Aromatic L-amino acid decarboxylase deficiency

Genetic MONDO:0012084 Pathograph 60 Show in embeddings browser Neurotransmitter Metabolic Disorder Inborn Error of Metabolism Movement Disorder

Aromatic L-amino acid decarboxylase deficiency is an ultra-rare autosomal recessive neurometabolic disorder caused by biallelic pathogenic variants in DDC. Loss of aromatic L-amino acid decarboxylase activity disrupts dopamine, serotonin, norepinephrine, and epinephrine synthesis, causing early-onset hypotonia, global developmental delay, oculogyric crises, dystonia, autonomic dysfunction, and characteristic CSF neurotransmitter metabolite abnormalities.

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1
Inheritance
6
Pathophys.
41
Phenotypes
3
Gaps
60
Pathograph
1
Genes
7
Medical Actions
2
Differentials
1
Datasets
3
Trials
2
Models
25
References
1
Deep Research
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Inheritance

1
Autosomal recessive inheritance HP:0000007
AADC deficiency is inherited in an autosomal recessive manner and is caused by biallelic DDC variants.
Autosomal recessive inheritance
Show evidence (3 references)
ORPHA:35708 SUPPORT Other
"Autosomal recessive"
Orphanet lists autosomal recessive inheritance.
PMID:28100251 SUPPORT Other
"Aromatic L-amino acid decarboxylase deficiency (AADCD) is a rare, autosomal recessive neurometabolic disorder"
Consensus guideline supports autosomal recessive inheritance.
PMID:37824694 SUPPORT Other
"AADC deficiency is inherited in an autosomal recessive manner."
GeneReviews directly states the inheritance mode in its genetic-counseling section.
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Discussions and Knowledge Gaps

3
Which model can reproduce the near-absent AADC activity and profound motor phenotype of severe human disease while remaining viable for longitudinal mechanistic and treatment studies?
HUMAN MODEL MISMATCH OPEN aadc_residual_activity_mouse_model_mismatch
Attached to
pathophysiology#DDC Enzymatic Deficiency pathophysiology#Motor Circuit Dysfunction
The available S250F knock-in mouse retains enough activity for substantial dopamine production, has only modest dopamine depletion, and lacks dopaminergic-cell pathology. It is informative for mild residual-activity disease but cannot establish mechanisms or treatment thresholds for the severe phenotype that dominates clinical cohorts.
Proposed experiments
Isogenic human monoaminergic-neuron DDC allelic series
aadc_human_neuron_allelic_series
Compare DDC null, severe splice, ligand-binding-site, S250F, and corrected isogenic human iPSC-derived dopaminergic and serotonergic neurons for AADC activity, monoamine flux, maturation, electrophysiology, and rescue by gene addition or variant-directed substrate therapy.
Show evidence (1 reference)
PMID:28973165 SUPPORT Model Organism
"We conclude that even minute levels of active AADC are sufficient to allow for substantial amounts of dopamine to be produced in model mice harboring the S250F mutation. Such mutants represent a novel, mild model of human AADC deficiency."
The model authors explicitly identify residual dopamine production and mild fidelity.
How durable and broadly generalizable are gene-therapy benefits, and how do putaminal and midbrain targets compare in long-term efficacy and safety?
KNOWLEDGE GAP OPEN aadc_gene_therapy_long_term_comparative_gap
Attached to
treatments#Eladocagene exuparvovec gene therapy clinical_trials#NCT04903288
Published follow-up supports benefit beyond five years in a small, uncontrolled treated cohort, but comparative target-site data, rare adverse events, and outcomes across severity, age, and genotype remain uncertain. Structured independent follow-up is therefore essential after regulatory authorization.
Show evidence (2 references)
PMID:37402126 SUPPORT Other
"Due to lack of data on long-term outcomes and the comparative efficacy of alternative stereotactic procedures and brain target sites, a structured follow-up plan and systematic documentation of outcomes in a suitable, industry-independent registry study are necessary."
The international expert statement directly defines the unresolved evidence needs.
PMID:42389831 SUPPORT Human Clinical
"Six patients received bilateral intraputaminal rAAV2-hAADC infusion."
The newest cohort adds independent follow-up but remains too small and single-target to close the comparative evidence gap.
What are unbiased age-specific phenotype frequencies, developmental trajectories, and survival estimates across genotypes and ancestry groups?
KNOWLEDGE GAP OPEN aadc_natural_history_ascertainment_gap
Attached to
progression#Persistent motor and developmental disability progression#Survival and prognosis
The largest clinical synthesis combines heterogeneous reports susceptible to reporting bias, while the international natural-history cohort is retrospective and age-skewed. Current percentages are useful descriptive estimates, not population-based risks or causal genotype-phenotype rules.
Show evidence (1 reference)
PMID:36268467 SUPPORT Human Clinical
"Although reporting bias cannot be excluded, there is still a need for comprehensive clinical descriptions of symptoms at onset and during follow-up."
The systematic review explicitly identifies reporting bias and incomplete longitudinal description.
⚙

Pathophysiology

6
DDC Enzymatic Deficiency
Biallelic pathogenic variants in DDC reduce aromatic L-amino acid decarboxylase activity, blocking decarboxylation of neurotransmitter precursors.
DDC hgnc:2719 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves DDC (hgnc:2719). hgnc:2719 is a gene from the HUGO Gene Nomenclature Committee.
aromatic-L-amino-acid decarboxylase activity GO:0004058 Gene Ontology (GO) Relation: this pathophysiological event involves this molecular function This pathophysiological event involves decreased aromatic-L-amino-acid decarboxylase activity (GO:0004058). GO:0004058 is a molecular function from the Gene Ontology. ↓ DECREASED
Experimental models
DDC-knockout SH-SY5Y cell model CELL LINE DDC knockout directly models loss of AADC protein and catalytic activity.
Downstream
Biogenic Monoamine Synthesis Failure AADC catalyzes monoamine neurotransmitter synthesis from aromatic amino acid precursors.
Show evidence (2 references)
ORPHA:35708 SUPPORT Other
"DDC | dopa decarboxylase | hgnc:2719 | Disease-causing germline mutation(s) in"
Orphanet lists DDC as the disease-causing gene.
PMID:1357595 SUPPORT Human Clinical
"Activity of aromatic L-amino acid decarboxylase was virtually absent in a liver biopsy sample and greatly reduced in plasma."
The original case report directly documents absent or greatly reduced AADC activity.
Biogenic Monoamine Synthesis Failure
Loss of AADC activity decreases synthesis of dopamine, serotonin, norepinephrine, and epinephrine, producing central and peripheral monoamine deficiency.
dopamine biosynthetic process GO:0042416 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased dopamine biosynthetic process (GO:0042416). GO:0042416 is a biological process from the Gene Ontology. ↓ DECREASED serotonin biosynthetic process GO:0042427 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased serotonin biosynthetic process (GO:0042427). GO:0042427 is a biological process from the Gene Ontology. ↓ DECREASED norepinephrine biosynthetic process GO:0042421 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased norepinephrine biosynthetic process (GO:0042421). GO:0042421 is a biological process from the Gene Ontology. ↓ DECREASED
Downstream
CSF Neurotransmitter Metabolite Signature Monoamine synthesis failure lowers downstream CSF metabolites and raises precursors.
Motor Circuit Dysfunction Dopamine deficiency disrupts basal-ganglia motor function.
Autonomic Dysfunction Peripheral and central monoamine deficiency contributes to autonomic symptoms.
Neurodevelopmental Impairment Early combined monoamine deficiency disrupts neurodevelopment.
Show evidence (3 references)
ORPHA:35708 SUPPORT Other
"impaired synthesis of dopamine, noradrenaline, adrenaline and serotonin."
Orphanet definition states the affected monoamine synthesis pathways.
PMID:28100251 SUPPORT Other
"leads to a severe combined deficiency of serotonin, dopamine, norepinephrine and epinephrine."
Consensus guideline supports combined monoamine deficiency.
PMID:19172410 SUPPORT Human Clinical
"resulting in generalized combined deficiency of serotonin, dopamine and catecholamines."
Clinical cohort describes generalized biogenic amine deficiency.
CSF Neurotransmitter Metabolite Signature
AADC deficiency produces a diagnostic CSF neurotransmitter pattern with low homovanillic acid and 5-hydroxyindoleacetic acid and elevated 3-ortho-methyldopa.
Downstream
Decreased CSF homovanillic acid concentration Reduced dopamine metabolism lowers CSF homovanillic acid.
Decreased CSF 5-hydroxyindolacetic acid concentration Reduced serotonin metabolism lowers CSF 5-hydroxyindoleacetic acid.
Increased circulating prolactin concentration Dopamine deficiency can disinhibit prolactin secretion.
Show evidence (2 references)
PMID:19172410 SUPPORT Human Clinical
"In CSF all patients revealed the pattern typical of AADC with decreased concentrations of homovanillic and 5-hydroxyindoleacetic acid and elevated concentration of 3-ortho-methyldopa."
Cohort data support the characteristic CSF metabolite pattern.
PMID:1357595 SUPPORT Human Clinical
"Concentrations of L-dopa, 3-methoxytyrosine, and 5-hydroxytryptophan were elevated in CSF, plasma, and urine."
Original report supports precursor accumulation caused by AADC deficiency.
Motor Circuit Dysfunction
Deficient dopamine synthesis in basal-ganglia motor circuits produces hypotonia, hypokinesia, dystonia, oculogyric crises, dyskinesia, and delayed motor development.
Downstream
Hypotonia
Oculogyric crisis
Dystonia
Hypokinesia
Dyskinesia
Athetosis
Myoclonus Myoclonus is a recognized but incompletely quantified hyperkinetic manifestation.
Poor head control
Motor delay
Ptosis AADC deficiency commonly includes ocular motor manifestations including ptosis.
Reduced tendon reflexes Motor-system dysfunction can include reduced tendon reflexes.
Limb hypertonia Basal-ganglia and motor-circuit dysfunction can manifest as limb hypertonia.
Babinski sign Central motor dysfunction can manifest as Babinski sign.
Tremor Movement-disorder circuitry can rarely manifest as tremor.
Joint contracture Chronic neuromotor impairment can contribute to joint contractures.
Show evidence (2 references)
PMID:28100251 SUPPORT Other
"key clinical symptoms are hypotonia, movement disorders (oculogyric crisis, dystonia, and hypokinesia), developmental delay, and autonomic symptoms."
Consensus guideline links the biochemical disorder to core motor symptoms.
PMID:30689738 SUPPORT Human Clinical
"a decrease in catecholamines and serotonin levels in the brain leads to developmental delay and movement disorders."
Gene-therapy study background links monoamine deficiency to motor and developmental manifestations.
Autonomic Dysfunction
Combined catecholamine and serotonin deficiency contributes to autonomic and extraneurological symptoms including hyperhidrosis, nasal congestion, hypersalivation/drooling, sleep disturbance, hypotension, and miosis.
Downstream
Hyperhidrosis
Nasal congestion
Drooling
Sleep abnormality
Hypotension
Miosis
Temperature instability
Hypoglycemia
Constipation Dysautonomia and neuromotor dysfunction can manifest as constipation.
Diarrhea Gastrointestinal autonomic dysfunction can rarely manifest as diarrhea.
Gastroesophageal reflux Autonomic and neuromotor gastrointestinal dysfunction can contribute to reflux.
Show evidence (2 references)
PMID:19172410 SUPPORT Human Clinical
"All patients presented distinct extraneurological symptoms, such as hypersalivation, hyperhidrosis, nasal congestion, sleep disturbances and hypoglycaemia."
Clinical cohort supports autonomic and extraneurologic manifestations.
PMID:32409695 SUPPORT Human Clinical
"autonomic symptoms such as excessive sweating, nasal congestion and profuse nasal, and oropharyngeal secretions, were common in our patients."
Mainland China cohort supports frequent autonomic symptoms.
Neurodevelopmental Impairment
Early combined monoamine deficiency impairs developmental acquisition and is associated with global developmental delay, intellectual disability, seizures, feeding difficulties, and failure to thrive.
Downstream
Global developmental delay
Intellectual disability
Feeding difficulties
Failure to thrive
Dysarthria
Atypical behavior Early serotonin and catecholamine deficiency is associated with behavioral disorders.
Autistic behavior Neurodevelopmental monoamine deficiency can include autistic behavior.
Irritability Non-motor neurobehavioral manifestations include irritability.
EEG abnormality Neurotransmitter imbalance and seizures can be accompanied by EEG abnormalities.
Dysphagia Neurodevelopmental and motor impairment can contribute to swallowing difficulty.
Short stature Chronic feeding difficulty and neurometabolic disease can contribute to impaired growth.
Show evidence (2 references)
PMID:36268467 SUPPORT Human Clinical
"Hypotonia and developmental delay are cardinal signs, reported as present in 73.9% and 72% of cases, respectively."
Systematic review supports common developmental delay and hypotonia.
PMID:30689738 SUPPORT Human Clinical
"In patients with aromatic l-amino acid decarboxylase (AADC) deficiency, a decrease in catecholamines and serotonin levels in the brain leads to developmental delay and movement disorders."
Gene-therapy study background links brain monoamine deficiency to developmental delay.
⬡

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for Aromatic L-amino acid decarboxylase deficiency Interactive directed graph showing how pathophysiology mechanisms, phenotypes, genetic factors and variants, experimental models, environmental triggers, and treatments relate through causal and linked edges.
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Phenotypes

