RLBP1-related retinopathy is an autosomal recessive inherited retinal disease caused by biallelic pathogenic variants in RLBP1, encoding cellular retinaldehyde-binding protein (CRALBP), a retinoid-carrier chaperone (not an enzyme) expressed in both the retinal pigment epithelium (RPE) and Muller glial cells of the neuroretina. CRALBP binds and shuttles 11-cis-retinol and 11-cis-retinal within the visual (retinoid) cycle; its loss slows regeneration of the chromophore for rod and cone opsins in both cell compartments. This dual-cell involvement -- Muller-cell CRALBP is specifically required for cone dark adaptation -- distinguishes RLBP1 disease mechanistically from RDH5-related retinopathy, an RPE-only enzymatic block in the same pathway. Disease severity forms an allelic continuum: null (splice-junction or truncating) alleles produce the most severe, earliest-onset course (historically termed Newfoundland rod-cone dystrophy), the recurrent missense founder variant p.Arg234Trp produces a well-characterized intermediate course in Scandinavian populations (Bothnia dystrophy), and rare hypomorphic missense alleles can produce near-normal function. Most patients progress from childhood night blindness through retinitis punctata albescens to macular degeneration and legal blindness in early adulthood, materially more consistently progressive than RDH5-related disease. An active AAV8-RLBP1 (CPK850) gene therapy program has reported favorable phase 1/2 interim safety and efficacy data.
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name: RLBP1-Related Retinopathy
creation_date: "2026-07-22T05:00:00Z"
category: Mendelian
description: >-
RLBP1-related retinopathy is an autosomal recessive inherited retinal disease
caused by biallelic pathogenic variants in RLBP1, encoding cellular
retinaldehyde-binding protein (CRALBP), a retinoid-carrier chaperone (not an
enzyme) expressed in both the retinal pigment epithelium (RPE) and Muller glial
cells of the neuroretina. CRALBP binds and shuttles 11-cis-retinol and
11-cis-retinal within the visual (retinoid) cycle; its loss slows regeneration of
the chromophore for rod and cone opsins in both cell compartments. This dual-cell
involvement -- Muller-cell CRALBP is specifically required for cone dark
adaptation -- distinguishes RLBP1 disease mechanistically from RDH5-related
retinopathy, an RPE-only enzymatic block in the same pathway. Disease severity
forms an allelic continuum: null (splice-junction or truncating) alleles produce
the most severe, earliest-onset course (historically termed Newfoundland
rod-cone dystrophy), the recurrent missense founder variant p.Arg234Trp produces
a well-characterized intermediate course in Scandinavian populations (Bothnia
dystrophy), and rare hypomorphic missense alleles can produce near-normal
function. Most patients progress from childhood night blindness through
retinitis punctata albescens to macular degeneration and legal blindness in
early adulthood, materially more consistently progressive than RDH5-related
disease. An active AAV8-RLBP1 (CPK850) gene therapy program has reported
favorable phase 1/2 interim safety and efficacy data.
disease_term:
preferred_term: RLBP1-related retinopathy
term:
id: MONDO:0100444
label: RLBP1-related retinopathy
synonyms:
- Bothnia retinal dystrophy
- Newfoundland rod-cone dystrophy
- Retinitis punctata albescens
- Fundus albipunctatus
- RLBP1 retinopathy
- Pigmentary retinal dystrophy
parents:
- Ophthalmological Disease
- Retinal Dystrophy
- Inherited retinal dystrophy
notes: >-
"Fundus albipunctatus" and "retinitis punctata albescens" are included as
historical synonyms because MONDO lists both as narrow synonyms of
MONDO:0100444, but both terms are genetically heterogeneous: RPA and FA have
each been separately associated with RLBP1, RHO, PRPH2 (RDS), and RDH5 --
mutations in RLBP1 and RDH5 are the two most common causes but neither term is
RLBP1-specific. "Newfoundland rod-cone dystrophy" is likewise not a strictly
geography-locked label: it originated as the name for the disease in a
Newfoundland founder population with RLBP1 null alleles, but a later French
cohort applied the same NFRCD label (and found the same recurrent
exons-7-to-9 deletion producing an equally severe early-onset course) in
patients with no Newfoundland ancestry -- the term now functions as much as a
genotype-severity class as a population-specific entity. A companion dismech
entry, RDH5-Related_Retinopathy (MONDO:0100443), covers the mechanistically
distinct RPE-only enzymatic form of the same clinical phenotype spectrum; the
two genes are directly compared in a shared cohort study cited throughout this
entry.
has_subtypes:
- name: Bothnia Dystrophy
display_name: Bothnia Retinal Dystrophy
description: >-
A founder-population phenotype in Vasterbotten, northern Sweden, caused by
the homozygous missense variant p.Arg234Trp. Night blindness from early
childhood is followed in young adulthood by retinitis punctata albescens,
then macular degeneration and a decline in visual acuity leading to legal
blindness in early adulthood. Regional prevalence is unusually high for an
inherited retinal disease (approximately 1 in 4500).
evidence:
- reference: PMID:11176989
reference_title: "Ocular phenotype of bothnia dystrophy, an autosomal recessive retinitis pigmentosa associated with an R234W mutation in the RLBP1 gene."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Patients typically show night blindness from early childhood. In young adults, retinitis punctata albescens was observed, followed by macular degeneration and a decrease in visual acuity that led to legal blindness in early adulthood."
explanation: >-
This study of 24 individuals homozygous for the R234W founder variant
establishes the characteristic clinical course of Bothnia dystrophy.
