Ornithine aminotransferase deficiency is a rare autosomal recessive amino acid metabolism disorder caused by OAT dysfunction and classically presenting as gyrate atrophy of the choroid and retina with hyperornithinemia and progressive ophthalmologic decline.
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name: ornithine aminotransferase deficiency
creation_date: "2026-04-15T17:35:00Z"
updated_date: "2026-05-19T17:53:57Z"
description: >-
Ornithine aminotransferase deficiency is a rare autosomal recessive amino acid
metabolism disorder caused by OAT dysfunction and classically presenting as
gyrate atrophy of the choroid and retina with hyperornithinemia and
progressive ophthalmologic decline.
category: Mendelian
parents:
- hereditary disease
disease_term:
preferred_term: ornithine aminotransferase deficiency
term:
id: MONDO:0009796
label: ornithine aminotransferase deficiency
synonyms:
- gyrate atrophy of the choroid and retina
inheritance:
- name: Autosomal recessive inheritance
inheritance_term:
preferred_term: Autosomal recessive inheritance
term:
id: HP:0000007
label: Autosomal recessive inheritance
description: >-
Gyrate atrophy caused by OAT dysfunction follows autosomal recessive
inheritance.
evidence:
- reference: DOI:10.1002/prot.70134
reference_title: "Current Insight into Human Ornithine Aminotransferase: A Review"
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Human OAT holds significant clinical and scientific interest because (i) its dysfunction causes gyrate atrophy (GA) of the choroid and retina, a rare autosomal recessive disease, and (ii) it is recognized as a potential target for chemotherapeutic drug development, being overexpressed in some types of cancer.
explanation: >-
This review directly states the autosomal recessive inheritance of gyrate
atrophy due to OAT dysfunction.
- reference: PMID:33068755
reference_title: "Deficit of human ornithine aminotransferase in gyrate atrophy: Molecular, cellular, and clinical aspects."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Gyrate Atrophy (GA) of the choroid and retina (MIM# 258870) is an autosomal recessive disorder due to mutations of the OAT gene encoding ornithine-delta-aminotransferase (OAT), associated with progressive retinal deterioration and blindness.
explanation: >-
Comprehensive review confirms autosomal recessive inheritance of gyrate
atrophy due to OAT gene mutations.
pathophysiology:
- name: OAT deficiency and impaired ornithine transamination
description: >-
OAT deficiency disrupts mitochondrial matrix, PLP-dependent ornithine
transamination, blocking L-ornithine catabolism to glutamate
semialdehyde/P5C and glutamate and causing the metabolic defect underlying
gyrate atrophy.
genes:
- preferred_term: OAT
term:
id: hgnc:8091
label: OAT
biological_processes:
- preferred_term: ornithine metabolic process
term:
id: GO:0006591
label: ornithine metabolic process
modifier: DECREASED
- preferred_term: L-ornithine catabolic process
term:
id: GO:0006593
label: L-ornithine catabolic process
modifier: DECREASED
- preferred_term: L-proline biosynthetic process
term:
id: GO:0055129
label: L-proline biosynthetic process
modifier: DECREASED
molecular_functions:
- preferred_term: L-ornithine transaminase activity
term:
id: GO:0004587
label: L-ornithine transaminase activity
modifier: DECREASED
locations:
- preferred_term: mitochondrial matrix
term:
id: GO:0005759
label: mitochondrial matrix
chemical_entities:
- preferred_term: L-ornithine
term:
id: CHEBI:15729
label: L-ornithine
modifier: INCREASED
- preferred_term: L-glutamic acid
term:
id: CHEBI:16015
label: L-glutamic acid
modifier: DECREASED
- preferred_term: L-lysine
term:
id: CHEBI:18019
label: L-lysine
modifier: DECREASED
- preferred_term: creatine
term:
id: CHEBI:16919
label: creatine
modifier: DECREASED
evidence:
- reference: DOI:10.1002/prot.70134
reference_title: "Current Insight into Human Ornithine Aminotransferase: A Review"
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
Human ornithine aminotransferase (hOAT) is a mitochondrial matrix pyridoxal‐5′‐phosphate enzyme (PLP) that catalyzes the reversible transfer of the δ‐amino group of L‐ornithine (L‐Orn) to α‐ketoglutarate (α‐KG) yielding glutamate‐5‐semialdehyde (GSA) and glutamate.
explanation: >-
This directly supports the primary enzymatic function disrupted in OAT
deficiency.
- reference: PMID:33068755
reference_title: "Deficit of human ornithine aminotransferase in gyrate atrophy: Molecular, cellular, and clinical aspects."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
OAT is mainly involved in ornithine catabolism in adults, thus explaining the hyperornithinemia as hallmark of the disease.
explanation: >-
Confirms the role of OAT in ornithine catabolism and its link to the
disease hallmark of hyperornithinemia.
- reference: PMID:34395527
reference_title: "Molecular and Cellular Studies Reveal Folding Defects of Human Ornithine Aminotransferase Variants Associated With Gyrate Atrophy of the Choroid and Retina."