41
Cardiovascular 1
Hypotension OCCASIONAL HP:0002615 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hypotension (HP:0002615). HP:0002615 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:35708 SUPPORT Other
"HP:0002615 | Hypotension | Occasional (29-5%)"
Orphanet provides the phenotype association and frequency band.
Digestive 5
Diarrhea VERY_RARE HP:0002014 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Diarrhea (HP:0002014). HP:0002014 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:35708 SUPPORT Other
"HP:0002014 | Diarrhea | Very rare (<4-1%)"
Orphanet provides the phenotype association and frequency band.
Dysphagia OCCASIONAL HP:0002015 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Dysphagia (HP:0002015). HP:0002015 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:35708 SUPPORT Other
"HP:0002015 | Dysphagia | Occasional (29-5%)"
Orphanet provides the phenotype association and frequency band.
Constipation OCCASIONAL HP:0002019 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Constipation (HP:0002019). HP:0002019 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:35708 SUPPORT Other
"HP:0002019 | Constipation | Occasional (29-5%)"
Orphanet provides the phenotype association and frequency band.
Gastroesophageal reflux FREQUENT HP:0002020 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Gastroesophageal reflux (HP:0002020). HP:0002020 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:35708 SUPPORT Other
"HP:0002020 | Gastroesophageal reflux | Frequent (79-30%)"
Orphanet provides the phenotype association and frequency band.
Feeding difficulties FREQUENT HP:0011968 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Feeding difficulties (HP:0011968). HP:0011968 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:35708 SUPPORT Other
"HP:0011968 | Feeding difficulties | Frequent (79-30%)"
Orphanet provides the phenotype association and frequency band.
Eye 1
Ptosis OCCASIONAL HP:0000508 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Ptosis (HP:0000508). HP:0000508 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
ORPHA:35708 SUPPORT Other
"HP:0000508 | Ptosis | Occasional (29-5%)"
Orphanet provides the phenotype association and frequency band.
PMID:36268467 SUPPORT Human Clinical
"Oculogyric crises were seen in 67% of patients while hypokinesia in 42% and ptosis in 26%."
Systematic review quantifies ptosis in the occasional range.
Head and Neck 2
Nasal congestion OCCASIONAL HP:0001742 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Nasal congestion (HP:0001742). HP:0001742 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
ORPHA:35708 SUPPORT Other
"HP:0001742 | Nasal congestion | Occasional (29-5%)"
Orphanet provides the phenotype association and frequency band.
PMID:32409695 SUPPORT Human Clinical
"autonomic symptoms such as excessive sweating, nasal congestion and profuse nasal, and oropharyngeal secretions, were common in our patients."
Mainland China cohort supports nasal congestion as an autonomic manifestation.
Drooling OCCASIONAL HP:0002307 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Drooling (HP:0002307). HP:0002307 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:35708 SUPPORT Other
"HP:0002307 | Drooling | Occasional (29-5%)"
Orphanet provides the phenotype association and frequency band.
Integument 1
Hyperhidrosis FREQUENT HP:0000975 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hyperhidrosis (HP:0000975). HP:0000975 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
ORPHA:35708 SUPPORT Other
"HP:0000975 | Hyperhidrosis | Frequent (79-30%)"
Orphanet provides the phenotype association and frequency band.
PMID:19172410 SUPPORT Human Clinical
"All patients presented distinct extraneurological symptoms, such as hypersalivation, hyperhidrosis, nasal congestion, sleep disturbances and hypoglycaemia."
Clinical cohort supports hyperhidrosis as an AADC deficiency manifestation.
Metabolism 1
Hypoglycemia OCCASIONAL HP:0001943 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hypoglycemia (HP:0001943). HP:0001943 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
ORPHA:35708 SUPPORT Other
"HP:0001943 | Hypoglycemia | Occasional (29-5%)"
Orphanet provides the phenotype association and frequency band.
PMID:19172410 SUPPORT Human Clinical
"All patients presented distinct extraneurological symptoms, such as hypersalivation, hyperhidrosis, nasal congestion, sleep disturbances and hypoglycaemia."
Clinical cohort documents hypoglycemia among extraneurological symptoms.
Musculoskeletal 2
Hypotonia FREQUENT HP:0001252 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hypotonia (HP:0001252). HP:0001252 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
ORPHA:35708 SUPPORT Other
"HP:0001252 | Hypotonia | Frequent (79-30%)"
Orphanet provides the phenotype association and frequency band.
PMID:36268467 SUPPORT Human Clinical
"Hypotonia and developmental delay are cardinal signs, reported as present in 73.9% and 72% of cases, respectively."
Systematic review quantifies hypotonia in the frequent range.
Joint contracture VERY_RARE HP:0034392 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Joint contracture (HP:0034392). HP:0034392 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:35708 SUPPORT Other
"HP:0034392 | Joint contracture | Very rare (<4-1%)"
Orphanet provides the phenotype association and frequency band.
Nervous System 14
Atypical behavior FREQUENT HP:0000708 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Atypical behavior (HP:0000708). HP:0000708 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
ORPHA:35708 SUPPORT Other
"HP:0000708 | Atypical behavior | Frequent (79-30%)"
Orphanet provides the phenotype association and frequency band.
PMID:36268467 SUPPORT Human Clinical
"With 37% and 30% of patients reported being affected by sleep and behavioural disorders"
Systematic review supports frequent behavioral manifestations.
Autistic behavior OCCASIONAL HP:0000729 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Autistic behavior (HP:0000729). HP:0000729 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:35708 SUPPORT Other
"HP:0000729 | Autistic behavior | Occasional (29-5%)"
Orphanet provides the phenotype association and frequency band.
Irritability FREQUENT HP:0000737 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Irritability (HP:0000737). HP:0000737 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:35708 SUPPORT Other
"HP:0000737 | Irritability | Frequent (79-30%)"
Orphanet provides the phenotype association and frequency band.
Intellectual disability FREQUENT HP:0001249 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Intellectual disability (HP:0001249). HP:0001249 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:35708 SUPPORT Other
"HP:0001249 | Intellectual disability | Frequent (79-30%)"
Orphanet provides the phenotype association and frequency band.
Seizure VERY_RARE HP:0001250 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Seizure (HP:0001250). HP:0001250 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:37824694 SUPPORT Other
"Seizures are an uncommon finding, occurring in fewer than 5% of affected individuals."
GeneReviews provides the current frequency estimate and corrects the conflicting Orphanet band.
PMID:19172410 SUPPORT Human Clinical
"Three patients had single seizures."
Clinical cohort documents seizures in AADC deficiency.
Myoclonus HP:0001336 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Myoclonus (HP:0001336). HP:0001336 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:28100251 SUPPORT Other
"Hypokinesia and/ or bradykinesia ± ++ ++ ++ ++ Myoclonus ± ± ± ± ± Tremor ± ± ± ± ±"
The consensus table records myoclonus as possible (±) in its neonatal, infancy, childhood, adolescence, and adulthood columns without providing a defensible population frequency.
Dysarthria OCCASIONAL HP:0001260 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Dysarthria (HP:0001260). HP:0001260 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:35708 SUPPORT Other
"HP:0001260 | Dysarthria | Occasional (29-5%)"
Orphanet provides the phenotype association and frequency band.
Global developmental delay VERY_FREQUENT HP:0001263 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Global developmental delay (HP:0001263). HP:0001263 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
ORPHA:35708 SUPPORT Other
"HP:0001263 | Global developmental delay | Very frequent (99-80%)"
Orphanet provides the phenotype association and frequency band.
PMID:36268467 SUPPORT Human Clinical
"Hypotonia and developmental delay are cardinal signs, reported as present in 73.9% and 72% of cases, respectively."
Systematic review supports developmental delay as a cardinal sign.
Motor delay FREQUENT HP:0001270 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Motor delay (HP:0001270). HP:0001270 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:35708 SUPPORT Other
"HP:0001270 | Motor delay | Frequent (79-30%)"
Orphanet provides the phenotype association and frequency band.
Dystonia FREQUENT HP:0001332 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Dystonia (HP:0001332). HP:0001332 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
ORPHA:35708 SUPPORT Other
"HP:0001332 | Dystonia | Frequent (79-30%)"
Orphanet provides the phenotype association and frequency band.
PMID:28100251 SUPPORT Other
"movement disorders (oculogyric crisis, dystonia, and hypokinesia)"
Consensus guideline lists dystonia as a key movement disorder.
Tremor VERY_RARE HP:0001337 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Tremor (HP:0001337). HP:0001337 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:35708 SUPPORT Other
"HP:0001337 | Tremor | Very rare (<4-1%)"
Orphanet provides the phenotype association and frequency band.
EEG abnormality OCCASIONAL HP:0002353 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is EEG abnormality (HP:0002353). HP:0002353 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:35708 SUPPORT Other
"HP:0002353 | EEG abnormality | Occasional (29-5%)"
Orphanet provides the phenotype association and frequency band.
Sleep abnormality FREQUENT Sleep disturbance HP:0002360 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Sleep abnormality, annotated with Sleep disturbance (HP:0002360). HP:0002360 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
ORPHA:35708 SUPPORT Other
"HP:0002360 | Sleep abnormality | Frequent (79-30%)"
Orphanet provides the phenotype association and frequency band.
PMID:36268467 SUPPORT Human Clinical
"With 37% and 30% of patients reported being affected by sleep and behavioural disorders"
Systematic review supports sleep abnormality in the frequent range.
Dyskinesia OCCASIONAL HP:0100660 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Dyskinesia (HP:0100660). HP:0100660 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:35708 SUPPORT Other
"HP:0100660 | Dyskinesia | Occasional (29-5%)"
Orphanet provides the phenotype association and frequency band.
Growth 2
Failure to thrive FREQUENT HP:0001508 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Failure to thrive (HP:0001508). HP:0001508 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:35708 SUPPORT Other
"HP:0001508 | Failure to thrive | Frequent (79-30%)"
Orphanet provides the phenotype association and frequency band.
Short stature OCCASIONAL HP:0004322 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Short stature (HP:0004322). HP:0004322 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:35708 SUPPORT Other
"HP:0004322 | Short stature | Occasional (29-5%)"
Orphanet provides the phenotype association and frequency band.
Other 12
Miosis OCCASIONAL HP:0000616 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Miosis (HP:0000616). HP:0000616 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:35708 SUPPORT Other
"HP:0000616 | Miosis | Occasional (29-5%)"
Orphanet provides the phenotype association and frequency band.
Increased circulating prolactin concentration OCCASIONAL HP:0000870 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Increased circulating prolactin concentration (HP:0000870). HP:0000870 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:35708 SUPPORT Other
"HP:0000870 | Increased circulating prolactin concentration | Occasional (29-5%)"
Orphanet provides the phenotype association and frequency band.
Temperature instability HP:0005968 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Temperature instability (HP:0005968). HP:0005968 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:37824694 SUPPORT Other
"autonomic dysfunction (excessive sweating, temperature instability, ptosis, nasal congestion, hypoglycemic episodes)."
GeneReviews explicitly includes temperature instability in the autonomic phenotype.
Athetosis HP:0002305 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Athetosis (HP:0002305). HP:0002305 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:12891654 SUPPORT Human Clinical
"The phenomenology of the movement disorder is identical to that previously reported, and includes intermittent oculogyric crises and limb dystonia, generalized athetosis, and impaired voluntary movement in all patients."
The 11-patient series directly documents generalized athetosis without asserting population-wide frequency.
Reduced tendon reflexes OCCASIONAL HP:0001315 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Reduced tendon reflexes (HP:0001315). HP:0001315 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:35708 SUPPORT Other
"HP:0001315 | Reduced tendon reflexes | Occasional (29-5%)"
Orphanet provides the phenotype association and frequency band.
Hypokinesia OCCASIONAL HP:0002375 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hypokinesia (HP:0002375). HP:0002375 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:35708 SUPPORT Other
"HP:0002375 | Hypokinesia | Occasional (29-5%)"
Orphanet provides the phenotype association and frequency band.
Poor head control FREQUENT HP:0002421 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Poor head control (HP:0002421). HP:0002421 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:35708 SUPPORT Other
"HP:0002421 | Poor head control | Frequent (79-30%)"
Orphanet provides the phenotype association and frequency band.
Limb hypertonia OCCASIONAL HP:0002509 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Limb hypertonia (HP:0002509). HP:0002509 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:35708 SUPPORT Other
"HP:0002509 | Limb hypertonia | Occasional (29-5%)"
Orphanet provides the phenotype association and frequency band.
Babinski sign OCCASIONAL HP:0003487 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Babinski sign (HP:0003487). HP:0003487 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:35708 SUPPORT Other
"HP:0003487 | Babinski sign | Occasional (29-5%)"
Orphanet provides the phenotype association and frequency band.
Decreased CSF homovanillic acid concentration VERY_FREQUENT HP:0003785 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Decreased CSF homovanillic acid concentration (HP:0003785). HP:0003785 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
ORPHA:35708 SUPPORT Other
"HP:0003785 | Decreased CSF homovanillic acid concentration | Very frequent (99-80%)"
Orphanet provides the phenotype association and frequency band.
PMID:19172410 SUPPORT Human Clinical
"In CSF all patients revealed the pattern typical of AADC with decreased concentrations of homovanillic and 5-hydroxyindoleacetic acid and elevated concentration of 3-ortho-methyldopa."
Clinical cohort supports decreased CSF homovanillic acid.
Oculogyric crisis FREQUENT HP:0010553 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Oculogyric crisis (HP:0010553). HP:0010553 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
ORPHA:35708 SUPPORT Other
"HP:0010553 | Oculogyric crisis | Frequent (79-30%)"
Orphanet provides the phenotype association and frequency band.
PMID:36268467 SUPPORT Human Clinical
"Oculogyric crises were seen in 67% of patients while hypokinesia in 42% and ptosis in 26%."
Systematic review quantifies oculogyric crises in the frequent range.
Decreased CSF 5-hydroxyindolacetic acid concentration VERY_FREQUENT HP:0025455 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Decreased CSF 5-hydroxyindolacetic acid concentration (HP:0025455). HP:0025455 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
ORPHA:35708 SUPPORT Other
"HP:0025455 | Decreased CSF 5-hydroxyindolacetic acid concentration | Very frequent (99-80%)"
Orphanet provides the phenotype association and frequency band.
PMID:19172410 SUPPORT Human Clinical
"In CSF all patients revealed the pattern typical of AADC with decreased concentrations of homovanillic and 5-hydroxyindoleacetic acid and elevated concentration of 3-ortho-methyldopa."
Clinical cohort supports decreased CSF 5-hydroxyindoleacetic acid.
🧬

Genetic Associations

1
DDC (Biallelic pathogenic variants)
Gene: DDC hgnc:2719 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is DDC (hgnc:2719). hgnc:2719 is a gene from the HUGO Gene Nomenclature Committee.
Show evidence (6 references)
ORPHA:35708 SUPPORT Other
"DDC | dopa decarboxylase | hgnc:2719 | Disease-causing germline mutation(s) in"
Orphanet lists DDC as the disease-causing gene.
PMID:36268467 SUPPORT Human Clinical
"caused by pathogenic homozygous or compound heterozygous variants in the dopa decarboxylase (DDC) gene."
Systematic review supports biallelic pathogenic DDC variants.
PMID:32409695 SUPPORT Human Clinical
"Twenty-three patients with clinical features of AADCD and DDC gene variants were recruited."
Mainland China cohort supports disease association with DDC variants.
+ 3 more references
💊

Medical Actions

7
Eladocagene exuparvovec gene therapy
Action: gene therapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is gene therapy (NCIT:C15238). NCIT:C15238 is a clinical intervention from the NCI Thesaurus. Ontology label: Gene Therapy NCIT:C15238
Agent: eladocagene exuparvovec NCIT:C171796 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses eladocagene exuparvovec (NCIT:C171796). NCIT:C171796 is a therapeutic agent from the NCI Thesaurus.
Eladocagene exuparvovec delivers DDC via an adeno-associated viral vector to the putamen, aiming to restore dopamine synthesis and improve motor, developmental, and oculogyric manifestations. The US indication includes adult and pediatric patients of any severity who have sufficient skull maturity for surgery; the European indication is limited to patients aged at least 18 months with severe, clinically and molecularly confirmed disease.
Mechanism Target:
RESTORES DDC Enzymatic Deficiency — Gene addition supplies the human DDC coding sequence to restore AADC activity in the putamen.
Show evidence (1 reference)
PMID:30689738 SUPPORT Human Clinical
"The patients received a total of 2 × 1011 vector genomes of adeno-associated virus vector harbouring DDC via bilateral intraputaminal infusions."
Open-label clinical study describes AAV vector delivery of DDC to the putamen.
RESTORES Biogenic Monoamine Synthesis Failure — Restored putaminal DDC expression increases dopamine synthesis.
Show evidence (1 reference)
PMID:30689738 SUPPORT Human Clinical
"The restoration of dopamine synthesis in the putamen via gene transfer provides transformative medical benefit across all patient ages"
Clinical study supports restoration of putaminal dopamine synthesis.
Show evidence (9 references)
PMID:30689738 SUPPORT Human Clinical
"At up to 2 years after gene therapy, the motor function was remarkably improved in all patients."
Open-label phase 1/2 study supports motor improvement after AAV-DDC gene therapy.
PMID:30689738 SUPPORT Human Clinical
"Dystonia disappeared and oculogyric crisis was markedly decreased in all patients."
Gene therapy improved key movement disorder manifestations.
DOI:10.1001/jama.2024.28666 SUPPORT Other
"US Food and Drug Administration approval of Kebilidi, eladocagene exuparvovec, for the treatment of aromatic L-amino acid decarboxylase deficiency in adult and pediatric patients."
JAMA Insights reports FDA approval for AADC deficiency.
+ 6 more references
Pyridoxine pharmacotherapy
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: pyridoxine CHEBI:16709 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses pyridoxine (CHEBI:16709). CHEBI:16709 is a therapeutic agent from Chemical Entities of Biological Interest.
Pyridoxine or pyridoxal phosphate is used as cofactor-directed symptomatic therapy, often in combination with dopamine agonists and MAO inhibitors; clinical responses are variable.
Mechanism Target:
MODULATES DDC Enzymatic Deficiency — Pyridoxine provides vitamin B6 cofactor support for residual AADC activity.
Show evidence (1 reference)
PMID:28100251 SUPPORT Other
"treatment with one of several available forms of vitamin B6 might increase residual activity of the AADC enzyme."
The consensus states the cofactor rationale while retaining uncertainty about clinical effect.
Show evidence (3 references)
PMID:19172410 SUPPORT Human Clinical
"Drug regimes consisted of vitamin B6, dopamine agonists, MAO inhibitors and anticholinergics in different combinations."
Clinical cohort lists vitamin B6 among AADC deficiency drug regimens.
PMID:32409695 SUPPORT Human Clinical
"Eighteen patients (78.3%) got various degree of improvement after using pyridoxine monotherapy or different combination of pyridoxine, dopamine agonists, and monoamine oxidase (MAO) inhibitors."
Mainland China cohort supports partial improvement with pyridoxine-based regimens.
PMID:32369189 SUPPORT Human Clinical
"Pyridoxine was the most commonly tried medication (78%, 46/59), but only 3/46 respondents (7%) reported noticeable improvement (“increased energy” in all cases)."
The larger international cohort shows limited reported benefit from pyridoxine monotherapy, tempering combination-regimen evidence.
Dopamine agonist and MAO inhibitor pharmacotherapy
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: dopamine agonist NCIT:C66884 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses dopamine agonist (NCIT:C66884). NCIT:C66884 is a therapeutic agent from the NCI Thesaurus. monoamine oxidase inhibitor NCIT:C667 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses monoamine oxidase inhibitor (NCIT:C667). NCIT:C667 is a therapeutic agent from the NCI Thesaurus.
Dopamine agonists and monoamine oxidase inhibitors are used as symptomatic neurotransmitter-directed treatment classes, sometimes with vitamin B6 and anticholinergics.
Mechanism Target:
MODULATES Biogenic Monoamine Synthesis Failure — These drugs augment dopaminergic signaling or reduce monoamine breakdown despite impaired synthesis.
Show evidence (1 reference)
PMID:28100251 SUPPORT Other
"MAO inhibitors prevent breakdown of dopamine and serotonin"
The consensus directly states the MAO-inhibitor mechanism.
Show evidence (4 references)
PMID:1357595 SUPPORT Human Clinical
"Treatment with either bromocriptine or tranylcypromine stopped the abnormal eye movements; tranylcypromine treatment also improved muscle tone"
Original cases improved with dopamine agonist and MAO inhibitor therapy.
PMID:19172410 SUPPORT Human Clinical
"Drug regimes consisted of vitamin B6, dopamine agonists, MAO inhibitors and anticholinergics in different combinations."
Clinical cohort supports dopamine agonist and MAO inhibitor use.
PMID:32409695 SUPPORT Human Clinical
"Eighteen patients (78.3%) got various degree of improvement after using pyridoxine monotherapy or different combination of pyridoxine, dopamine agonists, and monoamine oxidase (MAO) inhibitors."
Mainland China cohort supports partial improvement with combination regimens.
+ 1 more reference
Variant-directed levodopa pharmacotherapy
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: levodopa CHEBI:15765 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses levodopa, annotated with L-dopa (CHEBI:15765). CHEBI:15765 is a therapeutic agent from Chemical Entities of Biological Interest.
Levodopa without carbidopa is first-line only for rare DDC variants in the ligand-binding site; outside that subgroup, a trial is conditional on failure of other options. This is not routine treatment for all AADC deficiency.
Mechanism Target:
MODULATES DDC Enzymatic Deficiency — Binding-site variants may retain enzyme that responds to increased substrate availability.
Show evidence (1 reference)
PMID:28100251 SUPPORT Other
"L-Dopa is first line treatment only for patients with L-Dopa binding-site variants"
The variant-restricted response supports modulation rather than general restoration of the enzyme defect.
Show evidence (1 reference)
PMID:28100251 SUPPORT Other
"L-Dopa is first line treatment only for patients with L-Dopa binding-site variants"
The recommendation defines the variant-restricted indication and formulation.
Folinic acid supplementation
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: folinic acid CHEBI:15640 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses folinic acid, annotated with 5-formyltetrahydrofolic acid (CHEBI:15640). CHEBI:15640 is a therapeutic agent from Chemical Entities of Biological Interest.
Folinic acid is clearly indicated when CSF 5-methyltetrahydrofolate is low; broader supplementation remains conditional because published experience is sparse.
Show evidence (1 reference)
PMID:28100251 SUPPORT Other
"Low CSF 5-MTHF levels must be supplemented with folinic acid, not folic acid."
The consensus distinguishes a clear biochemical indication from optional empiric use.
Medication precautions and avoidance
Action: supportive careNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is supportive care (NCIT:C15747). NCIT:C15747 is a clinical intervention from the NCI Thesaurus. Ontology label: Supportive Care NCIT:C15747
Avoid dopamine receptor antagonists because they may worsen core symptoms, and avoid strongly serotonergic ergot-derived dopamine agonists because of valvular and fibrotic risk. Routine levodopa is avoided outside the narrow variant-directed setting described separately.
Show evidence (2 references)
PMID:37824694 SUPPORT Other
"Ergot-derived dopamine agonists with strong serotonergic (5-HT2B) agonist action (pergolide and cabergoline) due to risk of cardiac valvulopathy and other fibrotic complications"
GeneReviews states the ergot-derived dopamine-agonist safety rationale.
PMID:37824694 SUPPORT Other
"dopamine receptor antagonists (e.g., metoclopramide, antipsychotic medications), which may worsen primary disease symptoms."
GeneReviews directly warns against dopamine receptor antagonists.
Multidisciplinary supportive care
Action: supportive careNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is supportive care (NCIT:C15747). NCIT:C15747 is a clinical intervention from the NCI Thesaurus. Ontology label: Supportive Care NCIT:C15747
Supportive care addresses feeding, sleep, mobility, seizures, and other neurologic or autonomic complications while disease-directed and symptomatic therapies are optimized.
Target Phenotypes: Feeding difficulties HP:0011968 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Feeding difficulties (HP:0011968). HP:0011968 is a phenotype from the Human Phenotype Ontology. Sleep abnormality HP:0002360 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Sleep abnormality, annotated with Sleep disturbance (HP:0002360). HP:0002360 is a phenotype from the Human Phenotype Ontology. Seizure HP:0001250 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Seizure (HP:0001250). HP:0001250 is a phenotype from the Human Phenotype Ontology. Hypotonia HP:0001252 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Hypotonia (HP:0001252). HP:0001252 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:28100251 SUPPORT Other
"practical recommendations on clinical diagnosis, laboratory diagnosis, imaging and electroencephalograpy, medical treatments and non-medical treatments."
Consensus guideline supports medical and non-medical care recommendations for AADC deficiency.
PMID:37824694 SUPPORT Other
"Feeding therapy with consideration of gastrostomy tube placement or jejunal feeding; anticholinergic drugs and/or sleep induction for movement disorders / oculogyric crisis"
GeneReviews supplies concrete supportive feeding and movement-disorder measures.
🔬

