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Mappings

MONDO

MONDO:0010079 Canavan disease

Orphanet ORPHA:141 lists MONDO:0010079 as an exact cross-reference for Canavan disease.

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Definitions

1

Orphanet Canavan disease definition

A neurodegenerative disorder ranging from severe leukodystrophy with macrocephaly and severe developmental delay to very rare mild/juvenile disease with milder developmental delay.

OTHER

Show evidence (1 reference)

ORPHA:141 SUPPORT Other

"neurodegenerative disorder; its spectrum varies between severe forms with leukodystrophy"

Orphanet defines Canavan disease as a spectrum neurodegenerative leukodystrophy.

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Inheritance

1

Autosomal recessive inheritance HP:0000007

Autosomal recessive. Heterozygous carriers are asymptomatic. When both parents carry a pathogenic ASPA variant, each pregnancy has a 25% affected, 50% carrier, and 25% unaffected noncarrier probability. Parental testing supports recurrence-risk assessment.

Autosomal recessive inheritance

Show evidence (4 references)

ORPHA:141 SUPPORT Other

"Autosomal recessive"

Orphanet records autosomal recessive inheritance for Canavan disease.

PMID:20301412 SUPPORT Other

"Canavan disease is inherited in an autosomal recessive manner."

GeneReviews confirms autosomal recessive inheritance.

url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/ SUPPORT Other

"Heterozygotes (carriers) are asymptomatic and are not at risk of developing the disorder."

Distinguishes carrier status from disease.

+ 1 more reference

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Subtypes

2

Typical infantile Canavan disease

The more severe infantile presentation, accounting for approximately 85%-90% in GeneReviews. Early developmental impairment, hypotonia and macrocephaly precede progressive disability.

Show evidence (1 reference)

url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/ SUPPORT Other

"The phenotypic spectrum ranges from the more severe typical Canavan disease (85%-90% of individuals) to the less severe atypical Canavan disease (10%-15%)."

Clinical spectrum proportions are expert synthesis, not a population prevalence estimate.

Atypical Canavan disease

The less severe and variable presentation, approximately 10%-15% in GeneReviews, with later or milder manifestations, sometimes preserved walking and speech, and possible later regression.

Show evidence (2 references)

url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/ SUPPORT Other

"The phenotypic spectrum ranges from the more severe typical Canavan disease (85%-90% of individuals) to the less severe atypical Canavan disease (10%-15%)."

Clinical spectrum proportions are expert synthesis, not a population prevalence estimate.

url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/ SUPPORT Other

"The life span is not well-described; however, individuals with atypical Canavan disease may survive to adulthood."

Avoids extrapolating the severe infantile prognosis to all atypical individuals.

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Mechanistic Hypotheses

3

NAA accumulation and cellular injury

naa_injury EMERGING

Evidence balance 2 support

Aspa/Nat8l genetic perturbations support a causal role for excess NAA in mouse leukodystrophy and neuronal loss. Osmotic disequilibrium is proposed, but substrate reduction does not identify a single downstream injury mechanism or prove every human causal step.

Pathograph links

NAA accumulation in CNS and body fluids -> Spongiform white-matter vacuolation INDIRECT UNKNOWN INTERMEDIATES Reducing NAA synthesis rescues this pathology in Aspa-deficient mice; the intervening injury mechanism and its contribution in humans remain incompletely resolved.

NAA accumulation in CNS and body fluids -> Neuronal loss and cortical thinning INDIRECT UNKNOWN INTERMEDIATES Reducing NAA synthesis rescues this pathology in Aspa-deficient mice; the intervening injury mechanism and its contribution in humans remain incompletely resolved.

Show evidence (2 references)

PMID:25712859 SUPPORT Model Organism

"Aspanur7/nur7 mice were entirely protected against development of leukodystrophy when their capacity to synthesize NAA was ablated by constitutive deletion of Nat8l"

Genetic substrate-reduction experiment supports a causal role for excess NAA in the mouse model.

PMID:34011350 SUPPORT BACKGROUND Other

"high levels of NAA, as found in CD, are thought to cause a toxic imbalance of brain water homeostasis"

The clinical report discusses a proposed, incompletely resolved connection to neurological disease.

Acetate-dependent metabolism contributes to myelin pathology

acetate_contribution EMERGING

Evidence balance 1 support 1 refute

Reduced acetate and lipid synthesis are observed in ASPA deficiency. Their contribution to injury remains debated: Nat8l deletion preserves or rescues myelination without restoring NAA-derived acetate.

Pathograph links

Reduced NAA-derived acetate and myelin lipid synthesis -> Oligodendrocyte maturation and myelination defect INDIRECT UNKNOWN INTERMEDIATES Proposed contribution of deficient acetate-dependent lipid metabolism; challenged as a necessary or sole mechanism by Nat8l deletion experiments.

Show evidence (2 references)

PMID:15784740 SUPPORT Model Organism

"myelin lipid synthesis is significantly compromised in CD"

Mouse and human white-matter lipid data support impaired myelin lipid synthesis.

PMID:26511242 REFUTE Model Organism

"acetate derived from NAA is not essential for myelin lipid synthesis"

Normal myelin composition in double-mutant mice argues against obligatory NAA-derived acetate supply.

Brain injury contributes to clinical neurological impairment

clinical_injury EMERGING

Evidence balance 1 support

White-matter and neuronal abnormalities plausibly contribute to the neurological phenotype, but cohort associations do not resolve the pathway for each manifestation. Edges in this group are explanatory hypotheses rather than experimentally established direct steps.

Pathograph links

Oligodendrocyte maturation and myelination defect -> Global developmental delay INDIRECT UNKNOWN INTERMEDIATES White-matter dysfunction disrupts early neurodevelopmental progress. This is a proposed clinical consequence; the precise intervening pathway is unresolved.

Oligodendrocyte maturation and myelination defect -> Hypotonia INDIRECT UNKNOWN INTERMEDIATES Early white-matter disease contributes to impaired motor control and hypotonia. This is a proposed clinical consequence; the precise intervening pathway is unresolved.

Spongiform white-matter vacuolation -> Macrocephaly INDIRECT UNKNOWN INTERMEDIATES Diffuse white-matter disease contributes to progressive head enlargement. This is a proposed clinical consequence; the precise intervening pathway is unresolved.

Spongiform white-matter vacuolation -> Hypertonia INDIRECT UNKNOWN INTERMEDIATES Progressive white-matter disease contributes to later spasticity and hypertonia. This is a proposed clinical consequence; the precise intervening pathway is unresolved.

Spongiform white-matter vacuolation -> Seizure INDIRECT UNKNOWN INTERMEDIATES Progressive brain involvement contributes to epilepsy over time. This is a proposed clinical consequence; the precise intervening pathway is unresolved.

Spongiform white-matter vacuolation -> Flexion contracture INDIRECT UNKNOWN INTERMEDIATES Progressive tone abnormality and reduced mobility increase risk for contractures. This is a proposed clinical consequence; the precise intervening pathway is unresolved.

Visual pathway and ocular involvement -> Blindness INDIRECT UNKNOWN INTERMEDIATES Severe visual pathway and ocular involvement can manifest as blindness. This is a proposed clinical consequence; the precise intervening pathway is unresolved.

Visual pathway and ocular involvement -> Abnormality of visual evoked potentials INDIRECT UNKNOWN INTERMEDIATES Visual pathway disease can produce abnormal visual evoked potentials. This is a proposed clinical consequence; the precise intervening pathway is unresolved.

Visual pathway and ocular involvement -> Nystagmus INDIRECT UNKNOWN INTERMEDIATES Early abnormal eye movements, including nystagmus, occur in Canavan disease. This is a proposed clinical consequence; the precise intervening pathway is unresolved.

Feeding and aspiration vulnerability -> Gastroesophageal reflux INDIRECT UNKNOWN INTERMEDIATES Feeding and swallowing impairment can coexist with reflux in severe neurologic disease. This is a proposed clinical consequence; the precise intervening pathway is unresolved.

Neuronal loss and cortical thinning -> Cognitive impairment INDIRECT UNKNOWN INTERMEDIATES Neuronal and cortical injury contributes to cognitive impairment. This is a proposed clinical consequence; the precise intervening pathway is unresolved.

Neuronal loss and cortical thinning -> Developmental regression INDIRECT UNKNOWN INTERMEDIATES Progressive neuronal and white-matter injury leads to loss of acquired skills. This is a proposed clinical consequence; the precise intervening pathway is unresolved.

Show evidence (1 reference)

PMID:34011350 SUPPORT Human Clinical

"visual impairment is more commonly caused by white matter disease affecting the visual pathways."

The natural-history authors link visual impairment to white-matter disease of visual pathways. This supports one clinical consequence; the broader group remains an explanatory hypothesis, not proof of each clinical edge.

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Pathophysiology

12

Deep intronic ASPA SVA_E insertion

Approximately 2.6-kb SVA_E insertion in intron 4 of 5 of ASPA transcript NM_000049.4. In the 2025 series it was homozygous or in trans with another pathogenic allele. Long-read sequencing resolved the insertion; fibroblast RNA-seq supported a new splice acceptor, inclusion of SVA sequence, and transcript degradation. Population databases suggest a common pathogenic allele across ancestries, but this is not a disease-incidence estimate.

ASPA hgnc:756

Genetic context ASPA hgnc:756 Variant type: insertion Genomic context: intron functional_impact_category: LOSS_OF_FUNCTION

Downstream

Aberrant ASPA splicing The inserted SVA sequence creates a novel splice acceptor.

Show evidence (1 reference)

PMID:40995055 SUPPORT Human Clinical

"We identified an ∼2,600-bp SVA_E retrotransposon intronic insertion in ASPA in all 8 individuals."

Eight affected individuals from seven families with previously incomplete molecular diagnoses carried the insertion.

Aberrant ASPA splicing

The intron-4 SVA_E allele introduces a novel splice acceptor and an SVA-containing exon, demonstrated by RNA sequencing of fibroblasts. This is an allele-specific RNA-processing mechanism.

ASPA hgnc:756

mRNA splicing, via spliceosome GO:0000398 ⚠ ABNORMAL

Experimental models

SVA_E carrier and patient fibroblast RNA sequencing PRIMARY CELL CULTURE

Downstream

Degradation of aberrant ASPA transcripts Aberrant allele-derived transcripts are revealed by cycloheximide treatment, consistent with degradation.

Show evidence (1 reference)

PMID:40995055 SUPPORT In Vitro

"the SVA_E insertion creates a novel splice acceptor site within intron 4 of ASPA"

Fibroblast RNA-seq from an affected individual and a parental carrier demonstrates altered splicing.

Degradation of aberrant ASPA transcripts

In fibroblasts carrying the intronic SVA_E insertion, aberrant transcripts were detectable after cycloheximide treatment but not without treatment. The resulting loss of functional ASPA RNA provides a route to enzyme deficiency; the study did not quantify expression in all tissues.

ASPA hgnc:756

Experimental models

SVA_E carrier and patient fibroblast RNA sequencing PRIMARY CELL CULTURE

Downstream

Aspartoacylase enzyme deficiency Aberrant splicing and transcript degradation lead to loss of function from the insertion allele.

Show evidence (1 reference)

PMID:40995055 SUPPORT In Vitro

"The transcript incorporating the SVA_E was only observed in CHX-treated samples, indicating that the products from this allele are targeted for degradation."

Cycloheximide-unmasked transcript supports degradation of the aberrant RNA in fibroblasts.

ASPA variant protein destabilization

Many, but not all, disease-associated ASPA missense variants destabilize the protein. Cultured-cell abundance screens and structural analyses support protein-quality-control degradation as one route to enzyme deficiency; normal abundance does not establish normal catalytic activity.

ASPA hgnc:756

protein folding GO:0006457 ⚠ ABNORMAL

Downstream

Aspartoacylase enzyme deficiency Destabilized ASPA variants reduce functional aspartoacylase activity.

Show evidence (2 references)

PMID:38582917 SUPPORT Other

"most disease linked ASPA gene variants lead to a structural destabilization"

Recent review supports ASPA protein destabilization as a common mechanism.

PMID:28101991 REFUTE In Vitro

"All variants presented detectable expression of ASPA with no major differences concerning level of expression when compared to the WT"

The tested GFP-fusion variants had low catalytic activities despite detectable abundance, limiting a universal degradation explanation.

Aspartoacylase enzyme deficiency

Loss of ASPA activity impairs the cytosolic/oligodendroglial hydrolysis of N-acetyl-L-aspartate to acetate and aspartate, initiating the core biochemical disease cascade.

oligodendrocyte CL:0000128

ASPA hgnc:756

N-acetylaspartate/aspartate metabolism GO:0006531 ⚠ ABNORMAL

aspartoacylase activity GO:0019807 ↓ DECREASED

cytosol GO:0005829

Experimental models

HEK293 ASPA variant functional assay CELL LINE

Downstream

NAA accumulation in CNS and body fluids Failure to catabolize NAA causes substrate accumulation.

Reduced NAA-derived acetate and myelin lipid synthesis Loss of NAA hydrolysis limits acetate availability for myelin lipid synthesis.

Show evidence (3 references)

PMID:38582917 SUPPORT Other

"deficiency of the cytosolic aspartoacylase (ASPA) enzyme"

Mechanistic review directly identifies aspartoacylase deficiency.

PMID:15784740 SUPPORT Model Organism

"ASPA acts to hydrolyze N-acetylaspartate (NAA) into l-aspartate and acetate"

Mouse model study describes the enzymatic reaction blocked in Canavan disease.

url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/ SUPPORT Other

"Loss or reduction of aspartoacylase activity causes Canavan disease."

Human disease mechanism.

NAA accumulation in CNS and body fluids

Aspartoacylase deficiency causes N-acetyl-L-aspartate to accumulate in the brain, urine, blood, cerebrospinal fluid, and other body fluids. Elevated urinary NAA and brain NAA by proton magnetic resonance spectroscopy are key diagnostic biochemical markers.

NAA accumulation and cellular injury

Animal models

Aspa nur7 mice with Nat8l gene-dose reduction Mus musculus perturbs

Downstream

Spongiform white-matter vacuolation Reducing NAA synthesis rescues this pathology in Aspa-deficient mice; the intervening injury mechanism and its contribution in humans remain incompletely resolved.

Neuronal loss and cortical thinning Reducing NAA synthesis rescues this pathology in Aspa-deficient mice; the intervening injury mechanism and its contribution in humans remain incompletely resolved.

Elevated urinary N-acetylaspartic acid Elevated urinary NAA is a diagnostic readout of systemic NAA accumulation.

Elevated brain NAA by proton MR spectroscopy Elevated brain NAA by MRS is a diagnostic readout of CNS NAA accumulation.

Show evidence (2 references)

PMID:8412017 SUPPORT Human Clinical

"Deficiency of the enzyme aspartoacylase and the accumulation of N-acetylaspartic acid"

Biochemical study supports the enzyme-substrate defect.

PMID:34011350 SUPPORT Human Clinical

"loss of ASPA activity results in an accumulation of N-acetylaspartic acid"

Natural history study summarizes NAA accumulation from ASPA loss.

Reduced NAA-derived acetate and myelin lipid synthesis

Reduced brain acetate and myelin-lipid synthesis were measured in an ASPA-deficient mouse model; one human white-matter sample also had reduced cerebroside and sulfatide. The hypothesis that loss of NAA-derived acetate is necessary for myelin failure is challenged by normally myelinated Nat8l-deficient mice and rescue of myelin pathology in Aspa/Nat8l double mutants. These experiments do not exclude a contributory metabolic role under other conditions.

Acetate-dependent metabolism contributes to myelin pathology

oligodendrocyte CL:0000128

lipid biosynthetic process GO:0008610 ↓ DECREASED central nervous system myelination GO:0022010 ↓ DECREASED

Downstream

Oligodendrocyte maturation and myelination defect Proposed contribution of deficient acetate-dependent lipid metabolism; challenged as a necessary or sole mechanism by Nat8l deletion experiments.

Show evidence (2 references)

PMID:15784740 SUPPORT Model Organism

"myelin lipid synthesis is significantly compromised in CD"

Mouse and human white-matter lipid data support impaired myelin lipid synthesis.

PMID:26511242 REFUTE Model Organism

"acetate derived from NAA is not essential for myelin lipid synthesis"

Normal myelin composition in double-mutant mice argues against obligatory NAA-derived acetate supply.

Oligodendrocyte maturation and myelination defect

ASPA-deficient mice show altered oligodendrocyte maturation, reduced myelin proteins, noncompact myelin, increased histone acetylation, and oligodendrocyte apoptosis during early postnatal development. These model findings establish cellular abnormalities but do not establish that histone acetylation or acetate shortage alone causes the human disease. In a separate nur7 study, oxidative stress preceded oligodendrocyte loss; ASPA overexpression partially rescued ATP under glucose deprivation in primary mouse oligodendrocytes, supporting a possible energetic contribution.

Brain injury contributes to clinical neurological impairment

oligodendrocyte CL:0000128

central nervous system myelination GO:0022010 ↓ DECREASED

Downstream

Spongiform white-matter vacuolation Myelination defects and glial stress contribute to spongiform leukodystrophy.

Global developmental delay White-matter dysfunction disrupts early neurodevelopmental progress. This is a proposed clinical consequence; the precise intervening pathway is unresolved.

Hypotonia Early white-matter disease contributes to impaired motor control and hypotonia. This is a proposed clinical consequence; the precise intervening pathway is unresolved.

Show evidence (3 references)

PMID:20637282 SUPPORT Model Organism

"ASPA deficiency affects oligodendrocyte maturation and myelination"

Mouse study directly supports oligodendrocyte maturation and myelination defects.