- name: Newfoundland Rod-Cone Dystrophy
display_name: Newfoundland Rod-Cone Dystrophy (NFRCD)
description: >-
An early-onset, more rapidly and distinctively progressive retinal
dystrophy first described in a Newfoundland founder population, caused by
RLBP1 null alleles (splice-junction mutations disrupting mRNA splicing, or
an exon 7-9 deletion reported in an unrelated French cohort) that are
predicted to produce no residual CRALBP activity, unlike the partial-function
missense alleles underlying Bothnia dystrophy and retinitis punctata
albescens.
evidence:
- reference: PMID:11868161
reference_title: "Newfoundland rod-cone dystrophy, an early-onset retinal dystrophy, is caused by splice-junction mutations in RLBP1."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "we identified a group of families exhibiting a retinal dystrophy reminiscent of retinitis punctata albescens but with a substantially lower age at onset and more-rapid and distinctive progression, a disorder that we termed \"Newfoundland rod-cone dystrophy\" (NFRCD)."
explanation: >-
This is the original description of NFRCD as a distinctly more severe,
earlier-onset entity than retinitis punctata albescens.
- reference: PMID:11868161
reference_title: "Newfoundland rod-cone dystrophy, an early-onset retinal dystrophy, is caused by splice-junction mutations in RLBP1."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "In contrast to some previously reported RLBP1 mutations, which yield a protein that may retain some residual activity, each NFRCD mutation is likely to give rise to a null allele. This difference may account for the severe phenotype in these families and exemplifies the molecular continuum that underlies clinically distinct but genetically related entities."
explanation: >-
This directly establishes the null-allele mechanism underlying the more
severe NFRCD phenotype relative to partial-function missense alleles.
- reference: PMID:36247817
reference_title: "Retinitis Punctata Albescens and RLBP1-Allied Phenotypes: Phenotype-Genotype Correlation and Natural History in the Aim of Gene Therapy."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "The most frequent form was NFRCD with 12 patients (8 families) homozygous for the recurrent deletion of exons 7 through 9 in RLBP1"
explanation: >-
This French reference-center cohort applies the NFRCD label to patients
with a distinct recurrent deletion, demonstrating the term now functions
as a genotype-severity class beyond the original Newfoundland population.
- name: Retinitis Punctata Albescens
display_name: Retinitis Punctata Albescens / Fundus-Albipunctatus-like Presentation
description: >-
Missense or nonsense RLBP1 alleles of intermediate severity (e.g., p.Arg150Gln,
p.Arg156Ter combined with p.Gly116Arg) can present in childhood and
adolescence as an apparently stationary, fundus-albipunctatus-like flecked
retina, then evolve over decades in the same individuals into progressive
retinitis punctata albescens with generalized retinal atrophy -- direct
evidence that the "stationary" and "progressive" clinical labels can reflect
different life stages of a single genotype rather than fixed, distinct
disease entities.
evidence:
- reference: PMID:11453974
reference_title: Fundus albipunctatus and retinitis punctata albescens in a pedigree with an R150Q mutation in RLBP1.
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Examination of several patients aged 3-20 years over a 9-year period presented no evidence for either RP or RPA. In contrast, clinical examination of individuals with the same mutation in their fourth and fifth decade revealed signs consistent with RPA."
explanation: >-
This directly demonstrates age-dependent phenotype conversion within a
single RLBP1 genotype (R150Q), from an apparently stationary childhood
presentation to progressive RPA in adulthood.
- reference: PMID:21447491
reference_title: Mutations in RLBP1 associated with fundus albipunctatus in consanguineous Pakistani families.
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "RPA and FA are genetically heterogeneous disorders: mutations in RLBP1 and occasionally in RHO, RDS and RDH5 have been causally associated with RPA, whereas mutations in RLBP1 and RDH5 have been identified with patients diagnosed with FA."
explanation: >-
This confirms the genetic heterogeneity of the RPA/FA clinical labels
across multiple visual-cycle genes, of which RLBP1 and RDH5 are the two
most frequently implicated.
inheritance:
- name: Autosomal recessive
inheritance_term:
preferred_term: Autosomal recessive inheritance
term:
id: HP:0000007
label: Autosomal recessive inheritance
description: >-
RLBP1-related retinopathy is caused by biallelic (homozygous or compound
heterozygous) pathogenic variants in RLBP1.
evidence:
- reference: PMID:11176989
reference_title: "Ocular phenotype of bothnia dystrophy, an autosomal recessive retinitis pigmentosa associated with an R234W mutation in the RLBP1 gene."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "To describe the phenotype of Bothnia dystrophy, an autosomal recessive retinal dystrophy with an R234W mutation in the RLBP1 gene encoding cellular retinaldehyde-binding protein."
explanation: >-
Confirms autosomal recessive inheritance as the mode for RLBP1-related
retinopathy.