Biochemical Markers

6
Low CSF homovanillic acid (DECREASED)
Pathograph Readouts
Readout Of CSF Neurotransmitter Metabolite Signature Negative Diagnostic
Decreased CSF HVA reports the dopamine-metabolite arm of the AADC deficiency CSF signature.
Show evidence (1 reference)
PMID:19172410 SUPPORT Human Clinical
"In CSF all patients revealed the pattern typical of AADC with decreased concentrations of homovanillic and 5-hydroxyindoleacetic acid and elevated concentration of 3-ortho-methyldopa."
The cohort directly supports the HVA readout direction.
Show evidence (1 reference)
PMID:19172410 SUPPORT Human Clinical
"In CSF all patients revealed the pattern typical of AADC with decreased concentrations of homovanillic and 5-hydroxyindoleacetic acid and elevated concentration of 3-ortho-methyldopa."
Clinical cohort supports decreased CSF homovanillic acid in the diagnostic profile.
Low CSF 5-hydroxyindoleacetic acid (DECREASED)
Pathograph Readouts
Readout Of CSF Neurotransmitter Metabolite Signature Negative Diagnostic
Decreased CSF 5-HIAA reports the serotonin-metabolite arm of the AADC deficiency CSF signature.
Show evidence (1 reference)
PMID:19172410 SUPPORT Human Clinical
"In CSF all patients revealed the pattern typical of AADC with decreased concentrations of homovanillic and 5-hydroxyindoleacetic acid and elevated concentration of 3-ortho-methyldopa."
The cohort directly supports the 5-HIAA readout direction.
Show evidence (1 reference)
PMID:19172410 SUPPORT Human Clinical
"In CSF all patients revealed the pattern typical of AADC with decreased concentrations of homovanillic and 5-hydroxyindoleacetic acid and elevated concentration of 3-ortho-methyldopa."
Clinical cohort supports decreased CSF 5-hydroxyindoleacetic acid in the diagnostic profile.
Elevated CSF 3-O-methyldopa (INCREASED)
Pathograph Readouts
Readout Of CSF Neurotransmitter Metabolite Signature Positive Diagnostic
Elevated 3-OMD reports precursor shunting in the AADC deficiency CSF signature.
Show evidence (1 reference)
PMID:19172410 SUPPORT Human Clinical
"In CSF all patients revealed the pattern typical of AADC with decreased concentrations of homovanillic and 5-hydroxyindoleacetic acid and elevated concentration of 3-ortho-methyldopa."
The cohort directly supports the CSF 3-OMD readout direction.
Show evidence (1 reference)
PMID:19172410 SUPPORT Human Clinical
"In CSF all patients revealed the pattern typical of AADC with decreased concentrations of homovanillic and 5-hydroxyindoleacetic acid and elevated concentration of 3-ortho-methyldopa."
Clinical cohort supports elevated 3-ortho-methyldopa in the diagnostic CSF profile.
Reduced plasma AADC activity (DECREASED)
Pathograph Readouts
Readout Of DDC Enzymatic Deficiency Negative Diagnostic
Reduced plasma AADC activity reports the primary DDC enzyme deficiency.
Show evidence (1 reference)
PMID:19172410 SUPPORT Human Clinical
"Diagnosis was confirmed by measurement of AADC activity in plasma in all patients."
The cohort directly supports plasma activity as a diagnostic readout.
Show evidence (2 references)
PMID:19172410 SUPPORT Human Clinical
"Diagnosis was confirmed by measurement of AADC activity in plasma in all patients."
Clinical cohort supports plasma AADC activity as an enzymatic diagnostic readout.
PMID:1357595 SUPPORT Human Clinical
"Activity of aromatic L-amino acid decarboxylase was virtually absent in a liver biopsy sample and greatly reduced in plasma."
Original report supports reduced AADC activity in plasma and tissue.
Elevated dried-blood-spot 3-O-methyldopa (INCREASED)
Pathograph Readouts
Readout Of DDC Enzymatic Deficiency Positive Diagnostic
Elevated blood 3-OMD reports precursor shunting caused by deficient AADC activity.
Show evidence (1 reference)
PMID:38302374 SUPPORT Human Clinical
"A prospective, multicenter (n = 3) NBS pilot study evaluated screening for AADCD by quantifying 3-OMD in dried blood spots (DBS) using tandem mass spectrometry (MS/MS)."
The prospective pilot directly supports the blood 3-OMD readout.
Show evidence (2 references)
PMID:38302374 SUPPORT Human Clinical
"A prospective, multicenter (n = 3) NBS pilot study evaluated screening for AADCD by quantifying 3-OMD in dried blood spots (DBS) using tandem mass spectrometry (MS/MS)."
The prospective pilot directly evaluates the screening biomarker and specimen type.
PMID:38302374 SUPPORT Human Clinical
"False-positive results were caused by maternal L-Dopa use (n = 2) and prematurity (30th and 36th week of gestation, n = 2)."
Observed false positives establish that DBS 3-OMD is a screening rather than standalone diagnostic result.
Elevated urinary vanillactic acid (INCREASED)
Pathograph Readouts
Readout Of DDC Enzymatic Deficiency Positive Diagnostic
Elevated urinary vanillactic acid reports alternative metabolism upstream of the AADC block.
Show evidence (1 reference)
PMID:28100251 SUPPORT Other
"Increased urine vanillactic acid (VLA) levels, measured by organic acid analysis, are reported in AADCD."
The consensus directly supports the urinary VLA readout direction.
Show evidence (1 reference)
PMID:28100251 SUPPORT Other
"Increased urine vanillactic acid (VLA) levels, measured by organic acid analysis, are reported in AADCD."
The consensus supports the direction, specimen, assay, and sensitivity limitation.
🔬

Diagnosis

4
DDC molecular genetic testing
Molecular genetic testing confirms pathogenic DDC variants and supports definitive diagnosis in a compatible clinical and biochemical setting.
genetic testing NCIT:C15709 NCI Thesaurus (NCIT)
Show evidence (3 references)
PMID:36268467 SUPPORT Human Clinical
"molecular and/or biochemical diagnosis of AADC deficiency"
Systematic review includes molecular diagnosis as a defining diagnostic route.
PMID:32409695 SUPPORT Human Clinical
"Twenty-three patients with clinical features of AADCD and DDC gene variants were recruited."
Cohort diagnosis used clinical features with DDC variants.
PMID:37824694 SUPPORT Other
"biallelic pathogenic variants in DDC identified by molecular genetic testing"
GeneReviews includes biallelic DDC variants as a core diagnostic route.
CSF neurotransmitter metabolite testing
CSF neurotransmitter testing shows low homovanillic acid and 5-hydroxyindoleacetic acid with elevated 3-ortho-methyldopa.
cerebrospinal fluid analysis NCIT:C173272 NCI Thesaurus (NCIT)
Show evidence (1 reference)
PMID:19172410 SUPPORT Human Clinical
"In CSF all patients revealed the pattern typical of AADC with decreased concentrations of homovanillic and 5-hydroxyindoleacetic acid and elevated concentration of 3-ortho-methyldopa."
Cohort data support CSF neurotransmitter metabolite testing.
Plasma AADC enzyme activity assay
Plasma aromatic L-amino acid decarboxylase activity measurement can confirm the enzymatic deficiency.
Show evidence (2 references)
PMID:19172410 SUPPORT Human Clinical
"Diagnosis was confirmed by measurement of AADC activity in plasma in all patients."
Clinical cohort supports plasma AADC activity measurement.
PMID:1357595 SUPPORT Human Clinical
"Activity of aromatic L-amino acid decarboxylase was virtually absent in a liver biopsy sample and greatly reduced in plasma."
Original case report supports enzyme activity measurement.
Newborn screening by dried-blood-spot 3-O-methyldopa
Tandem-mass-spectrometry measurement of 3-O-methyldopa in dried blood spots can identify presymptomatic newborns for confirmatory DDC and enzyme testing; it is a screening strategy, not a standalone definitive test.
newborn screening NCIT:C81178 NCI Thesaurus (NCIT)
Show evidence (2 references)
PMID:38302374 SUPPORT Human Clinical
"The proposed screening strategy with 3-OMD detection in DBS is feasible and effective to identify individuals with AADCD."
The largest prospective pilot supports feasibility and case detection.
PMID:37635029 SUPPORT Human Clinical
"Eight newborns exhibited an elevated 3-OMD concentration (839-5170 ng/mL). Among them, six newborns were confirmed to carry two pathogenic DDC variants."
Prospective Taiwan screening demonstrates confirmatory molecular follow-up after an elevated screen.
📈

Progression

3
Early-onset neurometabolic disease
Most reported patients have symptom onset in the first six months of life, with early hypotonia, oculogyric crises, global developmental delay, and autonomic dysfunction.
Show evidence (3 references)
ORPHA:35708 SUPPORT Other
"Age of onset: Infancy"
Orphanet lists infancy as an age of onset.
ORPHA:35708 SUPPORT Other
"Age of onset: Neonatal"
Orphanet also lists neonatal onset.
PMID:36268467 SUPPORT Human Clinical
"we found symptom onset to occur in the first 6 months of life in 93% of cases."
Systematic review supports very early symptom onset in most patients.
Persistent motor and developmental disability
Severity is heterogeneous. In a 63-person international cohort, 70% had no head control and minimal voluntary movement, whereas 17% walked independently; early regression was reported in 24%, commonly around the onset of oculogyric crises.
Show evidence (2 references)
PMID:32369189 SUPPORT Human Clinical
"The majority of subjects (70%) had profound motor impairment characterized by absent head control and minimal voluntary movement, while 17% had mild motor impairment and were able to walk independently."
The international cohort quantifies the broad motor-outcome spectrum.
PMID:32369189 SUPPORT Human Clinical
"An early regression in motor or developmental skills was reported in 15/63 patients (24%), typically occurring during infancy at the onset of oculogyric crises and other disease symptoms."
The cohort documents early regression in a minority of patients.
Survival and prognosis
Survival extends into adulthood for some individuals, especially those with milder motor phenotypes, but severe disease carries childhood mortality risk. In the international cohort, five deaths occurred from age 2 to 21 years, attributed by caregivers to pneumonia, acute complications during an oculogyric crisis, or myocardial infarction.
Show evidence (2 references)
PMID:32369189 SUPPORT Human Clinical
"The parents of five individuals who had died responded to the survey. Ages of death were 2 years (n = 2), 7 years, 13 years, and 21 years, respectively. Causes of death reported by parents were pneumonia (n = 2), acute complications during an OGC (n = 2), and “myocardial infarction” (n = 1)."
The cohort provides directly reported ages and attributed causes of death.
PMID:32369189 SUPPORT Human Clinical
"the observation of a greater proportion of patients with a more severe disease phenotype in the younger compared to the older patients, both suggest a significant mortality risk during childhood for patients with severe disease."
The age distribution suggests, but does not directly estimate, childhood mortality risk.
📊

Prevalence

3
Worldwide
Point Prevalence ≤0.1 per 100,000 <1 in 1,000,000
Less than 1 per 1,000,000. Orphanet classifies AADC deficiency as ultra-rare, with worldwide point prevalence below one per million.
Show evidence (1 reference)
ORPHA:35708 SUPPORT Other
"<1 / 1 000 000 | Worldwide | Point prevalence | PMID:30689738"
Orphanet reports worldwide point prevalence below one per million.
Germany
Birth Prevalence 0.1304–0.2609 per 100,000 1–9 per 1,000,000
Approximately 1 per 766,660 to 1 per 383,330 live births. One confirmed infant and one infant who died before confirmation were found among 766,660 screened newborns; this population estimate should not be generalized across ancestry groups.
Show evidence (1 reference)
PMID:38302374 SUPPORT Human Clinical
"Estimated birth prevalence (95% confidence interval) was 1:766,660 (95% CI 1:775,194; 1:769,231) to 1:383,330 (95% CI 1:384,615; 1:383,142)."
Prospective multicenter newborn screening supplies the German birth-prevalence range.
Taiwan
Birth Prevalence 3.8462–3.8462 per 100,000 1–9 per 100,000
Approximately 1 per 26,000 live births. This substantially higher estimate reflects a founder-variant population and is not a worldwide prevalence estimate.
Show evidence (1 reference)
PMID:37635029 SUPPORT Human Clinical
"Among them, six newborns were confirmed to carry two pathogenic DDC variants, indicating an incidence of AADC deficiency of ~1:26,000 (95% confidence interval: 1 in 12,021 to 1 in 57,228)."
Prospective newborn screening supplies the Taiwan-specific incidence estimate.
🔀

Differential Diagnoses

2

Conditions with similar clinical presentations that must be differentiated from Aromatic L-amino acid decarboxylase deficiency:

Tetrahydrobiopterin synthesis or recycling disorders
Overlapping Features BH4 disorders can share dopamine- and serotonin-pathway abnormalities, but AADC deficiency characteristically retains normal CSF pterins.
Distinguishing Features
  • Normal CSF neopterin, dihydrobiopterin, and tetrahydrobiopterin in AADC deficiency
Show evidence (1 reference)
PMID:28100251 SUPPORT Other
"Reduced 5-HIAA and HVA, and elevated 3-OMD, L-Dopa and 5-HTP , with normal pterins, point to AADCD."
The consensus identifies normal pterins as part of the biochemical pattern that points to AADC deficiency.
PNPO deficiency MONDO:0012407
Overlapping Features PNPO deficiency can secondarily reduce AADC activity and resemble the AADC CSF profile. Very low CSF pyridoxal phosphate with elevated glycine and threonine, together with neonatal epileptic encephalopathy, favors PNPO deficiency.
Distinguishing Features
  • Very low CSF pyridoxal phosphate with increased CSF glycine and threonine
  • Severe neonatal epileptic encephalopathy rather than the usual AADC presentation
Show evidence (2 references)
PMID:28100251 SUPPORT Other
"there is a secondary failure of AADC due to a deficiency of its cofactor pyridoxal phosphate"
The guideline directly describes the overlapping secondary AADC mechanism.
PMID:28100251 SUPPORT Other
"very low PLP , and increased glycine and threonine in CSF."
The guideline gives the discriminating CSF analytes.
📊

Related Datasets

1
An iPSC-derived midbrain dopaminergic neuronal model of aromatic amino acid decarboxylase (AADC) deficiency gives insight into neurodevelopmental disease features geo:GSE153990
Aromatic L-amino acid decarboxylase (AADC) deficiency is a complex inherited neurological disorder of monoamine synthesis which results in dopamine and serotonin deficiency. Affected patients have severe cognitive and motor delay, recurrent oculogyric crises, a complex movement disorder and high risk of premature mortality. Standard pharmacological treatment provides limited clinical benefit. Promising gene therapy approaches are emerging, though may not be either suitable or easily accessible for all patients.
human BULK RNA SEQ n=9
PMID:33734312
Identified by GEO DataSets index search for Aromatic L-amino acid decarboxylase deficiency (scripts/discover_datasets.py); accession and metadata verified against NCBI E-utilities on 2026-08-01. Title, sample count, and organism are GEO's own values.
🔬

Clinical Trials

3
NCT01395641 PHASE_I COMPLETED
Completed phase 1/2, open-label Taiwanese study of bilateral intracerebral AAV2-hAADC delivery for safety and efficacy in AADC deficiency.
Show evidence (1 reference)
clinicaltrials:NCT01395641 SUPPORT Human Clinical
"This Phase I/II trial is to prove the efficacy and safety of AAV2-hAADC to treat patients with AADC deficiency."
The registry summary states the intervention and study objectives.
NCT02926066 PHASE_II COMPLETED
Completed phase 2 expansion study that broadened treatment experience and evaluated a modestly higher intraputaminal AAV2-hAADC dose.
Show evidence (1 reference)
clinicaltrials:NCT02926066 SUPPORT Human Clinical
"This clinical trial expansion is to offer patients, who are not enrolled into the Phase I/II trial, a chance of treatment, to provide the experience in this gene therapy, and to increase the dose slightly."
The registry summary states the expansion and dose-escalation rationale.
NCT04903288 PHASE_II ACTIVE_NOT_RECRUITING
Phase 2 open-label trial assessing pharmacodynamics and safety of eladocagene exuparvovec administered with an MR-compatible ventricular cannula in pediatric AADC deficiency, with extension follow-up for motor development, AADC-specific symptoms, and long-term safety and efficacy.
Target Phenotypes: Motor delay HP:0001270 Human Phenotype Ontology (HP) Relation: this clinical trial targets this phenotype This clinical trial targets Motor delay (HP:0001270). HP:0001270 is a phenotype from the Human Phenotype Ontology. Decreased CSF homovanillic acid concentration HP:0003785 Human Phenotype Ontology (HP) Relation: this clinical trial targets this phenotype This clinical trial targets Decreased CSF homovanillic acid concentration (HP:0003785). HP:0003785 is a phenotype from the Human Phenotype Ontology.
Show evidence (3 references)
clinicaltrials:NCT04903288 SUPPORT Human Clinical
"The primary objectives of the trial phase are to assess the pharmacodynamics (PD) of eladocagene exuparvovec treatment by evaluation of homovanillic acid (HVA) levels"
ClinicalTrials.gov identifies pharmacodynamic assessment of eladocagene exuparvovec in AADC deficiency.
clinicaltrials:NCT04903288 SUPPORT Human Clinical
"The extension phase is designed to capture additional clinical information for eladocagene exuparvovec through study evaluations, changes in motor development, AADC-specific symptoms, and other PD measures."
Trial follow-up includes motor development, AADC-specific symptoms, and pharmacodynamic measures.
PMID:41724580 SUPPORT Human Clinical
"Study GT-002 (NCT04903288) is a phase 2, multicenter, open-label trial assessing the pharmacodynamics, safety, and efficacy of eladocagene exuparvovec administered to the putamen bilaterally in pediatric patients with AADC deficiency using a magnetic resonance (MR)-compatible cannula."
The 2026 publication confirms the trial identity, phase, design, intervention, population, and delivery system.
🧫