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
The deficit of hOAT leads to a 10-to-15 fold increase in the plasmatic L-Orn concentration, along with a small reduction in the levels of glutamate, glutamine, lysine and creatine
explanation: >-
Review text supports elevated L-ornithine and secondary reductions in
glutamate, lysine, and creatine downstream of hOAT deficiency.
downstream:
- target: Hyperornithinemia
description: Loss of OAT activity causes elevated plasma ornithine.
causal_link_type: DIRECT
evidence:
- reference: PMID:33068755
reference_title: "Deficit of human ornithine aminotransferase in gyrate atrophy: Molecular, cellular, and clinical aspects."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
OAT is mainly involved in ornithine catabolism in adults, thus
explaining the hyperornithinemia as hallmark of the disease.
explanation: >-
Human review directly links loss of OAT-mediated ornithine catabolism
to hyperornithinemia.
- target: Secondary amino acid and creatine depletion
description: >-
OAT deficiency is associated with reduced glutamate, lysine, and creatine
pools, including low cerebral creatine in some affected patients.
causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
evidence:
- reference: PMID:34395527
reference_title: "Molecular and Cellular Studies Reveal Folding Defects of Human Ornithine Aminotransferase Variants Associated With Gyrate Atrophy of the Choroid and Retina."
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
The deficit of hOAT leads to a 10-to-15 fold increase in the plasmatic L-Orn concentration, along with a small reduction in the levels of glutamate, glutamine, lysine and creatine
explanation: >-
Review text links hOAT deficit to secondary reductions in amino-acid
and creatine pools.
- name: Hyperornithinemia
description: >-
Loss of ornithine aminotransferase activity causes marked plasma ornithine
accumulation, the central biochemical lesion in the disease.
biological_processes:
- preferred_term: ornithine metabolic process
term:
id: GO:0006591
label: ornithine metabolic process
modifier: INCREASED
chemical_entities:
- preferred_term: L-ornithine
term:
id: CHEBI:15729
label: L-ornithine
modifier: INCREASED
evidence:
- reference: DOI:10.1186/s13023-026-04265-x
reference_title: "Gyrate atrophy of the choroid and retina: a tertiary center experience"
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
All patients had high plasma ornithine levels at the time of diagnosis, and they were all started on an arginine-restricted diet.
explanation: >-
This directly supports hyperornithinemia as the key metabolic
intermediate between OAT deficiency and retinal degeneration.
- reference: PMID:10655512
reference_title: "Correction of ornithine accumulation prevents retinal degeneration in a mouse model of gyrate atrophy of the choroid and retina."
supports: SUPPORT
evidence_source: MODEL_ORGANISM
snippet: >-
Deficiency of ornithine-delta-aminotransferase (OAT) in humans results in gyrate atrophy of the choroid and retina (GA), an autosomal recessive disorder characterized by ornithine accumulation and a progressive chorioretinal degeneration of unknown pathogenesis.
explanation: >-
Mouse model study confirms ornithine accumulation as the characteristic
biochemical feature of OAT deficiency.
downstream:
- target: Progressive chorioretinal degeneration
description: Sustained hyperornithinemia drives the retinal degenerative process.
causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
evidence:
- reference: PMID:10655512
reference_title: "Correction of ornithine accumulation prevents retinal degeneration in a mouse model of gyrate atrophy of the choroid and retina."
supports: SUPPORT
evidence_source: MODEL_ORGANISM
snippet: >-
This result indicates that ornithine accumulation is a necessary factor
in the pathophysiology of the retinal degeneration in GA
explanation: >-
Oat-deficient mouse data support ornithine accumulation as necessary for
retinal degeneration.
- reference: PMID:34894815
reference_title: "Gyrate Atrophy of the Choroid and Retina: A Review."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Accumulation of ornithine occurs in various body tissues but leads
primarily to characteristic ophthalmic manifestations including myopia,
cataract, progressive chorioretinal atrophy, and macular changes.
explanation: >-
Human clinical review connects ornithine accumulation to the
characteristic ophthalmic manifestations.
- target: Retinal pigment epithelial cell injury
description: >-
Chronic hyperornithinemia first injures retinal pigment epithelial cells
in OAT-deficient mouse retina.
causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
evidence:
- reference: PMID:8675686
reference_title: "A mouse model of gyrate atrophy of the choroid and retina. Early retinal pigment epithelium damage and progressive retinal degeneration."
supports: SUPPORT
evidence_source: MODEL_ORGANISM
snippet: >-
Like human GA patients, adult OAT-deficient mice exhibit chronic hyperornithinemia to levels 10-15-fold above normal and massive ornithinuria. Slowly progressive retinal degeneration is reflected by a gradual decline in electroretinogram amplitudes over the first 12 mo of life. At 2 mo, the retinal pigment epithelium is histologically normal, but electron microscopy reveals sporadic degeneration of scattered pigment epithelial cells.
explanation: >-
OAT-deficient mouse data link chronic hyperornithinemia to early RPE
injury before progressive retinal degeneration.
- target: Plasma ornithine
description: Hyperornithinemia is measured as elevated plasma ornithine.
causal_link_type: DIRECT
evidence:
- reference: DOI:10.1186/s13023-026-04265-x
reference_title: "Gyrate atrophy of the choroid and retina: a tertiary center experience"
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
All patients had high plasma ornithine levels at the time of diagnosis,
and they were all started on an arginine-restricted diet.
explanation: >-
Cohort evidence directly supports elevated plasma ornithine as the
measured biochemical expression of hyperornithinemia.