pathophysiology:
- name: CRALBP Retinoid-Binding Chaperone Deficiency
biological_scale: MOLECULAR
description: >-
Biallelic pathogenic RLBP1 variants reduce or abolish the function of
cellular retinaldehyde-binding protein (CRALBP), a cytosolic retinoid
carrier (not an enzyme) expressed in both the RPE and Muller glial cells,
which selects and protects 11-cis-retinaldehyde/11-cis-retinol from
photoisomerization within the visual cycle.
gene:
preferred_term: RLBP1
modifier: DECREASED
term:
id: hgnc:10024
label: RLBP1
cell_types:
- preferred_term: retinal pigment epithelial cell
term:
id: CL:0002586
label: retinal pigment epithelial cell
- preferred_term: Muller cell
term:
id: CL:0000636
label: Mueller cell
molecular_functions:
- preferred_term: retinol binding
modifier: DECREASED
term:
id: GO:0019841
label: retinol binding
- preferred_term: retinoid binding
modifier: DECREASED
term:
id: GO:0005501
label: retinoid binding
downstream:
- target: Impaired Visual Cycle Flux in RPE and Muller Glia
description: >-
Loss of CRALBP's retinoid-carrier function impairs 11-cis-retinal
regeneration in both the RPE and Muller glia, the latter supplying a
distinct, cone-dedicated arm of the visual cycle not present in
RDH5-related retinopathy's RPE-only enzymatic block.
evidence:
- reference: PMID:11301032
reference_title: Visual cycle impairment in cellular retinaldehyde binding protein (CRALBP) knockout mice results in delayed dark adaptation.
supports: SUPPORT
evidence_source: MODEL_ORGANISM
snippet: "These findings support a role for CRALBP as an acceptor of 11-cis-retinol in the isomerization reaction of the visual cycle."
explanation: >-
This Rlbp1-knockout mouse study establishes CRALBP's proposed
biochemical role in the isomerization step of the visual cycle.
evidence:
- reference: PMID:21447491
reference_title: Mutations in RLBP1 associated with fundus albipunctatus in consanguineous Pakistani families.
supports: SUPPORT
evidence_source: OTHER
snippet: "CRALBP has been localised in adult species to the retinal pigment epithelium, Müller cells of neural retina and ocular ciliary epithelium."
explanation: >-
This confirms CRALBP's expression in both the RPE and Muller cells, the
structural basis for the disease's dual-cell mechanism.
- name: Impaired Visual Cycle Flux in RPE and Muller Glia
biological_scale: MOLECULAR
description: >-
Loss of CRALBP delays rhodopsin regeneration, 11-cis-retinal production, and
dark adaptation by more than 10-fold in a knockout mouse model, with
accumulation of all-trans-retinyl esters indicating impaired isomerization.
Muller-cell CRALBP specifically is required for M-opsin localization,
M-cone survival, and cone dark adaptation, independent of RPE CRALBP.
cell_types:
- preferred_term: retinal pigment epithelial cell
term:
id: CL:0002586
label: retinal pigment epithelial cell
- preferred_term: Muller cell
term:
id: CL:0000636
label: Mueller cell
- 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
downstream:
- target: Prolonged Rod and Cone Dark Adaptation
description: >-
In milder or hypomorphic alleles, and in the early years of intermediate
alleles, the primary consequence is a delayed but retained rod and cone
dark-adaptation response rather than outright photoreceptor loss.
evidence:
- reference: PMID:11301032
reference_title: Visual cycle impairment in cellular retinaldehyde binding protein (CRALBP) knockout mice results in delayed dark adaptation.
supports: SUPPORT
evidence_source: MODEL_ORGANISM
snippet: "The photosensitivity of Rlbp1(-/-) mice is normal but rhodopsin regeneration, 11-cis-retinal production, and dark adaptation after illumination are delayed by >10-fold."
explanation: >-
This quantifies the delayed-regeneration mechanism directly in a
CRALBP-null mouse model.
- target: Progressive Rod-Then-Cone Photoreceptor Stress and Macular Degeneration
description: >-
In most disease alleles, chronic impairment of visual-cycle flux in both
the RPE and Muller glia produces cumulative photoreceptor stress that
progresses from early rod dysfunction to cone dysfunction and macular
degeneration, more consistently than in RDH5-related retinopathy.
evidence:
- reference: PMID:25607845
reference_title: CRALBP supports the mammalian retinal visual cycle and cone vision.
supports: SUPPORT
evidence_source: MODEL_ORGANISM
snippet: "M-cone loss, and impaired cone-driven visual behavior and light responses."
explanation: >-
This mouse study directly links loss of Muller-cell CRALBP to
progressive cone-specific pathology, distinct from the rod-first
stationary presentation.
evidence:
- reference: PMID:25607845
reference_title: CRALBP supports the mammalian retinal visual cycle and cone vision.
supports: SUPPORT
evidence_source: MODEL_ORGANISM
snippet: "identify Müller cell CRALBP as a key component of the retinal visual cycle"
explanation: >-
This rescue experiment (AAV-mediated restoration specifically in Müller
cells, not RPE) isolates Müller-cell CRALBP as necessary and sufficient
for cone-specific visual cycle function, the key mechanistic distinction
from the RPE-only RDH5 pathway.
- name: Prolonged Rod and Cone Dark Adaptation
biological_scale: TISSUE
description: >-
In hypomorphic alleles and in the early years of some intermediate alleles,
delayed but ultimately functional rod and cone photopigment regeneration
produces an apparently stationary, fundus-albipunctatus-like presentation.