Experimental Models

1
DDC-knockout SH-SY5Y cell model CELL_LINE
A human neuroblastoma DDC-knockout system models AADC protein and activity loss, low HVA, and high 3-O-methyldopa. Re-expression of R347Q and L353P was used for structural and functional variant analysis; tumor-cell context limits inference about developing human monoaminergic circuits.
Parental SH-SY5Y cells CRISPR-Cas9 DDC-knockout SH-SY5Y cells DDC-knockout cells transfected with R347Q or L353P AADC
Organism
human NCBITaxon:9606 NCBI Taxonomy (NCBITaxon) Relation: this experimental model is built in this organism This experimental model is built in human, annotated with Homo sapiens (NCBITaxon:9606). NCBITaxon:9606 is an organism from the NCBI Taxonomy.
Cell source
CRISPR-Cas9 DDC-knockout SH-SY5Y neuroblastoma cells
Pathograph links
DDC Enzymatic Deficiency DDC knockout directly models loss of AADC protein and catalytic activity.
Show evidence (1 reference)
PMID:40318155 SUPPORT In Vitro
"This model showed a deficiency in AADC protein and activity, with an altered dopamine metabolites profile (low homovanillic acid and high 3-O-methyldopa)"
The cell model directly reproduces the primary enzyme defect and diagnostic metabolite direction.
Show evidence (1 reference)
PMID:40318155 SUPPORT In Vitro
"Overall, the DDC-KO model recapitulates some key features of AADC deficiency, is useful to study the molecular basis of the disease, and represents an ideal system for small molecule screening regarding specific enzyme defects"
The authors define the model's supported use while limiting the claim to some disease features.
🐁

Animal Models

1
Homozygous Ddc p.S250F knock-in Mus musculus Mild hypomorphic knock-in model
Homozygous S250F mice retain minute AADC activity and are viable. They show marked serotonin depletion with behavioral and autonomic abnormalities, but only modest brain dopamine reduction and no loss or morphologic abnormality of dopaminergic neurons. The model therefore represents disease with mild residual enzyme activity rather than the severe human phenotype.
Markedly reduced brain serotonin Modestly reduced brain dopamine Behavioral abnormality Autonomic dysfunction
Species
Mus musculus
Genotype
Homozygous Ddc p.S250F knock-in
Genes
Ddc MGI:94872 Mouse Genome Informatics (MGI) Relation: this experimental model concerns this gene This experimental model concerns Ddc (MGI:94872). MGI:94872 is a gene from Mouse Genome Informatics.
Show evidence (1 reference)
PMID:28973165 SUPPORT Model Organism
"Although the low enzymatic activity of the protein resulted in only modestly reduced concentrations of brain dopamine, serotonin levels were markedly diminished, and this perturbed behavior as well as autonomic function in mutant mice."
The knock-in study directly reports the biochemical and organismal phenotypes.
{ }