- target: Cataract
description: Ornithine accumulation contributes to cataract as part of the ocular disease.
causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
evidence:
- reference: PMID:34894815
reference_title: "Gyrate Atrophy of the Choroid and Retina: A Review."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Accumulation of ornithine occurs in various body tissues but leads
primarily to characteristic ophthalmic manifestations including myopia,
cataract, progressive chorioretinal atrophy, and macular changes.
explanation: >-
Review lists cataract among the characteristic ophthalmic manifestations
associated with ornithine accumulation.
- target: Myopia
description: Ornithine accumulation is associated with childhood myopia as an early ocular feature.
causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
evidence:
- reference: PMID:34894815
reference_title: "Gyrate Atrophy of the Choroid and Retina: A Review."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Accumulation of ornithine occurs in various body tissues but leads
primarily to characteristic ophthalmic manifestations including myopia,
cataract, progressive chorioretinal atrophy, and macular changes.
explanation: >-
Review links tissue ornithine accumulation to myopia and other
ophthalmic manifestations.
- name: Progressive chorioretinal degeneration
description: >-
The downstream ophthalmologic disease causes progressive retinal and choroidal
damage that drives nyctalopia, visual field constriction, and visual decline.
cell_types:
- preferred_term: retinal pigment epithelial cell
term:
id: CL:0002586
label: retinal pigment epithelial cell
evidence:
- reference: DOI:10.1186/s13023-026-04265-x
reference_title: "Gyrate atrophy of the choroid and retina: a tertiary center experience"
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
The patients primarily present with progressive ophthalmological findings.
explanation: >-
This cohort study directly supports progressive ophthalmologic degeneration
as the key downstream disease process.
- reference: PMID:10655512
reference_title: "Correction of ornithine accumulation prevents retinal degeneration in a mouse model of gyrate atrophy of the choroid and retina."
supports: SUPPORT
evidence_source: MODEL_ORGANISM
snippet: >-
an arginine-restricted diet substantially reduces plasma ornithine levels and completely prevents retinal degeneration in Oat(-/-)
explanation: >-
Mouse model demonstrates that reducing ornithine accumulation prevents
retinal degeneration, confirming that hyperornithinemia drives
chorioretinal damage.
- reference: PMID:8675686
reference_title: "A mouse model of gyrate atrophy of the choroid and retina. Early retinal pigment epithelium damage and progressive retinal degeneration."
supports: SUPPORT
evidence_source: MODEL_ORGANISM
snippet: >-
Our results indicate that retinal pigment epithelial cells are the initial site of insult in GA and that the OAT-deficient mouse is an excellent animal model of GA in human patients.
explanation: >-
Mouse-model evidence identifies RPE cells as the initial cellular site of
injury in gyrate atrophy.
downstream:
- target: Nyctalopia
description: Chorioretinal degeneration leads to early night blindness.
causal_link_type: DIRECT
evidence:
- reference: PMID:34894815
reference_title: "Gyrate Atrophy of the Choroid and Retina: A Review."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Patients usually present with night blindness that starts in the first
decade of life followed by visual field constriction and eventually
diminution of the central visual acuity and blindness.
explanation: >-
Review describes night blindness as the first manifestation in the
progressive ophthalmologic sequence.
- target: Chorioretinal atrophy
description: Progressive retinal and choroidal degeneration manifests as chorioretinal atrophy.
causal_link_type: DIRECT
evidence:
- reference: PMID:34894815
reference_title: "Gyrate Atrophy of the Choroid and Retina: A Review."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Accumulation of ornithine occurs in various body tissues but leads
primarily to characteristic ophthalmic manifestations including myopia,
cataract, progressive chorioretinal atrophy, and macular changes.
explanation: >-
Review identifies progressive chorioretinal atrophy as a characteristic
ophthalmic manifestation of gyrate atrophy.
- target: Constriction of peripheral visual field
description: Peripheral retinal degeneration causes progressive visual field constriction.
causal_link_type: DIRECT
evidence:
- reference: PMID:34894815
reference_title: "Gyrate Atrophy of the Choroid and Retina: A Review."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Patients usually present with night blindness that starts in the first
decade of life followed by visual field constriction and eventually
diminution of the central visual acuity and blindness.
explanation: >-
Review places visual field constriction after night blindness in the
progressive ophthalmologic course.
- target: Visual loss
description: Ongoing retinal degeneration causes progressive visual loss.
causal_link_type: DIRECT
evidence:
- reference: PMID:34894815
reference_title: "Gyrate Atrophy of the Choroid and Retina: A Review."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Patients usually present with night blindness that starts in the first
decade of life followed by visual field constriction and eventually
diminution of the central visual acuity and blindness.
explanation: >-
Review supports progressive loss of central visual acuity and blindness
as downstream outcomes of ocular degeneration.
- name: Retinal pigment epithelial cell injury
description: >-
Retinal pigment epithelial cells are an early site of insult in the
hyperornithinemic OAT-deficient retina, preceding progressive photoreceptor
disorganization and cell loss.
cell_types:
- preferred_term: retinal pigment epithelial cell
term:
id: CL:0002586
label: retinal pigment epithelial cell
evidence:
- reference: PMID:8675686
reference_title: "A mouse model of gyrate atrophy of the choroid and retina. Early retinal pigment epithelium damage and progressive retinal degeneration."
supports: SUPPORT
evidence_source: MODEL_ORGANISM
snippet: >-
At 2 mo, the retinal pigment epithelium is histologically normal, but electron microscopy reveals sporadic degeneration of scattered pigment epithelial cells.
explanation: >-
Mouse-model evidence shows early RPE ultrastructural injury in OAT
deficiency.