This can convert with age, in the same genotype, to the progressive
phenotype below.
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
downstream:
- target: Progressive Rod-Then-Cone Photoreceptor Stress and Macular Degeneration
description: >-
A subset of patients who present in childhood with an apparently
stationary phenotype develop, in the same genotype, unmistakable signs
of the progressive phenotype by the fourth or fifth decade of life.
evidence:
- reference: PMID:11453974
reference_title: Fundus albipunctatus and retinitis punctata albescens in a pedigree with an R150Q mutation in RLBP1.
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "younger individuals diagnosed with the milder disorder FA thought to be stationary may evolve to a more devastating and progressive phenotype"
explanation: >-
This directly documents age-dependent conversion from the apparently
stationary presentation to the progressive phenotype within a single
RLBP1 genotype.
evidence:
- reference: PMID:21447491
reference_title: Mutations in RLBP1 associated with fundus albipunctatus in consanguineous Pakistani families.
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "the scotopic ERG responses were non-detectable, whereas the photopic response was severely reduced in affected individuals"
explanation: >-
This documents the electrophysiological pattern in the stationary
fundus-albipunctatus-like presentation of RLBP1 disease.
- name: Progressive Rod-Then-Cone Photoreceptor Stress and Macular Degeneration
biological_scale: TISSUE
conforms_to: "photoreceptor_degeneration#Rod Photoreceptor Apoptosis"
description: >-
In the majority of disease alleles, sustained visual-cycle impairment
produces an initial loss of rod function followed by progressive reduction
of cone responses in older patients, with early central macular thinning
detectable even in young patients and progressing to generalized macular
degeneration. Severity is graded by allele class: null alleles (Newfoundland
rod-cone dystrophy) produce the most severe, earliest course; the
p.Arg234Trp founder allele (Bothnia dystrophy) produces an intermediate,
well-documented course; and rare hypomorphic alleles can show minimal or no
measurable rod/cone impairment and no macular atrophy.
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
- preferred_term: retinal pigment epithelial cell
term:
id: CL:0002586
label: retinal pigment epithelial cell
downstream:
- target: Legal Blindness in Early Adulthood
description: >-
Progressive macular degeneration and declining visual acuity culminate
in legal blindness in early adulthood for most disease alleles.
evidence:
- reference: PMID:11176989
reference_title: "Ocular phenotype of bothnia dystrophy, an autosomal recessive retinitis pigmentosa associated with an R234W mutation in the RLBP1 gene."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "macular degeneration and a decrease in visual acuity that led to legal blindness in early adulthood"
explanation: >-
This documents the natural-history endpoint of the progressive
phenotype in the well-characterized Bothnia dystrophy cohort.
evidence:
- reference: PMID:11176989
reference_title: "Ocular phenotype of bothnia dystrophy, an autosomal recessive retinitis pigmentosa associated with an R234W mutation in the RLBP1 gene."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Dark adaptometry and electrophysiologic testing showed an initial loss of rod function followed by a progressive reduction of the cone responses in older ages."
explanation: >-
This directly establishes the rod-then-cone progression sequence in the
Bothnia dystrophy cohort.
- reference: PMID:20696998
reference_title: Central retinal findings in Bothnia dystrophy caused by RLBP1 sequence variation.
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "a loss of function and thinning of the central macula are found, indicating early damage of the cone photoreceptors in this disease of the visual cycle"
explanation: >-
This study of young patients (ages 9-34) documents early central macular
thinning, showing cone-region damage begins well before the classic
late-stage macular atrophy.
- reference: PMID:38945349
reference_title: "RDH5 and RLBP1-Associated Inherited Retinal Diseases: Refining the Spectrum of Stationary and Progressive Phenotypes."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "The RLBP1 genotype was associated with a lower macular volume by 0.28 mm3 (95% CI, -0.46 to -0.11; P = .005) compared to the RDH5 genotype."
explanation: >-
This head-to-head cohort comparison quantifies RLBP1-associated
retinopathy as more severe (lower macular volume) than RDH5-related
retinopathy at a comparable disease stage.
- reference: PMID:38945349
reference_title: "RDH5 and RLBP1-Associated Inherited Retinal Diseases: Refining the Spectrum of Stationary and Progressive Phenotypes."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Three unrelated patients homozygous for the c.361C>T p.(Arg121Trp) RLBP1 variant showed minimal impairment of both the rod and cone systems function on ffERG and absence of MA."
explanation: >-
This documents the mild end of the allelic severity gradient: a
hypomorphic RLBP1 variant producing near-normal function, in contrast to
the null and founder-missense alleles.
- name: Legal Blindness in Early Adulthood
biological_scale: ORGANISM
description: >-
The endpoint of the progressive disease course for most RLBP1 alleles is
legal blindness reached in early adulthood, driven by combined rod-cone
loss and macular degeneration.
evidence:
- reference: PMID:11176989
reference_title: "Ocular phenotype of bothnia dystrophy, an autosomal recessive retinitis pigmentosa associated with an R234W mutation in the RLBP1 gene."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "macular degeneration and a decrease in visual acuity that led to legal blindness in early adulthood"
explanation: >-
This documents the natural-history endpoint — progression to legal blindness in
early adulthood — in the well-characterized Bothnia dystrophy cohort.
phenotypes:
- category: Ophthalmological
name: Nyctalopia
frequency: VERY_FREQUENT
description: >-
Night blindness from early childhood is the presenting symptom across all
RLBP1 disease alleles.
phenotype_term:
preferred_term: Night blindness
term:
id: HP:0000662
label: Nyctalopia
evidence:
- reference: PMID:11176989
reference_title: "Ocular phenotype of bothnia dystrophy, an autosomal recessive retinitis pigmentosa associated with an R234W mutation in the RLBP1 gene."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Patients typically show night blindness from early childhood."
explanation: >-
Confirms childhood-onset night blindness as the presenting feature of
Bothnia dystrophy.