PMID:22617649 SUPPORT Model Organism

"markers of oxidative stress preceding oligodendrocyte loss and dysmyelination"

Model study supports metabolic stress before oligodendrocyte loss and dysmyelination.

PMID:22617649 SUPPORT In Vitro

"indicating the partial rescue of an oxidative deficit by ASPA."

ASPA overexpression in glucose-deprived primary mouse oligodendrocytes increased ATP; this is an in-vitro energetic readout, not proof of clinical rescue.

Spongiform white-matter vacuolation

Canavan disease causes dysmyelination, vacuolation, astrogliosis, and spongiform white-matter degeneration, the tissue pathology that underlies macrocephaly and progressive neurologic impairment.

Brain injury contributes to clinical neurological impairment

oligodendrocyte CL:0000128 astrocyte CL:0000127

Animal models

Aspa nur7 mice with Nat8l gene-dose reduction Mus musculus rescues

TALEN-generated Aspa knockout rat Rattus norvegicus partially recapitulates

Downstream

Macrocephaly Diffuse white-matter disease contributes to progressive head enlargement. This is a proposed clinical consequence; the precise intervening pathway is unresolved.

Visual impairment CNS white-matter and visual pathway involvement contribute to visual impairment.

Hypertonia Progressive white-matter disease contributes to later spasticity and hypertonia. This is a proposed clinical consequence; the precise intervening pathway is unresolved.

Seizure Progressive brain involvement contributes to epilepsy over time. This is a proposed clinical consequence; the precise intervening pathway is unresolved.

Visual pathway and ocular involvement White-matter disease affecting visual pathways contributes to visual and ocular manifestations.

Feeding and aspiration vulnerability Severe neurologic and white-matter disease contributes to impaired feeding, swallowing safety, and reflux risk.

Flexion contracture Progressive tone abnormality and reduced mobility increase risk for contractures. This is a proposed clinical consequence; the precise intervening pathway is unresolved.

Leukodystrophy White-matter pathology manifests as the leukodystrophy imaging phenotype.

Show evidence (2 references)

PMID:29456021 SUPPORT Model Organism

"brain dysmyelination, vacuolation, and astrogliosis"

Aspa-deficient mouse model supports spongiform leukodystrophy pathology.

PMID:20637282 SUPPORT Model Organism

"degeneration of the white matter, demyelination"

Study links Canavan disease to white-matter degeneration and demyelination.

Visual pathway and ocular involvement

Cerebral visual impairment is often attributed to white-matter visual pathway involvement. Optic atrophy can occur but is not required for impaired tracking or blindness; retinal findings remain separate clinical observations with uncertain causal placement.

Brain injury contributes to clinical neurological impairment

Downstream

Visual impairment White-matter involvement of visual pathways produces impaired visual function.

Blindness Severe visual pathway and ocular involvement can manifest as blindness. This is a proposed clinical consequence; the precise intervening pathway is unresolved.

Abnormality of visual evoked potentials Visual pathway disease can produce abnormal visual evoked potentials. This is a proposed clinical consequence; the precise intervening pathway is unresolved.

Nystagmus Early abnormal eye movements, including nystagmus, occur in Canavan disease. This is a proposed clinical consequence; the precise intervening pathway is unresolved.

Show evidence (2 references)

PMID:34011350 SUPPORT Human Clinical

"visual impairment is more commonly caused by white matter disease affecting the visual pathways."

Natural history authors connect visual impairment in Canavan disease to white-matter visual pathway disease.

url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/ SUPPORT Other

"Early in life there is a decreased ability to fix and follow, most commonly due to cerebral visual impairment"

Supports cerebral visual impairment rather than assuming optic atrophy.

Feeding and aspiration vulnerability

Severe Canavan neurologic impairment commonly affects feeding, nutrition, and oral intake safety. Feeding therapy is recommended to maintain weight gain and reduce aspiration risk, and natural history scoring treats aspiration, inadequate weight gain, or tube feeding as feeding-severity markers.

Brain injury contributes to clinical neurological impairment

Downstream

Feeding difficulties in infancy Neurologic feeding impairment manifests as early feeding difficulty.

Gastroesophageal reflux Feeding and swallowing impairment can coexist with reflux in severe neurologic disease. This is a proposed clinical consequence; the precise intervening pathway is unresolved.

Show evidence (2 references)

PMID:20301412 SUPPORT Other

"feeding therapy (to assure adequate nutrition and weight gain, minimize risk of"

GeneReviews supports feeding and aspiration-risk management as part of Canavan care.

PMID:34011350 SUPPORT Human Clinical

"Feeding: Score 1 if oral feeding is possible but aspiration occurs and/or weight gain is insufficient"

Natural history severity scoring includes aspiration, poor weight gain, and tube feeding as feeding manifestations.

Neuronal loss and cortical thinning

Aspartoacylase-deficient mice show cortical and cerebellar neuron depletion and cortical thinning that can be prevented by lowering NAA synthesis. These are model-specific findings; they do not establish that neuronal loss is the dominant cause of each human neurological manifestation.

Brain injury contributes to clinical neurological impairment

neuron CL:0000540

Animal models

TALEN-generated Aspa knockout rat Rattus norvegicus fails to recapitulate

Downstream

Cognitive impairment Neuronal and cortical injury contributes to cognitive impairment. This is a proposed clinical consequence; the precise intervening pathway is unresolved.

Developmental regression Progressive neuronal and white-matter injury leads to loss of acquired skills. This is a proposed clinical consequence; the precise intervening pathway is unresolved.

Show evidence (1 reference)

PMID:28077719 SUPPORT Model Organism

"cerebral cortical and cerebellar neurons are decreased"

Model study supports neuronal loss downstream of ASPA deficiency.

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Pathograph

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

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Phenotypes

21

Digestive 2

Gastroesophageal reflux Frequent (79-30%) HP:0002020

Show evidence (1 reference)

ORPHA:141 SUPPORT Other

"HP:0002020 | Gastroesophageal reflux | Frequent"

Orphanet reports gastroesophageal reflux as frequent.

Feeding difficulties in infancy Very frequent (99-80%) HP:0008872

Show evidence (1 reference)

ORPHA:141 SUPPORT Other

"HP:0008872 | Feeding difficulties in infancy | Very frequent"

Orphanet reports feeding difficulties in infancy as very frequent.

Ear 1

Hearing impairment HP:0000365

Show evidence (2 references)

ORPHA:141 SUPPORT Other

"HP:0000365 | Hearing impairment | Frequent"

Orphanet reports hearing impairment as frequent.

PMID:34011350 REFUTE Human Clinical

"All CD patients were reported by caregivers and medical records to be able to hear at birth and throughout the course of disease."

All 23 patients retained hearing, although this was caregiver/record reporting rather than systematic audiometry.

Eye 6

Visual impairment Frequent (79-30%) HP:0000505

Show evidence (2 references)

ORPHA:141 SUPPORT Other

"HP:0000505 | Visual impairment | Frequent"

Orphanet reports visual impairment as frequent.

url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/ SUPPORT Other

"Early in life there is a decreased ability to fix and follow, most commonly due to cerebral visual impairment"

Supports cerebral visual impairment rather than assuming optic atrophy.

Blindness Frequent (79-30%) HP:0000618

Show evidence (1 reference)

ORPHA:141 SUPPORT Other

"HP:0000618 | Blindness | Frequent"

Orphanet reports blindness as frequent.

Optic atrophy HP:0000648

Show evidence (2 references)

ORPHA:141 SUPPORT Other

"HP:0000648 | Optic atrophy | Very frequent"

Orphanet reports optic atrophy as very frequent.

PMID:34011350 REFUTE Human Clinical

"Considering that only two patients were reported to suffer from optic nerve atrophy, we conclude that visual impairment is more commonly caused by white matter disease affecting the visual pathways."

Documents the discrepancy with the structured-source frequency band.

Abnormality of visual evoked potentials Frequent (79-30%) HP:0000649

Show evidence (1 reference)

ORPHA:141 SUPPORT Other

"HP:0000649 | Abnormality of visual evoked potentials | Frequent"

Orphanet reports abnormal visual evoked potentials as frequent.

Nystagmus Frequent (79-30%) HP:0000639

Show evidence (1 reference)

url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/ SUPPORT Other

"Nystagmus frequently develops early in infancy."

Specifically supports nystagmus; the earlier cohort quote described a broader category of abnormal eye movements.

Abnormal retinal pigmentation Occasional (29-5%) HP:0007703

Show evidence (1 reference)

ORPHA:141 SUPPORT Other

"HP:0007703 | Abnormality of retinal pigmentation | Occasional"

Orphanet reports abnormal retinal pigmentation as occasional.

Head and Neck 1

Macrocephaly Frequent (79-30%) HP:0000256

Show evidence (2 references)

ORPHA:141 SUPPORT Other

"HP:0000256 | Macrocephaly | Frequent"

Orphanet reports macrocephaly as frequent.

PMID:34011350 SUPPORT Human Clinical

"Macrocephaly became apparent between 4 and 18 months of age."

Natural history cohort supports progressive macrocephaly in infancy.

Musculoskeletal 3

Hypotonia Frequent (79-30%) HP:0001252

Show evidence (3 references)

ORPHA:141 SUPPORT Other

"HP:0001252 | Hypotonia | Frequent"

Orphanet reports hypotonia as frequent.

PMID:20301412 SUPPORT Other

"neurodevelopmental delays, macrocephaly, and tone abnormalities"

GeneReviews identifies tone abnormalities as a core disease feature.

url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/ SUPPORT Other

"Hypotonia ... is an early finding associated with poor head control."

Specific support for the motor-tone phenotype.

Hypertonia Frequent (79-30%) HP:0001276

Show evidence (3 references)

ORPHA:141 SUPPORT Other

"HP:0001276 | Hypertonia | Frequent"

Orphanet reports hypertonia as frequent.

PMID:20301412 SUPPORT Other

"neurodevelopmental delays, macrocephaly, and tone abnormalities"

GeneReviews supports abnormal tone as a core clinical feature.

url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/ SUPPORT Other

"With age, hypotonia evolves to spasticity."

Supports the common evolution of tone; coexistence is also seen in the cohort.

Flexion contracture Occasional (29-5%) HP:0001371

Show evidence (1 reference)

ORPHA:141 SUPPORT Other

"HP:0001371 | Flexion contracture | Occasional"

Orphanet reports flexion contracture as occasional.

Nervous System 8

Seizure HP:0001250

Show evidence (3 references)

ORPHA:141 SUPPORT Other

"HP:0001250 | Seizure | Occasional"

Orphanet reports seizure as occasional.

PMID:34011350 SUPPORT Human Clinical

"Seizure frequency was highest towards the end of the first decade."

Natural history cohort supports increasing seizure burden over time.

url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/ SUPPORT Other

"Seizures occur in the first year of life in one third of children with Canavan disease and become more prevalent over time"

Age-dependent frequency from GeneReviews.

Global developmental delay Very frequent (99-80%) HP:0001263

Show evidence (2 references)

ORPHA:141 SUPPORT Other

"HP:0001263 | Global developmental delay | Very frequent"

Orphanet reports global developmental delay as very frequent.

PMID:34011350 SUPPORT Human Clinical

"Psychomotor development of patients was limited"

Natural history cohort supports severe psychomotor developmental limitation.

EEG abnormality HP:0002353

Show evidence (2 references)

ORPHA:141 SUPPORT Other

"HP:0002353 | EEG abnormality | Very frequent"

Orphanet reports EEG abnormality as very frequent.

PMID:28101991 SUPPORT Human Clinical

"In five patients, EEGs were diffusely slow"

Five of eight tested patients had diffuse slowing; this was a clinically selected subset, not a population frequency.

Developmental regression HP:0002376

Show evidence (3 references)

ORPHA:141 SUPPORT Other

"HP:0002376 | Developmental regression | Occasional"

Orphanet reports developmental regression as occasional.

PMID:20301412 SUPPORT Other

"followed by neurodegeneration and developmental regression"

GeneReviews identifies regression as part of typical disease course.

url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/ SUPPORT Other

"Children with atypical Canavan disease frequently continue to make slow developmental progress without regression until later in the disease course."

Preserves the variable atypical trajectory.

Reduced consciousness HP:0004372

Show evidence (1 reference)

ORPHA:141 SUPPORT Other

"HP:0004372 | Reduced consciousness/confusion | Very frequent"

Orphanet reports reduced consciousness/confusion as very frequent.

Cognitive impairment Very frequent (99-80%) HP:0100543

Show evidence (1 reference)

ORPHA:141 SUPPORT Other

"HP:0100543 | Cognitive impairment | Very frequent"

Orphanet reports cognitive impairment as very frequent.

Leukodystrophy HP:0002415

Show evidence (1 reference)

url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/ SUPPORT Other

"Neuroimaging changes reveal generalized leukodystrophy characterized by diffuse, symmetric changes observed in subcortical white matter and cortical areas as well as the brain stem and cerebellum"

Clinical baseline supports this phenotype and its context.

Ataxia HP:0001251

Show evidence (1 reference)

url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/ SUPPORT Other

"Ataxia, coordination difficulties, and gait disturbances are frequently reported in atypical Canavan disease"

Clinical baseline supports this phenotype and its context.

🧬

Genetic Associations

1

ASPA (Causal loss-of-function variant)

Gene: ASPA hgnc:756

Show evidence (4 references)

PMID:20301412 SUPPORT Other

"biallelic ASPA pathogenic variants identified by molecular genetic testing"

GeneReviews identifies biallelic ASPA pathogenic variants as diagnostic.

PMID:28101991 SUPPORT Human Clinical

"We have detected a correlation between clinical presentation, enzyme activity, and genotype"

Patient variant study supports genotype-enzyme-phenotype correlation.

CGGV:assertion_66306eff-659f-4508-a41b-1820e47e0e1d-2020-10-08T161701.633Z SUPPORT Other

ClinGen classifies the ASPA-Canavan disease gene-disease relationship as definitive with autosomal recessive inheritance.

+ 1 more reference

🔬

Variants

1

Deep intronic ASPA SVA_E insertion Pathogenic

Gene: ASPA hgnc:756 insertion

Genomic context: intron

Approximately 2.6-kb SVA_E insertion in intron 4 of 5 of ASPA transcript NM_000049.4. In the 2025 series it was homozygous or in trans with another pathogenic allele. Long-read sequencing resolved the insertion; fibroblast RNA-seq supported a new splice acceptor, inclusion of SVA sequence, and transcript degradation. Population databases suggest a common pathogenic allele across ancestries, but this is not a disease-incidence estimate.

Show evidence (3 references)

PMID:40995055 SUPPORT Human Clinical

"We identified an ∼2,600-bp SVA_E retrotransposon intronic insertion in ASPA in all 8 individuals."

Eight affected individuals from seven families with previously incomplete molecular diagnoses carried the insertion.

PMID:40995055 SUPPORT In Vitro

"the SVA_E insertion creates a novel splice acceptor site within intron 4 of ASPA"

Fibroblast RNA-seq from an affected individual and a parental carrier demonstrates altered splicing.

PMID:40995055 SUPPORT In Vitro

"The transcript incorporating the SVA_E was only observed in CHX-treated samples, indicating that the products from this allele are targeted for degradation."

Cycloheximide-unmasked transcript supports degradation of the aberrant RNA in fibroblasts.

🗃️

External Assertions

1

Orphanet Canavan disease record

Orphanet structured disease record ORPHA:141

Orphanet's ORPHA:141 structured record for Canavan disease includes the exact MONDO cross-reference, definition, autosomal recessive inheritance, epidemiology, OMIM cross-reference, and HPO phenotype annotations used in this entry.

Show evidence (2 references)

ORPHA:141 SUPPORT Other

"MONDO:0010079 | Exact"

Orphanet maps ORPHA:141 to the MONDO identifier used by this entry.

ORPHA:141 SUPPORT Other

"OMIM:271900 | Exact"

Orphanet lists OMIM:271900 as an exact external cross-reference.

💊

Medical Actions

6

Multidisciplinary supportive care

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

Expert-based multidisciplinary supportive care addresses seizures, spasticity, nutrition and swallowing safety, mobility and contractures, communication and learning, respiratory health, and family support. GeneReviews reports no published disease-specific practice guideline; these recommendations reflect specialist experience. Nutrition, mobility and neurological review are typically repeated every three to six months, with respiratory and aspiration concerns assessed at each visit.

Target Phenotypes: Seizure HP:0001250 Hypertonia HP:0001276 Feeding difficulties in infancy HP:0008872

Show evidence (2 references)

PMID:20301412 SUPPORT Other

"Multidisciplinary care by specialists in neurology"

GeneReviews supports multidisciplinary supportive management.

url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/ SUPPORT Other

"the following recommendations are based on the authors' personal experience managing individuals with this disorder."

Distinguishes expert management from a formal practice guideline.

ASPA gene replacement therapy

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

Platform: Gene therapy

ASPA gene replacement remains investigational. A 2023 expanded-access AAV9 case and a 2025 open-label rAAV-Olig001-ASPA trial support biological activity. The latter interim report included eight children with typical disease and found lower CSF NAA, increased myelin volume, and improved MSEL developmental scores against natural-history data. Gross-motor GMFM-88 slopes were not statistically significant. All participants had adverse events; seven had serious events, none attributed to the vector product, although procedure-related seizures and CSF leakage occurred. Small size, open-label design, historical comparisons, missing follow-up, and exclusion of atypical cases limit efficacy and durability conclusions. The AAV9 case corresponds to single-patient expanded access NCT05317780, listed by the registry as no longer available on 2026-10-04.

Mechanism Target:

RESTORES Aspartoacylase enzyme deficiency — AAV-ASPA strategies provide a functional ASPA transgene to restore enzyme activity.