- reference: PMID:8675686
reference_title: "A mouse model of gyrate atrophy of the choroid and retina. Early retinal pigment epithelium damage and progressive retinal degeneration."
supports: SUPPORT
evidence_source: MODEL_ORGANISM
snippet: >-
Our results indicate that retinal pigment epithelial cells are the initial site of insult in GA and that the OAT-deficient mouse is an excellent animal model of GA in human patients.
explanation: >-
The study identifies RPE cells as the initial injury site in the disease
model.
downstream:
- target: Progressive chorioretinal degeneration
description: Early RPE injury progresses to broader retinal degeneration and photoreceptor cell loss.
causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
intermediate_mechanisms:
- photoreceptor outer segment disorganization
- cumulative photoreceptor cell loss
evidence:
- reference: PMID:8675686
reference_title: "A mouse model of gyrate atrophy of the choroid and retina. Early retinal pigment epithelium damage and progressive retinal degeneration."
supports: SUPPORT
evidence_source: MODEL_ORGANISM
snippet: >-
Although morphologically normal at 2 mo, the photo-receptor outer segments become highly disorganized and shortened to 60% of control length by 10 mo. Additionally, there is cumulative loss of the photoreceptor cells, which reaches 33% by 10 mo and is most pronounced in the central region of the retina.
explanation: >-
Mouse-model evidence places photoreceptor disorganization and cell loss
downstream of early RPE injury.
- name: Secondary amino acid and creatine depletion
description: >-
The OAT metabolic lesion is accompanied by reduced glutamate, lysine, and
creatine pools; low cerebral creatine provides a plausible biochemical link
to extraocular neurologic and neuromuscular manifestations in a subset of
patients.
biological_processes:
- preferred_term: creatine metabolic process
term:
id: GO:0006600
label: creatine metabolic process
modifier: DECREASED
chemical_entities:
- preferred_term: creatine
term:
id: CHEBI:16919
label: creatine
modifier: DECREASED
- preferred_term: L-glutamic acid
term:
id: CHEBI:16015
label: L-glutamic acid
modifier: DECREASED
- preferred_term: L-lysine
term:
id: CHEBI:18019
label: L-lysine
modifier: DECREASED
evidence:
- reference: PMID:34395527
reference_title: "Molecular and Cellular Studies Reveal Folding Defects of Human Ornithine Aminotransferase Variants Associated With Gyrate Atrophy of the Choroid and Retina."
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
The deficit of hOAT leads to a 10-to-15 fold increase in the plasmatic L-Orn concentration, along with a small reduction in the levels of glutamate, glutamine, lysine and creatine
explanation: >-
Review text supports secondary reductions in amino-acid and creatine
pools downstream of hOAT deficiency.
- reference: PMID:32418451
reference_title: "First report of c.425-1G>A mutation in ornithine aminotransferase gene causing gyrate atrophy of the choroid and retina with hyperornithinemia."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
the increased ornithine level is the clinical manifestation of gyrate atrophy of choroid and retina, muscle weakness, moderate mental retardation, and low cerebral creatine.
explanation: >-
Case-report abstract supports low cerebral creatine alongside extraocular
neurologic and neuromuscular manifestations.
downstream:
- target: Cognitive impairment
description: Low cerebral creatine may contribute to cognitive impairment in the extraocular disease spectrum.
causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
evidence:
- reference: PMID:32418451
reference_title: "First report of c.425-1G>A mutation in ornithine aminotransferase gene causing gyrate atrophy of the choroid and retina with hyperornithinemia."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
the increased ornithine level is the clinical manifestation of gyrate atrophy of choroid and retina, muscle weakness, moderate mental retardation, and low cerebral creatine.
explanation: >-
Case-report abstract colocates cognitive impairment and low cerebral
creatine in the clinical spectrum.
- target: Muscle weakness
description: Low cerebral creatine and secondary metabolic imbalance may contribute to muscle weakness in some patients.
causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
evidence:
- reference: PMID:32418451
reference_title: "First report of c.425-1G>A mutation in ornithine aminotransferase gene causing gyrate atrophy of the choroid and retina with hyperornithinemia."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
the increased ornithine level is the clinical manifestation of gyrate atrophy of choroid and retina, muscle weakness, moderate mental retardation, and low cerebral creatine.
explanation: >-
Case-report abstract links muscle weakness with low cerebral creatine
in an affected patient.
phenotypes:
- name: Nyctalopia
category: Ophthalmologic
description: >-
Night blindness is typically the earliest visual symptom, starting in the
first decade of life.
phenotype_term:
preferred_term: Nyctalopia
term:
id: HP:0000662
label: Nyctalopia
evidence:
- reference: DOI:10.1186/s13023-026-04265-x
reference_title: "Gyrate atrophy of the choroid and retina: a tertiary center experience"
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Night blindness, cataracts, vision loss, and impaired cognitive functions can be seen.
explanation: >-
This directly supports nyctalopia as part of the core ophthalmologic
phenotype.