- category: Ophthalmological
name: Retinal flecks
frequency: VERY_FREQUENT
description: >-
Aggregation of white or yellow-white retinal flecks/dots, most concentrated
in the midperiphery, is the characteristic fundus finding across the
fundus-albipunctatus-like and retinitis-punctata-albescens presentations.
phenotype_term:
preferred_term: Retinal flecks
term:
id: HP:0012045
label: Retinal flecks
evidence:
- reference: PMID:11453974
reference_title: Fundus albipunctatus and retinitis punctata albescens in a pedigree with an R150Q mutation in RLBP1.
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "retinitis punctata albescens (RPA), is also characterized by aggregation of irregular white flecks but is progressive and evolves to generalized atrophy of the retina"
explanation: >-
This defines the characteristic flecked-retina finding of the RPA
presentation and its progressive natural history.
- category: Ophthalmological
name: Abnormal dark-adapted electroretinogram
frequency: VERY_FREQUENT
description: >-
Severely delayed dark adaptation with a progressive shift from rod to
cone-predominant ERG deficits is the diagnostic electrophysiological
hallmark.
phenotype_term:
preferred_term: Abnormal dark-adapted electroretinogram
term:
id: HP:0030469
label: Abnormal dark-adapted electroretinogram
reports_on:
- target: Impaired Visual Cycle Flux in RPE and Muller Glia
relationship: READOUT_OF
endpoint_context: DIAGNOSTIC
interpretation: >-
The severely delayed and progressively worsening dark-adapted ERG
directly measures the impaired visual-cycle flux in RPE and Muller
glia caused by CRALBP loss.
evidence:
- reference: PMID:11176989
reference_title: "Ocular phenotype of bothnia dystrophy, an autosomal recessive retinitis pigmentosa associated with an R234W mutation in the RLBP1 gene."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Dark adaptometry and electrophysiologic testing showed an initial loss of rod function followed by a progressive reduction of the cone responses in older ages."
explanation: >-
This establishes the rod-then-cone electrophysiological progression
characteristic of RLBP1-related retinopathy.
- reference: PMID:21447491
reference_title: Mutations in RLBP1 associated with fundus albipunctatus in consanguineous Pakistani families.
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "the scotopic ERG responses were non-detectable, whereas the photopic response was severely reduced in affected individuals"
explanation: >-
This confirms severe scotopic and photopic ERG impairment in the
milder, fundus-albipunctatus-like presentation.
- category: Ophthalmological
name: Cone dystrophy
subtype: Newfoundland Rod-Cone Dystrophy
frequency: FREQUENT
description: >-
Progressive cone dysfunction, more consistently observed than in
RDH5-related retinopathy, is driven by loss of Muller-cell CRALBP required
for cone dark adaptation.
phenotype_term:
preferred_term: Cone dystrophy
term:
id: HP:0008020
label: Cone dystrophy
evidence:
- reference: PMID:36247817
reference_title: "Retinitis Punctata Albescens and RLBP1-Allied Phenotypes: Phenotype-Genotype Correlation and Natural History in the Aim of Gene Therapy."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "rod-cone dystrophy associated with RLBP1 pathogenic variants"
explanation: >-
This large natural-history cohort (21 patients, 15 families) confirms
rod-cone dystrophy as the characteristic disease pattern across RLBP1
allele classes.
- category: Ophthalmological
name: Macular atrophy
subtype: Bothnia Dystrophy
frequency: FREQUENT
description: >-
Progressive macular degeneration, detectable as central retinal thinning
even in young patients, is a consistent feature of the more severe RLBP1
disease alleles.
phenotype_term:
preferred_term: Macular atrophy
term:
id: HP:0007401
label: Macular atrophy
evidence:
- reference: PMID:20696998
reference_title: Central retinal findings in Bothnia dystrophy caused by RLBP1 sequence variation.
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "generalized retinal thinning in the central foveal, foveal (innermost ring"
explanation: >-
This documents early, generalized central retinal thinning in young
patients (ages 9-34) with Bothnia dystrophy.
- category: Ophthalmological
name: Reduced visual acuity
frequency: FREQUENT
description: >-
Declining visual acuity progressing to legal blindness in early adulthood
is typical of the more severe RLBP1 disease alleles.
phenotype_term:
preferred_term: Reduced visual acuity
term:
id: HP:0007663
label: Reduced visual acuity
evidence:
- reference: PMID:36247817
reference_title: "Retinitis Punctata Albescens and RLBP1-Allied Phenotypes: Phenotype-Genotype Correlation and Natural History in the Aim of Gene Therapy."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "all patients showed a visual acuity of worse than 20/200"
explanation: >-
This large natural-history cohort quantifies severely reduced visual
acuity as a consistent finding across RLBP1 genotypes at the point of
gene-therapy-eligibility assessment.