Show evidence (1 reference)

PMID:37601414 SUPPORT Human Clinical

"Gene replacement therapy is a rational therapeutic strategy"

Expanded-access case report supports ASPA gene replacement rationale.

Show evidence (7 references)

PMID:37601414 SUPPORT Human Clinical

"NAA level was reduced at 3 months"

Single-patient biochemical response; not controlled efficacy evidence.

PMID:40957959 SUPPORT Human Clinical

"A total of 8 participants received intracranial doses"

Small open-label interim cohort.

PMID:40957959 SUPPORT Human Clinical

"Treatment reduced NAA concentrations in cerebrospinal fluid"

Biochemical target engagement.

+ 4 more references

NAT8L/NAA-lowering strategy

Partial inhibition of NAT8L-mediated NAA synthesis is a preclinical substrate-reduction approach. Genetic deletion and neonatal AAV-shRNA experiments rescued aspects of Aspa-deficient mouse pathology. Complete NAA ablation rescued myelin pathology but did not prolong survival in one double-mutant model, whereas partial reduction improved survival; these results caution against assuming maximal suppression is optimal. Human clinical benefit is unestablished.

Mechanism Target:

INHIBITS NAA accumulation in CNS and body fluids — Reducing neuronal NAA synthesis lowers substrate accumulation upstream of spongiform leukodystrophy.

Show evidence (1 reference)

PMID:29456021 SUPPORT Model Organism

"suppresses development of spongiform leukodystrophy"

AAV-shRNA Nat8l knockdown lowered brain NAA and suppressed leukodystrophy in mice.

Show evidence (2 references)

PMID:28077719 SUPPORT Model Organism

"prevents neuron loss and cerebral cortical atrophy"

Model study supports NAA synthesis suppression as a neuroprotective strategy.

PMID:26511242 SUPPORT Model Organism

"although pathology was fully reversed, the survival time of the mice was not prolonged."

Complete Nat8l deletion did not confer a survival advantage in this model.

Individualized antiseizure treatment

Action: Pharmacotherapy NCIT:C15986

An experienced neurologist selects antiseizure medication according to seizure type and response. No medication has demonstrated disease-specific superiority; some patients require multiple agents.

Target Phenotypes: Seizure HP:0001250

Show evidence (1 reference)

url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/ SUPPORT Other

"Many ASMs may be effective; none have been demonstrated specifically effective for this disorder."

No preferred disease-specific drug is established.

Feeding and swallowing support

Action: Supportive Care NCIT:C15747

Feeding therapy and nutritional assessment address weight gain and aspiration risk. Gastrostomy may be needed for persistent feeding problems; swallowing assessment informs safe oral intake.

Target Phenotypes: Feeding difficulties in infancy HP:0008872

Show evidence (2 references)

url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/ SUPPORT Other

"Gastrostomy tube placement may be required for persistent feeding issues."

Expert guidance for escalating nutrition support.

PMID:34011350 SUPPORT Human Clinical

"A gastric tube was placed in 10/22 patients."

Natural-history cohort documents enteral support burden.

Genetic counseling and family testing

Offer counseling and molecular testing for relatives and reproductive partners, with prenatal or preimplantation testing available once familial pathogenic variants are identified. Carrier status does not cause Canavan disease; reproductive decisions depend on individual and family preferences.

Show evidence (1 reference)

PMID:20301412 SUPPORT Other

"carrier testing for at-risk relatives and prenatal/preimplantation genetic testing are possible."

GeneReviews genetic counseling baseline.

🔬

Biochemical Markers

2

Elevated urinary N-acetylaspartic acid (INCREASED)

Context: Elevated urinary NAA is the classic biochemical diagnostic marker of Canavan disease and reports systemic accumulation caused by ASPA deficiency.

Pathograph Readouts

Readout Of NAA accumulation in CNS and body fluids Positive Diagnostic

Higher urinary NAA reflects the NAA accumulation caused by impaired ASPA-mediated catabolism.

Show evidence (1 reference)

PMID:28101991 SUPPORT Human Clinical

"Elevation of NAA levels in urine is the biochemical hallmark of CD."

Patient variant study identifies urinary NAA elevation as the biochemical hallmark.

Show evidence (2 references)

PMID:20301412 SUPPORT Other

"elevated N-acetylaspartic acid (NAA) in urine"

GeneReviews supports elevated urinary NAA as biochemical diagnostic evidence.

PMID:28101991 SUPPORT Human Clinical

"Elevation of NAA levels in urine is the biochemical hallmark of CD."

Patient variant study supports urinary NAA as the biochemical hallmark.

Elevated brain NAA by proton MR spectroscopy (INCREASED)

Context: Proton MR spectroscopy can detect elevated NAA in the brain, providing a CNS biochemical readout of the same substrate accumulation.

Pathograph Readouts

Readout Of NAA accumulation in CNS and body fluids Positive Diagnostic

Elevated brain NAA by MRS reports CNS NAA accumulation downstream of ASPA deficiency.

Show evidence (1 reference)

PMID:34011350 SUPPORT Human Clinical

"CD is diagnosed by detection of elevated NAA in urine or blood or in brain by proton MR spectroscopy"

Natural history study supports MRS-detected brain NAA as a diagnostic readout.

Show evidence (2 references)

PMID:20301412 SUPPORT Other

"in the brain by proton magnetic resonance spectroscopy"

GeneReviews supports proton MRS detection of brain NAA.

PMID:34011350 SUPPORT Human Clinical

"CD is diagnosed by detection of elevated NAA in urine or blood or in brain by proton MR spectroscopy"

Natural history study supports elevated NAA in brain by proton MR spectroscopy.

🔬

Diagnosis

4

Urinary N-acetylaspartic acid testing

Urine NAA by gas chromatography-mass spectrometry establishes biochemical diagnosis in a compatible clinical presentation. Elevation is usually much greater in typical than atypical disease. Normal peripheral measurements do not exclude all cases; brain MRS can clarify a strongly suggestive presentation.

Results: Elevated urinary NAA supports Canavan disease.

Show evidence (3 references)

PMID:20301412 SUPPORT Other

"elevated N-acetylaspartic acid (NAA) in urine"

GeneReviews supports urinary NAA testing for biochemical diagnosis.

PMID:28101991 SUPPORT Human Clinical

"Elevation of NAA levels in urine is the biochemical hallmark"

Patient variant study supports urinary NAA as a biochemical hallmark.

url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/ SUPPORT Other

"even those with normal serum and urine N-acetylaspartic acid levels"

GeneReviews describes infants diagnosed by brain MRS despite normal peripheral NAA.

Brain proton magnetic resonance spectroscopy for NAA

Proton magnetic resonance spectroscopy can detect elevated brain NAA and supports diagnosis when combined with clinical and genetic findings.

Results: Elevated brain NAA supports Canavan disease.

Show evidence (1 reference)

PMID:20301412 SUPPORT Other

"in the brain by proton magnetic resonance spectroscopy"

GeneReviews supports brain MRS for detecting NAA.

ASPA molecular genetic testing

Biallelic pathogenic or likely pathogenic ASPA variants confirm a molecular diagnosis in a compatible presentation. A VUS alone or paired with a pathogenic allele is not diagnostic. Sequence analysis may require deletion/duplication testing and targeted investigation of deep intronic structural variants, including the SVA_E insertion, when only one or no allele is found despite biochemical disease.

molecular genetic testing NCIT:C19770

Results: Biallelic pathogenic ASPA variants confirm Canavan disease.

Show evidence (3 references)

PMID:20301412 SUPPORT Other

"biallelic ASPA pathogenic variants identified by molecular genetic testing"

GeneReviews supports ASPA molecular testing as confirmatory.

url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/ SUPPORT Other

"Identification of ... biallelic ... ASPA ... variants of ... uncertain significance ... does not establish or rule out the diagnosis."

GeneReviews cautions that uncertain ASPA variants neither establish nor exclude disease.

PMID:40995055 SUPPORT Human Clinical

"We identified an ∼2,600-bp SVA_E retrotransposon intronic insertion in ASPA in all 8 individuals."

Eight affected individuals from seven families with previously incomplete molecular diagnoses carried the insertion.

Brain MRI with proton MR spectroscopy

Typical disease shows diffuse symmetric leukodystrophy; imaging in early infancy may appear normal. Atypical disease may lack generalized white-matter changes and resemble a mitochondrial disorder with bilateral deep gray matter involvement. MRS NAA, urine biochemistry, and genetics help distinguish Canavan disease.

Show evidence (2 references)

url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/ SUPPORT Other

"Brain CT or MRI performed in early infancy may be interpreted as normal"

Timing affects sensitivity of structural imaging.

url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/ SUPPORT Other

"Atypical Canavan disease may be misdiagnosed as a mitochondrial disorder given the overlapping neuroimaging features of bilateral deep gray matter involvement"

Important differential-diagnosis pitfall.

📈

Progression

3

Typical infantile Canavan disease

Age: Infancy

Typical disease presents after early normal appearance, with hypotonia, head lag, macrocephaly, neurodevelopmental impairment by three to five months, followed by neurodegeneration, developmental regression, increasing feeding problems, seizures, and reduced survival. GeneReviews estimates that typical disease accounts for 85%-90% of affected individuals. Axial hypotonia and limb hypertonia can coexist; tone does not necessarily change in a strictly sequential fashion.

Show evidence (3 references)

PMID:20301412 SUPPORT Other

"neurodevelopmental impairment evident by ages three to five months"

GeneReviews describes the typical early-infantile onset window.

PMID:34011350 SUPPORT Human Clinical

"Onset of symptoms was between 0 and 6 months."

Natural history cohort supports early infantile symptom onset.

url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/ SUPPORT Other

"The phenotypic spectrum ranges from the more severe typical Canavan disease (85%-90% of individuals) to the less severe atypical Canavan disease (10%-15%)."

Clinical spectrum proportions are expert synthesis, not a population prevalence estimate.

Atypical milder Canavan disease

Age: Infancy to childhood or adolescence

Atypical disease represents approximately 10%-15% of affected individuals, with variable onset from infancy to childhood or adolescence, milder developmental delay, sometimes normal head size, ataxia, and possible later regression. Some individuals walk and attend school; survival into adulthood occurs and lifespan is incompletely described.

Show evidence (3 references)

PMID:20301412 SUPPORT Other

"atypical Canavan disease is more variable"

GeneReviews describes atypical Canavan disease as a variable milder spectrum.

PMID:28101991 SUPPORT Human Clinical

"The mutations found in the mild patients corresponded to the variants with the highest residual enzyme activities"

Residual ASPA activity supports the milder phenotypic spectrum.

url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/ SUPPORT Other

"The life span is not well-described; however, individuals with atypical Canavan disease may survive to adulthood."

Avoids extrapolating the severe infantile prognosis to all atypical individuals.

Longitudinal survival in historical clinical cohorts

Kaplan-Meier analysis pooling 23 study patients with 59 literature patients estimated 73% survival to age ten years. This is an ascertainment-dependent cohort estimate, not a prediction for an individual or a result of current gene therapy.

Show evidence (2 references)

PMID:34011350 SUPPORT Human Clinical

"Kaplan Meier survival probability with confidence interval (dotted line) for 82 CD patients, pooled data: study cohort (N = 23) & literature cohort (N = 59) /Traeger et al."

Defines the pooled cohort denominator.

PMID:34011350 SUPPORT Human Clinical

"73% of the CD patients reached the age of 10 years"

Survival estimate from the historical pooled cohort.

📊

Prevalence

1

Worldwide

Unknown

Orphanet records worldwide point prevalence as unknown and worldwide prevalence at birth in the 1-9 per 100,000 band.

Show evidence (2 references)

ORPHA:141 SUPPORT Other

"Unknown | Worldwide | Point prevalence | ORPHANET"

Orphanet records worldwide point prevalence as unknown.

ORPHA:141 SUPPORT Other

"1-9 / 100 000 | Worldwide | Prevalence at birth"

Orphanet records a worldwide prevalence-at-birth band.

🔬

Clinical Trials

2

NCT04998396 PHASE_I RECRUITING

Phase 1/2 open-label study of BBP-812, an investigational systemic AAV9-based ASPA gene therapy, in pediatric participants with Canavan disease.

Target Phenotypes: Global developmental delay HP:0001263 Hypotonia HP:0001252

Show evidence (1 reference)

clinicaltrials:NCT04998396 SUPPORT Human Clinical

"The main objective of this trial is to evaluate the safety, tolerability, and pharmacodynamic activity of BBP-812, an investigational AAV9-based gene therapy, in pediatric participants with Canavan disease."

ClinicalTrials.gov records an active pediatric AAV9-ASPA gene-therapy trial for Canavan disease.

NCT04833907 PHASE_I ENROLLING_BY_INVITATION

Phase 1/2 open-label study of intracranial AVASPA/rAAV-Olig001-ASPA (MYR-101) in typical Canavan disease. The 2025 publication reports an interim eight-participant analysis; results cannot be generalized to atypical disease or interpreted as established curative efficacy.

Target Phenotypes: Hypomyelination HP:0003429 Seizure HP:0001250

Show evidence (2 references)

clinicaltrials:NCT04833907 SUPPORT Human Clinical

"The latest generation AAV viral vector (rAAV-Olig001-ASPA) will be administered to patients using neurosurgical procedure which involves direct administration of gene therapy to affected regions of the brain."

ClinicalTrials.gov records an intracranial oligodendrocyte-targeted ASPA gene-therapy trial for typical Canavan disease.

PMID:40957959 SUPPORT Human Clinical

"This open-label phase 1/2 clinical study uses a novel recombinant vector, rAAV-Olig001, with selective tropism for oligodendrocytes"

Published interim report of the oligodendrocyte-targeted trial; its registry identifier is NCT04833907.

🧫

Experimental Models

2

HEK293 ASPA variant functional assay CELL_LINE

Transient expression of ASPA-GFP variants in HEK293 cells measured catalytic activity by LC-MS/MS and protein expression by Western blot. This distinguishes activity from abundance, but is not a patient oligodendrocyte model.

Pathograph links

Aspartoacylase enzyme deficiency measures

Show evidence (1 reference)

PMID:28101991 SUPPORT In Vitro

"The majority of the studied variants presented with enzyme activities lower than 1% of the WT."

Direct heterologous-cell activity measurements.

Show evidence (1 reference)

PMID:28101991 SUPPORT In Vitro

"All variants presented detectable expression of ASPA with no major differences concerning level of expression when compared to the WT"

Low activity need not imply low measured protein abundance in this assay.

SVA_E carrier and patient fibroblast RNA sequencing PRIMARY_CELL_CULTURE

RNA sequencing with and without cycloheximide in fibroblasts from a carrier parent and an affected individual linked the intronic insertion to aberrant RNA and transcript loss. This does not measure enzyme activity in brain or establish an all-tissue expression pattern.

Pathograph links

Aberrant ASPA splicing measures

Show evidence (1 reference)

PMID:40995055 SUPPORT In Vitro

"the SVA_E insertion creates a novel splice acceptor site within intron 4 of ASPA"

Fibroblast RNA-seq from an affected individual and a parental carrier demonstrates altered splicing.

Degradation of aberrant ASPA transcripts measures

Show evidence (1 reference)

PMID:40995055 SUPPORT In Vitro

"The transcript incorporating the SVA_E was only observed in CHX-treated samples, indicating that the products from this allele are targeted for degradation."

Cycloheximide-unmasked transcript supports degradation of the aberrant RNA in fibroblasts.

Show evidence (2 references)

PMID:40995055 SUPPORT In Vitro

"the SVA_E insertion creates a novel splice acceptor site within intron 4 of ASPA"

Fibroblast RNA-seq from an affected individual and a parental carrier demonstrates altered splicing.

PMID:40995055 SUPPORT In Vitro

"The transcript incorporating the SVA_E was only observed in CHX-treated samples, indicating that the products from this allele are targeted for degradation."

Cycloheximide-unmasked transcript supports degradation of the aberrant RNA in fibroblasts.

🐁

Animal Models

2

Aspa nur7 mice with Nat8l gene-dose reduction

Aspa-deficient mice with partial or complete Nat8l loss separate substrate accumulation from acetate deprivation. Complete loss rescued myelin pathology but not survival in the Maier study; partial loss improved survival. Outcomes depend on genotype, background, and endpoint and do not establish human treatment efficacy.

Species

Mus musculus

Genotype

Aspa nur7/nur7 with Nat8l +/+, +/-, or -/-

Pathograph links

Spongiform white-matter vacuolation rescues

Show evidence (1 reference)

PMID:26511242 SUPPORT Model Organism

"full reversal of spongy myelin and axonal degeneration"

Complete Nat8l deletion rescued tissue pathology.

NAA accumulation in CNS and body fluids perturbs

Show evidence (1 reference)

PMID:26511242 SUPPORT Model Organism

"These mice have no detectable NAA."

Double-mutant substrate ablation.

Show evidence (2 references)

PMID:26511242 SUPPORT Model Organism

"although pathology was fully reversed, the survival time of the mice was not prolonged."

Important endpoint dissociation.

PMID:25712859 SUPPORT Model Organism

"permits normal CNS myelination and prevents leukodystrophy in a murine Canavan disease model."

Independent genetic experiment supports the tissue rescue.

TALEN-generated Aspa knockout rat

The engineered rat showed CNS vacuolation, hypomyelination, swollen axons and astrocyte activation, particularly in brainstem and motor pathways. No overt neurological signs or quantitative neuron loss were found in the studied animals. CNS NAA was not measured in this study; histological similarity does not establish a full clinical phenocopy.