- reference: PMID:34894815
reference_title: "Gyrate Atrophy of the Choroid and Retina: A Review."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Patients usually present with night blindness that starts in the first decade of life followed by visual field constriction and eventually diminution of the central visual acuity and blindness.
explanation: >-
Review confirms night blindness as the presenting symptom beginning in
the first decade of life.
- name: Cataract
category: Ophthalmologic
description: >-
Cataracts are a frequent component of the progressive eye disease.
phenotype_term:
preferred_term: Cataract
term:
id: HP:0000518
label: Cataract
evidence:
- reference: DOI:10.1186/s13023-026-04265-x
reference_title: "Gyrate atrophy of the choroid and retina: a tertiary center experience"
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Night blindness, cataracts, vision loss, and impaired cognitive functions can be seen.
explanation: >-
This directly supports cataract as a common ophthalmologic manifestation.
- reference: PMID:34894815
reference_title: "Gyrate Atrophy of the Choroid and Retina: A Review."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
leads primarily to characteristic ophthalmic manifestations including myopia, cataract, progressive chorioretinal atrophy, and macular changes.
explanation: >-
Review confirms cataract as one of the characteristic ophthalmic
manifestations.
- name: Visual loss
category: Ophthalmologic
description: >-
Progressive retinal degeneration leads to declining visual function over
time, ultimately progressing to blindness.
phenotype_term:
preferred_term: Progressive visual loss
term:
id: HP:0000529
label: Progressive visual loss
clinical_course: PROGRESSIVE
evidence:
- reference: DOI:10.1186/s13023-026-04265-x
reference_title: "Gyrate atrophy of the choroid and retina: a tertiary center experience"
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Night blindness, cataracts, vision loss, and impaired cognitive functions can be seen.
explanation: >-
This directly supports progressive visual loss as a core phenotype.
- reference: PMID:34340878
reference_title: "A review of treatment modalities in gyrate atrophy of the choroid and retina (GACR)."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
GACR is characterised by vision decline in early life eventually leading to complete blindness, and high plasma ornithine levels.
explanation: >-
Systematic review confirms vision decline progressing to complete
blindness.
- name: Cognitive impairment
category: Neurologic
description: >-
Cognitive impairment can be present in some affected individuals alongside
the core ophthalmologic manifestations, although most patients have
unaffected cognition.
phenotype_term:
preferred_term: Cognitive impairment
term:
id: HP:0100543
label: Cognitive impairment
evidence:
- reference: DOI:10.1186/s13023-026-04265-x
reference_title: "Gyrate atrophy of the choroid and retina: a tertiary center experience"
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Night blindness, cataracts, vision loss, and impaired cognitive functions can be seen.
explanation: >-
This directly supports cognitive impairment as part of the clinical
spectrum of gyrate atrophy due to OAT deficiency.
- reference: PMID:34395527
reference_title: "Molecular and Cellular Studies Reveal Folding Defects of Human Ornithine Aminotransferase Variants Associated With Gyrate Atrophy of the Choroid and Retina."
supports: PARTIAL
evidence_source: IN_VITRO
snippet: >-
In most GA patients cognition is unaffected
explanation: >-
This full-text review notes that cognition is unaffected in most patients,
indicating cognitive impairment is a variable rather than universal feature.
- name: Myopia
category: Ophthalmologic
description: >-
Myopia develops during childhood and is a characteristic early ophthalmic
feature of gyrate atrophy.
phenotype_term:
preferred_term: Myopia
term:
id: HP:0000545
label: Myopia
evidence:
- reference: PMID:34894815
reference_title: "Gyrate Atrophy of the Choroid and Retina: A Review."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
leads primarily to characteristic ophthalmic manifestations including myopia, cataract, progressive chorioretinal atrophy, and macular changes.
explanation: >-
Review identifies myopia as one of the characteristic ophthalmic
manifestations of gyrate atrophy.
- reference: PMID:34395527
reference_title: "Molecular and Cellular Studies Reveal Folding Defects of Human Ornithine Aminotransferase Variants Associated With Gyrate Atrophy of the Choroid and Retina."
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
Patients develop myopia during childhood, and show a progressive decrease in visual acuity from the 2° to the 3° decade leading to blindness within the 5° decade
explanation: >-
Full-text review confirms childhood-onset myopia as a typical feature.
- name: Chorioretinal atrophy
category: Ophthalmologic
description: >-
Progressive chorioretinal atrophy is the hallmark ophthalmologic finding,
with characteristic patches of atrophy in the peripheral retina extending
into the macular area.
phenotype_term:
preferred_term: Chorioretinal atrophy
term:
id: HP:0000533
label: Chorioretinal atrophy
clinical_course: PROGRESSIVE
evidence:
- reference: PMID:34894815
reference_title: "Gyrate Atrophy of the Choroid and Retina: A Review."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
leads primarily to characteristic ophthalmic manifestations including myopia, cataract, progressive chorioretinal atrophy, and macular changes.
explanation: >-
Review identifies progressive chorioretinal atrophy as a characteristic
ophthalmic manifestation.