Source YAML

click to show 
name: Aromatic L-amino acid decarboxylase deficiency
creation_date: "2026-05-06T21:19:10Z"
category: Genetic
parents:
- Neurotransmitter Metabolic Disorder
- Inborn Error of Metabolism
- Movement Disorder
synonyms:
- AADC deficiency
description: >-
  Aromatic L-amino acid decarboxylase deficiency is an ultra-rare autosomal
  recessive neurometabolic disorder caused by biallelic pathogenic variants in
  DDC. Loss of aromatic L-amino acid decarboxylase activity disrupts dopamine,
  serotonin, norepinephrine, and epinephrine synthesis, causing early-onset
  hypotonia, global developmental delay, oculogyric crises, dystonia, autonomic
  dysfunction, and characteristic CSF neurotransmitter metabolite abnormalities.
disease_term:
  preferred_term: aromatic L-amino acid decarboxylase deficiency
  term:
    id: MONDO:0012084
    label: aromatic L-amino acid decarboxylase deficiency
references:
- reference: ORPHA:35708
  title: Aromatic L-amino acid decarboxylase deficiency
  found_in:
  - Aromatic_L_Amino_Acid_Decarboxylase_Deficiency-deep-research-fallback.md
  findings:
  - statement: >-
      Orphanet defines AADC deficiency as a rare severe genetic neurometabolic
      disorder caused by impaired catecholamine and serotonin synthesis.
    supporting_text: >-
      A rare, severe, genetic neurometabolic disorder associated with clinical
      manifestations related to impaired synthesis of dopamine, noradrenaline,
      adrenaline and serotonin.
- reference: PMID:28100251
  title: Consensus guideline for the diagnosis and treatment of aromatic l-amino acid decarboxylase (AADC) deficiency.
  found_in:
  - Aromatic_L_Amino_Acid_Decarboxylase_Deficiency-deep-research-fallback.md
  findings:
  - statement: >-
      The international consensus guideline supports autosomal recessive
      inheritance, early onset, key motor/autonomic symptoms, laboratory
      diagnosis, imaging/EEG considerations, and medical management.
    supporting_text: >-
      In the face of limited definitive evidence, we constructed practical
      recommendations on clinical diagnosis, laboratory diagnosis, imaging and
      electroencephalograpy, medical treatments and non-medical treatments.
- reference: PMID:19172410
  title: "Aromatic L-amino acid decarboxylase deficiency: clinical features, drug therapy and follow-up."
  found_in:
  - Aromatic_L_Amino_Acid_Decarboxylase_Deficiency-deep-research-fallback.md
  findings:
  - statement: >-
      A German clinical cohort supports the combined serotonin/dopamine/
      catecholamine deficiency, core neurologic and extraneurologic features,
      characteristic CSF profile, plasma enzyme confirmation, and symptomatic
      drug treatment classes.
    supporting_text: >-
      AADC deficiency is a disorder of biogenic amine metabolism resulting in
      generalized combined deficiency of serotonin, dopamine and catecholamines.
- reference: PMID:36268467
  title: "Clinical Features in Aromatic L-Amino Acid Decarboxylase (AADC) Deficiency: A Systematic Review."
  found_in:
  - Aromatic_L_Amino_Acid_Decarboxylase_Deficiency-deep-research-fallback.md
  findings:
  - statement: >-
      A systematic review of 261 molecularly or biochemically diagnosed patients
      supports DDC causation, early onset, frequent hypotonia, developmental
      delay, oculogyric crises, hypokinesia, ptosis, dysautonomia,
      gastrointestinal symptoms, sleep disorders, and behavioral disorders.
    supporting_text: >-
      By analysing 261 patients from 41 papers with molecular and/or
      biochemical diagnosis of AADC deficiency for which individuality could be
      determined with certainty, we found symptom onset to occur in the first 6
      months of life in 93% of cases.
- reference: PMID:30689738
  title: Gene therapy improves motor and mental function of aromatic l-amino acid decarboxylase deficiency.
  found_in:
  - Aromatic_L_Amino_Acid_Decarboxylase_Deficiency-deep-research-fallback.md
  findings:
  - statement: >-
      An open-label phase 1/2 intraputaminal AAV-DDC study supports restored
      putaminal dopamine synthesis and improved motor, oculogyric, dystonic,
      cognitive, and verbal function after gene therapy.
    supporting_text: >-
      The restoration of dopamine synthesis in the putamen via gene transfer
      provides transformative medical benefit across all patient ages,
      genotypes, and disease severities included in this study.
- reference: PMID:1357595
  title: "Aromatic L-amino acid decarboxylase deficiency: clinical features, diagnosis, and treatment of a new inborn error of neurotransmitter amine synthesis."
  found_in:
  - Aromatic_L_Amino_Acid_Decarboxylase_Deficiency-deep-research-fallback.md
  findings:
  - statement: >-
      The original case report documents severe hypotonia, oculogyric crises,
      absent/reduced AADC activity, reduced biogenic amines, elevated precursors,
      and partial response to bromocriptine/tranylcypromine-based therapy.
    supporting_text: >-
      Activity of aromatic L-amino acid decarboxylase was virtually absent in a
      liver biopsy sample and greatly reduced in plasma.
- reference: PMID:32409695
  title: The genetic and clinical characteristics of aromatic L-amino acid decarboxylase deficiency in mainland China.
  found_in:
  - Aromatic_L_Amino_Acid_Decarboxylase_Deficiency-deep-research-fallback.md
  findings:
  - statement: >-
      A 23-patient mainland China cohort supports DDC variants, early onset,
      hypotonia, oculogyric crises, autonomic symptoms, and frequent partial
      improvement with pyridoxine, dopamine agonist, and MAO inhibitor regimens.
    supporting_text: >-
      Eighteen patients (78.3%) got various degree of improvement after using
      pyridoxine monotherapy or different combination of pyridoxine, dopamine
      agonists, and monoamine oxidase (MAO) inhibitors.
- reference: DOI:10.1001/jama.2024.28666
  title: Eladocagene Exuparvovec for Aromatic L-Amino Acid Decarboxylase Deficiency
  found_in:
  - Aromatic_L_Amino_Acid_Decarboxylase_Deficiency-deep-research-fallback.md
  findings:
  - statement: >-
      JAMA Insights reports FDA approval of Kebilidi, eladocagene exuparvovec,
      for AADC deficiency in adult and pediatric patients.
    supporting_text: >-
      This JAMA Insights discusses the US Food and Drug Administration approval
      of Kebilidi, eladocagene exuparvovec, for the treatment of aromatic
      L-amino acid decarboxylase deficiency in adult and pediatric patients.
- reference: clinicaltrials:NCT04903288
  title: An Open-Label Trial to Address the Safety of the SmartFlow MR-Compatible Ventricular Cannula for Administering Eladocagene Exuparvovec to Pediatric Subjects
  found_in:
  - Aromatic_L_Amino_Acid_Decarboxylase_Deficiency-deep-research-fallback.md
  findings:
  - statement: >-
      ClinicalTrials.gov documents an active-not-recruiting phase 2 trial of
      eladocagene exuparvovec in pediatric AADC deficiency.
    supporting_text: >-
      The primary objectives of the trial phase are to assess the
      pharmacodynamics (PD) of eladocagene exuparvovec treatment by evaluation
      of homovanillic acid (HVA) levels and to assess the safety of the
      SmartFlow magnetic resonance compatible ventricular cannula.
- reference: PMID:37824694
  title: Aromatic L-Amino Acid Decarboxylase Deficiency.
  tags:
  - GeneReviews
  findings:
  - statement: >-
      GeneReviews provides the current clinical baseline for presentation,
      diagnosis, management, surveillance, and genetic counseling.
    supporting_text: >-
      The diagnosis of AADC deficiency is established in a proband who has the
      following core diagnostic testing results: biallelic pathogenic variants
      in DDC identified by molecular genetic testing OR cerebrospinal fluid
      (CSF) or plasma neurotransmitter profile consistent with AADC deficiency
      AND significantly reduced AADC enzyme activity in plasma.
- reference: PMID:12891654
  title: "Aromatic L-amino acid decarboxylase deficiency: overview of clinical features and outcomes."
  findings:
  - statement: >-
      An 11-patient series documents the characteristic early movement disorder
      and broad but generally poor functional outcomes.
    supporting_text: >-
      Functional clinical outcomes as a group remain poor, in spite of a
      variety of attempted treatment interventions, with marked impairment in
      motor abilities as well as in speech and communication; however, outcome
      was quite variable from patient to patient and covered a broad spectrum
      of neurological disability.
- reference: PMID:32369189
  title: "AADC deficiency from infancy to adulthood: Symptoms and developmental outcome in an international cohort of 63 patients."
  findings:
  - statement: >-
      A 63-person international cohort defines early presentation, motor
      severity, developmental outcomes, treatment response, and mortality.
    supporting_text: >-
      The majority of subjects (70%) had profound motor impairment
      characterized by absent head control and minimal voluntary movement,
      while 17% had mild motor impairment and were able to walk independently.
- reference: PMID:34763085
  title: Long-term efficacy and safety of eladocagene exuparvovec in patients with AADC deficiency.
  findings:
  - statement: >-
      Follow-up of 26 treated patients supports sustained motor and cognitive
      benefit beyond five years while identifying transient postoperative
      dyskinesia and procedure-related complications.
    supporting_text: >-
      Rapid improvements in motor and cognitive function occurred within 12
      months after gene therapy and were sustained during follow-up for >5
      years.
- reference: PMID:38302374
  title: "Newborn screening for aromatic l-amino acid decarboxylase deficiency - Strategies, results, and implication for prevalence calculations."
  findings:
  - statement: >-
      A prospective German pilot supports dried-blood-spot 3-O-methyldopa
      screening and supplies a population-specific birth-prevalence estimate.
    supporting_text: >-
      The proposed screening strategy with 3-OMD detection in DBS is feasible
      and effective to identify individuals with AADCD.
- reference: PMID:37635029
  title: "Streamlined determination of 3-O-methyldopa in dried blood spots: Prospective screening for aromatic l-amino-acid decarboxylase deficiency."
  findings:
  - statement: >-
      Prospective Taiwanese screening found six molecularly confirmed newborns
      among 157,371 screened.
    supporting_text: >-
      Among them, six newborns were confirmed to carry two pathogenic DDC
      variants, indicating an incidence of AADC deficiency of ~1:26,000 (95%
      confidence interval: 1 in 12,021 to 1 in 57,228).
- reference: PMID:37348148
  title: Prevalence of DDC genotypes in patients with aromatic L-amino acid decarboxylase (AADC) deficiency and in silico prediction of structural protein changes.
  findings:
  - statement: >-
      The largest assembled genotype dataset identifies the East Asian
      c.714+4A>T founder allele as the most common reported DDC variant.
    supporting_text: >-
      The splice variant c.714+4A>T, with a founder effect in Taiwan and China,
      was the most common variant (allele frequency = 32.4%), and
      c.[714+4A>T];[714+4A>T] was the most common genotype (genotype frequency =
      21.3%).
- reference: PMID:28973165
  title: A pathogenic S250F missense mutation results in a mouse model of mild aromatic l-amino acid decarboxylase (AADC) deficiency.
  findings:
  - statement: >-
      The homozygous S250F knock-in mouse is a viable, mild model with residual
      enzyme activity, marked serotonin loss, and behavioral and autonomic
      abnormalities.
    supporting_text: >-
      Such mutants represent a novel, mild model of human AADC deficiency.
- reference: PMID:40318155
  title: "The CRISPR-Cas9 knockout DDC SH-SY5Y in vitro model for AADC deficiency provides insight into the pathogenicity of R347Q and L353P variants: a cross-sectional structural and functional analysis."
  findings:
  - statement: >-
      A DDC-knockout human neuroblastoma model reproduces enzyme loss and the
      low-HVA/high-3-OMD biochemical signature and supports variant testing.
    supporting_text: >-
      This model showed a deficiency in AADC protein and activity, with an
      altered dopamine metabolites profile (low homovanillic acid and high
      3-O-methyldopa).
- reference: PMID:37402126
  title: "Gene therapy for aromatic L-amino acid decarboxylase deficiency: Requirements for safe application and knowledge-generating follow-up."
  findings:
  - statement: >-
      International experts identify unresolved long-term and comparative
      effectiveness questions after intracerebral AAV2 gene therapy.
    supporting_text: >-
      Due to lack of data on long-term outcomes and the comparative efficacy of
      alternative stereotactic procedures and brain target sites, a structured
      follow-up plan and systematic documentation of outcomes in a suitable,
      industry-independent registry study are necessary.
- reference: PMID:41724580
  title: "Pharmacodynamics, Efficacy, and Safety of Intraputaminal Eladocagene Exuparvovec Administered to Pediatric Patients With Aromatic L-Amino Acid Decarboxylase Deficiency Using an MR-Compatible Cannula: 48 Weeks of Follow-Up."
  findings:
  - statement: >-
      The 2026 phase 2 report from NCT04903288 documents increased CSF HVA,
      acquired motor milestones, and no deaths or withdrawals through 48 weeks.
    supporting_text: >-
      At baseline (n = 13), all patients showed severe motor developmental
      delay; at week 48 (n = 12), nine achieved full head control, four could sit
      unassisted, two could stand with support, and two could walk independently
      to a toy.
- reference: PMID:42389831
  title: "Gene Therapy for Amino Acid Decarboxylase Deficiency: Clinical and Imaging Outcomes in a French Cohort."
  findings:
  - statement: >-
      A July 2026 six-patient French cohort relates clinical recovery to
      dopamine-production dynamics rather than exhaustive putaminal coverage.
    supporting_text: >-
      Clinical recovery did not correlate with the putaminal coverage volume,
      indicating a biological threshold effect.
- reference: PMID:36103022
  title: "Eladocagene Exuparvovec: First Approval."
  findings:
  - statement: >-
      The European authorization is restricted to patients aged at least 18
      months with severe, clinically and molecularly confirmed disease.
    supporting_text: >-
      Eladocagene exuparvovec was approved in July 2022 in the EU for the
      treatment of patients aged 18 months and older with a clinical,
      molecular, and genetically confirmed diagnosis of AADC deficiency with a
      severe phenotype (i.e. patients who cannot sit, stand or walk).
- reference: clinicaltrials:NCT01395641
  title: A Phase I/II Clinical Trial for Treatment of Aromatic L-amino Acid Decarboxylase (AADC) Deficiency Using AAV2-hAADC
  findings:
  - statement: The completed phase 1/2 study evaluated AAV2-hAADC safety and efficacy.
    supporting_text: >-
      This Phase I/II trial is to prove the efficacy and safety of AAV2-hAADC to
      treat patients with AADC deficiency.
- reference: clinicaltrials:NCT02926066
  title: A Clinical Trial for Treatment of Aromatic L-amino Acid Decarboxylase (AADC) Deficiency Using AAV2-hAADC - An Expansion (NTUH-AADC-011)
  findings:
  - statement: The completed phase 2 expansion increased experience and evaluated a modestly higher dose.
    supporting_text: >-
      This clinical trial expansion is to offer patients, who are not enrolled
      into the Phase I/II trial, a chance of treatment, to provide the
      experience in this gene therapy, and to increase the dose slightly.
- reference: CGGV:assertion_1dea33e3-7cf6-47f9-aa52-2525b439031a-2022-02-25T170000.000Z
  title: DDC / aromatic L-amino acid decarboxylase deficiency (Definitive)
prevalence:
- population: Worldwide
  measure_type: POINT_PREVALENCE
  prevalence_class: BELOW_1_IN_1000000
  rate_high: 0.1
  notes: >-
    Less than 1 per 1,000,000. Orphanet classifies AADC deficiency as
    ultra-rare, with worldwide point prevalence below one per million.
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "<1 / 1 000 000 | Worldwide | Point prevalence | PMID:30689738"
    explanation: Orphanet reports worldwide point prevalence below one per million.
- population: Germany
  measure_type: BIRTH_PREVALENCE
  prevalence_class: BAND_1_9_PER_1000000
  rate_low: 0.1304
  rate_high: 0.2609
  notes: >-
    Approximately 1 per 766,660 to 1 per 383,330 live births. One confirmed
    infant and one infant who died before confirmation were found among 766,660
    screened newborns; this population estimate should not be generalized
    across ancestry groups.
  evidence:
  - reference: PMID:38302374
    reference_title: "Newborn screening for aromatic l-amino acid decarboxylase deficiency - Strategies, results, and implication for prevalence calculations."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Estimated birth prevalence (95% confidence interval) was 1:766,660 (95%
      CI 1:775,194; 1:769,231) to 1:383,330 (95% CI 1:384,615; 1:383,142).
    explanation: Prospective multicenter newborn screening supplies the German birth-prevalence range.
- population: Taiwan
  measure_type: BIRTH_PREVALENCE
  prevalence_class: BAND_1_9_PER_100000
  rate_low: 3.8462
  rate_high: 3.8462
  notes: >-
    Approximately 1 per 26,000 live births. This substantially higher estimate
    reflects a founder-variant population and is not a worldwide prevalence
    estimate.
  evidence:
  - reference: PMID:37635029
    reference_title: "Streamlined determination of 3-O-methyldopa in dried blood spots: Prospective screening for aromatic l-amino-acid decarboxylase deficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Among them, six newborns were confirmed to carry two pathogenic DDC
      variants, indicating an incidence of AADC deficiency of ~1:26,000 (95%
      confidence interval: 1 in 12,021 to 1 in 57,228).
    explanation: Prospective newborn screening supplies the Taiwan-specific incidence estimate.
progression:
- phase: Early-onset neurometabolic disease
  notes: >-
    Most reported patients have symptom onset in the first six months of life,
    with early hypotonia, oculogyric crises, global developmental delay, and
    autonomic dysfunction.
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Age of onset: Infancy"
    explanation: Orphanet lists infancy as an age of onset.
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Age of onset: Neonatal"
    explanation: Orphanet also lists neonatal onset.
  - reference: PMID:36268467
    reference_title: "Clinical Features in Aromatic L-Amino Acid Decarboxylase (AADC) Deficiency: A Systematic Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "we found symptom onset to occur in the first 6 months of life in 93% of cases."
    explanation: Systematic review supports very early symptom onset in most patients.
- phase: Persistent motor and developmental disability
  notes: >-
    Severity is heterogeneous. In a 63-person international cohort, 70% had no
    head control and minimal voluntary movement, whereas 17% walked
    independently; early regression was reported in 24%, commonly around the
    onset of oculogyric crises.
  evidence:
  - reference: PMID:32369189
    reference_title: "AADC deficiency from infancy to adulthood: Symptoms and developmental outcome in an international cohort of 63 patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The majority of subjects (70%) had profound motor impairment
      characterized by absent head control and minimal voluntary movement,
      while 17% had mild motor impairment and were able to walk independently.
    explanation: The international cohort quantifies the broad motor-outcome spectrum.
  - reference: PMID:32369189
    reference_title: "AADC deficiency from infancy to adulthood: Symptoms and developmental outcome in an international cohort of 63 patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      An early regression in motor or developmental skills was reported in
      15/63 patients (24%), typically occurring during infancy at the onset of
      oculogyric crises and other disease symptoms.
    explanation: The cohort documents early regression in a minority of patients.
- phase: Survival and prognosis
  notes: >-
    Survival extends into adulthood for some individuals, especially those with
    milder motor phenotypes, but severe disease carries childhood mortality
    risk. In the international cohort, five deaths occurred from age 2 to 21
    years, attributed by caregivers to pneumonia, acute complications during an
    oculogyric crisis, or myocardial infarction.
  evidence:
  - reference: PMID:32369189
    reference_title: "AADC deficiency from infancy to adulthood: Symptoms and developmental outcome in an international cohort of 63 patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The parents of five individuals who had died responded to the survey.
      Ages of death were 2 years (n = 2), 7 years, 13 years, and 21 years,
      respectively. Causes of death reported by parents were pneumonia (n = 2),
      acute complications during an OGC (n = 2), and “myocardial infarction” (n
      = 1).
    explanation: The cohort provides directly reported ages and attributed causes of death.
  - reference: PMID:32369189
    reference_title: "AADC deficiency from infancy to adulthood: Symptoms and developmental outcome in an international cohort of 63 patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      the observation of a greater proportion of patients with a more severe
      disease phenotype in the younger compared to the older patients, both
      suggest a significant mortality risk during childhood for patients with
      severe disease.
    explanation: The age distribution suggests, but does not directly estimate, childhood mortality risk.
inheritance:
- name: Autosomal recessive inheritance
  inheritance_term:
    preferred_term: Autosomal recessive inheritance
    term:
      id: HP:0000007
      label: Autosomal recessive inheritance
  description: >-
    AADC deficiency is inherited in an autosomal recessive manner and is caused
    by biallelic DDC variants.
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Autosomal recessive"
    explanation: Orphanet lists autosomal recessive inheritance.
  - reference: PMID:28100251
    reference_title: "Consensus guideline for the diagnosis and treatment of aromatic l-amino acid decarboxylase (AADC) deficiency."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Aromatic L-amino acid decarboxylase deficiency (AADCD) is a rare, autosomal recessive neurometabolic disorder"
    explanation: Consensus guideline supports autosomal recessive inheritance.
  - reference: PMID:37824694
    reference_title: Aromatic L-Amino Acid Decarboxylase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "AADC deficiency is inherited in an autosomal recessive manner."
    explanation: GeneReviews directly states the inheritance mode in its genetic-counseling section.
genetic:
- name: DDC
  association: Biallelic pathogenic variants
  presence: Positive
  gene_term:
    preferred_term: DDC
    term:
      id: hgnc:2719
      label: DDC
  notes: >-
    DDC encodes dopa decarboxylase/aromatic L-amino acid decarboxylase; loss of
    function produces combined monoamine neurotransmitter deficiency. The
    c.714+4A>T founder variant is enriched in Taiwan and China. Clinically
    actionable variant-specific evidence is currently narrow; rare DDC
    ligand-binding-site variants can be levodopa responsive.
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "DDC | dopa decarboxylase | hgnc:2719 | Disease-causing germline mutation(s) in"
    explanation: Orphanet lists DDC as the disease-causing gene.
  - reference: PMID:36268467
    reference_title: "Clinical Features in Aromatic L-Amino Acid Decarboxylase (AADC) Deficiency: A Systematic Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "caused by pathogenic homozygous or compound heterozygous variants in the dopa decarboxylase (DDC) gene."
    explanation: Systematic review supports biallelic pathogenic DDC variants.
  - reference: PMID:32409695
    reference_title: "The genetic and clinical characteristics of aromatic L-amino acid decarboxylase deficiency in mainland China."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Twenty-three patients with clinical features of AADCD and DDC gene variants were recruited."
    explanation: Mainland China cohort supports disease association with DDC variants.
  - reference: CGGV:assertion_1dea33e3-7cf6-47f9-aa52-2525b439031a-2022-02-25T170000.000Z
    reference_title: "DDC / aromatic L-amino acid decarboxylase deficiency (Definitive)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "DDC | HGNC:2719 | aromatic L-amino acid decarboxylase deficiency | MONDO:0012084 | AR | Definitive"
    explanation: ClinGen classifies the DDC-aromatic L-amino acid decarboxylase deficiency gene-disease relationship as definitive with autosomal recessive inheritance.
  - reference: PMID:37348148
    reference_title: Prevalence of DDC genotypes in patients with aromatic L-amino acid decarboxylase (AADC) deficiency and in silico prediction of structural protein changes.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The splice variant c.714+4A>T, with a founder effect in Taiwan and China,
      was the most common variant (allele frequency = 32.4%).
    explanation: The international genotype dataset quantifies the founder variant.
  - reference: PMID:28100251
    reference_title: "Consensus guideline for the diagnosis and treatment of aromatic l-amino acid decarboxylase (AADC) deficiency."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      L-Dopa is first line treatment only for patients with L-Dopa binding-site
      variants
    explanation: The consensus supports the narrow clinically actionable ligand-binding-site association.