Species

Rattus norvegicus

Genotype

Aspa knockout

Pathograph links

Spongiform white-matter vacuolation partially recapitulates

Show evidence (1 reference)

PMID:38538326 SUPPORT Model Organism

"vacuolation with swollen axons, hypomyelination, and activated swollen astrocytes were observed mainly in the brainstem reticular formation"

Rat histopathology reproduces selected white-matter lesions.

Neuronal loss and cortical thinning fails to recapitulate

Limitations: Morphometry found no obvious neuron-number change in the sampled regions; this does not exclude subtle functional deficits.

Show evidence (1 reference)

PMID:38538326 SUPPORT Model Organism

"Morphometrical analysis revealed no obvious change in the number of neurons."

Neuronal-number findings differ from the mouse neuronal-loss model.

Show evidence (3 references)

PMID:38538326 SUPPORT Model Organism

"vacuolation with swollen axons, hypomyelination, and activated swollen astrocytes were observed mainly in the brainstem reticular formation"

Rat histopathology reproduces selected white-matter lesions.

PMID:38538326 SUPPORT Model Organism

"Morphometrical analysis revealed no obvious change in the number of neurons."

Neuronal-number findings differ from the mouse neuronal-loss model.

PMID:38538326 SUPPORT Model Organism

"None of the Aspa-knockout rats showed any neurological signs."

Major clinical limitation of this model.