- reference: PMID:33068755
reference_title: "Deficit of human ornithine aminotransferase in gyrate atrophy: Molecular, cellular, and clinical aspects."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Gyrate Atrophy (GA) of the choroid and retina (MIM# 258870) is an autosomal recessive disorder due to mutations of the OAT gene encoding ornithine-delta-aminotransferase (OAT), associated with progressive retinal deterioration and blindness.
explanation: >-
Confirms progressive retinal deterioration as a defining feature.
- name: Constriction of peripheral visual field
category: Ophthalmologic
description: >-
Visual field constriction follows the onset of night blindness as
chorioretinal atrophy progresses from the periphery toward the macula.
phenotype_term:
preferred_term: Constriction of peripheral visual field
term:
id: HP:0001133
label: Constriction of peripheral visual field
clinical_course: PROGRESSIVE
evidence:
- reference: PMID:34894815
reference_title: "Gyrate Atrophy of the Choroid and Retina: A Review."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Patients usually present with night blindness that starts in the first decade of life followed by visual field constriction and eventually diminution of the central visual acuity and blindness.
explanation: >-
Review describes visual field constriction as part of the progressive
ophthalmologic course.
- name: Hyperornithinemia
category: Metabolic
description: >-
Markedly elevated plasma ornithine is the defining biochemical hallmark of
the disorder, resulting from impaired ornithine catabolism due to OAT
deficiency.
phenotype_term:
preferred_term: Hyperornithinemia
term:
id: HP:0012026
label: Hyperornithinemia
evidence:
- reference: PMID:33068755
reference_title: "Deficit of human ornithine aminotransferase in gyrate atrophy: Molecular, cellular, and clinical aspects."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
OAT is mainly involved in ornithine catabolism in adults, thus explaining the hyperornithinemia as hallmark of the disease.
explanation: >-
Review directly identifies hyperornithinemia as the hallmark of the
disease.
- reference: PMID:34894815
reference_title: "Gyrate Atrophy of the Choroid and Retina: A Review."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Gyrate atrophy (GA) of the choroid and retina is a rare autosomal recessive genetic condition characterized by elevation of the plasma level of the amino acid ornithine due to deficiency of the enzyme ornithine ketoacid aminotransferase.
explanation: >-
Review confirms elevated plasma ornithine as the defining biochemical
feature.
- name: Muscle weakness
category: Musculoskeletal
description: >-
Muscle weakness and hypotonia can occur in some patients with gyrate atrophy,
associated with low cerebral creatine levels.
phenotype_term:
preferred_term: Muscle weakness
term:
id: HP:0001324
label: Muscle weakness
evidence:
- reference: PMID:32418451
reference_title: "First report of c.425-1G>A mutation in ornithine aminotransferase gene causing gyrate atrophy of the choroid and retina with hyperornithinemia."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
the increased ornithine level is the clinical manifestation of gyrate atrophy of choroid and retina, muscle weakness, moderate mental retardation, and low cerebral creatine.
explanation: >-
Case report identifies muscle weakness as a clinical manifestation
associated with gyrate atrophy and hyperornithinemia.
genetic:
- name: OAT
association: Loss of function mutation
gene_term:
preferred_term: OAT
term:
id: hgnc:8091
label: OAT
evidence:
- reference: PMID:34395527
reference_title: "Molecular and Cellular Studies Reveal Folding Defects of Human Ornithine Aminotransferase Variants Associated With Gyrate Atrophy of the Choroid and Retina."
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
The deficit of human ornithine aminotransferase (hOAT) is responsible for gyrate atrophy (GA), a rare recessive inherited disorder.
explanation: >-
This directly supports OAT deficiency as the causal genetic lesion.
- reference: PMID:34340878
reference_title: "A review of treatment modalities in gyrate atrophy of the choroid and retina (GACR)."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Gyrate atrophy of the choroid and retina (GACR) is a rare inborn error of amino acid metabolism caused by bi-allelic variations in OAT.
explanation: >-
Systematic review confirms bi-allelic OAT mutations as the genetic cause.
- reference: CGGV:assertion_edbab666-9ae6-46db-b818-809a4bf8333e-2019-07-10T160000.000Z
reference_title: "OAT / ornithine aminotransferase deficiency (Definitive)"
supports: SUPPORT
evidence_source: OTHER
snippet: "OAT | HGNC:8091 | ornithine aminotransferase deficiency | MONDO:0009796 | AR | Definitive"
explanation: ClinGen classifies the OAT-ornithine aminotransferase deficiency gene-disease relationship as definitive with autosomal recessive inheritance.
biochemical:
- name: Plasma ornithine
presence: INCREASED
context: >-
Elevated plasma ornithine is the core biochemical hallmark of the disorder,
with levels typically elevated 10- to 15-fold above normal.
biomarker_term:
preferred_term: L-ornithine
term:
id: CHEBI:15729
label: L-ornithine
readouts:
- target: Hyperornithinemia
relationship: READOUT_OF
direction: POSITIVE
endpoint_context: DIAGNOSTIC
interpretation: >-
Elevated plasma L-ornithine directly reports the hyperornithinemia caused
by impaired OAT-mediated ornithine catabolism.
evidence:
- reference: DOI:10.1186/s13023-026-04265-x
reference_title: "Gyrate atrophy of the choroid and retina: a tertiary center experience"
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
All patients had high plasma ornithine levels at the time of diagnosis, and they were all started on an arginine-restricted diet.
explanation: >-
This directly supports hyperornithinemia as the defining biochemical
abnormality.