pathophysiology:
- name: DDC Enzymatic Deficiency
  biological_scale: MOLECULAR
  description: >-
    Biallelic pathogenic variants in DDC reduce aromatic L-amino acid
    decarboxylase activity, blocking decarboxylation of neurotransmitter
    precursors.
  genes:
  - preferred_term: DDC
    term:
      id: hgnc:2719
      label: DDC
  molecular_functions:
  - preferred_term: aromatic-L-amino-acid decarboxylase activity
    term:
      id: GO:0004058
      label: aromatic-L-amino-acid decarboxylase activity
    modifier: DECREASED
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "DDC | dopa decarboxylase | hgnc:2719 | Disease-causing germline mutation(s) in"
    explanation: Orphanet lists DDC as the disease-causing gene.
  - reference: PMID:1357595
    reference_title: "Aromatic L-amino acid decarboxylase deficiency: clinical features, diagnosis, and treatment of a new inborn error of neurotransmitter amine synthesis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Activity of aromatic L-amino acid decarboxylase was virtually absent in a liver biopsy sample and greatly reduced in plasma."
    explanation: The original case report directly documents absent or greatly reduced AADC activity.
  downstream:
  - target: Biogenic Monoamine Synthesis Failure
    causal_link_type: DIRECT
    description: AADC catalyzes monoamine neurotransmitter synthesis from aromatic amino acid precursors.
- name: Biogenic Monoamine Synthesis Failure
  biological_scale: MOLECULAR
  description: >-
    Loss of AADC activity decreases synthesis of dopamine, serotonin,
    norepinephrine, and epinephrine, producing central and peripheral monoamine
    deficiency.
  biological_processes:
  - preferred_term: dopamine biosynthetic process
    term:
      id: GO:0042416
      label: dopamine biosynthetic process
    modifier: DECREASED
  - preferred_term: serotonin biosynthetic process
    term:
      id: GO:0042427
      label: serotonin biosynthetic process
    modifier: DECREASED
  - preferred_term: norepinephrine biosynthetic process
    term:
      id: GO:0042421
      label: norepinephrine biosynthetic process
    modifier: DECREASED
  chemical_entities:
  - preferred_term: dopamine
    modifier: DECREASED
    term:
      id: CHEBI:18243
      label: dopamine
  - preferred_term: serotonin
    modifier: DECREASED
    term:
      id: CHEBI:28790
      label: serotonin
  - preferred_term: norepinephrine / noradrenaline
    modifier: DECREASED
    term:
      id: CHEBI:33569
      label: noradrenaline
  - preferred_term: epinephrine / adrenaline
    modifier: DECREASED
    term:
      id: CHEBI:28918
      label: (R)-adrenaline
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "impaired synthesis of dopamine, noradrenaline, adrenaline and serotonin."
    explanation: Orphanet definition states the affected monoamine synthesis pathways.
  - reference: PMID:28100251
    reference_title: "Consensus guideline for the diagnosis and treatment of aromatic l-amino acid decarboxylase (AADC) deficiency."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "leads to a severe combined deficiency of serotonin, dopamine, norepinephrine and epinephrine."
    explanation: Consensus guideline supports combined monoamine deficiency.
  - reference: PMID:19172410
    reference_title: "Aromatic L-amino acid decarboxylase deficiency: clinical features, drug therapy and follow-up."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "resulting in generalized combined deficiency of serotonin, dopamine and catecholamines."
    explanation: Clinical cohort describes generalized biogenic amine deficiency.
  downstream:
  - target: CSF Neurotransmitter Metabolite Signature
    causal_link_type: DIRECT
    description: Monoamine synthesis failure lowers downstream CSF metabolites and raises precursors.
  - target: Motor Circuit Dysfunction
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - dopamine deficiency in basal-ganglia motor circuits
    description: Dopamine deficiency disrupts basal-ganglia motor function.
  - target: Autonomic Dysfunction
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - peripheral and central catecholamine-serotonin deficiency
    description: Peripheral and central monoamine deficiency contributes to autonomic symptoms.
  - target: Neurodevelopmental Impairment
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - early serotonin and catecholamine deficiency during neurodevelopment
    description: Early combined monoamine deficiency disrupts neurodevelopment.
- name: CSF Neurotransmitter Metabolite Signature
  biological_scale: ORGANISM
  description: >-
    AADC deficiency produces a diagnostic CSF neurotransmitter pattern with low
    homovanillic acid and 5-hydroxyindoleacetic acid and elevated
    3-ortho-methyldopa.
  evidence:
  - reference: PMID:19172410
    reference_title: "Aromatic L-amino acid decarboxylase deficiency: clinical features, drug therapy and follow-up."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In CSF all patients revealed the pattern typical of AADC with decreased concentrations of homovanillic and 5-hydroxyindoleacetic acid and elevated concentration of 3-ortho-methyldopa."
    explanation: Cohort data support the characteristic CSF metabolite pattern.
  - reference: PMID:1357595
    reference_title: "Aromatic L-amino acid decarboxylase deficiency: clinical features, diagnosis, and treatment of a new inborn error of neurotransmitter amine synthesis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Concentrations of L-dopa, 3-methoxytyrosine, and 5-hydroxytryptophan were elevated in CSF, plasma, and urine."
    explanation: Original report supports precursor accumulation caused by AADC deficiency.
  chemical_entities:
  - preferred_term: homovanillic acid
    modifier: DECREASED
    term:
      id: CHEBI:545959
      label: homovanillic acid
  - preferred_term: 5-hydroxyindoleacetic acid
    modifier: DECREASED
    term:
      id: CHEBI:27823
      label: (5-hydroxyindol-3-yl)acetic acid
  - preferred_term: 3-O-methyldopa
    modifier: INCREASED
    term:
      id: CHEBI:82913
      label: 3-O-methyldopa
  downstream:
  - target: Decreased CSF homovanillic acid concentration
    causal_link_type: DIRECT
    description: Reduced dopamine metabolism lowers CSF homovanillic acid.
  - target: Decreased CSF 5-hydroxyindolacetic acid concentration
    causal_link_type: DIRECT
    description: Reduced serotonin metabolism lowers CSF 5-hydroxyindoleacetic acid.
  - target: Increased circulating prolactin concentration
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - central dopamine deficiency
    description: Dopamine deficiency can disinhibit prolactin secretion.
- name: Motor Circuit Dysfunction
  biological_scale: TISSUE
  description: >-
    Deficient dopamine synthesis in basal-ganglia motor circuits produces
    hypotonia, hypokinesia, dystonia, oculogyric crises, dyskinesia, and delayed
    motor development.
  evidence:
  - reference: PMID:28100251
    reference_title: "Consensus guideline for the diagnosis and treatment of aromatic l-amino acid decarboxylase (AADC) deficiency."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "key clinical symptoms are hypotonia, movement disorders (oculogyric crisis, dystonia, and hypokinesia), developmental delay, and autonomic symptoms."
    explanation: Consensus guideline links the biochemical disorder to core motor symptoms.
  - reference: PMID:30689738
    reference_title: "Gene therapy improves motor and mental function of aromatic l-amino acid decarboxylase deficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "a decrease in catecholamines and serotonin levels in the brain leads to developmental delay and movement disorders."
    explanation: Gene-therapy study background links monoamine deficiency to motor and developmental manifestations.
  downstream:
  - target: Hypotonia
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - dopamine-dependent motor control disruption
  - target: Oculogyric crisis
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - basal-ganglia dopamine deficiency
  - target: Dystonia
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - basal-ganglia dopamine deficiency
  - target: Hypokinesia
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - basal-ganglia dopamine deficiency
  - target: Dyskinesia
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - basal-ganglia motor circuit dysfunction
  - target: Athetosis
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - basal-ganglia motor circuit dysfunction
    evidence:
    - reference: PMID:12891654
      reference_title: "Aromatic L-amino acid decarboxylase deficiency: overview of clinical features and outcomes."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        The phenomenology of the movement disorder is identical to that
        previously reported, and includes intermittent oculogyric crises and
        limb dystonia, generalized athetosis, and impaired voluntary movement
        in all patients.
      explanation: The clinical series places athetosis within the characteristic AADC movement disorder.
  - target: Myoclonus
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Myoclonus is a recognized but incompletely quantified hyperkinetic manifestation.
    evidence:
    - reference: PMID:28100251
      reference_title: "Consensus guideline for the diagnosis and treatment of aromatic l-amino acid decarboxylase (AADC) deficiency."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >-
        Hypokinesia and/ or bradykinesia ± ++ ++ ++ ++ Myoclonus ± ± ± ± ±
        Tremor ± ± ± ± ±
      explanation: The consensus table records myoclonus as possible (±) in its neonatal, infancy, childhood, adolescence, and adulthood columns while leaving its precise circuit mechanism unresolved.
  - target: Poor head control
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - axial hypotonia
  - target: Motor delay
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - early motor circuit dysfunction
  - target: Ptosis
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: AADC deficiency commonly includes ocular motor manifestations including ptosis.
    evidence:
    - reference: PMID:36268467
      reference_title: "Clinical Features in Aromatic L-Amino Acid Decarboxylase (AADC) Deficiency: A Systematic Review."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Oculogyric crises were seen in 67% of patients while hypokinesia in 42% and ptosis in 26%."
      explanation: Systematic review quantifies ptosis among neurologic/ocular motor manifestations.
  - target: Reduced tendon reflexes
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - abnormal motor tone and reflex control
    description: Motor-system dysfunction can include reduced tendon reflexes.
    evidence:
    - reference: ORPHA:35708
      reference_title: "Aromatic L-amino acid decarboxylase deficiency"
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "HP:0001315 | Reduced tendon reflexes | Occasional (29-5%)"
      explanation: Orphanet lists reduced tendon reflexes among AADC deficiency neurologic manifestations.
  - target: Limb hypertonia
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - abnormal motor tone regulation
    description: Basal-ganglia and motor-circuit dysfunction can manifest as limb hypertonia.
    evidence:
    - reference: ORPHA:35708
      reference_title: "Aromatic L-amino acid decarboxylase deficiency"
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "HP:0002509 | Limb hypertonia | Occasional (29-5%)"
      explanation: Orphanet lists limb hypertonia as an occasional neurologic manifestation.
  - target: Babinski sign
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - central motor pathway dysfunction
    description: Central motor dysfunction can manifest as Babinski sign.
    evidence:
    - reference: ORPHA:35708
      reference_title: "Aromatic L-amino acid decarboxylase deficiency"
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "HP:0003487 | Babinski sign | Occasional (29-5%)"
      explanation: Orphanet lists Babinski sign as an occasional neurologic manifestation.
  - target: Tremor
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - basal-ganglia motor circuit dysfunction
    description: Movement-disorder circuitry can rarely manifest as tremor.
    evidence:
    - reference: ORPHA:35708
      reference_title: "Aromatic L-amino acid decarboxylase deficiency"
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "HP:0001337 | Tremor | Very rare (<4-1%)"
      explanation: Orphanet lists tremor as a very rare movement manifestation.
  - target: Joint contracture
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - chronic abnormal motor tone and limited mobility
    description: Chronic neuromotor impairment can contribute to joint contractures.
    evidence:
    - reference: ORPHA:35708
      reference_title: "Aromatic L-amino acid decarboxylase deficiency"
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "HP:0034392 | Joint contracture | Very rare (<4-1%)"
      explanation: Orphanet lists joint contracture as a very rare musculoskeletal manifestation.
- name: Autonomic Dysfunction
  biological_scale: ORGANISM
  description: >-
    Combined catecholamine and serotonin deficiency contributes to autonomic and
    extraneurological symptoms including hyperhidrosis, nasal congestion,
    hypersalivation/drooling, sleep disturbance, hypotension, and miosis.
  evidence:
  - reference: PMID:19172410
    reference_title: "Aromatic L-amino acid decarboxylase deficiency: clinical features, drug therapy and follow-up."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All patients presented distinct extraneurological symptoms, such as hypersalivation, hyperhidrosis, nasal congestion, sleep disturbances and hypoglycaemia."
    explanation: Clinical cohort supports autonomic and extraneurologic manifestations.
  - reference: PMID:32409695
    reference_title: "The genetic and clinical characteristics of aromatic L-amino acid decarboxylase deficiency in mainland China."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "autonomic symptoms such as excessive sweating, nasal congestion and profuse nasal, and oropharyngeal secretions, were common in our patients."
    explanation: Mainland China cohort supports frequent autonomic symptoms.
  downstream:
  - target: Hyperhidrosis
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - autonomic monoamine deficiency
  - target: Nasal congestion
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - autonomic monoamine deficiency
  - target: Drooling
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - hypersalivation from autonomic dysfunction
  - target: Sleep abnormality
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - serotonin and catecholamine deficiency
  - target: Hypotension
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - catecholamine deficiency
  - target: Miosis
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - autonomic dysfunction
  - target: Temperature instability
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - impaired central and peripheral autonomic homeostasis
    evidence:
    - reference: PMID:37824694
      reference_title: Aromatic L-Amino Acid Decarboxylase Deficiency.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >-
        autonomic dysfunction (excessive sweating, temperature instability,
        ptosis, nasal congestion, hypoglycemic episodes).
      explanation: GeneReviews directly places temperature instability within autonomic dysfunction.
  - target: Hypoglycemia
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - autonomic and catecholamine deficiency
  - target: Constipation
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - autonomic gastrointestinal dysmotility
    description: Dysautonomia and neuromotor dysfunction can manifest as constipation.
    evidence:
    - reference: ORPHA:35708
      reference_title: "Aromatic L-amino acid decarboxylase deficiency"
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "HP:0002019 | Constipation | Occasional (29-5%)"
      explanation: Orphanet lists constipation as an occasional gastrointestinal manifestation.
  - target: Diarrhea
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - autonomic gastrointestinal dysmotility
    description: Gastrointestinal autonomic dysfunction can rarely manifest as diarrhea.
    evidence:
    - reference: ORPHA:35708
      reference_title: "Aromatic L-amino acid decarboxylase deficiency"
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "HP:0002014 | Diarrhea | Very rare (<4-1%)"
      explanation: Orphanet lists diarrhea as a very rare gastrointestinal manifestation.
  - target: Gastroesophageal reflux
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - gastrointestinal dysmotility
    - hypotonia and impaired feeding coordination
    description: Autonomic and neuromotor gastrointestinal dysfunction can contribute to reflux.
    evidence:
    - reference: ORPHA:35708
      reference_title: "Aromatic L-amino acid decarboxylase deficiency"
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "HP:0002020 | Gastroesophageal reflux | Frequent (79-30%)"
      explanation: Orphanet lists gastroesophageal reflux as a frequent gastrointestinal manifestation.
- name: Neurodevelopmental Impairment
  biological_scale: ORGANISM
  description: >-
    Early combined monoamine deficiency impairs developmental acquisition and is
    associated with global developmental delay, intellectual disability,
    seizures, feeding difficulties, and failure to thrive.
  evidence:
  - reference: PMID:36268467
    reference_title: "Clinical Features in Aromatic L-Amino Acid Decarboxylase (AADC) Deficiency: A Systematic Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Hypotonia and developmental delay are cardinal signs, reported as present in 73.9% and 72% of cases, respectively."
    explanation: Systematic review supports common developmental delay and hypotonia.
  - reference: PMID:30689738
    reference_title: "Gene therapy improves motor and mental function of aromatic l-amino acid decarboxylase deficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In patients with aromatic l-amino acid decarboxylase (AADC) deficiency, a decrease in catecholamines and serotonin levels in the brain leads to developmental delay and movement disorders."
    explanation: Gene-therapy study background links brain monoamine deficiency to developmental delay.
  downstream:
  - target: Global developmental delay
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - early monoamine neurotransmitter deficiency
  - target: Intellectual disability
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - early monoamine neurotransmitter deficiency
  - target: Feeding difficulties
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - hypotonia and neuromotor dysfunction
  - target: Failure to thrive
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - feeding difficulties and neurometabolic disease
  - target: Dysarthria
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - motor and neurodevelopmental impairment
  - target: Atypical behavior
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - early monoamine neurotransmitter deficiency
    description: Early serotonin and catecholamine deficiency is associated with behavioral disorders.
    evidence:
    - reference: PMID:36268467
      reference_title: "Clinical Features in Aromatic L-Amino Acid Decarboxylase (AADC) Deficiency: A Systematic Review."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "With 37% and 30% of patients reported being affected by sleep and behavioural disorders"
      explanation: Systematic review supports behavioral manifestations downstream of the neurometabolic disorder.
  - target: Autistic behavior
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - early monoamine neurotransmitter deficiency
    description: Neurodevelopmental monoamine deficiency can include autistic behavior.
    evidence:
    - reference: ORPHA:35708
      reference_title: "Aromatic L-amino acid decarboxylase deficiency"
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "HP:0000729 | Autistic behavior | Occasional (29-5%)"
      explanation: Orphanet lists autistic behavior as an occasional behavioral manifestation.
  - target: Irritability
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - serotonin and catecholamine deficiency
    description: Non-motor neurobehavioral manifestations include irritability.
    evidence:
    - reference: ORPHA:35708
      reference_title: "Aromatic L-amino acid decarboxylase deficiency"
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "HP:0000737 | Irritability | Frequent (79-30%)"
      explanation: Orphanet lists irritability as a frequent behavioral manifestation.
  - target: EEG abnormality
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - neurotransmitter imbalance
    description: Neurotransmitter imbalance and seizures can be accompanied by EEG abnormalities.
    evidence:
    - reference: ORPHA:35708
      reference_title: "Aromatic L-amino acid decarboxylase deficiency"
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "HP:0002353 | EEG abnormality | Occasional (29-5%)"
      explanation: Orphanet lists EEG abnormality as an occasional neurologic manifestation.
  - target: Dysphagia
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - hypotonia and impaired feeding coordination
    description: Neurodevelopmental and motor impairment can contribute to swallowing difficulty.
    evidence:
    - reference: ORPHA:35708
      reference_title: "Aromatic L-amino acid decarboxylase deficiency"
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "HP:0002015 | Dysphagia | Occasional (29-5%)"
      explanation: Orphanet lists dysphagia as an occasional growth and feeding manifestation.
  - target: Short stature
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - chronic feeding difficulty and neurometabolic disease
    description: Chronic feeding difficulty and neurometabolic disease can contribute to impaired growth.
    evidence:
    - reference: ORPHA:35708
      reference_title: "Aromatic L-amino acid decarboxylase deficiency"
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "HP:0004322 | Short stature | Occasional (29-5%)"
      explanation: Orphanet lists short stature as an occasional growth manifestation.
phenotypes:
- category: Ophthalmologic
  name: Ptosis
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Ptosis
    term:
      id: HP:0000508
      label: Ptosis
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0000508 | Ptosis | Occasional (29-5%)"
    explanation: Orphanet provides the phenotype association and frequency band.
  - reference: PMID:36268467
    reference_title: "Clinical Features in Aromatic L-Amino Acid Decarboxylase (AADC) Deficiency: A Systematic Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Oculogyric crises were seen in 67% of patients while hypokinesia in 42% and ptosis in 26%."
    explanation: Systematic review quantifies ptosis in the occasional range.
- category: Ophthalmologic
  name: Miosis
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Miosis
    term:
      id: HP:0000616
      label: Miosis
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0000616 | Miosis | Occasional (29-5%)"
    explanation: Orphanet provides the phenotype association and frequency band.
- category: Behavioral
  name: Atypical behavior
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Atypical behavior
    term:
      id: HP:0000708
      label: Atypical behavior
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0000708 | Atypical behavior | Frequent (79-30%)"
    explanation: Orphanet provides the phenotype association and frequency band.
  - reference: PMID:36268467
    reference_title: "Clinical Features in Aromatic L-Amino Acid Decarboxylase (AADC) Deficiency: A Systematic Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "With 37% and 30% of patients reported being affected by sleep and behavioural disorders"
    explanation: Systematic review supports frequent behavioral manifestations.
- category: Behavioral
  name: Autistic behavior
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Autistic behavior
    term:
      id: HP:0000729
      label: Autistic behavior
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0000729 | Autistic behavior | Occasional (29-5%)"
    explanation: Orphanet provides the phenotype association and frequency band.
- category: Behavioral
  name: Irritability
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Irritability
    term:
      id: HP:0000737
      label: Irritability
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0000737 | Irritability | Frequent (79-30%)"
    explanation: Orphanet provides the phenotype association and frequency band.
- category: Biochemical
  name: Increased circulating prolactin concentration
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Increased circulating prolactin concentration
    term:
      id: HP:0000870
      label: Increased circulating prolactin concentration
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0000870 | Increased circulating prolactin concentration | Occasional (29-5%)"
    explanation: Orphanet provides the phenotype association and frequency band.
- category: Autonomic
  name: Hyperhidrosis
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Hyperhidrosis
    term:
      id: HP:0000975
      label: Hyperhidrosis
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0000975 | Hyperhidrosis | Frequent (79-30%)"
    explanation: Orphanet provides the phenotype association and frequency band.
  - reference: PMID:19172410
    reference_title: "Aromatic L-amino acid decarboxylase deficiency: clinical features, drug therapy and follow-up."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All patients presented distinct extraneurological symptoms, such as hypersalivation, hyperhidrosis, nasal congestion, sleep disturbances and hypoglycaemia."
    explanation: Clinical cohort supports hyperhidrosis as an AADC deficiency manifestation.
- category: Autonomic