{ }

Source YAML

click to show

name: Canavan disease
category: Mendelian
creation_date: '2026-05-03T17:22:49Z'
synonyms:
- ACY2 deficiency
- Aminoacylase 2 deficiency
- Aspartoacylase deficiency
- Spongy degeneration of the brain
description: >-
  Canavan disease is an autosomal recessive leukodystrophy caused by biallelic pathogenic ASPA variants
  and deficient aspartoacylase activity. Impaired N-acetyl-L-aspartate (NAA) hydrolysis causes substrate
  accumulation and spongiform white-matter disease. The spectrum includes typical infantile disease with
  profound developmental impairment, macrocephaly, early hypotonia, later spasticity, visual and feeding
  problems, and increasingly prevalent seizures, and less common atypical disease with milder or later
  manifestations. The contribution of NAA toxicity, altered water homeostasis, and deficient acetate-dependent
  metabolism remains incompletely resolved.
disease_term:
  preferred_term: Canavan disease
  term:
    id: MONDO:0010079
    label: Canavan disease
parents:
- Leukodystrophy
mappings:
  mondo_mappings:
  - term:
      id: MONDO:0010079
      label: Canavan disease
    mapping_predicate: skos:exactMatch
    mapping_source: Orphanet ORPHA:141
    mapping_justification: >
      Orphanet ORPHA:141 lists MONDO:0010079 as an exact cross-reference for
      Canavan disease.
external_assertions:
- name: Orphanet Canavan disease record
  source: Orphanet
  assertion_type: structured_disease_record
  external_id: ORPHA:141
  url: http://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=en&Expert=141
  description: >-
    Orphanet's ORPHA:141 structured record for Canavan disease includes the exact MONDO cross-reference,
    definition, autosomal recessive inheritance, epidemiology, OMIM cross-reference, and HPO phenotype
    annotations used in this entry.
  evidence:
  - reference: ORPHA:141
    reference_title: Canavan disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: MONDO:0010079 | Exact
    explanation: Orphanet maps ORPHA:141 to the MONDO identifier used by this entry.
  - reference: ORPHA:141
    reference_title: Canavan disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: OMIM:271900 | Exact
    explanation: Orphanet lists OMIM:271900 as an exact external cross-reference.
definitions:
- name: Orphanet Canavan disease definition
  definition_type: OTHER
  description: >-
    A neurodegenerative disorder ranging from severe leukodystrophy with macrocephaly and severe developmental
    delay to very rare mild/juvenile disease with milder developmental delay.
  evidence:
  - reference: ORPHA:141
    reference_title: Canavan disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: neurodegenerative disorder; its spectrum varies between severe forms with leukodystrophy
    explanation: Orphanet defines Canavan disease as a spectrum neurodegenerative leukodystrophy.
inheritance:
- name: Autosomal recessive inheritance
  description: >-
    Autosomal recessive. Heterozygous carriers are asymptomatic. When both parents carry a pathogenic
    ASPA variant, each pregnancy has a 25% affected, 50% carrier, and 25% unaffected noncarrier probability.
    Parental testing supports recurrence-risk assessment.
  inheritance_term:
    preferred_term: Autosomal recessive inheritance
    term:
      id: HP:0000007
      label: Autosomal recessive inheritance
  evidence:
  - reference: ORPHA:141
    reference_title: Canavan disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Autosomal recessive
    explanation: Orphanet records autosomal recessive inheritance for Canavan disease.
  - reference: PMID:20301412
    reference_title: Canavan Disease.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Canavan disease is inherited in an autosomal recessive manner.
    explanation: GeneReviews confirms autosomal recessive inheritance.
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/
    reference_title: Canavan Disease - GeneReviews® - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Heterozygotes (carriers) are asymptomatic and are not at risk of developing the disorder.
    explanation: Distinguishes carrier status from disease.
  - reference: PMID:20301412
    reference_title: Canavan Disease.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier.
    explanation: Conditional recurrence risks when both parents are carriers.
prevalence:
- population: Worldwide
  prevalence_class: UNKNOWN
  notes: >-
    Orphanet records worldwide point prevalence as unknown and worldwide prevalence at birth in the 1-9
    per 100,000 band.
  evidence:
  - reference: ORPHA:141
    reference_title: Canavan disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Unknown | Worldwide | Point prevalence | ORPHANET
    explanation: Orphanet records worldwide point prevalence as unknown.
  - reference: ORPHA:141
    reference_title: Canavan disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: 1-9 / 100 000 | Worldwide | Prevalence at birth
    explanation: Orphanet records a worldwide prevalence-at-birth band.
progression:
- phase: Typical infantile Canavan disease
  age_range: Infancy
  notes: >-
    Typical disease presents after early normal appearance, with hypotonia, head lag, macrocephaly, neurodevelopmental
    impairment by three to five months, followed by neurodegeneration, developmental regression, increasing
    feeding problems, seizures, and reduced survival. GeneReviews estimates that typical disease accounts
    for 85%-90% of affected individuals. Axial hypotonia and limb hypertonia can coexist; tone does not
    necessarily change in a strictly sequential fashion.
  evidence:
  - reference: PMID:20301412
    reference_title: Canavan Disease.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: neurodevelopmental impairment evident by ages three to five months
    explanation: GeneReviews describes the typical early-infantile onset window.
  - reference: PMID:34011350
    reference_title: 'The natural history of Canavan disease: 23 new cases and comparison with patients from literature.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Onset of symptoms was between 0 and 6 months.
    explanation: Natural history cohort supports early infantile symptom onset.
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/
    reference_title: Canavan Disease - GeneReviews® - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: The phenotypic spectrum ranges from the more severe typical Canavan disease (85%-90% of individuals) to the less severe atypical Canavan disease (10%-15%).
    explanation: Clinical spectrum proportions are expert synthesis, not a population prevalence estimate.
- phase: Atypical milder Canavan disease
  age_range: Infancy to childhood or adolescence
  notes: >-
    Atypical disease represents approximately 10%-15% of affected individuals, with variable onset from
    infancy to childhood or adolescence, milder developmental delay, sometimes normal head size, ataxia,
    and possible later regression. Some individuals walk and attend school; survival into adulthood occurs
    and lifespan is incompletely described.
  evidence:
  - reference: PMID:20301412
    reference_title: Canavan Disease.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: atypical Canavan disease is more variable
    explanation: GeneReviews describes atypical Canavan disease as a variable milder spectrum.
  - reference: PMID:28101991
    reference_title: Clinically Distinct Phenotypes of Canavan Disease Correlate with Residual Aspartoacylase Enzyme Activity.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: The mutations found in the mild patients corresponded to the variants with the highest residual enzyme activities
    explanation: Residual ASPA activity supports the milder phenotypic spectrum.
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/
    reference_title: Canavan Disease - GeneReviews® - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: The life span is not well-described; however, individuals with atypical Canavan disease may survive to adulthood.
    explanation: Avoids extrapolating the severe infantile prognosis to all atypical individuals.
- phase: Longitudinal survival in historical clinical cohorts
  notes: >-
    Kaplan-Meier analysis pooling 23 study patients with 59 literature patients estimated 73% survival
    to age ten years. This is an ascertainment-dependent cohort estimate, not a prediction for an individual
    or a result of current gene therapy.
  evidence:
  - reference: PMID:34011350
    reference_title: 'The natural history of Canavan disease: 23 new cases and comparison with patients from literature.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: 'Kaplan Meier survival probability with confidence interval (dotted line) for 82 CD patients, pooled data: study cohort (N = 23) & literature cohort (N = 59) /Traeger et al.'
    explanation: Defines the pooled cohort denominator.
  - reference: PMID:34011350
    reference_title: 'The natural history of Canavan disease: 23 new cases and comparison with patients from literature.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: 73% of the CD patients reached the age of 10 years
    explanation: Survival estimate from the historical pooled cohort.
genetic:
- name: ASPA
  association: Causal loss-of-function variant
  gene_term:
    preferred_term: ASPA
    term:
      id: hgnc:756
      label: ASPA
  notes: >-
    Biallelic ASPA loss-of-function variants include missense, nonsense, frameshift, splice, deletion,
    and deep intronic insertion alleles. Residual enzyme activity can correlate with milder disease, but
    prediction is imperfect and assay dependent. In one HEK293 assay p.Asp204His retained approximately
    12% activity, whereas p.Ile170Thr remained a variant of uncertain clinical significance in that study.
    Founder p.Glu285Ala and p.Tyr231Ter occur in Ashkenazi Jewish populations; disease occurs across ancestries
    and most new diagnoses are outside that ancestry group.
  evidence:
  - reference: PMID:20301412
    reference_title: Canavan Disease.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: biallelic ASPA pathogenic variants identified by molecular genetic testing
    explanation: GeneReviews identifies biallelic ASPA pathogenic variants as diagnostic.
  - reference: PMID:28101991
    reference_title: Clinically Distinct Phenotypes of Canavan Disease Correlate with Residual Aspartoacylase Enzyme Activity.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: We have detected a correlation between clinical presentation, enzyme activity, and genotype
    explanation: Patient variant study supports genotype-enzyme-phenotype correlation.
  - reference: CGGV:assertion_66306eff-659f-4508-a41b-1820e47e0e1d-2020-10-08T161701.633Z
    reference_title: ASPA / Canavan disease (Definitive)
    supports: SUPPORT
    evidence_source: OTHER
    snippet: ASPA | HGNC:756 | Canavan disease | MONDO:0010079 | AR | Definitive
    explanation: >-
      ClinGen classifies the ASPA-Canavan disease gene-disease relationship as definitive with autosomal
      recessive inheritance.
  - reference: PMID:28101991
    reference_title: Clinically Distinct Phenotypes of Canavan Disease Correlate with Residual Aspartoacylase Enzyme Activity.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: For the time being, we propose to consider this as a rare variant of unknown clinical significance.
    explanation: >-
      The authors retained p.Ile170Thr as uncertain despite residual activity; residual activity alone
      does not classify every variant.
pathophysiology:
- name: Deep intronic ASPA SVA_E insertion
  description: >-
    Approximately 2.6-kb SVA_E insertion in intron 4 of 5 of ASPA transcript NM_000049.4. In the 2025
    series it was homozygous or in trans with another pathogenic allele. Long-read sequencing resolved
    the insertion; fibroblast RNA-seq supported a new splice acceptor, inclusion of SVA sequence, and
    transcript degradation. Population databases suggest a common pathogenic allele across ancestries,
    but this is not a disease-incidence estimate.
  genes:
  - preferred_term: ASPA
    term:
      id: hgnc:756
      label: ASPA
  genetic_context:
    gene:
      preferred_term: ASPA
      term:
        id: hgnc:756
        label: ASPA
    variant_type: insertion
    genomic_contexts:
    - intron
    functional_impact_category: LOSS_OF_FUNCTION
  evidence:
  - reference: PMID:40995055
    reference_title: 'Deep Intronic SVA_E Insertion Identified as the Most Common Pathogenic Variant Associated With Canavan Disease: A Diagnostic Blind Spot.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: We identified an ∼2,600-bp SVA_E retrotransposon intronic insertion in ASPA in all 8 individuals.
    explanation: >-
      Eight affected individuals from seven families with previously incomplete molecular diagnoses carried
      the insertion.
  downstream:
  - target: Aberrant ASPA splicing
    description: The inserted SVA sequence creates a novel splice acceptor.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:40995055
      reference_title: 'Deep Intronic SVA_E Insertion Identified as the Most Common Pathogenic Variant Associated With Canavan Disease: A Diagnostic Blind Spot.'
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: the SVA_E insertion creates a novel splice acceptor site within intron 4 of ASPA
      explanation: Fibroblast RNA-seq from an affected individual and a parental carrier demonstrates altered splicing.
- name: Aberrant ASPA splicing
  description: >-
    The intron-4 SVA_E allele introduces a novel splice acceptor and an SVA-containing exon, demonstrated
    by RNA sequencing of fibroblasts. This is an allele-specific RNA-processing mechanism.
  genes:
  - preferred_term: ASPA
    term:
      id: hgnc:756
      label: ASPA
  biological_processes:
  - preferred_term: mRNA splicing, via spliceosome
    term:
      id: GO:0000398
      label: mRNA splicing, via spliceosome
    modifier: ABNORMAL
  evidence:
  - reference: PMID:40995055
    reference_title: 'Deep Intronic SVA_E Insertion Identified as the Most Common Pathogenic Variant Associated With Canavan Disease: A Diagnostic Blind Spot.'
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: the SVA_E insertion creates a novel splice acceptor site within intron 4 of ASPA
    explanation: Fibroblast RNA-seq from an affected individual and a parental carrier demonstrates altered splicing.
  downstream:
  - target: Degradation of aberrant ASPA transcripts
    description: Aberrant allele-derived transcripts are revealed by cycloheximide treatment, consistent with degradation.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:40995055
      reference_title: 'Deep Intronic SVA_E Insertion Identified as the Most Common Pathogenic Variant Associated With Canavan Disease: A Diagnostic Blind Spot.'
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: The transcript incorporating the SVA_E was only observed in CHX-treated samples, indicating that the products from this allele are targeted for degradation.
      explanation: Cycloheximide-unmasked transcript supports degradation of the aberrant RNA in fibroblasts.
- name: Degradation of aberrant ASPA transcripts
  description: >-
    In fibroblasts carrying the intronic SVA_E insertion, aberrant transcripts were detectable after cycloheximide
    treatment but not without treatment. The resulting loss of functional ASPA RNA provides a route to
    enzyme deficiency; the study did not quantify expression in all tissues.
  genes:
  - preferred_term: ASPA
    term:
      id: hgnc:756
      label: ASPA
  evidence:
  - reference: PMID:40995055
    reference_title: 'Deep Intronic SVA_E Insertion Identified as the Most Common Pathogenic Variant Associated With Canavan Disease: A Diagnostic Blind Spot.'
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: The transcript incorporating the SVA_E was only observed in CHX-treated samples, indicating that the products from this allele are targeted for degradation.
    explanation: Cycloheximide-unmasked transcript supports degradation of the aberrant RNA in fibroblasts.
  downstream:
  - target: Aspartoacylase enzyme deficiency
    description: Aberrant splicing and transcript degradation lead to loss of function from the insertion allele.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:40995055
      reference_title: 'Deep Intronic SVA_E Insertion Identified as the Most Common Pathogenic Variant Associated With Canavan Disease: A Diagnostic Blind Spot.'
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: aberrant splicing that leads to transcript degradation and, consequently, loss of function of ASPA.
      explanation: Functional interpretation from fibroblast RNA studies.
- name: ASPA variant protein destabilization
  description: >-
    Many, but not all, disease-associated ASPA missense variants destabilize the protein. Cultured-cell
    abundance screens and structural analyses support protein-quality-control degradation as one route
    to enzyme deficiency; normal abundance does not establish normal catalytic activity.
  genes:
  - preferred_term: ASPA
    term:
      id: hgnc:756
      label: ASPA
  biological_processes:
  - preferred_term: protein folding
    modifier: ABNORMAL
    term:
      id: GO:0006457
      label: protein folding
  evidence:
  - reference: PMID:38582917
    reference_title: Cellular and molecular mechanisms of aspartoacylase and its role in Canavan disease.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: most disease linked ASPA gene variants lead to a structural destabilization
    explanation: Recent review supports ASPA protein destabilization as a common mechanism.
  - reference: PMID:28101991
    reference_title: Clinically Distinct Phenotypes of Canavan Disease Correlate with Residual Aspartoacylase Enzyme Activity.
    supports: REFUTE
    evidence_source: IN_VITRO
    snippet: All variants presented detectable expression of ASPA with no major differences concerning level of expression when compared to the WT
    explanation: >-
      The tested GFP-fusion variants had low catalytic activities despite detectable abundance, limiting
      a universal degradation explanation.
  downstream:
  - target: Aspartoacylase enzyme deficiency
    description: Destabilized ASPA variants reduce functional aspartoacylase activity.
    causal_link_type: DIRECT
- name: Aspartoacylase enzyme deficiency
  description: >-
    Loss of ASPA activity impairs the cytosolic/oligodendroglial hydrolysis of N-acetyl-L-aspartate to
    acetate and aspartate, initiating the core biochemical disease cascade.
  genes:
  - preferred_term: ASPA
    term:
      id: hgnc:756
      label: ASPA
  cell_types:
  - preferred_term: oligodendrocyte
    term:
      id: CL:0000128
      label: oligodendrocyte
  cellular_components:
  - preferred_term: cytosol
    term:
      id: GO:0005829
      label: cytosol
  biological_processes:
  - preferred_term: N-acetylaspartate/aspartate metabolism
    modifier: ABNORMAL
    term:
      id: GO:0006531
      label: aspartate metabolic process
  molecular_functions:
  - preferred_term: aspartoacylase activity
    term:
      id: GO:0019807
      label: aspartoacylase activity
    modifier: DECREASED
  evidence:
  - reference: PMID:38582917
    reference_title: Cellular and molecular mechanisms of aspartoacylase and its role in Canavan disease.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: deficiency of the cytosolic aspartoacylase (ASPA) enzyme
    explanation: Mechanistic review directly identifies aspartoacylase deficiency.
  - reference: PMID:15784740
    reference_title: Defective N-acetylaspartate catabolism reduces brain acetate levels and myelin lipid synthesis in Canavan's disease.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: ASPA acts to hydrolyze N-acetylaspartate (NAA) into l-aspartate and acetate
    explanation: Mouse model study describes the enzymatic reaction blocked in Canavan disease.
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/
    reference_title: Canavan Disease - GeneReviews® - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Loss or reduction of aspartoacylase activity causes Canavan disease.
    explanation: Human disease mechanism.
  downstream:
  - target: NAA accumulation in CNS and body fluids
    description: Failure to catabolize NAA causes substrate accumulation.
    causal_link_type: DIRECT
  - target: Reduced NAA-derived acetate and myelin lipid synthesis
    description: Loss of NAA hydrolysis limits acetate availability for myelin lipid synthesis.
    causal_link_type: DIRECT
- name: NAA accumulation in CNS and body fluids
  description: >-
    Aspartoacylase deficiency causes N-acetyl-L-aspartate to accumulate in the brain, urine, blood, cerebrospinal
    fluid, and other body fluids. Elevated urinary NAA and brain NAA by proton magnetic resonance spectroscopy
    are key diagnostic biochemical markers.
  chemical_entities:
  - preferred_term: N-acetyl-L-aspartic acid
    modifier: INCREASED
    term:
      id: CHEBI:21547
      label: N-acetyl-L-aspartic acid
  evidence:
  - reference: PMID:8412017
    reference_title: 'Canavan disease: biochemical and molecular studies.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Deficiency of the enzyme aspartoacylase and the accumulation of N-acetylaspartic acid
    explanation: Biochemical study supports the enzyme-substrate defect.
  - reference: PMID:34011350
    reference_title: 'The natural history of Canavan disease: 23 new cases and comparison with patients from literature.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: loss of ASPA activity results in an accumulation of N-acetylaspartic acid
    explanation: Natural history study summarizes NAA accumulation from ASPA loss.
  downstream:
  - target: Spongiform white-matter vacuolation
    description: >-
      Reducing NAA synthesis rescues this pathology in Aspa-deficient mice; the intervening injury mechanism
      and its contribution in humans remain incompletely resolved.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    hypothesis_groups:
    - naa_injury
    evidence:
    - reference: PMID:25712859
      reference_title: Ablating N-acetylaspartate prevents leukodystrophy in a Canavan disease model.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: Aspanur7/nur7 mice were entirely protected against development of leukodystrophy when their capacity to synthesize NAA was ablated by constitutive deletion of Nat8l
      explanation: Genetic substrate-reduction experiment supports a causal role for excess NAA in the mouse model.
  - target: Neuronal loss and cortical thinning
    description: >-
      Reducing NAA synthesis rescues this pathology in Aspa-deficient mice; the intervening injury mechanism
      and its contribution in humans remain incompletely resolved.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    hypothesis_groups:
    - naa_injury
    evidence:
    - reference: PMID:28077719
      reference_title: Suppressing N-Acetyl-l-Aspartate Synthesis Prevents Loss of Neurons in a Murine Model of Canavan Leukodystrophy.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: cerebral cortical and cerebellar neurons are decreased
      explanation: Model study supports neuronal loss downstream of ASPA deficiency.
  - target: Elevated urinary N-acetylaspartic acid
    description: Elevated urinary NAA is a diagnostic readout of systemic NAA accumulation.
    causal_link_type: DIRECT
  - target: Elevated brain NAA by proton MR spectroscopy
    description: Elevated brain NAA by MRS is a diagnostic readout of CNS NAA accumulation.
    causal_link_type: DIRECT
- name: Reduced NAA-derived acetate and myelin lipid synthesis
  description: >-
    Reduced brain acetate and myelin-lipid synthesis were measured in an ASPA-deficient mouse model; one
    human white-matter sample also had reduced cerebroside and sulfatide. The hypothesis that loss of
    NAA-derived acetate is necessary for myelin failure is challenged by normally myelinated Nat8l-deficient
    mice and rescue of myelin pathology in Aspa/Nat8l double mutants. These experiments do not exclude
    a contributory metabolic role under other conditions.
  cell_types:
  - preferred_term: oligodendrocyte
    term:
      id: CL:0000128
      label: oligodendrocyte
  biological_processes:
  - preferred_term: lipid biosynthetic process
    modifier: DECREASED
    term:
      id: GO:0008610
      label: lipid biosynthetic process
  - preferred_term: central nervous system myelination
    modifier: DECREASED
    term:
      id: GO:0022010
      label: central nervous system myelination
  chemical_entities:
  - preferred_term: acetate
    modifier: DECREASED
    term:
      id: CHEBI:30089
      label: acetate
  evidence:
  - reference: PMID:15784740
    reference_title: Defective N-acetylaspartate catabolism reduces brain acetate levels and myelin lipid synthesis in Canavan's disease.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: myelin lipid synthesis is significantly compromised in CD
    explanation: Mouse and human white-matter lipid data support impaired myelin lipid synthesis.
  - reference: PMID:26511242