- reference: PMID:34395527
reference_title: "Molecular and Cellular Studies Reveal Folding Defects of Human Ornithine Aminotransferase Variants Associated With Gyrate Atrophy of the Choroid and Retina."
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
The deficit of hOAT leads to a 10-to-15 fold increase in the plasmatic L-Orn concentration, along with a small reduction in the levels of glutamate, glutamine, lysine and creatine
explanation: >-
Full-text review quantifies the magnitude of ornithine elevation and
notes associated reductions in glutamate, glutamine, lysine, and creatine.
- name: Cerebral creatine
presence: DECREASED
context: >-
Low cerebral creatine has been reported with extraocular neurologic and
neuromuscular manifestations in OAT deficiency and reflects secondary
amino-acid/creatine metabolic imbalance.
biomarker_term:
preferred_term: creatine
term:
id: CHEBI:16919
label: creatine
readouts:
- target: Secondary amino acid and creatine depletion
relationship: READOUT_OF
direction: NEGATIVE
endpoint_context: DIAGNOSTIC
interpretation: >-
Low cerebral creatine reports the secondary creatine depletion node that
may contribute to extraocular neurologic and neuromuscular features.
evidence:
- reference: PMID:32418451
reference_title: "First report of c.425-1G>A mutation in ornithine aminotransferase gene causing gyrate atrophy of the choroid and retina with hyperornithinemia."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
the increased ornithine level is the clinical manifestation of gyrate atrophy of choroid and retina, muscle weakness, moderate mental retardation, and low cerebral creatine.
explanation: >-
Case-report abstract supports low cerebral creatine as a biochemical
finding in OAT deficiency with extraocular manifestations.
diagnosis:
- name: OAT molecular genetic testing
description: >-
Molecular testing confirms the diagnosis by identifying pathogenic OAT
variants.
diagnosis_term:
preferred_term: molecular genetic testing
term:
id: MAXO:0000533
label: molecular genetic testing
qualifiers:
- predicate:
preferred_term: has participant
term:
id: RO:0000057
label: has participant
value:
preferred_term: OAT
term:
id: hgnc:8091
label: OAT
results: Pathogenic OAT variants in a patient with gyrate atrophy and hyperornithinemia.
evidence:
- reference: DOI:10.1186/s13023-026-04265-x
reference_title: "Gyrate atrophy of the choroid and retina: a tertiary center experience"
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Patients followed by the Gazi University Faculty of Medicine, Department of Pediatric Metabolism and Nutrition, and Department of Ophthalmology who were genetically or biochemically diagnosed with GACR were included in the study.
explanation: >-
This directly supports molecular or biochemical confirmation as part of the
diagnostic framework.
treatments:
- name: Arginine-restricted diet
description: >-
Dietary arginine restriction is used to improve metabolic control and lower
plasma ornithine burden.
treatment_term:
preferred_term: dietary intervention
term:
id: MAXO:0000088
label: dietary intervention
target_phenotypes:
- preferred_term: Hyperornithinemia
term:
id: HP:0012026
label: Hyperornithinemia
target_mechanisms:
- target: Hyperornithinemia
treatment_effect: INHIBITS
description: >-
Arginine or protein restriction lowers ornithine burden, targeting the
central hyperornithinemia node upstream of retinal degeneration.
evidence:
- reference: PMID:34340878
reference_title: "A review of treatment modalities in gyrate atrophy of the choroid and retina (GACR)."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Protein-restricted diets lowered ornithine levels ranging from 16.0-91.2%."
explanation: >-
Systematic review directly supports dietary protein or arginine
restriction reducing the hyperornithinemia treatment target.
- reference: PMID:10655512
reference_title: "Correction of ornithine accumulation prevents retinal degeneration in a mouse model of gyrate atrophy of the choroid and retina."
supports: SUPPORT
evidence_source: MODEL_ORGANISM
snippet: >-
an arginine-restricted diet substantially reduces plasma ornithine
levels and completely prevents retinal degeneration in Oat(-/-)
explanation: >-
Oat-deficient mouse data support arginine restriction lowering plasma
ornithine and preventing retinal degeneration.
evidence:
- reference: DOI:10.1186/s13023-026-04265-x
reference_title: "Gyrate atrophy of the choroid and retina: a tertiary center experience"
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
An arginine-restricted diet is combined with supplementation with pyridoxine, lysine, proline, or creatine to improve metabolic control.
explanation: >-
This directly supports arginine restriction as the core disease-specific
treatment strategy.
- reference: PMID:34340878
reference_title: "A review of treatment modalities in gyrate atrophy of the choroid and retina (GACR)."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Protein-restricted diets lowered ornithine levels ranging from 16.0-91.2%.
explanation: >-
Systematic review quantifies the effectiveness of protein-restricted
diets in lowering ornithine levels.
- reference: PMID:10655512
reference_title: "Correction of ornithine accumulation prevents retinal degeneration in a mouse model of gyrate atrophy of the choroid and retina."
supports: SUPPORT
evidence_source: MODEL_ORGANISM
snippet: >-
an arginine-restricted diet substantially reduces plasma ornithine levels and completely prevents retinal degeneration in Oat(-/-)
explanation: >-
Mouse model demonstrates that arginine-restricted diet prevents retinal
degeneration by reducing ornithine accumulation.