- category: Ophthalmological
name: Progressive visual loss
subtype: Newfoundland Rod-Cone Dystrophy
frequency: FREQUENT
description: >-
Null RLBP1 alleles produce a substantially more rapid and distinctive
progression than the missense alleles underlying Bothnia dystrophy or
retinitis punctata albescens.
phenotype_term:
preferred_term: Progressive visual loss
term:
id: HP:0000529
label: Progressive visual loss
evidence:
- reference: PMID:11868161
reference_title: "Newfoundland rod-cone dystrophy, an early-onset retinal dystrophy, is caused by splice-junction mutations in RLBP1."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "a retinal dystrophy reminiscent of retinitis punctata albescens but with a substantially lower age at onset and more-rapid and distinctive progression"
explanation: >-
This establishes NFRCD's more rapid progression relative to other
RLBP1-related disease presentations.
genetic:
- name: RLBP1 pathogenic variants
gene_term:
preferred_term: RLBP1
term:
id: hgnc:10024
label: RLBP1
association: Causative
features: >-
Biallelic RLBP1 variants form an allelic severity continuum. Null alleles
(splice-junction mutations, truncating variants, or a recurrent exon 7-9
deletion) predicted to abolish CRALBP function entirely produce the most
severe, earliest-onset course (Newfoundland rod-cone dystrophy). The
recurrent missense founder variant p.Arg234Trp, which retains partial
function, produces the intermediate, well-characterized Bothnia dystrophy
course. A rare hypomorphic missense variant, p.Arg121Trp, has been reported
with minimal or no measurable rod/cone impairment and no macular atrophy.
inheritance:
- name: Autosomal recessive
evidence:
- reference: PMID:11176989
reference_title: "Ocular phenotype of bothnia dystrophy, an autosomal recessive retinitis pigmentosa associated with an R234W mutation in the RLBP1 gene."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "an autosomal recessive retinal dystrophy with an R234W mutation in the RLBP1 gene"
explanation: >-
Confirms autosomal recessive inheritance for the RLBP1 R234W founder
variant.
evidence:
- reference: PMID:11868161
reference_title: "Newfoundland rod-cone dystrophy, an early-onset retinal dystrophy, is caused by splice-junction mutations in RLBP1."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "each NFRCD mutation is likely to give rise to a null allele. This difference may account for the severe phenotype in these families and exemplifies the molecular continuum that underlies clinically distinct but genetically related entities."
explanation: >-
This establishes the null-vs-partial-function allelic mechanism
underlying the phenotypic continuum across RLBP1-related disease
presentations.
- reference: PMID:38945349
reference_title: "RDH5 and RLBP1-Associated Inherited Retinal Diseases: Refining the Spectrum of Stationary and Progressive Phenotypes."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "hypomorphic RLBP1 variants may cause milder retinal phenotypes rather than the typical severe rod-cone dystrophy with MA"
explanation: >-
This confirms that hypomorphic RLBP1 alleles can produce a materially
milder phenotype than the typical severe rod-cone dystrophy course.
treatments:
- name: AAV8-RLBP1 (CPK850) Gene Therapy
therapeutic_modality: GENE_THERAPY
description: >-
Subretinal delivery of an adeno-associated viral vector expressing RLBP1
cDNA (AAV8-RLBP1, development code CPK850). An open-label, first-in-human,
dose-escalation phase 1/2 trial in 12 patients with biallelic RLBP1
mutations reported up to 3-year interim safety and efficacy data:
dose-dependent intraocular inflammation (responsive to corticosteroids) and
focal RPE atrophy as the dose-limiting toxicity, with significant
improvement in dark adaptation kinetics (the primary efficacy endpoint) in
all dose cohorts and resolution of disease-related retinal deposits. This
is a materially different treatment landscape than RDH5-related
retinopathy, which has no active gene therapy program.
treatment_term:
preferred_term: gene therapy
term:
id: NCIT:C15238
label: Gene Therapy
target_mechanisms:
- target: CRALBP Retinoid-Binding Chaperone Deficiency
treatment_effect: RESTORES
description: >-
Subretinal AAV8-mediated delivery of wild-type RLBP1 cDNA restores CRALBP
expression in RPE and Muller cells, directly addressing the proximal
chaperone deficiency rather than a downstream consequence of it.
evidence:
- reference: PMID:39256350
reference_title: "Interim safety and efficacy of gene therapy for RLBP1-associated retinal dystrophy: a phase 1/2 trial."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Treatment with AAV8-RLBP1 resulted in the resolution of disease-related retinal deposits, suggestive of successful restoration of the visual cycle."
explanation: >-
The resolution of retinal deposits and improved dark adaptation
kinetics are consistent with restored CRALBP function upstream in
the visual cycle.
evidence:
- reference: PMID:39256350
reference_title: "Interim safety and efficacy of gene therapy for RLBP1-associated retinal dystrophy: a phase 1/2 trial."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Subretinal delivery of an adeno-associated viral vector (AAV8-RLBP1) was well tolerated with dose-dependent intraocular inflammation which responded to corticosteroid treatment, and focal atrophy of the retinal pigment epithelium as the dose limiting toxicity. Dark adaptation kinetics, the primary efficacy endpoint, improved significantly in all dose-cohorts."
explanation: >-
This phase 1/2 interim analysis (12 patients, up to 3-year follow-up)
is the primary evidence for the safety and efficacy of AAV8-RLBP1 gene
therapy.