    reference_title: N-Acetylaspartate Synthase Deficiency Corrects the Myelin Phenotype in a Canavan Disease Mouse Model But Does Not Affect Survival Time.
    supports: REFUTE
    evidence_source: MODEL_ORGANISM
    snippet: acetate derived from NAA is not essential for myelin lipid synthesis
    explanation: Normal myelin composition in double-mutant mice argues against obligatory NAA-derived acetate supply.
  downstream:
  - target: Oligodendrocyte maturation and myelination defect
    description: >-
      Proposed contribution of deficient acetate-dependent lipid metabolism; challenged as a necessary
      or sole mechanism by Nat8l deletion experiments.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:15784740
      reference_title: Defective N-acetylaspartate catabolism reduces brain acetate levels and myelin lipid synthesis in Canavan's disease.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: myelin lipid synthesis is significantly compromised in CD
      explanation: Mouse and human white-matter lipid data support impaired myelin lipid synthesis.
    - reference: PMID:26511242
      reference_title: N-Acetylaspartate Synthase Deficiency Corrects the Myelin Phenotype in a Canavan Disease Mouse Model But Does Not Affect Survival Time.
      supports: REFUTE
      evidence_source: MODEL_ORGANISM
      snippet: acetate derived from NAA is not essential for myelin lipid synthesis
      explanation: Normal myelin composition in double-mutant mice argues against obligatory NAA-derived acetate supply.
    hypothesis_groups:
    - acetate_contribution
- name: Oligodendrocyte maturation and myelination defect
  conforms_to: cns_myelin_failure#Oligodendrocyte Differentiation Arrest and Death
  description: >-
    ASPA-deficient mice show altered oligodendrocyte maturation, reduced myelin proteins, noncompact myelin,
    increased histone acetylation, and oligodendrocyte apoptosis during early postnatal development. These
    model findings establish cellular abnormalities but do not establish that histone acetylation or acetate
    shortage alone causes the human disease. In a separate nur7 study, oxidative stress preceded oligodendrocyte
    loss; ASPA overexpression partially rescued ATP under glucose deprivation in primary mouse oligodendrocytes,
    supporting a possible energetic contribution.
  cell_types:
  - preferred_term: oligodendrocyte
    term:
      id: CL:0000128
      label: oligodendrocyte
  biological_processes:
  - preferred_term: central nervous system myelination
    modifier: DECREASED
    term:
      id: GO:0022010
      label: central nervous system myelination
  evidence:
  - reference: PMID:20637282
    reference_title: Aspartoacylase deficiency affects early postnatal development of oligodendrocytes and myelination.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: ASPA deficiency affects oligodendrocyte maturation and myelination
    explanation: Mouse study directly supports oligodendrocyte maturation and myelination defects.
  - reference: PMID:22617649
    reference_title: Aspartoacylase supports oxidative energy metabolism during myelination.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: markers of oxidative stress preceding oligodendrocyte loss and dysmyelination
    explanation: Model study supports metabolic stress before oligodendrocyte loss and dysmyelination.
  - reference: PMID:22617649
    reference_title: Aspartoacylase supports oxidative energy metabolism during myelination.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: indicating the partial rescue of an oxidative deficit by ASPA.
    explanation: ASPA overexpression in glucose-deprived primary mouse oligodendrocytes increased ATP; this is an in-vitro energetic readout, not proof of clinical rescue.
  downstream:
  - target: Spongiform white-matter vacuolation
    description: Myelination defects and glial stress contribute to spongiform leukodystrophy.
    causal_link_type: DIRECT
  - target: Global developmental delay
    description: >-
      White-matter dysfunction disrupts early neurodevelopmental progress. This is a proposed clinical
      consequence; the precise intervening pathway is unresolved.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    hypothesis_groups:
    - clinical_injury
  - target: Hypotonia
    description: >-
      Early white-matter disease contributes to impaired motor control and hypotonia. This is a proposed
      clinical consequence; the precise intervening pathway is unresolved.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    hypothesis_groups:
    - clinical_injury
- name: Spongiform white-matter vacuolation
  description: >-
    Canavan disease causes dysmyelination, vacuolation, astrogliosis, and spongiform white-matter degeneration,
    the tissue pathology that underlies macrocephaly and progressive neurologic impairment.
  cell_types:
  - preferred_term: oligodendrocyte
    term:
      id: CL:0000128
      label: oligodendrocyte
  - preferred_term: astrocyte
    term:
      id: CL:0000127
      label: astrocyte
  evidence:
  - reference: PMID:29456021
    reference_title: Brain Nat8l Knockdown Suppresses Spongiform Leukodystrophy in an Aspartoacylase-Deficient Canavan Disease Mouse Model.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: brain dysmyelination, vacuolation, and astrogliosis
    explanation: Aspa-deficient mouse model supports spongiform leukodystrophy pathology.
  - reference: PMID:20637282
    reference_title: Aspartoacylase deficiency affects early postnatal development of oligodendrocytes and myelination.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: degeneration of the white matter, demyelination
    explanation: Study links Canavan disease to white-matter degeneration and demyelination.
  downstream:
  - target: Macrocephaly
    description: >-
      Diffuse white-matter disease contributes to progressive head enlargement. This is a proposed clinical
      consequence; the precise intervening pathway is unresolved.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    hypothesis_groups:
    - clinical_injury
  - target: Visual impairment
    description: CNS white-matter and visual pathway involvement contribute to visual impairment.
    causal_link_type: DIRECT
  - target: Hypertonia
    description: >-
      Progressive white-matter disease contributes to later spasticity and hypertonia. This is a proposed
      clinical consequence; the precise intervening pathway is unresolved.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    hypothesis_groups:
    - clinical_injury
  - target: Seizure
    description: >-
      Progressive brain involvement contributes to epilepsy over time. This is a proposed clinical consequence;
      the precise intervening pathway is unresolved.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    hypothesis_groups:
    - clinical_injury
  - target: Visual pathway and ocular involvement
    description: White-matter disease affecting visual pathways contributes to visual and ocular manifestations.
    causal_link_type: DIRECT
  - target: Feeding and aspiration vulnerability
    description: >-
      Severe neurologic and white-matter disease contributes to impaired feeding, swallowing safety, and
      reflux risk.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
  - target: Flexion contracture
    description: >-
      Progressive tone abnormality and reduced mobility increase risk for contractures. This is a proposed
      clinical consequence; the precise intervening pathway is unresolved.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    hypothesis_groups:
    - clinical_injury
  - target: Leukodystrophy
    description: White-matter pathology manifests as the leukodystrophy imaging phenotype.
    causal_link_type: DIRECT
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/
      reference_title: Canavan Disease - GeneReviews® - NCBI Bookshelf
      supports: SUPPORT
      evidence_source: OTHER
      snippet: Neuroimaging changes reveal generalized leukodystrophy characterized by diffuse, symmetric changes observed in subcortical white matter and cortical areas as well as the brain stem and cerebellum
      explanation: Clinical baseline supports this phenotype and its context.
- name: Visual pathway and ocular involvement
  description: >-
    Cerebral visual impairment is often attributed to white-matter visual pathway involvement. Optic atrophy
    can occur but is not required for impaired tracking or blindness; retinal findings remain separate
    clinical observations with uncertain causal placement.
  evidence:
  - reference: PMID:34011350
    reference_title: 'The natural history of Canavan disease: 23 new cases and comparison with patients from literature.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: visual impairment is more commonly caused by white matter disease affecting the visual pathways.
    explanation: Natural history authors connect visual impairment in Canavan disease to white-matter visual pathway disease.
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/
    reference_title: Canavan Disease - GeneReviews® - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Early in life there is a decreased ability to fix and follow, most commonly due to cerebral visual impairment
    explanation: Supports cerebral visual impairment rather than assuming optic atrophy.
  downstream:
  - target: Visual impairment
    description: White-matter involvement of visual pathways produces impaired visual function.
    causal_link_type: DIRECT
  - target: Blindness
    description: >-
      Severe visual pathway and ocular involvement can manifest as blindness. This is a proposed clinical
      consequence; the precise intervening pathway is unresolved.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    hypothesis_groups:
    - clinical_injury
  - target: Abnormality of visual evoked potentials
    description: >-
      Visual pathway disease can produce abnormal visual evoked potentials. This is a proposed clinical
      consequence; the precise intervening pathway is unresolved.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    hypothesis_groups:
    - clinical_injury
  - target: Nystagmus
    description: >-
      Early abnormal eye movements, including nystagmus, occur in Canavan disease. This is a proposed
      clinical consequence; the precise intervening pathway is unresolved.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    hypothesis_groups:
    - clinical_injury
- name: Feeding and aspiration vulnerability
  description: >-
    Severe Canavan neurologic impairment commonly affects feeding, nutrition, and oral intake safety.
    Feeding therapy is recommended to maintain weight gain and reduce aspiration risk, and natural history
    scoring treats aspiration, inadequate weight gain, or tube feeding as feeding-severity markers.
  evidence:
  - reference: PMID:20301412
    reference_title: Canavan Disease.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: feeding therapy (to assure adequate nutrition and weight gain, minimize risk of
    explanation: GeneReviews supports feeding and aspiration-risk management as part of Canavan care.
  - reference: PMID:34011350
    reference_title: 'The natural history of Canavan disease: 23 new cases and comparison with patients from literature.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: 'Feeding: Score 1 if oral feeding is possible but aspiration occurs and/or weight gain is insufficient'
    explanation: >-
      Natural history severity scoring includes aspiration, poor weight gain, and tube feeding as feeding
      manifestations.
  downstream:
  - target: Feeding difficulties in infancy
    description: Neurologic feeding impairment manifests as early feeding difficulty.
    causal_link_type: DIRECT
  - target: Gastroesophageal reflux
    description: >-
      Feeding and swallowing impairment can coexist with reflux in severe neurologic disease. This is
      a proposed clinical consequence; the precise intervening pathway is unresolved.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    hypothesis_groups:
    - clinical_injury
- name: Neuronal loss and cortical thinning
  description: >-
    Aspartoacylase-deficient mice show cortical and cerebellar neuron depletion and cortical thinning
    that can be prevented by lowering NAA synthesis. These are model-specific findings; they do not establish
    that neuronal loss is the dominant cause of each human neurological manifestation.
  cell_types:
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  evidence:
  - reference: PMID:28077719
    reference_title: Suppressing N-Acetyl-l-Aspartate Synthesis Prevents Loss of Neurons in a Murine Model of Canavan Leukodystrophy.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: cerebral cortical and cerebellar neurons are decreased
    explanation: Model study supports neuronal loss downstream of ASPA deficiency.
  downstream:
  - target: Cognitive impairment
    description: >-
      Neuronal and cortical injury contributes to cognitive impairment. This is a proposed clinical consequence;
      the precise intervening pathway is unresolved.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    hypothesis_groups:
    - clinical_injury
  - target: Developmental regression
    description: >-
      Progressive neuronal and white-matter injury leads to loss of acquired skills. This is a proposed
      clinical consequence; the precise intervening pathway is unresolved.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    hypothesis_groups:
    - clinical_injury
phenotypes:
- name: Macrocephaly
  category: Neurologic
  description: Macrocephaly is a frequent and often progressive finding in typical Canavan disease.
  phenotype_term:
    preferred_term: Macrocephaly
    term:
      id: HP:0000256
      label: Macrocephaly
  frequency: Frequent (79-30%)
  evidence:
  - reference: ORPHA:141
    reference_title: Canavan disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: HP:0000256 | Macrocephaly | Frequent
    explanation: Orphanet reports macrocephaly as frequent.
  - reference: PMID:34011350
    reference_title: 'The natural history of Canavan disease: 23 new cases and comparison with patients from literature.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Macrocephaly became apparent between 4 and 18 months of age.
    explanation: Natural history cohort supports progressive macrocephaly in infancy.
- name: Hearing impairment
  category: Neurologic
  description: >-
    Orphanet lists hearing impairment, but GeneReviews states that hearing is usually preserved and a
    23-patient natural-history cohort reported preserved hearing throughout disease. Its frequency is
    unresolved; do not interpret the Orphanet band as a reconciled estimate.
  phenotype_term:
    preferred_term: Hearing impairment
    term:
      id: HP:0000365
      label: Hearing impairment
  evidence:
  - reference: ORPHA:141
    reference_title: Canavan disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: HP:0000365 | Hearing impairment | Frequent
    explanation: Orphanet reports hearing impairment as frequent.
  - reference: PMID:34011350
    reference_title: 'The natural history of Canavan disease: 23 new cases and comparison with patients from literature.'
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: All CD patients were reported by caregivers and medical records to be able to hear at birth and throughout the course of disease.
    explanation: >-
      All 23 patients retained hearing, although this was caregiver/record reporting rather than systematic
      audiometry.
- name: Visual impairment
  category: Neurologic
  description: Visual impairment is frequent and may include poor visual tracking, nystagmus, and cerebral visual impairment.
  phenotype_term:
    preferred_term: Visual impairment
    term:
      id: HP:0000505
      label: Visual impairment
  frequency: Frequent (79-30%)
  evidence:
  - reference: ORPHA:141
    reference_title: Canavan disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: HP:0000505 | Visual impairment | Frequent
    explanation: Orphanet reports visual impairment as frequent.
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/
    reference_title: Canavan Disease - GeneReviews® - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Early in life there is a decreased ability to fix and follow, most commonly due to cerebral visual impairment
    explanation: Supports cerebral visual impairment rather than assuming optic atrophy.
- name: Blindness
  category: Neurologic
  description: Blindness is a frequent Orphanet phenotype for Canavan disease.
  phenotype_term:
    preferred_term: Blindness
    term:
      id: HP:0000618
      label: Blindness
  frequency: Frequent (79-30%)
  evidence:
  - reference: ORPHA:141
    reference_title: Canavan disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: HP:0000618 | Blindness | Frequent
    explanation: Orphanet reports blindness as frequent.
- name: Optic atrophy
  category: Ophthalmologic
  description: >-
    Optic atrophy is reported, but the Orphanet very-frequent annotation conflicts with the 23-patient
    natural-history cohort, in which only two patients had optic nerve atrophy. Cerebral visual impairment
    is a more common explanation for poor visual function.
  phenotype_term:
    preferred_term: Optic atrophy
    term:
      id: HP:0000648
      label: Optic atrophy
  evidence:
  - reference: ORPHA:141
    reference_title: Canavan disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: HP:0000648 | Optic atrophy | Very frequent
    explanation: Orphanet reports optic atrophy as very frequent.
  - reference: PMID:34011350
    reference_title: 'The natural history of Canavan disease: 23 new cases and comparison with patients from literature.'
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: Considering that only two patients were reported to suffer from optic nerve atrophy, we conclude that visual impairment is more commonly caused by white matter disease affecting the visual pathways.
    explanation: Documents the discrepancy with the structured-source frequency band.
- name: Abnormality of visual evoked potentials
  category: Neurophysiologic
  description: Abnormal visual evoked potentials are a frequent neurophysiologic manifestation.
  phenotype_term:
    preferred_term: Abnormality of visual evoked potentials
    term:
      id: HP:0000649
      label: Abnormality of visual evoked potentials
  frequency: Frequent (79-30%)
  evidence:
  - reference: ORPHA:141
    reference_title: Canavan disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: HP:0000649 | Abnormality of visual evoked potentials | Frequent
    explanation: Orphanet reports abnormal visual evoked potentials as frequent.
- name: Nystagmus
  category: Ophthalmologic
  description: Nystagmus and other abnormal eye movements are common early manifestations.
  phenotype_term:
    preferred_term: Nystagmus
    term:
      id: HP:0000639
      label: Nystagmus
  frequency: Frequent (79-30%)
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/
    reference_title: Canavan Disease - GeneReviews® - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Nystagmus frequently develops early in infancy.
    explanation: >-
      Specifically supports nystagmus; the earlier cohort quote described a broader category of abnormal
      eye movements.
- name: Seizure
  category: Neurologic
  description: >-
    Seizures are age dependent: about one third of children have seizures in the first year, and most
    are affected by the end of the first decade. Reported types include tonic spasms, generalized tonic-clonic
    seizures, and infantile epileptic spasms. Seizures can persist despite medication; a single low frequency
    band obscures the longitudinal course.
  phenotype_term:
    preferred_term: Seizure
    term:
      id: HP:0001250
      label: Seizure
  evidence:
  - reference: ORPHA:141
    reference_title: Canavan disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: HP:0001250 | Seizure | Occasional
    explanation: Orphanet reports seizure as occasional.
  - reference: PMID:34011350
    reference_title: 'The natural history of Canavan disease: 23 new cases and comparison with patients from literature.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Seizure frequency was highest towards the end of the first decade.
    explanation: Natural history cohort supports increasing seizure burden over time.
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/
    reference_title: Canavan Disease - GeneReviews® - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Seizures occur in the first year of life in one third of children with Canavan disease and become more prevalent over time
    explanation: Age-dependent frequency from GeneReviews.
- name: Hypotonia
  category: Neurologic
  description: Hypotonia is a frequent early motor-tone abnormality in typical Canavan disease.
  phenotype_term:
    preferred_term: Hypotonia
    term:
      id: HP:0001252
      label: Hypotonia
  frequency: Frequent (79-30%)
  evidence:
  - reference: ORPHA:141
    reference_title: Canavan disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: HP:0001252 | Hypotonia | Frequent
    explanation: Orphanet reports hypotonia as frequent.
  - reference: PMID:20301412
    reference_title: Canavan Disease.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: neurodevelopmental delays, macrocephaly, and tone abnormalities
    explanation: GeneReviews identifies tone abnormalities as a core disease feature.
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/
    reference_title: Canavan Disease - GeneReviews® - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Hypotonia ... is an early finding associated with poor head control.
    explanation: Specific support for the motor-tone phenotype.
- name: Global developmental delay
  category: Neurodevelopmental
  description: Global developmental delay is a very frequent core manifestation.
  phenotype_term:
    preferred_term: Global developmental delay
    term:
      id: HP:0001263
      label: Global developmental delay
  frequency: Very frequent (99-80%)
  evidence:
  - reference: ORPHA:141
    reference_title: Canavan disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: HP:0001263 | Global developmental delay | Very frequent
    explanation: Orphanet reports global developmental delay as very frequent.
  - reference: PMID:34011350
    reference_title: 'The natural history of Canavan disease: 23 new cases and comparison with patients from literature.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Psychomotor development of patients was limited
    explanation: Natural history cohort supports severe psychomotor developmental limitation.
- name: Hypertonia
  category: Neurologic
  description: Hypertonia is frequent and often develops as hypotonia evolves into spasticity.
  phenotype_term:
    preferred_term: Hypertonia
    term:
      id: HP:0001276
      label: Hypertonia
  frequency: Frequent (79-30%)
  evidence:
  - reference: ORPHA:141
    reference_title: Canavan disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: HP:0001276 | Hypertonia | Frequent
    explanation: Orphanet reports hypertonia as frequent.
  - reference: PMID:20301412
    reference_title: Canavan Disease.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: neurodevelopmental delays, macrocephaly, and tone abnormalities
    explanation: GeneReviews supports abnormal tone as a core clinical feature.
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/
    reference_title: Canavan Disease - GeneReviews® - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: With age, hypotonia evolves to spasticity.
    explanation: Supports the common evolution of tone; coexistence is also seen in the cohort.
- name: Flexion contracture
  category: Musculoskeletal
  description: Flexion contractures are an occasional musculoskeletal complication of progressive motor impairment.
  phenotype_term:
    preferred_term: Flexion contracture
    term:
      id: HP:0001371
      label: Flexion contracture
  frequency: Occasional (29-5%)
  evidence:
  - reference: ORPHA:141
    reference_title: Canavan disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: HP:0001371 | Flexion contracture | Occasional
    explanation: Orphanet reports flexion contracture as occasional.
- name: Gastroesophageal reflux
  category: Gastrointestinal
  description: Gastroesophageal reflux is a frequent gastrointestinal manifestation.
  phenotype_term:
    preferred_term: Gastroesophageal reflux
    term:
      id: HP:0002020
      label: Gastroesophageal reflux
  frequency: Frequent (79-30%)
  evidence:
  - reference: ORPHA:141
    reference_title: Canavan disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: HP:0002020 | Gastroesophageal reflux | Frequent
    explanation: Orphanet reports gastroesophageal reflux as frequent.
- name: EEG abnormality
  category: Neurophysiologic
  description: >-
    Abnormal EEGs include diffuse slowing and paroxysmal abnormalities in tested patients. The tested
    subsets are selected and do not establish a precise frequency across the full disease spectrum.
