL1-Associated Leber Congenital Amaurosis/Early-Onset Severe Retinal Dystrophy.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Electroretinography showed severe cone-rod patterns in 78.6% (11/14) of patients with EOSRD, while classical extinguished pattern was documented in all patients with LCA available for the examination."
    explanation: >-
      This directly establishes the ERG pattern as a key diagnostic
      differentiator between the two clinical subtypes.
- name: Multimodal retinal imaging
  diagnosis_term:
    preferred_term: diagnostic procedure
    term:
      id: NCIT:C18020
      label: Diagnostic Procedure
  description: >-
    Optical coherence tomography (OCT) assesses residual foveal ellipsoid-zone
    structure, which is preserved only in the youngest patients and is
    important for identifying an early therapeutic window for gene therapy.
  results: >-
    Foveal ellipsoid zone preservation is documented in the youngest EOSRD and
    LCA children; patients with a damaging AIPL1 variant generally lack
    residual outer retinal structure beyond about age 4 years.
  evidence:
  - reference: PMID:38880373
    reference_title: Clinical and Molecular Characterization of AIPL1-Associated Leber Congenital Amaurosis/Early-Onset Severe Retinal Dystrophy.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Optical coherence tomography imaging demonstrated preservation of foveal ellipsoid zone in the 5 youngest EOSRD patients and 9 LCA children."
    explanation: >-
      This documents the age-dependent window of residual foveal structure
      relevant to gene-therapy candidacy.
  - reference: PMID:33712480
    reference_title: "Leber congenital amaurosis/early-onset severe retinal dystrophy: current management and clinical trials."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "AIPL1 generally do not have residual outer retinal structure"
    explanation: >-
      This management review states that patients with damaging AIPL1
      variants generally lose residual outer retinal structure beyond
      approximately age 4 years.
epidemiology:
- name: Contribution to Leber congenital amaurosis
  description: >-
    Estimates of the AIPL1 contribution to LCA vary substantially by cohort
    era and size: an early, small, non-representative screen suggested
    approximately 20%, while a later worldwide screen of 512 probands found
    approximately 7%. No single figure is treated as definitive across the
    literature.
  evidence:
  - reference: PMID:10873396
    reference_title: Prevalence of AIPL1 mutations in inherited retinal degenerative disease.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Our results suggest that AIPL1 mutations cause approximately 7% of LCA worldwide and may cause dominant retinopathy."
    explanation: >-
      This larger, 512-proband worldwide screen is the most commonly cited
      prevalence estimate for AIPL1 among LCA cases.
  - reference: PMID:10615133
    reference_title: Mutations in a new photoreceptor-pineal gene on 17p cause Leber congenital amaurosis.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "AIPL1 mutations may cause approximately 20% of recessive LCA, as disease-causing mutations were identified in 3 of 14 LCA families not tested previously for linkage."
    explanation: >-
      This original gene-discovery paper's estimate came from a small,
      non-representative sub-cohort and is higher than later, larger
      screens.
progression:
- phase: Congenital severe visual impairment (classic LCA, null alleles)
  age_range: Birth to early infancy
  notes: >-
    Severe visual impairment or blindness, nystagmus, and an extinguished ERG
    are present from birth or the first few months of life in patients with
    biallelic null AIPL1 variants.
  evidence:
  - reference: PMID:10615133
    reference_title: Mutations in a new photoreceptor-pineal gene on 17p cause Leber congenital amaurosis.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Individuals affected with LCA are diagnosed at birth or in the first few months of life with severely impaired vision or blindness, nystagmus and an abnormal or flat electroretinogram (ERG)."
    explanation: >-
      This establishes the congenital onset and severity of the classic LCA
      presentation.
- phase: Slower progressive decline (milder EOSRD/RP, missense alleles)
  age_range: Childhood through adulthood
  notes: >-
    Patients with at least one nonnull allele show a measurable but gradual
    annual decline in visual acuity rather than congenital near-total vision
    loss, with foveal structure preserved longer than in classic LCA.
  evidence:
  - reference: PMID:38880373
    reference_title: Clinical and Molecular Characterization of AIPL1-Associated Leber Congenital Amaurosis/Early-Onset Severe Retinal Dystrophy.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "with an average annual decline of 0.03 logMAR"
    explanation: >-
      This quantifies the gradual, measurable rate of visual acuity decline
      in the milder EOSRD subtype, in contrast to the congenital severe loss
      of the classic LCA subtype.
clinical_trials:
- name: NCT-pending (Specials Licence compassionate program)
  phase: PHASE_I
  status: COMPLETED
  description: >-
    Open-label, first-in-human, non-randomised, single-arm study of subretinal
    rAAV8.hRKp.AIPL1 gene therapy in four children (ages 1.0-2.8 years) with
    biallelic AIPL1 disease-causing variants and severe retinal dystrophy,
    conducted at Moorfields Eye Hospital/Great Ormond Street Hospital (UK)
    under a Specials Licence from the UK Medicines and Healthcare products
    Regulatory Agency rather than as a formally registered trial at study
    outset. Results published as PMID:39986747.
  target_phenotypes:
  - preferred_term: Congenital blindness
    term:
      id: HP:0007875
      label: Congenital blindness
  - preferred_term: Undetectable electroretinogram
    term:
      id: HP:0000550
      label: Undetectable electroretinogram
  evidence:
  - reference: PMID:39986747
    reference_title: "Gene therapy in children with AIPL1-associated severe retinal dystrophy: an open-label, first-in-human interventional study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "This non-randomised, single-arm, clinical study conducted in the UK"
    explanation: >-
      This describes the study design of the first-in-human AIPL1 gene
      therapy program (four children, ages 1.0-2.8 years, treated between
      July 2019 and March 2020). Note this study was conducted under a
      Specials Licence rather than a standard registered clinical trial, so
      no independently verifiable NCT identifier is cited here (see notes
      on avoiding citation of mismatched trial identifiers).
references:
- reference: PMID:30285347
  title: Nonsyndromic Leber Congenital Amaurosis / Early-Onset Severe Retinal Dystrophy Overview.
  tags:
  - GeneReviews

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PMID:30285347

Nonsyndromic Leber Congenital Amaurosis / Early-Onset Severe Retinal Dystrophy Overview.

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AIPL1-Related Retinopathy

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