  name: Temperature instability
  phenotype_term:
    preferred_term: Temperature instability
    term:
      id: HP:0005968
      label: Temperature instability
  evidence:
  - reference: PMID:37824694
    reference_title: Aromatic L-Amino Acid Decarboxylase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      autonomic dysfunction (excessive sweating, temperature instability,
      ptosis, nasal congestion, hypoglycemic episodes).
    explanation: GeneReviews explicitly includes temperature instability in the autonomic phenotype.
- category: Neurologic
  name: Intellectual disability
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Intellectual disability
    term:
      id: HP:0001249
      label: Intellectual disability
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0001249 | Intellectual disability | Frequent (79-30%)"
    explanation: Orphanet provides the phenotype association and frequency band.
- category: Neurologic
  name: Seizure
  frequency: VERY_RARE
  phenotype_term:
    preferred_term: Seizure
    term:
      id: HP:0001250
      label: Seizure
  evidence:
  - reference: PMID:37824694
    reference_title: Aromatic L-Amino Acid Decarboxylase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Seizures are an uncommon finding, occurring in fewer than 5% of affected individuals."
    explanation: GeneReviews provides the current frequency estimate and corrects the conflicting Orphanet band.
  - reference: PMID:19172410
    reference_title: "Aromatic L-amino acid decarboxylase deficiency: clinical features, drug therapy and follow-up."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Three patients had single seizures."
    explanation: Clinical cohort documents seizures in AADC deficiency.
- category: Neurologic
  name: Athetosis
  phenotype_term:
    preferred_term: Athetosis
    term:
      id: HP:0002305
      label: Athetosis
  evidence:
  - reference: PMID:12891654
    reference_title: "Aromatic L-amino acid decarboxylase deficiency: overview of clinical features and outcomes."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The phenomenology of the movement disorder is identical to that
      previously reported, and includes intermittent oculogyric crises and limb
      dystonia, generalized athetosis, and impaired voluntary movement in all
      patients.
    explanation: The 11-patient series directly documents generalized athetosis without asserting population-wide frequency.
- category: Neurologic
  name: Myoclonus
  phenotype_term:
    preferred_term: Myoclonus
    term:
      id: HP:0001336
      label: Myoclonus
  evidence:
  - reference: PMID:28100251
    reference_title: "Consensus guideline for the diagnosis and treatment of aromatic l-amino acid decarboxylase (AADC) deficiency."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Hypokinesia and/ or bradykinesia ± ++ ++ ++ ++ Myoclonus ± ± ± ± ±
      Tremor ± ± ± ± ±
    explanation: The consensus table records myoclonus as possible (±) in its neonatal, infancy, childhood, adolescence, and adulthood columns without providing a defensible population frequency.
- category: Neurologic
  name: Hypotonia
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Hypotonia
    term:
      id: HP:0001252
      label: Hypotonia
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0001252 | Hypotonia | Frequent (79-30%)"
    explanation: Orphanet provides the phenotype association and frequency band.
  - reference: PMID:36268467
    reference_title: "Clinical Features in Aromatic L-Amino Acid Decarboxylase (AADC) Deficiency: A Systematic Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Hypotonia and developmental delay are cardinal signs, reported as present in 73.9% and 72% of cases, respectively."
    explanation: Systematic review quantifies hypotonia in the frequent range.
- category: Neurologic
  name: Dysarthria
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Dysarthria
    term:
      id: HP:0001260
      label: Dysarthria
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0001260 | Dysarthria | Occasional (29-5%)"
    explanation: Orphanet provides the phenotype association and frequency band.
- category: Neurologic
  name: Global developmental delay
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Global developmental delay
    term:
      id: HP:0001263
      label: Global developmental delay
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0001263 | Global developmental delay | Very frequent (99-80%)"
    explanation: Orphanet provides the phenotype association and frequency band.
  - reference: PMID:36268467
    reference_title: "Clinical Features in Aromatic L-Amino Acid Decarboxylase (AADC) Deficiency: A Systematic Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Hypotonia and developmental delay are cardinal signs, reported as present in 73.9% and 72% of cases, respectively."
    explanation: Systematic review supports developmental delay as a cardinal sign.
- category: Neurologic
  name: Motor delay
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Motor delay
    term:
      id: HP:0001270
      label: Motor delay
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0001270 | Motor delay | Frequent (79-30%)"
    explanation: Orphanet provides the phenotype association and frequency band.
- category: Neurologic
  name: Reduced tendon reflexes
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Reduced tendon reflexes
    term:
      id: HP:0001315
      label: Reduced tendon reflexes
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0001315 | Reduced tendon reflexes | Occasional (29-5%)"
    explanation: Orphanet provides the phenotype association and frequency band.
- category: Neurologic
  name: Dystonia
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Dystonia
    term:
      id: HP:0001332
      label: Dystonia
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0001332 | Dystonia | Frequent (79-30%)"
    explanation: Orphanet provides the phenotype association and frequency band.
  - reference: PMID:28100251
    reference_title: "Consensus guideline for the diagnosis and treatment of aromatic l-amino acid decarboxylase (AADC) deficiency."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "movement disorders (oculogyric crisis, dystonia, and hypokinesia)"
    explanation: Consensus guideline lists dystonia as a key movement disorder.
- category: Neurologic
  name: Tremor
  frequency: VERY_RARE
  phenotype_term:
    preferred_term: Tremor
    term:
      id: HP:0001337
      label: Tremor
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0001337 | Tremor | Very rare (<4-1%)"
    explanation: Orphanet provides the phenotype association and frequency band.
- category: Growth and feeding
  name: Failure to thrive
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Failure to thrive
    term:
      id: HP:0001508
      label: Failure to thrive
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0001508 | Failure to thrive | Frequent (79-30%)"
    explanation: Orphanet provides the phenotype association and frequency band.
- category: Autonomic
  name: Nasal congestion
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Nasal congestion
    term:
      id: HP:0001742
      label: Nasal congestion
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0001742 | Nasal congestion | Occasional (29-5%)"
    explanation: Orphanet provides the phenotype association and frequency band.
  - reference: PMID:32409695
    reference_title: "The genetic and clinical characteristics of aromatic L-amino acid decarboxylase deficiency in mainland China."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "autonomic symptoms such as excessive sweating, nasal congestion and profuse nasal, and oropharyngeal secretions, were common in our patients."
    explanation: Mainland China cohort supports nasal congestion as an autonomic manifestation.
- category: Autonomic
  name: Hypoglycemia
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Hypoglycemia
    term:
      id: HP:0001943
      label: Hypoglycemia
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0001943 | Hypoglycemia | Occasional (29-5%)"
    explanation: Orphanet provides the phenotype association and frequency band.
  - reference: PMID:19172410
    reference_title: "Aromatic L-amino acid decarboxylase deficiency: clinical features, drug therapy and follow-up."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All patients presented distinct extraneurological symptoms, such as hypersalivation, hyperhidrosis, nasal congestion, sleep disturbances and hypoglycaemia."
    explanation: Clinical cohort documents hypoglycemia among extraneurological symptoms.
- category: Gastrointestinal
  name: Diarrhea
  frequency: VERY_RARE
  phenotype_term:
    preferred_term: Diarrhea
    term:
      id: HP:0002014
      label: Diarrhea
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0002014 | Diarrhea | Very rare (<4-1%)"
    explanation: Orphanet provides the phenotype association and frequency band.
- category: Growth and feeding
  name: Dysphagia
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Dysphagia
    term:
      id: HP:0002015
      label: Dysphagia
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0002015 | Dysphagia | Occasional (29-5%)"
    explanation: Orphanet provides the phenotype association and frequency band.
- category: Gastrointestinal
  name: Constipation
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Constipation
    term:
      id: HP:0002019
      label: Constipation
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0002019 | Constipation | Occasional (29-5%)"
    explanation: Orphanet provides the phenotype association and frequency band.
- category: Gastrointestinal
  name: Gastroesophageal reflux
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Gastroesophageal reflux
    term:
      id: HP:0002020
      label: Gastroesophageal reflux
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0002020 | Gastroesophageal reflux | Frequent (79-30%)"
    explanation: Orphanet provides the phenotype association and frequency band.
- category: Autonomic
  name: Drooling
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Drooling
    term:
      id: HP:0002307
      label: Drooling
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0002307 | Drooling | Occasional (29-5%)"
    explanation: Orphanet provides the phenotype association and frequency band.
- category: Neurologic
  name: EEG abnormality
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: EEG abnormality
    term:
      id: HP:0002353
      label: EEG abnormality
  electrophysiology:
    electrophysiology_modality: EEG
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0002353 | EEG abnormality | Occasional (29-5%)"
    explanation: Orphanet provides the phenotype association and frequency band.
- category: Neurologic
  name: Sleep abnormality
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Sleep abnormality
    term:
      id: HP:0002360
      label: Sleep disturbance
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0002360 | Sleep abnormality | Frequent (79-30%)"
    explanation: Orphanet provides the phenotype association and frequency band.
  - reference: PMID:36268467
    reference_title: "Clinical Features in Aromatic L-Amino Acid Decarboxylase (AADC) Deficiency: A Systematic Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "With 37% and 30% of patients reported being affected by sleep and behavioural disorders"
    explanation: Systematic review supports sleep abnormality in the frequent range.
- category: Neurologic
  name: Hypokinesia
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Hypokinesia
    term:
      id: HP:0002375
      label: Hypokinesia
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0002375 | Hypokinesia | Occasional (29-5%)"
    explanation: Orphanet provides the phenotype association and frequency band.
- category: Neurologic
  name: Poor head control
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Poor head control
    term:
      id: HP:0002421
      label: Poor head control
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0002421 | Poor head control | Frequent (79-30%)"
    explanation: Orphanet provides the phenotype association and frequency band.
- category: Neurologic
  name: Limb hypertonia
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Limb hypertonia
    term:
      id: HP:0002509
      label: Limb hypertonia
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0002509 | Limb hypertonia | Occasional (29-5%)"
    explanation: Orphanet provides the phenotype association and frequency band.
- category: Autonomic
  name: Hypotension
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Hypotension
    term:
      id: HP:0002615
      label: Hypotension
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0002615 | Hypotension | Occasional (29-5%)"
    explanation: Orphanet provides the phenotype association and frequency band.
- category: Neurologic
  name: Babinski sign
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Babinski sign
    term:
      id: HP:0003487
      label: Babinski sign
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0003487 | Babinski sign | Occasional (29-5%)"
    explanation: Orphanet provides the phenotype association and frequency band.
- category: Biochemical
  name: Decreased CSF homovanillic acid concentration
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Decreased CSF homovanillic acid concentration
    term:
      id: HP:0003785
      label: Decreased CSF homovanillic acid concentration
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0003785 | Decreased CSF homovanillic acid concentration | Very frequent (99-80%)"
    explanation: Orphanet provides the phenotype association and frequency band.
  - reference: PMID:19172410
    reference_title: "Aromatic L-amino acid decarboxylase deficiency: clinical features, drug therapy and follow-up."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In CSF all patients revealed the pattern typical of AADC with decreased concentrations of homovanillic and 5-hydroxyindoleacetic acid and elevated concentration of 3-ortho-methyldopa."
    explanation: Clinical cohort supports decreased CSF homovanillic acid.
- category: Growth and feeding
  name: Short stature
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Short stature
    term:
      id: HP:0004322
      label: Short stature
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0004322 | Short stature | Occasional (29-5%)"
    explanation: Orphanet provides the phenotype association and frequency band.
- category: Neurologic
  name: Oculogyric crisis
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Oculogyric crisis
    term:
      id: HP:0010553
      label: Oculogyric crisis
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0010553 | Oculogyric crisis | Frequent (79-30%)"
    explanation: Orphanet provides the phenotype association and frequency band.
  - reference: PMID:36268467
    reference_title: "Clinical Features in Aromatic L-Amino Acid Decarboxylase (AADC) Deficiency: A Systematic Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Oculogyric crises were seen in 67% of patients while hypokinesia in 42% and ptosis in 26%."
    explanation: Systematic review quantifies oculogyric crises in the frequent range.
- category: Growth and feeding
  name: Feeding difficulties
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Feeding difficulties
    term:
      id: HP:0011968
      label: Feeding difficulties
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0011968 | Feeding difficulties | Frequent (79-30%)"
    explanation: Orphanet provides the phenotype association and frequency band.
- category: Biochemical
  name: Decreased CSF 5-hydroxyindolacetic acid concentration
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Decreased CSF 5-hydroxyindolacetic acid concentration
    term:
      id: HP:0025455
      label: Decreased CSF 5-hydroxyindolacetic acid concentration
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0025455 | Decreased CSF 5-hydroxyindolacetic acid concentration | Very frequent (99-80%)"
    explanation: Orphanet provides the phenotype association and frequency band.
  - reference: PMID:19172410
    reference_title: "Aromatic L-amino acid decarboxylase deficiency: clinical features, drug therapy and follow-up."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In CSF all patients revealed the pattern typical of AADC with decreased concentrations of homovanillic and 5-hydroxyindoleacetic acid and elevated concentration of 3-ortho-methyldopa."
    explanation: Clinical cohort supports decreased CSF 5-hydroxyindoleacetic acid.
- category: Musculoskeletal
  name: Joint contracture
  frequency: VERY_RARE
  phenotype_term:
    preferred_term: Joint contracture
    term:
      id: HP:0034392
      label: Joint contracture
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0034392 | Joint contracture | Very rare (<4-1%)"
    explanation: Orphanet provides the phenotype association and frequency band.
- category: Neurologic
  name: Dyskinesia
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Dyskinesia
    term:
      id: HP:0100660
      label: Dyskinesia
  evidence:
  - reference: ORPHA:35708
    reference_title: "Aromatic L-amino acid decarboxylase deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0100660 | Dyskinesia | Occasional (29-5%)"
    explanation: Orphanet provides the phenotype association and frequency band.
biochemical:
- name: Low CSF homovanillic acid
  presence: DECREASED
  biomarker_term:
    preferred_term: homovanillic acid
    term:
      id: CHEBI:545959
      label: homovanillic acid
  notes: >-
    Low CSF homovanillic acid is a diagnostic readout of reduced dopamine
    synthesis and downstream dopamine metabolism.
  readouts:
  - target: CSF Neurotransmitter Metabolite Signature
    relationship: READOUT_OF
    direction: NEGATIVE
    endpoint_context: DIAGNOSTIC
    interpretation: Decreased CSF HVA reports the dopamine-metabolite arm of the AADC deficiency CSF signature.
    evidence:
    - reference: PMID:19172410
      reference_title: "Aromatic L-amino acid decarboxylase deficiency: clinical features, drug therapy and follow-up."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "In CSF all patients revealed the pattern typical of AADC with decreased concentrations of homovanillic and 5-hydroxyindoleacetic acid and elevated concentration of 3-ortho-methyldopa."
      explanation: The cohort directly supports the HVA readout direction.
  evidence:
  - reference: PMID:19172410
    reference_title: "Aromatic L-amino acid decarboxylase deficiency: clinical features, drug therapy and follow-up."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In CSF all patients revealed the pattern typical of AADC with decreased concentrations of homovanillic and 5-hydroxyindoleacetic acid and elevated concentration of 3-ortho-methyldopa."
    explanation: Clinical cohort supports decreased CSF homovanillic acid in the diagnostic profile.
- name: Low CSF 5-hydroxyindoleacetic acid
  presence: DECREASED
  biomarker_term:
    preferred_term: 5-hydroxyindoleacetic acid
    term:
      id: CHEBI:27823
      label: (5-hydroxyindol-3-yl)acetic acid
  notes: >-
    Low CSF 5-hydroxyindoleacetic acid is a diagnostic readout of reduced
    serotonin synthesis and serotonin turnover.
  readouts:
  - target: CSF Neurotransmitter Metabolite Signature
    relationship: READOUT_OF
    direction: NEGATIVE
    endpoint_context: DIAGNOSTIC
    interpretation: Decreased CSF 5-HIAA reports the serotonin-metabolite arm of the AADC deficiency CSF signature.
    evidence:
    - reference: PMID:19172410
      reference_title: "Aromatic L-amino acid decarboxylase deficiency: clinical features, drug therapy and follow-up."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "In CSF all patients revealed the pattern typical of AADC with decreased concentrations of homovanillic and 5-hydroxyindoleacetic acid and elevated concentration of 3-ortho-methyldopa."
      explanation: The cohort directly supports the 5-HIAA readout direction.
  evidence:
  - reference: PMID:19172410
    reference_title: "Aromatic L-amino acid decarboxylase deficiency: clinical features, drug therapy and follow-up."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In CSF all patients revealed the pattern typical of AADC with decreased concentrations of homovanillic and 5-hydroxyindoleacetic acid and elevated concentration of 3-ortho-methyldopa."
    explanation: Clinical cohort supports decreased CSF 5-hydroxyindoleacetic acid in the diagnostic profile.
- name: Elevated CSF 3-O-methyldopa
  presence: INCREASED
  biomarker_term:
    preferred_term: 3-O-methyldopa
    term:
      id: CHEBI:82913
      label: 3-O-methyldopa
  notes: >-
    Elevated 3-O-methyldopa reflects accumulation and alternative metabolism of
    aromatic amino acid precursors when AADC activity is deficient.
  readouts:
  - target: CSF Neurotransmitter Metabolite Signature
    relationship: READOUT_OF
    direction: POSITIVE
    endpoint_context: DIAGNOSTIC
    interpretation: Elevated 3-OMD reports precursor shunting in the AADC deficiency CSF signature.
    evidence:
    - reference: PMID:19172410
      reference_title: "Aromatic L-amino acid decarboxylase deficiency: clinical features, drug therapy and follow-up."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "In CSF all patients revealed the pattern typical of AADC with decreased concentrations of homovanillic and 5-hydroxyindoleacetic acid and elevated concentration of 3-ortho-methyldopa."
      explanation: The cohort directly supports the CSF 3-OMD readout direction.
  evidence:
  - reference: PMID:19172410
    reference_title: "Aromatic L-amino acid decarboxylase deficiency: clinical features, drug therapy and follow-up."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In CSF all patients revealed the pattern typical of AADC with decreased concentrations of homovanillic and 5-hydroxyindoleacetic acid and elevated concentration of 3-ortho-methyldopa."
    explanation: Clinical cohort supports elevated 3-ortho-methyldopa in the diagnostic CSF profile.
- name: Reduced plasma AADC activity
  presence: DECREASED
  notes: Plasma AADC activity is reduced or absent and confirms the enzymatic defect.
  readouts:
  - target: DDC Enzymatic Deficiency
    relationship: READOUT_OF
    direction: NEGATIVE
    endpoint_context: DIAGNOSTIC
    interpretation: Reduced plasma AADC activity reports the primary DDC enzyme deficiency.
    evidence:
    - reference: PMID:19172410
      reference_title: "Aromatic L-amino acid decarboxylase deficiency: clinical features, drug therapy and follow-up."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Diagnosis was confirmed by measurement of AADC activity in plasma in all patients."
      explanation: The cohort directly supports plasma activity as a diagnostic readout.
  evidence:
  - reference: PMID:19172410
    reference_title: "Aromatic L-amino acid decarboxylase deficiency: clinical features, drug therapy and follow-up."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Diagnosis was confirmed by measurement of AADC activity in plasma in all patients."
    explanation: Clinical cohort supports plasma AADC activity as an enzymatic diagnostic readout.
  - reference: PMID:1357595
    reference_title: "Aromatic L-amino acid decarboxylase deficiency: clinical features, diagnosis, and treatment of a new inborn error of neurotransmitter amine synthesis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Activity of aromatic L-amino acid decarboxylase was virtually absent in a liver biopsy sample and greatly reduced in plasma."
    explanation: Original report supports reduced AADC activity in plasma and tissue.
- name: Elevated dried-blood-spot 3-O-methyldopa
  presence: INCREASED
  biomarker_term:
    preferred_term: 3-O-methyldopa
    term:
      id: CHEBI:82913
      label: 3-O-methyldopa
  notes: >-
    Elevated 3-O-methyldopa in newborn dried blood spots is a scalable screening
    biomarker, but positive screens require confirmatory molecular and/or
    biochemical testing because false positives occur.
  readouts:
  - target: DDC Enzymatic Deficiency
    relationship: READOUT_OF
    direction: POSITIVE
    endpoint_context: DIAGNOSTIC
    interpretation: Elevated blood 3-OMD reports precursor shunting caused by deficient AADC activity.
    evidence:
    - reference: PMID:38302374
      reference_title: "Newborn screening for aromatic l-amino acid decarboxylase deficiency - Strategies, results, and implication for prevalence calculations."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        A prospective, multicenter (n = 3) NBS pilot study evaluated screening
        for AADCD by quantifying 3-OMD in dried blood spots (DBS) using tandem
        mass spectrometry (MS/MS).
      explanation: The prospective pilot directly supports the blood 3-OMD readout.
  evidence:
  - reference: PMID:38302374
    reference_title: "Newborn screening for aromatic l-amino acid decarboxylase deficiency - Strategies, results, and implication for prevalence calculations."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      A prospective, multicenter (n = 3) NBS pilot study evaluated screening for
      AADCD by quantifying 3-OMD in dried blood spots (DBS) using tandem mass
      spectrometry (MS/MS).
    explanation: The prospective pilot directly evaluates the screening biomarker and specimen type.
  - reference: PMID:38302374
    reference_title: "Newborn screening for aromatic l-amino acid decarboxylase deficiency - Strategies, results, and implication for prevalence calculations."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      False-positive results were caused by maternal L-Dopa use (n = 2) and
      prematurity (30th and 36th week of gestation, n = 2).
    explanation: Observed false positives establish that DBS 3-OMD is a screening rather than standalone diagnostic result.
- name: Elevated urinary vanillactic acid
  presence: INCREASED
  notes: >-
    Urinary vanillactic acid can support suspicion of AADC deficiency, but the