- name: Pyridoxine supplementation
description: >-
Pyridoxine is used as adjunctive therapy in an attempt to improve metabolic
control in some patients, although responsiveness is mutation-dependent and
not universal. Related supplementation regimens may also include lysine,
proline, or creatine in combination with arginine restriction.
treatment_term:
preferred_term: Pharmacotherapy
term:
id: NCIT:C15986
label: Pharmacotherapy
therapeutic_agent:
- preferred_term: pyridoxine
term:
id: CHEBI:16709
label: pyridoxine
target_phenotypes:
- preferred_term: Hyperornithinemia
term:
id: HP:0012026
label: Hyperornithinemia
target_mechanisms:
- target: Hyperornithinemia
treatment_effect: MODULATES
description: >-
Pyridoxine can reduce ornithine levels in responsive OAT variants, so it
is modeled as variant-dependent modulation of the hyperornithinemia node.
evidence:
- reference: PMID:34340878
reference_title: "A review of treatment modalities in gyrate atrophy of the choroid and retina (GACR)."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Based primarily on case reports ornithine levels can be reduced by
using a protein restricted diet, pyridoxine supplementation
(variation-dependent) and/or lysine supplementation.
explanation: >-
Systematic review supports variant-dependent ornithine reduction with
pyridoxine supplementation.
evidence:
- reference: DOI:10.1186/s13023-026-04265-x
reference_title: "Gyrate atrophy of the choroid and retina: a tertiary center experience"
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
An arginine-restricted diet is combined with supplementation with pyridoxine, lysine, proline, or creatine to improve metabolic control.
explanation: >-
This directly supports pyridoxine supplementation as part of the standard
metabolic management regimen.
- reference: PMID:34340878
reference_title: "A review of treatment modalities in gyrate atrophy of the choroid and retina (GACR)."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Pyridoxine responsiveness was reported in 30% of included mutations.
explanation: >-
Systematic review reports that pyridoxine responsiveness is
mutation-dependent and observed in about 30% of mutations.
- name: Adjunctive lysine, proline, and creatine supplementation
description: >-
Lysine, proline, or creatine supplementation may be combined with arginine
restriction and pyridoxine to improve metabolic control; lysine has reported
ornithine-lowering effects in case-based treatment literature, while
creatine supplementation is biologically aligned with reported low cerebral
creatine.
treatment_term:
preferred_term: Pharmacotherapy
term:
id: NCIT:C15986
label: Pharmacotherapy
therapeutic_agent:
- preferred_term: L-lysine
term:
id: CHEBI:18019
label: L-lysine
- preferred_term: L-proline
term:
id: CHEBI:17203
label: L-proline
- preferred_term: creatine
term:
id: CHEBI:16919
label: creatine
target_phenotypes:
- preferred_term: Hyperornithinemia
term:
id: HP:0012026
label: Hyperornithinemia
- preferred_term: Cognitive impairment
term:
id: HP:0100543
label: Cognitive impairment
- preferred_term: Muscle weakness
term:
id: HP:0001324
label: Muscle weakness
target_mechanisms:
- target: Hyperornithinemia
treatment_effect: MODULATES
description: >-
Lysine supplementation is reported with ornithine reduction in case-based
treatment literature.
evidence:
- reference: PMID:34340878
reference_title: "A review of treatment modalities in gyrate atrophy of the choroid and retina (GACR)."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Based primarily on case reports ornithine levels can be reduced by
using a protein restricted diet, pyridoxine supplementation
(variation-dependent) and/or lysine supplementation.
explanation: >-
Systematic review supports lysine supplementation as an ornithine-lowering
adjunct in reported cases.
- target: Secondary amino acid and creatine depletion
treatment_effect: MODULATES
description: >-
Creatine supplementation targets the reported low-creatine component of
the secondary biochemical imbalance.
evidence:
- reference: DOI:10.1186/s13023-026-04265-x
reference_title: "Gyrate atrophy of the choroid and retina: a tertiary center experience"
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
An arginine-restricted diet is combined with supplementation with pyridoxine, lysine, proline, or creatine to improve metabolic control.
explanation: >-
Cohort report supports creatine and related supplementation as part of
metabolic management.
evidence:
- reference: DOI:10.1186/s13023-026-04265-x
reference_title: "Gyrate atrophy of the choroid and retina: a tertiary center experience"
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
An arginine-restricted diet is combined with supplementation with pyridoxine, lysine, proline, or creatine to improve metabolic control.
explanation: >-
Cohort report directly lists lysine, proline, and creatine
supplementation as adjunctive metabolic-management options.
- reference: PMID:34340878
reference_title: "A review of treatment modalities in gyrate atrophy of the choroid and retina (GACR)."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Based primarily on case reports ornithine levels can be reduced by using a protein restricted diet, pyridoxine supplementation (variation-dependent) and/or lysine supplementation.
explanation: >-
Systematic review supports lysine supplementation as an adjunctive
ornithine-lowering treatment.
differential_diagnoses: []
clinical_trials: []
datasets: []
This report is retrieval-only and is generated directly from Asta results.
search_papers_by_relevance with snippet_search.