  phenotype_term:
    preferred_term: EEG abnormality
    term:
      id: HP:0002353
      label: EEG abnormality
  electrophysiology:
    electrophysiology_modality: EEG
  evidence:
  - reference: ORPHA:141
    reference_title: Canavan disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: HP:0002353 | EEG abnormality | Very frequent
    explanation: Orphanet reports EEG abnormality as very frequent.
  - reference: PMID:28101991
    reference_title: Clinically Distinct Phenotypes of Canavan Disease Correlate with Residual Aspartoacylase Enzyme Activity.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: In five patients, EEGs were diffusely slow
    explanation: >-
      Five of eight tested patients had diffuse slowing; this was a clinically selected subset, not a
      population frequency.
- name: Developmental regression
  category: Neurodevelopmental
  description: >-
    Regression follows early developmental impairment in typical disease. Atypical individuals may continue
    to make slow progress and regress later, while some do not regress; frequency depends on phenotype
    and follow-up.
  phenotype_term:
    preferred_term: Developmental regression
    term:
      id: HP:0002376
      label: Developmental regression
  evidence:
  - reference: ORPHA:141
    reference_title: Canavan disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: HP:0002376 | Developmental regression | Occasional
    explanation: Orphanet reports developmental regression as occasional.
  - reference: PMID:20301412
    reference_title: Canavan Disease.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: followed by neurodegeneration and developmental regression
    explanation: GeneReviews identifies regression as part of typical disease course.
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/
    reference_title: Canavan Disease - GeneReviews® - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Children with atypical Canavan disease frequently continue to make slow developmental progress without regression until later in the disease course.
    explanation: Preserves the variable atypical trajectory.
- name: Reduced consciousness
  category: Neurologic
  description: >-
    Reduced consciousness/confusion is reported in the Orphanet structured phenotype set. The associated
    very-frequent band is a source annotation, not a quantified estimate verified in the clinical cohorts
    used here.
  phenotype_term:
    preferred_term: Reduced consciousness
    term:
      id: HP:0004372
      label: Reduced consciousness
  evidence:
  - reference: ORPHA:141
    reference_title: Canavan disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: HP:0004372 | Reduced consciousness/confusion | Very frequent
    explanation: Orphanet reports reduced consciousness/confusion as very frequent.
- name: Abnormal retinal pigmentation
  category: Ophthalmologic
  description: Abnormal retinal pigmentation is an occasional ocular phenotype.
  phenotype_term:
    preferred_term: Abnormal retinal pigmentation
    term:
      id: HP:0007703
      label: Abnormal retinal pigmentation
  frequency: Occasional (29-5%)
  evidence:
  - reference: ORPHA:141
    reference_title: Canavan disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: HP:0007703 | Abnormality of retinal pigmentation | Occasional
    explanation: Orphanet reports abnormal retinal pigmentation as occasional.
- name: Feeding difficulties in infancy
  category: Gastrointestinal
  description: Feeding difficulty in infancy is a very frequent manifestation and may worsen as swallowing deteriorates.
  phenotype_term:
    preferred_term: Feeding difficulties in infancy
    term:
      id: HP:0008872
      label: Feeding difficulties in infancy
  frequency: Very frequent (99-80%)
  evidence:
  - reference: ORPHA:141
    reference_title: Canavan disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: HP:0008872 | Feeding difficulties in infancy | Very frequent
    explanation: Orphanet reports feeding difficulties in infancy as very frequent.
- name: Cognitive impairment
  category: Neurodevelopmental
  description: Cognitive impairment is a very frequent consequence of severe neurodevelopmental disease.
  phenotype_term:
    preferred_term: Cognitive impairment
    term:
      id: HP:0100543
      label: Cognitive impairment
  frequency: Very frequent (99-80%)
  evidence:
  - reference: ORPHA:141
    reference_title: Canavan disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: HP:0100543 | Cognitive impairment | Very frequent
    explanation: Orphanet reports cognitive impairment as very frequent.
- name: Leukodystrophy
  category: Neurologic
  description: >-
    Typical disease develops diffuse symmetric white-matter abnormalities. Early infant MRI can appear
    normal, and atypical disease may predominantly affect deep gray matter.
  phenotype_term:
    preferred_term: Leukodystrophy
    term:
      id: HP:0002415
      label: Leukodystrophy
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/
    reference_title: Canavan Disease - GeneReviews® - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Neuroimaging changes reveal generalized leukodystrophy characterized by diffuse, symmetric changes observed in subcortical white matter and cortical areas as well as the brain stem and cerebellum
    explanation: Clinical baseline supports this phenotype and its context.
- name: Ataxia
  category: Neurologic
  description: >-
    Ataxia and coordination or gait difficulties are particularly reported in atypical Canavan disease.
  phenotype_term:
    preferred_term: Ataxia
    term:
      id: HP:0001251
      label: Ataxia
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/
    reference_title: Canavan Disease - GeneReviews® - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Ataxia, coordination difficulties, and gait disturbances are frequently reported in atypical Canavan disease
    explanation: Clinical baseline supports this phenotype and its context.
biochemical:
- name: Elevated urinary N-acetylaspartic acid
  presence: INCREASED
  context: >-
    Elevated urinary NAA is the classic biochemical diagnostic marker of Canavan disease and reports systemic
    accumulation caused by ASPA deficiency.
  biomarker_term:
    preferred_term: N-acetyl-L-aspartic acid
    term:
      id: CHEBI:21547
      label: N-acetyl-L-aspartic acid
  readouts:
  - target: NAA accumulation in CNS and body fluids
    relationship: READOUT_OF
    direction: POSITIVE
    endpoint_context: DIAGNOSTIC
    interpretation: Higher urinary NAA reflects the NAA accumulation caused by impaired ASPA-mediated catabolism.
    evidence:
    - reference: PMID:28101991
      reference_title: Clinically Distinct Phenotypes of Canavan Disease Correlate with Residual Aspartoacylase Enzyme Activity.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Elevation of NAA levels in urine is the biochemical hallmark of CD.
      explanation: Patient variant study identifies urinary NAA elevation as the biochemical hallmark.
  evidence:
  - reference: PMID:20301412
    reference_title: Canavan Disease.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: elevated N-acetylaspartic acid (NAA) in urine
    explanation: GeneReviews supports elevated urinary NAA as biochemical diagnostic evidence.
  - reference: PMID:28101991
    reference_title: Clinically Distinct Phenotypes of Canavan Disease Correlate with Residual Aspartoacylase Enzyme Activity.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Elevation of NAA levels in urine is the biochemical hallmark of CD.
    explanation: Patient variant study supports urinary NAA as the biochemical hallmark.
- name: Elevated brain NAA by proton MR spectroscopy
  presence: INCREASED
  context: >-
    Proton MR spectroscopy can detect elevated NAA in the brain, providing a CNS biochemical readout of
    the same substrate accumulation.
  biomarker_term:
    preferred_term: N-acetyl-L-aspartic acid
    term:
      id: CHEBI:21547
      label: N-acetyl-L-aspartic acid
  readouts:
  - target: NAA accumulation in CNS and body fluids
    relationship: READOUT_OF
    direction: POSITIVE
    endpoint_context: DIAGNOSTIC
    interpretation: Elevated brain NAA by MRS reports CNS NAA accumulation downstream of ASPA deficiency.
    evidence:
    - reference: PMID:34011350
      reference_title: 'The natural history of Canavan disease: 23 new cases and comparison with patients from literature.'
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: CD is diagnosed by detection of elevated NAA in urine or blood or in brain by proton MR spectroscopy
      explanation: Natural history study supports MRS-detected brain NAA as a diagnostic readout.
  evidence:
  - reference: PMID:20301412
    reference_title: Canavan Disease.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: in the brain by proton magnetic resonance spectroscopy
    explanation: GeneReviews supports proton MRS detection of brain NAA.
  - reference: PMID:34011350
    reference_title: 'The natural history of Canavan disease: 23 new cases and comparison with patients from literature.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: CD is diagnosed by detection of elevated NAA in urine or blood or in brain by proton MR spectroscopy
    explanation: Natural history study supports elevated NAA in brain by proton MR spectroscopy.
diagnosis:
- name: Urinary N-acetylaspartic acid testing
  description: >-
    Urine NAA by gas chromatography-mass spectrometry establishes biochemical diagnosis in a compatible
    clinical presentation. Elevation is usually much greater in typical than atypical disease. Normal
    peripheral measurements do not exclude all cases; brain MRS can clarify a strongly suggestive presentation.
  results: Elevated urinary NAA supports Canavan disease.
  evidence:
  - reference: PMID:20301412
    reference_title: Canavan Disease.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: elevated N-acetylaspartic acid (NAA) in urine
    explanation: GeneReviews supports urinary NAA testing for biochemical diagnosis.
  - reference: PMID:28101991
    reference_title: Clinically Distinct Phenotypes of Canavan Disease Correlate with Residual Aspartoacylase Enzyme Activity.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Elevation of NAA levels in urine is the biochemical hallmark
    explanation: Patient variant study supports urinary NAA as a biochemical hallmark.
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/
    reference_title: Canavan Disease - GeneReviews® - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: even those with normal serum and urine N-acetylaspartic acid levels
    explanation: GeneReviews describes infants diagnosed by brain MRS despite normal peripheral NAA.
- name: Brain proton magnetic resonance spectroscopy for NAA
  description: >-
    Proton magnetic resonance spectroscopy can detect elevated brain NAA and supports diagnosis when combined
    with clinical and genetic findings.
  results: Elevated brain NAA supports Canavan disease.
  evidence:
  - reference: PMID:20301412
    reference_title: Canavan Disease.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: in the brain by proton magnetic resonance spectroscopy
    explanation: GeneReviews supports brain MRS for detecting NAA.
- name: ASPA molecular genetic testing
  description: >-
    Biallelic pathogenic or likely pathogenic ASPA variants confirm a molecular diagnosis in a compatible
    presentation. A VUS alone or paired with a pathogenic allele is not diagnostic. Sequence analysis
    may require deletion/duplication testing and targeted investigation of deep intronic structural variants,
    including the SVA_E insertion, when only one or no allele is found despite biochemical disease.
  diagnosis_term:
    preferred_term: molecular genetic testing
    term:
      id: NCIT:C19770
      label: Molecular Analysis
    qualifiers:
    - predicate:
        preferred_term: has participant
        term:
          id: RO:0000057
          label: has participant
      value:
        preferred_term: ASPA
        term:
          id: hgnc:756
          label: ASPA
  results: Biallelic pathogenic ASPA variants confirm Canavan disease.
  evidence:
  - reference: PMID:20301412
    reference_title: Canavan Disease.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: biallelic ASPA pathogenic variants identified by molecular genetic testing
    explanation: GeneReviews supports ASPA molecular testing as confirmatory.
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/
    reference_title: Canavan Disease - GeneReviews® - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Identification of ... biallelic ... ASPA ... variants of ... uncertain significance ... does not establish or rule out the diagnosis.
    explanation: GeneReviews cautions that uncertain ASPA variants neither establish nor exclude disease.
  - reference: PMID:40995055
    reference_title: 'Deep Intronic SVA_E Insertion Identified as the Most Common Pathogenic Variant Associated With Canavan Disease: A Diagnostic Blind Spot.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: We identified an ∼2,600-bp SVA_E retrotransposon intronic insertion in ASPA in all 8 individuals.
    explanation: >-
      Eight affected individuals from seven families with previously incomplete molecular diagnoses carried
      the insertion.
- name: Brain MRI with proton MR spectroscopy
  description: >-
    Typical disease shows diffuse symmetric leukodystrophy; imaging in early infancy may appear normal.
    Atypical disease may lack generalized white-matter changes and resemble a mitochondrial disorder with
    bilateral deep gray matter involvement. MRS NAA, urine biochemistry, and genetics help distinguish
    Canavan disease.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/
    reference_title: Canavan Disease - GeneReviews® - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Brain CT or MRI performed in early infancy may be interpreted as normal
    explanation: Timing affects sensitivity of structural imaging.
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/
    reference_title: Canavan Disease - GeneReviews® - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Atypical Canavan disease may be misdiagnosed as a mitochondrial disorder given the overlapping neuroimaging features of bilateral deep gray matter involvement
    explanation: Important differential-diagnosis pitfall.
treatments:
- name: Multidisciplinary supportive care
  description: >-
    Expert-based multidisciplinary supportive care addresses seizures, spasticity, nutrition and swallowing
    safety, mobility and contractures, communication and learning, respiratory health, and family support.
    GeneReviews reports no published disease-specific practice guideline; these recommendations reflect
    specialist experience. Nutrition, mobility and neurological review are typically repeated every three
    to six months, with respiratory and aspiration concerns assessed at each visit.
  treatment_term:
    preferred_term: supportive care
    term:
      id: NCIT:C15747
      label: Supportive Care
  target_phenotypes:
  - preferred_term: Seizure
    term:
      id: HP:0001250
      label: Seizure
  - preferred_term: Hypertonia
    term:
      id: HP:0001276
      label: Hypertonia
  - preferred_term: Feeding difficulties in infancy
    term:
      id: HP:0008872
      label: Feeding difficulties in infancy
  evidence:
  - reference: PMID:20301412
    reference_title: Canavan Disease.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Multidisciplinary care by specialists in neurology
    explanation: GeneReviews supports multidisciplinary supportive management.
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/
    reference_title: Canavan Disease - GeneReviews® - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: the following recommendations are based on the authors' personal experience managing individuals with this disorder.
    explanation: Distinguishes expert management from a formal practice guideline.
- name: ASPA gene replacement therapy
  description: >-
    ASPA gene replacement remains investigational. A 2023 expanded-access AAV9 case and a 2025 open-label
    rAAV-Olig001-ASPA trial support biological activity. The latter interim report included eight children
    with typical disease and found lower CSF NAA, increased myelin volume, and improved MSEL developmental
    scores against natural-history data. Gross-motor GMFM-88 slopes were not statistically significant.
    All participants had adverse events; seven had serious events, none attributed to the vector product,
    although procedure-related seizures and CSF leakage occurred. Small size, open-label design, historical
    comparisons, missing follow-up, and exclusion of atypical cases limit efficacy and durability conclusions.
    The AAV9 case corresponds to single-patient expanded access NCT05317780, listed by the registry as
    no longer available on 2026-10-04.
  therapeutic_modality: GENE_THERAPY
  treatment_term:
    preferred_term: gene therapy
    term:
      id: NCIT:C15238
      label: Gene Therapy
  target_mechanisms:
  - target: Aspartoacylase enzyme deficiency
    treatment_effect: RESTORES
    description: AAV-ASPA strategies provide a functional ASPA transgene to restore enzyme activity.
    evidence:
    - reference: PMID:37601414
      reference_title: Adeno-associated virus-mediated gene therapy in a patient with Canavan disease using dual routes of administration and immune modulation.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Gene replacement therapy is a rational therapeutic strategy
      explanation: Expanded-access case report supports ASPA gene replacement rationale.
  evidence:
  - reference: PMID:37601414
    reference_title: Adeno-associated virus-mediated gene therapy in a patient with Canavan disease using dual routes of administration and immune modulation.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: NAA level was reduced at 3 months
    explanation: Single-patient biochemical response; not controlled efficacy evidence.
  - reference: PMID:40957959
    reference_title: 'Oligodendrocyte-targeted adeno-associated virus gene therapy for Canavan disease in children: a phase 1/2 trial.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: A total of 8 participants received intracranial doses
    explanation: Small open-label interim cohort.
  - reference: PMID:40957959
    reference_title: 'Oligodendrocyte-targeted adeno-associated virus gene therapy for Canavan disease in children: a phase 1/2 trial.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Treatment reduced NAA concentrations in cerebrospinal fluid
    explanation: Biochemical target engagement.
  - reference: url:https://myrtellegtx.com/wp-content/uploads/2025/09/Leone_et_al-2025-Nature_Medicine.pdf
    reference_title: https://myrtellegtx.com/wp-content/uploads/2025/09/Leone_et_al-2025-Nature_Medicine.pdf
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Procedure-related SAEs included seizures and CSF leakage.
    explanation: >-
      Full text distinguishes procedure-related events from vector attribution. Source is the sponsor-hosted
      copy of PMID:40957959 (DOI:10.1038/s41591-025-03919-w); DOI fetching returned no quotable text,
      so the full-text PDF URL is retained. The publication title is "Oligodendrocyte-targeted adeno-associated
      virus gene therapy for Canavan disease in children: a phase 1/2 trial".
  - reference: url:https://myrtellegtx.com/wp-content/uploads/2025/09/Leone_et_al-2025-Nature_Medicine.pdf
    reference_title: https://myrtellegtx.com/wp-content/uploads/2025/09/Leone_et_al-2025-Nature_Medicine.pdf
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: GMFM-88 lying and rolling domain, ... 0.208 points per month (P = 0.2623).
    explanation: >-
      GMFM-88 lying and rolling slope was not statistically significant. Source is the sponsor-hosted
      copy of PMID:40957959 (DOI:10.1038/s41591-025-03919-w); DOI fetching returned no quotable text,
      so the full-text PDF URL is retained. The publication title is "Oligodendrocyte-targeted adeno-associated
      virus gene therapy for Canavan disease in children: a phase 1/2 trial".
  - reference: url:https://myrtellegtx.com/wp-content/uploads/2025/09/Leone_et_al-2025-Nature_Medicine.pdf
    reference_title: https://myrtellegtx.com/wp-content/uploads/2025/09/Leone_et_al-2025-Nature_Medicine.pdf
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: In the GMFM-88 sitting domain, the posttreatment population slope was estimated to be slightly lower at 0.157 points per month (P = 0.4114).
    explanation: >-
      GMFM-88 sitting slope was not statistically significant. Source is the sponsor-hosted copy of PMID:40957959
      (DOI:10.1038/s41591-025-03919-w); DOI fetching returned no quotable text, so the full-text PDF URL
      is retained. The publication title is "Oligodendrocyte-targeted adeno-associated virus gene therapy
      for Canavan disease in children: a phase 1/2 trial".
  - reference: PMID:40957959
    reference_title: 'Oligodendrocyte-targeted adeno-associated virus gene therapy for Canavan disease in children: a phase 1/2 trial.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: increased myelination (P = 0.0137) and improved MSEL developmental outcomes (P = 0.0171).
    explanation: >-
      The small open-label interim study reported improved myelination and developmental scores; these
      outcomes do not establish durable or controlled clinical efficacy.
- name: NAT8L/NAA-lowering strategy
  description: >-
    Partial inhibition of NAT8L-mediated NAA synthesis is a preclinical substrate-reduction approach.
    Genetic deletion and neonatal AAV-shRNA experiments rescued aspects of Aspa-deficient mouse pathology.
    Complete NAA ablation rescued myelin pathology but did not prolong survival in one double-mutant model,
    whereas partial reduction improved survival; these results caution against assuming maximal suppression
    is optimal. Human clinical benefit is unestablished.
  target_mechanisms:
  - target: NAA accumulation in CNS and body fluids
    treatment_effect: INHIBITS
    description: Reducing neuronal NAA synthesis lowers substrate accumulation upstream of spongiform leukodystrophy.
    evidence:
    - reference: PMID:29456021
      reference_title: Brain Nat8l Knockdown Suppresses Spongiform Leukodystrophy in an Aspartoacylase-Deficient Canavan Disease Mouse Model.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: suppresses development of spongiform leukodystrophy
      explanation: AAV-shRNA Nat8l knockdown lowered brain NAA and suppressed leukodystrophy in mice.
  evidence:
  - reference: PMID:28077719
    reference_title: Suppressing N-Acetyl-l-Aspartate Synthesis Prevents Loss of Neurons in a Murine Model of Canavan Leukodystrophy.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: prevents neuron loss and cerebral cortical atrophy
    explanation: Model study supports NAA synthesis suppression as a neuroprotective strategy.
  - reference: PMID:26511242
    reference_title: N-Acetylaspartate Synthase Deficiency Corrects the Myelin Phenotype in a Canavan Disease Mouse Model But Does Not Affect Survival Time.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: although pathology was fully reversed, the survival time of the mice was not prolonged.
    explanation: Complete Nat8l deletion did not confer a survival advantage in this model.
- name: Individualized antiseizure treatment
  description: >-
    An experienced neurologist selects antiseizure medication according to seizure type and response.
    No medication has demonstrated disease-specific superiority; some patients require multiple agents.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
  target_phenotypes:
  - preferred_term: Seizure
    term:
      id: HP:0001250
      label: Seizure
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/
    reference_title: Canavan Disease - GeneReviews® - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Many ASMs may be effective; none have been demonstrated specifically effective for this disorder.
    explanation: No preferred disease-specific drug is established.
- name: Feeding and swallowing support
  description: >-
    Feeding therapy and nutritional assessment address weight gain and aspiration risk. Gastrostomy may
    be needed for persistent feeding problems; swallowing assessment informs safe oral intake.
  treatment_term:
    preferred_term: Supportive Care
    term:
      id: NCIT:C15747
      label: Supportive Care
  target_phenotypes:
  - preferred_term: Feeding difficulties in infancy
    term:
      id: HP:0008872
      label: Feeding difficulties in infancy
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/
    reference_title: Canavan Disease - GeneReviews® - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Gastrostomy tube placement may be required for persistent feeding issues.
    explanation: Expert guidance for escalating nutrition support.
  - reference: PMID:34011350