- reference: PMID:39256350
reference_title: "Interim safety and efficacy of gene therapy for RLBP1-associated retinal dystrophy: a phase 1/2 trial."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Treatment with AAV8-RLBP1 resulted in the resolution of disease-related retinal deposits, suggestive of successful restoration of the visual cycle."
explanation: >-
This documents an imaging-based biomarker of visual-cycle restoration
following gene therapy.
- name: Genetic counseling
therapeutic_modality: OTHER
description: >-
Genetic counseling is indicated given the autosomal recessive inheritance
pattern and the availability of molecular allele classification, which is
prognostically important (null vs. partial-function vs. hypomorphic) and
increasingly relevant to gene-therapy eligibility.
treatment_term:
preferred_term: genetic counseling
term:
id: NCIT:C15240
label: Genetic Counseling
evidence:
- reference: PMID:11176989
reference_title: "Ocular phenotype of bothnia dystrophy, an autosomal recessive retinitis pigmentosa associated with an R234W mutation in the RLBP1 gene."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "an autosomal recessive retinal dystrophy with an R234W mutation in the RLBP1 gene"
explanation: >-
Confirms the autosomal recessive inheritance pattern underlying genetic
counseling recommendations.
- name: Supportive care and monitoring
therapeutic_modality: OTHER
description: >-
Routine ophthalmological follow-up, low-vision support, and monitoring for
gene-therapy eligibility (visual acuity, ellipsoid-zone imaging) are
standard supportive management alongside or pending gene therapy access.
treatment_term:
preferred_term: supportive care
term:
id: NCIT:C15747
label: Supportive Care
evidence:
- reference: PMID:36247817
reference_title: "Retinitis Punctata Albescens and RLBP1-Allied Phenotypes: Phenotype-Genotype Correlation and Natural History in the Aim of Gene Therapy."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "The eligibility for RLBP1 gene therapy first should be determined according to the biallelic variant combination using a robust classification as proposed herein."
explanation: >-
This establishes structured genotype and imaging-based classification
as the basis for gene-therapy-eligibility monitoring.
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 RLBP1 confirms the diagnosis and classifies the allele as
null, partial-function missense, or hypomorphic -- a classification that is
prognostically important and, per current natural-history cohorts, the
first step in gene-therapy eligibility assessment.
results: >-
Identification of biallelic pathogenic RLBP1 variants confirms the
diagnosis. Null alleles (splice-junction, truncating, or the recurrent
exon 7-9 deletion) predict the most severe (Newfoundland rod-cone
dystrophy) course; the p.Arg234Trp founder allele predicts the
intermediate Bothnia dystrophy course; other missense/nonsense
combinations predict a variable retinitis-punctata-albescens course.
evidence:
- reference: PMID:36247817
reference_title: "Retinitis Punctata Albescens and RLBP1-Allied Phenotypes: Phenotype-Genotype Correlation and Natural History in the Aim of Gene Therapy."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "The eligibility for RLBP1 gene therapy first should be determined according to the biallelic variant combination using a robust classification as proposed herein."
explanation: >-
This natural-history cohort establishes molecular allele classification
as the primary determinant of gene-therapy eligibility.
- name: Prolonged dark-adaptation electroretinography
diagnosis_term:
preferred_term: diagnostic procedure
term:
id: NCIT:C18020
label: Diagnostic Procedure
description: >-
Dark-adapted and light-adapted ERG testing characterizes the rod-then-cone
functional deficit and is a primary efficacy endpoint in the AAV8-RLBP1
gene therapy trial.
results: >-
Scotopic ERG responses are typically non-detectable or severely reduced,
with a progressive additional decline in photopic (cone) responses with
age; unlike RDH5-related retinopathy, recovery to normal amplitudes after
prolonged dark adaptation is not consistently described in the RLBP1
literature.
evidence:
- reference: PMID:21447491
reference_title: Mutations in RLBP1 associated with fundus albipunctatus in consanguineous Pakistani families.
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "the scotopic ERG responses were non-detectable, whereas the photopic response was severely reduced in affected individuals"
explanation: >-
This documents the severe scotopic/photopic ERG deficit pattern typical
of RLBP1-related retinopathy.
- name: Multimodal retinal imaging
diagnosis_term:
preferred_term: diagnostic procedure
term:
id: NCIT:C18020
label: Diagnostic Procedure
description: >-
Optical coherence tomography (OCT) quantifies central retinal thinning,
ellipsoid-zone/interdigitation-zone integrity, and macular volume, and is
used both diagnostically and to establish gene-therapy eligibility
thresholds.
results: >-
OCT shows generalized retinal thinning of the central fovea and inner ring
even in young patients, with retinitis-punctata-albescens spots visualized
near the RPE-choriocapillaris complex; natural-history cohorts have
proposed minimum ellipsoid-zone width and central retinal thickness
thresholds, with detectable ellipsoid and interdigitation lines, as
prerequisites for gene therapy candidacy.
evidence:
- reference: PMID:20696998
reference_title: Central retinal findings in Bothnia dystrophy caused by RLBP1 sequence variation.