    reference_title: 'The natural history of Canavan disease: 23 new cases and comparison with patients from literature.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: A gastric tube was placed in 10/22 patients.
    explanation: Natural-history cohort documents enteral support burden.
- name: Genetic counseling and family testing
  description: >-
    Offer counseling and molecular testing for relatives and reproductive partners, with prenatal or preimplantation
    testing available once familial pathogenic variants are identified. Carrier status does not cause
    Canavan disease; reproductive decisions depend on individual and family preferences.
  evidence:
  - reference: PMID:20301412
    reference_title: Canavan Disease.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: carrier testing for at-risk relatives and prenatal/preimplantation genetic testing are possible.
    explanation: GeneReviews genetic counseling baseline.
clinical_trials:
- name: NCT04998396
  phase: PHASE_I
  status: RECRUITING
  description: >-
    Phase 1/2 open-label study of BBP-812, an investigational systemic AAV9-based ASPA gene therapy, in
    pediatric participants with Canavan disease.
  target_phenotypes:
  - preferred_term: Global developmental delay
    term:
      id: HP:0001263
      label: Global developmental delay
  - preferred_term: Hypotonia
    term:
      id: HP:0001252
      label: Hypotonia
  evidence:
  - reference: clinicaltrials:NCT04998396
    reference_title: A Phase 1/2 Open-Label Study of the Safety and Clinical Activity of Gene Therapy for Canavan Disease Through Administration of an Adeno-Associated Virus (AAV) Serotype 9-Based Recombinant Vector Encoding the Human ASPA Gene
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: The main objective of this trial is to evaluate the safety, tolerability, and pharmacodynamic activity of BBP-812, an investigational AAV9-based gene therapy, in pediatric participants with Canavan disease.
    explanation: ClinicalTrials.gov records an active pediatric AAV9-ASPA gene-therapy trial for Canavan disease.
  notes: >-
    ClinicalTrials.gov lists this as a combined Phase 1/2 study; mapped to PHASE_I because the schema
    accepts a single phase value. Registry status checked through the ClinicalTrials.gov API on 2026-10-04;
    this is a registry status, not evidence of efficacy.
- name: NCT04833907
  phase: PHASE_I
  status: ENROLLING_BY_INVITATION
  description: >-
    Phase 1/2 open-label study of intracranial AVASPA/rAAV-Olig001-ASPA (MYR-101) in typical Canavan disease.
    The 2025 publication reports an interim eight-participant analysis; results cannot be generalized
    to atypical disease or interpreted as established curative efficacy.
  target_phenotypes:
  - preferred_term: Hypomyelination
    term:
      id: HP:0003429
      label: CNS hypomyelination
  - preferred_term: Seizure
    term:
      id: HP:0001250
      label: Seizure
  evidence:
  - reference: clinicaltrials:NCT04833907
    reference_title: Phase 1/2, Open Label, Sequential Cohort Study of a Single Intracranial Dose of AVASPA Gene Therapy for Treatment of Children With Typical Canavan Disease
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: The latest generation AAV viral vector (rAAV-Olig001-ASPA) will be administered to patients using neurosurgical procedure which involves direct administration of gene therapy to affected regions of the brain.
    explanation: >-
      ClinicalTrials.gov records an intracranial oligodendrocyte-targeted ASPA gene-therapy trial for
      typical Canavan disease.
  - reference: PMID:40957959
    reference_title: 'Oligodendrocyte-targeted adeno-associated virus gene therapy for Canavan disease in children: a phase 1/2 trial.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: This open-label phase 1/2 clinical study uses a novel recombinant vector, rAAV-Olig001, with selective tropism for oligodendrocytes
    explanation: Published interim report of the oligodendrocyte-targeted trial; its registry identifier is NCT04833907.
  notes: >-
    ClinicalTrials.gov lists this as a combined Phase 1/2 study; mapped to PHASE_I because the schema
    accepts a single phase value. Registry status checked through the ClinicalTrials.gov API on 2026-10-04;
    this is a registry status, not evidence of efficacy.
notes: >-
  NAA-associated injury and acetate-dependent metabolic hypotheses remain incompletely resolved. Clinical
  findings span typical and atypical disease, and source-specific Orphanet frequency bands sometimes conflict
  with longitudinal cohort evidence. Gene replacement and NAT8L suppression remain investigational; biochemical
  target engagement is not equivalent to established functional or survival benefit.
references:
- reference: ORPHA:141
  title: Canavan disease
  findings: []
- reference: PMID:20301412
  title: Canavan Disease.
  tags:
  - GeneReviews
  findings: []
- reference: PMID:34011350
  title: 'The natural history of Canavan disease: 23 new cases and comparison with patients from literature.'
  found_in:
  - Canavan_Disease-deep-research-falcon.md
  findings: []
- reference: PMID:8412017
  title: 'Canavan disease: biochemical and molecular studies.'
  findings: []
- reference: PMID:15784740
  title: Defective N-acetylaspartate catabolism reduces brain acetate levels and myelin lipid synthesis in Canavan's disease.
  findings: []
- reference: PMID:20637282
  title: Aspartoacylase deficiency affects early postnatal development of oligodendrocytes and myelination.
  findings: []
- reference: PMID:22617649
  title: Aspartoacylase supports oxidative energy metabolism during myelination.
  findings: []
- reference: PMID:28077719
  title: Suppressing N-Acetyl-l-Aspartate Synthesis Prevents Loss of Neurons in a Murine Model of Canavan Leukodystrophy.
  findings: []
- reference: PMID:28101991
  title: Clinically Distinct Phenotypes of Canavan Disease Correlate with Residual Aspartoacylase Enzyme Activity.
  findings: []
- reference: PMID:29456021
  title: Brain Nat8l Knockdown Suppresses Spongiform Leukodystrophy in an Aspartoacylase-Deficient Canavan Disease Mouse Model.
  findings: []
- reference: PMID:37601414
  title: Adeno-associated virus-mediated gene therapy in a patient with Canavan disease using dual routes of administration and immune modulation.
  found_in:
  - Canavan_Disease-deep-research-falcon.md
  findings: []
- reference: PMID:38582917
  title: Cellular and molecular mechanisms of aspartoacylase and its role in Canavan disease.
  found_in:
  - Canavan_Disease-deep-research-falcon.md
  findings: []
- reference: PMID:12162821
  title: 'Clinical protocol. Gene therapy of Canavan disease: AAV-2 vector for neurosurgical delivery of aspartoacylase gene (ASPA) to the human brain.'
  found_in:
  - Canavan_Disease-deep-research-falcon.md
  findings: []
- reference: PMID:37755460
  title: Update on leukodystrophies and developing trials.
  found_in:
  - Canavan_Disease-deep-research-falcon.md
  findings: []
- reference: PMID:35187608
  title: "Canavan's spongiform leukodystrophy (Aspartoacylase deficiency) with emphasis on sonographic features in infancy: description of a case report and review of the literature."
  found_in:
  - Canavan_Disease-deep-research-falcon.md
  findings: []
- reference: PMID:38538326
  title: Myelin lesion in the aspartoacylase (Aspa) knockout rat, an animal model for Canavan disease.
  found_in:
  - Canavan_Disease-deep-research-falcon.md
  findings: []
- reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/
  title: Canavan Disease - GeneReviews® - NCBI Bookshelf
  findings: []
  tags:
  - GeneReviews
- reference: CGGV:assertion_66306eff-659f-4508-a41b-1820e47e0e1d-2020-10-08T161701.633Z
  title: ASPA / Canavan disease (Definitive)
  findings: []
- reference: PMID:40995055
  title: 'Deep Intronic SVA_E Insertion Identified as the Most Common Pathogenic Variant Associated With Canavan Disease: A Diagnostic Blind Spot.'
  findings: []
- reference: PMID:25712859
  title: Ablating N-acetylaspartate prevents leukodystrophy in a Canavan disease model.
  findings: []
- reference: PMID:26511242
  title: N-Acetylaspartate Synthase Deficiency Corrects the Myelin Phenotype in a Canavan Disease Mouse Model But Does Not Affect Survival Time.
  findings: []
- reference: PMID:40957959
  title: 'Oligodendrocyte-targeted adeno-associated virus gene therapy for Canavan disease in children: a phase 1/2 trial.'
  findings: []
- reference: url:https://myrtellegtx.com/wp-content/uploads/2025/09/Leone_et_al-2025-Nature_Medicine.pdf
  title: https://myrtellegtx.com/wp-content/uploads/2025/09/Leone_et_al-2025-Nature_Medicine.pdf
  findings: []
- reference: clinicaltrials:NCT04998396
  title: A Phase 1/2 Open-Label Study of the Safety and Clinical Activity of Gene Therapy for Canavan Disease Through Administration of an Adeno-Associated Virus (AAV) Serotype 9-Based Recombinant Vector Encoding the Human ASPA Gene
  findings: []
- reference: clinicaltrials:NCT04833907
  title: Phase 1/2, Open Label, Sequential Cohort Study of a Single Intracranial Dose of AVASPA Gene Therapy for Treatment of Children With Typical Canavan Disease
  findings: []
variants:
- name: Deep intronic ASPA SVA_E insertion
  gene:
    preferred_term: ASPA
    term:
      id: hgnc:756
      label: ASPA
  variant_type: insertion
  genomic_contexts:
  - intron
  clinical_significance: PATHOGENIC
  description: >-
    Approximately 2.6-kb SVA_E insertion in intron 4 of 5 of ASPA transcript NM_000049.4. In the 2025
    series it was homozygous or in trans with another pathogenic allele. Long-read sequencing resolved
    the insertion; fibroblast RNA-seq supported a new splice acceptor, inclusion of SVA sequence, and
    transcript degradation. Population databases suggest a common pathogenic allele across ancestries,
    but this is not a disease-incidence estimate.
  evidence:
  - reference: PMID:40995055
    reference_title: 'Deep Intronic SVA_E Insertion Identified as the Most Common Pathogenic Variant Associated With Canavan Disease: A Diagnostic Blind Spot.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: We identified an ∼2,600-bp SVA_E retrotransposon intronic insertion in ASPA in all 8 individuals.
    explanation: >-
      Eight affected individuals from seven families with previously incomplete molecular diagnoses carried
      the insertion.
  - reference: PMID:40995055
    reference_title: 'Deep Intronic SVA_E Insertion Identified as the Most Common Pathogenic Variant Associated With Canavan Disease: A Diagnostic Blind Spot.'
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: the SVA_E insertion creates a novel splice acceptor site within intron 4 of ASPA
    explanation: Fibroblast RNA-seq from an affected individual and a parental carrier demonstrates altered splicing.
  - reference: PMID:40995055
    reference_title: 'Deep Intronic SVA_E Insertion Identified as the Most Common Pathogenic Variant Associated With Canavan Disease: A Diagnostic Blind Spot.'
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: The transcript incorporating the SVA_E was only observed in CHX-treated samples, indicating that the products from this allele are targeted for degradation.
    explanation: Cycloheximide-unmasked transcript supports degradation of the aberrant RNA in fibroblasts.
mechanistic_hypotheses:
- hypothesis_group_id: naa_injury
  hypothesis_label: NAA accumulation and cellular injury
  status: EMERGING
  description: >-
    Aspa/Nat8l genetic perturbations support a causal role for excess NAA in mouse leukodystrophy and
    neuronal loss. Osmotic disequilibrium is proposed, but substrate reduction does not identify a single
    downstream injury mechanism or prove every human causal step.
  evidence:
  - reference: PMID:25712859
    reference_title: Ablating N-acetylaspartate prevents leukodystrophy in a Canavan disease model.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: Aspanur7/nur7 mice were entirely protected against development of leukodystrophy when their capacity to synthesize NAA was ablated by constitutive deletion of Nat8l
    explanation: Genetic substrate-reduction experiment supports a causal role for excess NAA in the mouse model.
  - reference: PMID:34011350
    reference_title: 'The natural history of Canavan disease: 23 new cases and comparison with patients from literature.'
    supports: SUPPORT
    evidence_source: OTHER
    snippet: high levels of NAA, as found in CD, are thought to cause a toxic imbalance of brain water homeostasis
    explanation: The clinical report discusses a proposed, incompletely resolved connection to neurological disease.
    quote_role: BACKGROUND
- hypothesis_group_id: acetate_contribution
  hypothesis_label: Acetate-dependent metabolism contributes to myelin pathology
  status: EMERGING
  description: >-
    Reduced acetate and lipid synthesis are observed in ASPA deficiency. Their contribution to injury
    remains debated: Nat8l deletion preserves or rescues myelination without restoring NAA-derived acetate.
  evidence:
  - reference: PMID:15784740
    reference_title: Defective N-acetylaspartate catabolism reduces brain acetate levels and myelin lipid synthesis in Canavan's disease.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: myelin lipid synthesis is significantly compromised in CD
    explanation: Mouse and human white-matter lipid data support impaired myelin lipid synthesis.
  - reference: PMID:26511242
    reference_title: N-Acetylaspartate Synthase Deficiency Corrects the Myelin Phenotype in a Canavan Disease Mouse Model But Does Not Affect Survival Time.
    supports: REFUTE
    evidence_source: MODEL_ORGANISM
    snippet: acetate derived from NAA is not essential for myelin lipid synthesis
    explanation: Normal myelin composition in double-mutant mice argues against obligatory NAA-derived acetate supply.
- hypothesis_group_id: clinical_injury
  hypothesis_label: Brain injury contributes to clinical neurological impairment
  status: EMERGING
  description: >-
    White-matter and neuronal abnormalities plausibly contribute to the neurological phenotype, but cohort
    associations do not resolve the pathway for each manifestation. Edges in this group are explanatory
    hypotheses rather than experimentally established direct steps.
  evidence:
  - reference: PMID:34011350
    reference_title: 'The natural history of Canavan disease: 23 new cases and comparison with patients from literature.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: visual impairment is more commonly caused by white matter disease affecting the visual pathways.
    explanation: >-
      The natural-history authors link visual impairment to white-matter disease of visual pathways. This
      supports one clinical consequence; the broader group remains an explanatory hypothesis, not proof
      of each clinical edge.
experimental_models:
- name: HEK293 ASPA variant functional assay
  experimental_model_type: CELL_LINE
  description: >-
    Transient expression of ASPA-GFP variants in HEK293 cells measured catalytic activity by LC-MS/MS
    and protein expression by Western blot. This distinguishes activity from abundance, but is not a patient
    oligodendrocyte model.
  modeled_mechanisms:
  - target: Aspartoacylase enzyme deficiency
    relationship: MEASURES
    evidence:
    - reference: PMID:28101991
      reference_title: Clinically Distinct Phenotypes of Canavan Disease Correlate with Residual Aspartoacylase Enzyme Activity.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: The majority of the studied variants presented with enzyme activities lower than 1% of the WT.
      explanation: Direct heterologous-cell activity measurements.
  evidence:
  - reference: PMID:28101991
    reference_title: Clinically Distinct Phenotypes of Canavan Disease Correlate with Residual Aspartoacylase Enzyme Activity.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: All variants presented detectable expression of ASPA with no major differences concerning level of expression when compared to the WT
    explanation: Low activity need not imply low measured protein abundance in this assay.
- name: SVA_E carrier and patient fibroblast RNA sequencing
  experimental_model_type: PRIMARY_CELL_CULTURE
  description: >-
    RNA sequencing with and without cycloheximide in fibroblasts from a carrier parent and an affected
    individual linked the intronic insertion to aberrant RNA and transcript loss. This does not measure
    enzyme activity in brain or establish an all-tissue expression pattern.
  modeled_mechanisms:
  - target: Aberrant ASPA splicing
    relationship: MEASURES
    evidence:
    - reference: PMID:40995055
      reference_title: 'Deep Intronic SVA_E Insertion Identified as the Most Common Pathogenic Variant Associated With Canavan Disease: A Diagnostic Blind Spot.'
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: the SVA_E insertion creates a novel splice acceptor site within intron 4 of ASPA
      explanation: Fibroblast RNA-seq from an affected individual and a parental carrier demonstrates altered splicing.
  - target: Degradation of aberrant ASPA transcripts
    relationship: MEASURES
    evidence:
    - reference: PMID:40995055
      reference_title: 'Deep Intronic SVA_E Insertion Identified as the Most Common Pathogenic Variant Associated With Canavan Disease: A Diagnostic Blind Spot.'
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: The transcript incorporating the SVA_E was only observed in CHX-treated samples, indicating that the products from this allele are targeted for degradation.
      explanation: Cycloheximide-unmasked transcript supports degradation of the aberrant RNA in fibroblasts.
  evidence:
  - reference: PMID:40995055
    reference_title: 'Deep Intronic SVA_E Insertion Identified as the Most Common Pathogenic Variant Associated With Canavan Disease: A Diagnostic Blind Spot.'
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: the SVA_E insertion creates a novel splice acceptor site within intron 4 of ASPA
    explanation: Fibroblast RNA-seq from an affected individual and a parental carrier demonstrates altered splicing.
  - reference: PMID:40995055
    reference_title: 'Deep Intronic SVA_E Insertion Identified as the Most Common Pathogenic Variant Associated With Canavan Disease: A Diagnostic Blind Spot.'
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: The transcript incorporating the SVA_E was only observed in CHX-treated samples, indicating that the products from this allele are targeted for degradation.
    explanation: Cycloheximide-unmasked transcript supports degradation of the aberrant RNA in fibroblasts.
animal_models:
- name: Aspa nur7 mice with Nat8l gene-dose reduction
  species: Mus musculus
  genotype: Aspa nur7/nur7 with Nat8l +/+, +/-, or -/-
  description: >-
    Aspa-deficient mice with partial or complete Nat8l loss separate substrate accumulation from acetate
    deprivation. Complete loss rescued myelin pathology but not survival in the Maier study; partial loss
    improved survival. Outcomes depend on genotype, background, and endpoint and do not establish human
    treatment efficacy.
  modeled_mechanisms:
  - target: Spongiform white-matter vacuolation
    relationship: RESCUES
    evidence:
    - reference: PMID:26511242
      reference_title: N-Acetylaspartate Synthase Deficiency Corrects the Myelin Phenotype in a Canavan Disease Mouse Model But Does Not Affect Survival Time.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: full reversal of spongy myelin and axonal degeneration
      explanation: Complete Nat8l deletion rescued tissue pathology.
  - target: NAA accumulation in CNS and body fluids
    relationship: PERTURBS
    evidence:
    - reference: PMID:26511242
      reference_title: N-Acetylaspartate Synthase Deficiency Corrects the Myelin Phenotype in a Canavan Disease Mouse Model But Does Not Affect Survival Time.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: These mice have no detectable NAA.
      explanation: Double-mutant substrate ablation.
  evidence:
  - reference: PMID:26511242
    reference_title: N-Acetylaspartate Synthase Deficiency Corrects the Myelin Phenotype in a Canavan Disease Mouse Model But Does Not Affect Survival Time.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: although pathology was fully reversed, the survival time of the mice was not prolonged.
    explanation: Important endpoint dissociation.
  - reference: PMID:25712859
    reference_title: Ablating N-acetylaspartate prevents leukodystrophy in a Canavan disease model.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: permits normal CNS myelination and prevents leukodystrophy in a murine Canavan disease model.
    explanation: Independent genetic experiment supports the tissue rescue.
- name: TALEN-generated Aspa knockout rat
  species: Rattus norvegicus
  genotype: Aspa knockout
  description: >-
    The engineered rat showed CNS vacuolation, hypomyelination, swollen axons and astrocyte activation,
    particularly in brainstem and motor pathways. No overt neurological signs or quantitative neuron loss
    were found in the studied animals. CNS NAA was not measured in this study; histological similarity
    does not establish a full clinical phenocopy.
  modeled_mechanisms:
  - target: Spongiform white-matter vacuolation
    relationship: PARTIALLY_RECAPITULATES
    evidence:
    - reference: PMID:38538326
      reference_title: Myelin lesion in the aspartoacylase (Aspa) knockout rat, an animal model for Canavan disease.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: vacuolation with swollen axons, hypomyelination, and activated swollen astrocytes were observed mainly in the brainstem reticular formation
      explanation: Rat histopathology reproduces selected white-matter lesions.
  - target: Neuronal loss and cortical thinning
    relationship: FAILS_TO_RECAPITULATE
    limitations: Morphometry found no obvious neuron-number change in the sampled regions; this does not exclude subtle functional deficits.
    evidence:
    - reference: PMID:38538326
      reference_title: Myelin lesion in the aspartoacylase (Aspa) knockout rat, an animal model for Canavan disease.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: Morphometrical analysis revealed no obvious change in the number of neurons.
      explanation: Neuronal-number findings differ from the mouse neuronal-loss model.
  evidence:
  - reference: PMID:38538326
    reference_title: Myelin lesion in the aspartoacylase (Aspa) knockout rat, an animal model for Canavan disease.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: vacuolation with swollen axons, hypomyelination, and activated swollen astrocytes were observed mainly in the brainstem reticular formation
    explanation: Rat histopathology reproduces selected white-matter lesions.
  - reference: PMID:38538326
    reference_title: Myelin lesion in the aspartoacylase (Aspa) knockout rat, an animal model for Canavan disease.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: Morphometrical analysis revealed no obvious change in the number of neurons.
    explanation: Neuronal-number findings differ from the mouse neuronal-loss model.
  - reference: PMID:38538326
    reference_title: Myelin lesion in the aspartoacylase (Aspa) knockout rat, an animal model for Canavan disease.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: None of the Aspa-knockout rats showed any neurological signs.
    explanation: Major clinical limitation of this model.
has_subtypes:
- name: Typical infantile Canavan disease
  description: >-
    The more severe infantile presentation, accounting for approximately 85%-90% in GeneReviews. Early
    developmental impairment, hypotonia and macrocephaly precede progressive disability.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/
    reference_title: Canavan Disease - GeneReviews® - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: The phenotypic spectrum ranges from the more severe typical Canavan disease (85%-90% of individuals) to the less severe atypical Canavan disease (10%-15%).
    explanation: Clinical spectrum proportions are expert synthesis, not a population prevalence estimate.
- name: Atypical Canavan disease
  description: >-
    The less severe and variable presentation, approximately 10%-15% in GeneReviews, with later or milder
    manifestations, sometimes preserved walking and speech, and possible later regression.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/
    reference_title: Canavan Disease - GeneReviews® - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: The phenotypic spectrum ranges from the more severe typical Canavan disease (85%-90% of individuals) to the less severe atypical Canavan disease (10%-15%).
    explanation: Clinical spectrum proportions are expert synthesis, not a population prevalence estimate.
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK1234/
    reference_title: Canavan Disease - GeneReviews® - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: The life span is not well-described; however, individuals with atypical Canavan disease may survive to adulthood.
    explanation: Avoids extrapolating the severe infantile prognosis to all atypical individuals.

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References & Deep Research