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Homogeneous retinitis punctata albescence changes were visualized in and/or adjacent to the retinal pigment epithelium-choriocapillaris complex with high reflectance."
explanation: >-
This documents the multimodal localization of retinitis-punctata-albescens
spots to the RPE-choriocapillaris complex on imaging.
epidemiology:
- name: Founder-population prevalence
description: >-
RLBP1-related retinopathy is rare overall but shows unusually high
regional prevalence in specific founder populations due to recurrent
alleles: approximately 1 in 4500 in Vasterbotten, northern Sweden
(p.Arg234Trp, Bothnia dystrophy), and a distinct founder history in
Newfoundland, Canada (null alleles, Newfoundland rod-cone dystrophy).
evidence:
- reference: PMID:11176989
reference_title: "Ocular phenotype of bothnia dystrophy, an autosomal recessive retinitis pigmentosa associated with an R234W mutation in the RLBP1 gene."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Fifty-seven cases of Bothnia dystrophy have been diagnosed, indicating a prevalence as high as 1 per 4500 population in the geographic area studied."
explanation: >-
This is the primary quantitative regional-prevalence estimate for
RLBP1-related retinopathy, reflecting the founder effect in northern
Sweden.
- reference: PMID:11868161
reference_title: "Newfoundland rod-cone dystrophy, an early-onset retinal dystrophy, is caused by splice-junction mutations in RLBP1."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "The island of Newfoundland is a characteristic geographic isolate, settled by a small number of families primarily during the late 1700s and early 1800s."
explanation: >-
This describes the founder-population context underlying the distinct
Newfoundland rod-cone dystrophy presentation.
progression:
- phase: Childhood-onset night blindness
age_range: Early childhood
notes: >-
Night blindness from early childhood is the presenting feature across all
RLBP1 allele classes.
evidence:
- reference: PMID:11176989
reference_title: "Ocular phenotype of bothnia dystrophy, an autosomal recessive retinitis pigmentosa associated with an R234W mutation in the RLBP1 gene."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Patients typically show night blindness from early childhood."
explanation: >-
Establishes the earliest clinical phase common to RLBP1-related
retinopathy.
- phase: Retinitis punctata albescens with early macular thinning
age_range: Young adulthood
notes: >-
Retinitis punctata albescens (aggregated white flecks) develops in young
adults, with central retinal/macular thinning already detectable on OCT in
patients as young as 9-34 years old in the intermediate/severe alleles.
evidence:
- reference: PMID:11176989
reference_title: "Ocular phenotype of bothnia dystrophy, an autosomal recessive retinitis pigmentosa associated with an R234W mutation in the RLBP1 gene."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "In young adults, retinitis punctata albescens was observed, followed by macular degeneration and a decrease in visual acuity that led to legal blindness in early adulthood."
explanation: >-
Documents the transition from night blindness to retinitis punctata
albescens in young adulthood.
- phase: Macular degeneration and legal blindness
age_range: Early adulthood
notes: >-
Progressive macular degeneration and declining visual acuity culminate in
legal blindness in early adulthood for the majority of disease alleles
(null and founder-missense classes); rare hypomorphic alleles can show
minimal or no progression to this endpoint.
evidence:
- reference: PMID:38945349
reference_title: "RDH5 and RLBP1-Associated Inherited Retinal Diseases: Refining the Spectrum of Stationary and Progressive Phenotypes."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "we found a significant annual rate of macular volume loss, estimated at -0.007 mm3/y (95% CI, -0.012 to -0.001; P = .02), without any significant difference between the two genotypes"
explanation: >-
This quantifies the annual rate of macular volume loss in RLBP1-associated
retinopathy (measured in the same cohort study alongside RDH5).
clinical_trials:
- name: NCT03374657
phase: PHASE_I
status: COMPLETED
description: >-
Open-label, first-in-human, single-ascending-dose phase 1/2 trial of
subretinal AAV8-RLBP1 (CPK850) gene therapy in patients with retinitis
pigmentosa due to biallelic RLBP1 mutations. Primary endpoints were
systemic/ocular safety and recovery of dark adaptation; interim results
published as PMID:39256350.
target_phenotypes:
- preferred_term: Night blindness
term:
id: HP:0000662
label: Nyctalopia
- preferred_term: Abnormal dark-adapted electroretinogram
term:
id: HP:0030469
label: Abnormal dark-adapted electroretinogram
evidence:
- reference: clinicaltrials:NCT03374657
reference_title: An Open-label First-in-human Single Ascending Dose Study to Explore Safety, Tolerability and Efficacy of Subretinal Administration of CPK850 Gene Therapy in Patients With Retinitis Pigmentosa Due to Mutations in the Retinaldehyde Binding Protein 1 (RLBP1) Gene
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "This study will also evaluate the safety and potential efficacy of CPK850 on improving visual function in patients with decreased visual function from RLBP1 retinitis pigmentosa due to biallelic mutations in the RLBP1 gene."
explanation: >-
ClinicalTrials.gov record for the phase 1/2 AAV8-RLBP1 trial reported
in PMID:39256350; the NCT ID is directly and correctly cited in that
paper's own abstract (cross-checked to avoid the kind of ID mismatch
seen in an unrelated RDH5-treatment citation).