    increase may be subtle and a normal value does not exclude the diagnosis.
  readouts:
  - target: DDC Enzymatic Deficiency
    relationship: READOUT_OF
    direction: POSITIVE
    endpoint_context: DIAGNOSTIC
    interpretation: Elevated urinary vanillactic acid reports alternative metabolism upstream of the AADC block.
    evidence:
    - reference: PMID:28100251
      reference_title: "Consensus guideline for the diagnosis and treatment of aromatic l-amino acid decarboxylase (AADC) deficiency."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >-
        Increased urine vanillactic acid (VLA) levels, measured by organic acid
        analysis, are reported in AADCD.
      explanation: The consensus directly supports the urinary VLA readout direction.
  evidence:
  - reference: PMID:28100251
    reference_title: "Consensus guideline for the diagnosis and treatment of aromatic l-amino acid decarboxylase (AADC) deficiency."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Increased urine vanillactic acid (VLA) levels, measured by organic acid
      analysis, are reported in AADCD.
    explanation: The consensus supports the direction, specimen, assay, and sensitivity limitation.
diagnosis:
- name: DDC molecular genetic testing
  description: >-
    Molecular genetic testing confirms pathogenic DDC variants and supports
    definitive diagnosis in a compatible clinical and biochemical setting.
  diagnosis_term:
    preferred_term: genetic testing
    term:
      id: NCIT:C15709
      label: Genetic Testing
  evidence:
  - reference: PMID:36268467
    reference_title: "Clinical Features in Aromatic L-Amino Acid Decarboxylase (AADC) Deficiency: A Systematic Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "molecular and/or biochemical diagnosis of AADC deficiency"
    explanation: Systematic review includes molecular diagnosis as a defining diagnostic route.
  - reference: PMID:32409695
    reference_title: "The genetic and clinical characteristics of aromatic L-amino acid decarboxylase deficiency in mainland China."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Twenty-three patients with clinical features of AADCD and DDC gene variants were recruited."
    explanation: Cohort diagnosis used clinical features with DDC variants.
  - reference: PMID:37824694
    reference_title: Aromatic L-Amino Acid Decarboxylase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      biallelic pathogenic variants in DDC identified by molecular genetic
      testing
    explanation: GeneReviews includes biallelic DDC variants as a core diagnostic route.
- name: CSF neurotransmitter metabolite testing
  description: >-
    CSF neurotransmitter testing shows low homovanillic acid and
    5-hydroxyindoleacetic acid with elevated 3-ortho-methyldopa.
  diagnosis_term:
    preferred_term: cerebrospinal fluid analysis
    term:
      id: NCIT:C173272
      label: CSF Analysis
  evidence:
  - reference: PMID:19172410
    reference_title: "Aromatic L-amino acid decarboxylase deficiency: clinical features, drug therapy and follow-up."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In CSF all patients revealed the pattern typical of AADC with decreased concentrations of homovanillic and 5-hydroxyindoleacetic acid and elevated concentration of 3-ortho-methyldopa."
    explanation: Cohort data support CSF neurotransmitter metabolite testing.
- name: Plasma AADC enzyme activity assay
  description: >-
    Plasma aromatic L-amino acid decarboxylase activity measurement can confirm
    the enzymatic deficiency.
  evidence:
  - reference: PMID:19172410
    reference_title: "Aromatic L-amino acid decarboxylase deficiency: clinical features, drug therapy and follow-up."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Diagnosis was confirmed by measurement of AADC activity in plasma in all patients."
    explanation: Clinical cohort supports plasma AADC activity measurement.
  - reference: PMID:1357595
    reference_title: "Aromatic L-amino acid decarboxylase deficiency: clinical features, diagnosis, and treatment of a new inborn error of neurotransmitter amine synthesis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Activity of aromatic L-amino acid decarboxylase was virtually absent in a liver biopsy sample and greatly reduced in plasma."
    explanation: Original case report supports enzyme activity measurement.
- name: Newborn screening by dried-blood-spot 3-O-methyldopa
  description: >-
    Tandem-mass-spectrometry measurement of 3-O-methyldopa in dried blood spots
    can identify presymptomatic newborns for confirmatory DDC and enzyme testing;
    it is a screening strategy, not a standalone definitive test.
  diagnosis_term:
    preferred_term: newborn screening
    term:
      id: NCIT:C81178
      label: Newborn Screening
  evidence:
  - reference: PMID:38302374
    reference_title: "Newborn screening for aromatic l-amino acid decarboxylase deficiency - Strategies, results, and implication for prevalence calculations."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The proposed screening strategy with 3-OMD detection in DBS is feasible
      and effective to identify individuals with AADCD.
    explanation: The largest prospective pilot supports feasibility and case detection.
  - reference: PMID:37635029
    reference_title: "Streamlined determination of 3-O-methyldopa in dried blood spots: Prospective screening for aromatic l-amino-acid decarboxylase deficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Eight newborns exhibited an elevated 3-OMD concentration (839-5170
      ng/mL). Among them, six newborns were confirmed to carry two pathogenic
      DDC variants.
    explanation: Prospective Taiwan screening demonstrates confirmatory molecular follow-up after an elevated screen.
differential_diagnoses:
- name: Tetrahydrobiopterin synthesis or recycling disorders
  description: >-
    BH4 disorders can share dopamine- and serotonin-pathway abnormalities, but
    AADC deficiency characteristically retains normal CSF pterins.
  distinguishing_features:
  - Normal CSF neopterin, dihydrobiopterin, and tetrahydrobiopterin in AADC deficiency
  evidence:
  - reference: PMID:28100251
    reference_title: "Consensus guideline for the diagnosis and treatment of aromatic l-amino acid decarboxylase (AADC) deficiency."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Reduced 5-HIAA and HVA, and elevated 3-OMD, L-Dopa and 5-HTP , with
      normal pterins, point to AADCD.
    explanation: The consensus identifies normal pterins as part of the biochemical pattern that points to AADC deficiency.
- name: PNPO deficiency
  disease_term:
    preferred_term: PNPO deficiency
    term:
      id: MONDO:0012407
      label: pyridoxal phosphate-responsive seizures
  description: >-
    PNPO deficiency can secondarily reduce AADC activity and resemble the AADC
    CSF profile. Very low CSF pyridoxal phosphate with elevated glycine and
    threonine, together with neonatal epileptic encephalopathy, favors PNPO
    deficiency.
  distinguishing_features:
  - Very low CSF pyridoxal phosphate with increased CSF glycine and threonine
  - Severe neonatal epileptic encephalopathy rather than the usual AADC presentation
  evidence:
  - reference: PMID:28100251
    reference_title: "Consensus guideline for the diagnosis and treatment of aromatic l-amino acid decarboxylase (AADC) deficiency."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      there is a secondary failure of AADC due to a deficiency of its cofactor
      pyridoxal phosphate
    explanation: The guideline directly describes the overlapping secondary AADC mechanism.
  - reference: PMID:28100251
    reference_title: "Consensus guideline for the diagnosis and treatment of aromatic l-amino acid decarboxylase (AADC) deficiency."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "very low PLP , and increased glycine and threonine in CSF."
    explanation: The guideline gives the discriminating CSF analytes.
treatments:
- name: Eladocagene exuparvovec gene therapy
  description: >-
    Eladocagene exuparvovec delivers DDC via an adeno-associated viral vector to
    the putamen, aiming to restore dopamine synthesis and improve motor,
    developmental, and oculogyric manifestations. The US indication includes
    adult and pediatric patients of any severity who have sufficient skull
    maturity for surgery; the European indication is limited to patients aged
    at least 18 months with severe, clinically and molecularly confirmed disease.
  therapeutic_modality: GENE_THERAPY
  treatment_term:
    preferred_term: gene therapy
    term:
      id: NCIT:C15238
      label: Gene Therapy
    therapeutic_agent:
    - preferred_term: eladocagene exuparvovec
      term:
        id: NCIT:C171796
        label: Eladocagene Exuparvovec
  target_mechanisms:
  - target: DDC Enzymatic Deficiency
    treatment_effect: RESTORES
    description: Gene addition supplies the human DDC coding sequence to restore AADC activity in the putamen.
    evidence:
    - reference: PMID:30689738
      reference_title: "Gene therapy improves motor and mental function of aromatic l-amino acid decarboxylase deficiency."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "The patients received a total of 2 × 1011 vector genomes of adeno-associated virus vector harbouring DDC via bilateral intraputaminal infusions."
      explanation: Open-label clinical study describes AAV vector delivery of DDC to the putamen.
  - target: Biogenic Monoamine Synthesis Failure
    treatment_effect: RESTORES
    description: Restored putaminal DDC expression increases dopamine synthesis.
    evidence:
    - reference: PMID:30689738
      reference_title: "Gene therapy improves motor and mental function of aromatic l-amino acid decarboxylase deficiency."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "The restoration of dopamine synthesis in the putamen via gene transfer provides transformative medical benefit across all patient ages"
      explanation: Clinical study supports restoration of putaminal dopamine synthesis.
  evidence:
  - reference: PMID:30689738
    reference_title: "Gene therapy improves motor and mental function of aromatic l-amino acid decarboxylase deficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "At up to 2 years after gene therapy, the motor function was remarkably improved in all patients."
    explanation: Open-label phase 1/2 study supports motor improvement after AAV-DDC gene therapy.
  - reference: PMID:30689738
    reference_title: "Gene therapy improves motor and mental function of aromatic l-amino acid decarboxylase deficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Dystonia disappeared and oculogyric crisis was markedly decreased in all patients."
    explanation: Gene therapy improved key movement disorder manifestations.
  - reference: DOI:10.1001/jama.2024.28666
    reference_title: "Eladocagene Exuparvovec for Aromatic L-Amino Acid Decarboxylase Deficiency"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "US Food and Drug Administration approval of Kebilidi, eladocagene exuparvovec, for the treatment of aromatic L-amino acid decarboxylase deficiency in adult and pediatric patients."
    explanation: JAMA Insights reports FDA approval for AADC deficiency.
  - reference: PMID:34763085
    reference_title: Long-term efficacy and safety of eladocagene exuparvovec in patients with AADC deficiency.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Rapid improvements in motor and cognitive function occurred within 12
      months after gene therapy and were sustained during follow-up for >5
      years.
    explanation: Follow-up of 26 treated patients supports durable clinical benefit beyond five years.
  - reference: PMID:34763085
    reference_title: Long-term efficacy and safety of eladocagene exuparvovec in patients with AADC deficiency.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Most patients experienced mild to moderate dyskinesia that resolved in a
      few months.
    explanation: The long-term cohort documents a common transient post-treatment adverse effect.
  - reference: PMID:36103022
    reference_title: "Eladocagene Exuparvovec: First Approval."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Eladocagene exuparvovec was approved in July 2022 in the EU for the
      treatment of patients aged 18 months and older with a clinical,
      molecular, and genetically confirmed diagnosis of AADC deficiency with a
      severe phenotype (i.e. patients who cannot sit, stand or walk).
    explanation: The approval review records the narrower European indication.
  - reference: PMID:37824694
    reference_title: Aromatic L-Amino Acid Decarboxylase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      This treatment was also approved by the FDA for use in the United States
      to treat individuals of any disease severity with sufficient skull
      maturity to safely tolerate the neurosurgical procedure.
    explanation: GeneReviews states the US severity and surgical-maturity boundaries.
  - reference: PMID:41724580
    reference_title: "Pharmacodynamics, Efficacy, and Safety of Intraputaminal Eladocagene Exuparvovec Administered to Pediatric Patients With Aromatic L-Amino Acid Decarboxylase Deficiency Using an MR-Compatible Cannula: 48 Weeks of Follow-Up."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      At baseline (n = 13), all patients showed severe motor developmental
      delay; at week 48 (n = 12), nine achieved full head control, four could
      sit unassisted, two could stand with support, and two could walk
      independently to a toy.
    explanation: The 2026 phase 2 report quantifies milestone acquisition through 48 weeks.
  - reference: PMID:42389831
    reference_title: "Gene Therapy for Amino Acid Decarboxylase Deficiency: Clinical and Imaging Outcomes in a French Cohort."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      All patients achieved genotype-independent motor improvements and OGC
      reduction, with no serious adverse events.
    explanation: A small independent European cohort supports benefit across six genetically diverse patients but cannot establish broad genotype independence.
- name: Pyridoxine pharmacotherapy
  description: >-
    Pyridoxine or pyridoxal phosphate is used as cofactor-directed symptomatic
    therapy, often in combination with dopamine agonists and MAO inhibitors;
    clinical responses are variable.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: pyridoxine
      term:
        id: CHEBI:16709
        label: pyridoxine
  target_mechanisms:
  - target: DDC Enzymatic Deficiency
    treatment_effect: MODULATES
    description: Pyridoxine provides vitamin B6 cofactor support for residual AADC activity.
    evidence:
    - reference: PMID:28100251
      reference_title: "Consensus guideline for the diagnosis and treatment of aromatic l-amino acid decarboxylase (AADC) deficiency."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >-
        treatment with one of several available forms of vitamin B6 might
        increase residual activity of the AADC enzyme.
      explanation: The consensus states the cofactor rationale while retaining uncertainty about clinical effect.
  evidence:
  - reference: PMID:19172410
    reference_title: "Aromatic L-amino acid decarboxylase deficiency: clinical features, drug therapy and follow-up."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Drug regimes consisted of vitamin B6, dopamine agonists, MAO inhibitors and anticholinergics in different combinations."
    explanation: Clinical cohort lists vitamin B6 among AADC deficiency drug regimens.
  - reference: PMID:32409695
    reference_title: "The genetic and clinical characteristics of aromatic L-amino acid decarboxylase deficiency in mainland China."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Eighteen patients (78.3%) got various degree of improvement after using pyridoxine monotherapy or different combination of pyridoxine, dopamine agonists, and monoamine oxidase (MAO) inhibitors."
    explanation: Mainland China cohort supports partial improvement with pyridoxine-based regimens.
  - reference: PMID:32369189
    reference_title: "AADC deficiency from infancy to adulthood: Symptoms and developmental outcome in an international cohort of 63 patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Pyridoxine was the most commonly tried medication (78%, 46/59), but only
      3/46 respondents (7%) reported noticeable improvement (“increased energy”
      in all cases).
    explanation: The larger international cohort shows limited reported benefit from pyridoxine monotherapy, tempering combination-regimen evidence.
- name: Dopamine agonist and MAO inhibitor pharmacotherapy
  description: >-
    Dopamine agonists and monoamine oxidase inhibitors are used as symptomatic
    neurotransmitter-directed treatment classes, sometimes with vitamin B6 and
    anticholinergics.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: dopamine agonist
      term:
        id: NCIT:C66884
        label: Dopamine Agonist
    - preferred_term: monoamine oxidase inhibitor
      term:
        id: NCIT:C667
        label: Monoamine Oxidase Inhibitor
  target_mechanisms:
  - target: Biogenic Monoamine Synthesis Failure
    treatment_effect: MODULATES
    description: These drugs augment dopaminergic signaling or reduce monoamine breakdown despite impaired synthesis.
    evidence:
    - reference: PMID:28100251
      reference_title: "Consensus guideline for the diagnosis and treatment of aromatic l-amino acid decarboxylase (AADC) deficiency."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "MAO inhibitors prevent breakdown of dopamine and serotonin"
      explanation: The consensus directly states the MAO-inhibitor mechanism.
  evidence:
  - reference: PMID:1357595
    reference_title: "Aromatic L-amino acid decarboxylase deficiency: clinical features, diagnosis, and treatment of a new inborn error of neurotransmitter amine synthesis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Treatment with either bromocriptine or tranylcypromine stopped the abnormal eye movements; tranylcypromine treatment also improved muscle tone"
    explanation: Original cases improved with dopamine agonist and MAO inhibitor therapy.
  - reference: PMID:19172410
    reference_title: "Aromatic L-amino acid decarboxylase deficiency: clinical features, drug therapy and follow-up."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Drug regimes consisted of vitamin B6, dopamine agonists, MAO inhibitors and anticholinergics in different combinations."
    explanation: Clinical cohort supports dopamine agonist and MAO inhibitor use.
  - reference: PMID:32409695
    reference_title: "The genetic and clinical characteristics of aromatic L-amino acid decarboxylase deficiency in mainland China."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Eighteen patients (78.3%) got various degree of improvement after using pyridoxine monotherapy or different combination of pyridoxine, dopamine agonists, and monoamine oxidase (MAO) inhibitors."
    explanation: Mainland China cohort supports partial improvement with combination regimens.
  - reference: PMID:32369189
    reference_title: "AADC deficiency from infancy to adulthood: Symptoms and developmental outcome in an international cohort of 63 patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Dopamine agonists were the medications most likely to produce some
      symptomatic benefit, but were associated with dose-limiting side effects
      (dyskinesia, insomnia, irritability, vomiting) that led to discontinuation
      25% of the time.
    explanation: The international cohort supports benefit while quantifying tolerability limitations.
- name: Variant-directed levodopa pharmacotherapy
  description: >-
    Levodopa without carbidopa is first-line only for rare DDC variants in the
    ligand-binding site; outside that subgroup, a trial is conditional on
    failure of other options. This is not routine treatment for all AADC
    deficiency.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: levodopa
      term:
        id: CHEBI:15765
        label: L-dopa
  target_mechanisms:
  - target: DDC Enzymatic Deficiency
    treatment_effect: MODULATES
    description: Binding-site variants may retain enzyme that responds to increased substrate availability.
    evidence:
    - reference: PMID:28100251
      reference_title: "Consensus guideline for the diagnosis and treatment of aromatic l-amino acid decarboxylase (AADC) deficiency."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >-
        L-Dopa is first line treatment only for patients with L-Dopa binding-site
        variants
      explanation: The variant-restricted response supports modulation rather than general restoration of the enzyme defect.
  evidence:
  - reference: PMID:28100251
    reference_title: "Consensus guideline for the diagnosis and treatment of aromatic l-amino acid decarboxylase (AADC) deficiency."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      L-Dopa is first line treatment only for patients with L-Dopa binding-site
      variants
    explanation: The recommendation defines the variant-restricted indication and formulation.
- name: Folinic acid supplementation
  description: >-
    Folinic acid is clearly indicated when CSF 5-methyltetrahydrofolate is low;
    broader supplementation remains conditional because published experience
    is sparse.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: folinic acid
      term:
        id: CHEBI:15640
        label: 5-formyltetrahydrofolic acid
  evidence:
  - reference: PMID:28100251
    reference_title: "Consensus guideline for the diagnosis and treatment of aromatic l-amino acid decarboxylase (AADC) deficiency."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Low CSF 5-MTHF levels must be supplemented with folinic acid, not folic
      acid.
    explanation: The consensus distinguishes a clear biochemical indication from optional empiric use.
- name: Medication precautions and avoidance
  description: >-
    Avoid dopamine receptor antagonists because they may worsen core symptoms,
    and avoid strongly serotonergic ergot-derived dopamine agonists because of
    valvular and fibrotic risk. Routine levodopa is avoided outside the narrow
    variant-directed setting described separately.
  treatment_term:
    preferred_term: supportive care
    term:
      id: NCIT:C15747
      label: Supportive Care
  evidence:
  - reference: PMID:37824694
    reference_title: Aromatic L-Amino Acid Decarboxylase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Ergot-derived dopamine agonists with strong serotonergic (5-HT2B) agonist
      action (pergolide and cabergoline) due to risk of cardiac valvulopathy and
      other fibrotic complications
    explanation: GeneReviews states the ergot-derived dopamine-agonist safety rationale.
  - reference: PMID:37824694
    reference_title: Aromatic L-Amino Acid Decarboxylase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      dopamine receptor antagonists (e.g., metoclopramide, antipsychotic
      medications), which may worsen primary disease symptoms.
    explanation: GeneReviews directly warns against dopamine receptor antagonists.
- name: Multidisciplinary supportive care
  description: >-
    Supportive care addresses feeding, sleep, mobility, seizures, and other
    neurologic or autonomic complications while disease-directed and
    symptomatic therapies are optimized.
  treatment_term:
    preferred_term: supportive care
    term:
      id: NCIT:C15747
      label: Supportive Care
  target_phenotypes:
  - preferred_term: Feeding difficulties
    term:
      id: HP:0011968
      label: Feeding difficulties
  - preferred_term: Sleep abnormality
    term:
      id: HP:0002360
      label: Sleep disturbance
  - preferred_term: Seizure
    term:
      id: HP:0001250
      label: Seizure
  - preferred_term: Hypotonia
    term:
      id: HP:0001252
      label: Hypotonia
  evidence:
  - reference: PMID:28100251
    reference_title: "Consensus guideline for the diagnosis and treatment of aromatic l-amino acid decarboxylase (AADC) deficiency."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "practical recommendations on clinical diagnosis, laboratory diagnosis, imaging and electroencephalograpy, medical treatments and non-medical treatments."
    explanation: Consensus guideline supports medical and non-medical care recommendations for AADC deficiency.
  - reference: PMID:37824694
    reference_title: Aromatic L-Amino Acid Decarboxylase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Feeding therapy with consideration of gastrostomy tube placement or
      jejunal feeding; anticholinergic drugs and/or sleep induction for movement
      disorders / oculogyric crisis
    explanation: GeneReviews supplies concrete supportive feeding and movement-disorder measures.
clinical_trials:
- name: NCT01395641
  phase: PHASE_I
  status: COMPLETED
  description: >-
    Completed phase 1/2, open-label Taiwanese study of bilateral intracerebral
    AAV2-hAADC delivery for safety and efficacy in AADC deficiency.
  evidence:
  - reference: clinicaltrials:NCT01395641
    reference_title: A Phase I/II Clinical Trial for Treatment of Aromatic L-amino Acid Decarboxylase (AADC) Deficiency Using AAV2-hAADC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      This Phase I/II trial is to prove the efficacy and safety of AAV2-hAADC to
      treat patients with AADC deficiency.
    explanation: The registry summary states the intervention and study objectives.
  notes: >-
    The registry title identifies a combined Phase I/II design; represented as
    PHASE_I because the schema accepts one phase value.
- name: NCT02926066
  phase: PHASE_II
  status: COMPLETED
  description: >-
    Completed phase 2 expansion study that broadened treatment experience and
    evaluated a modestly higher intraputaminal AAV2-hAADC dose.
  evidence:
  - reference: clinicaltrials:NCT02926066
    reference_title: A Clinical Trial for Treatment of Aromatic L-amino Acid Decarboxylase (AADC) Deficiency Using AAV2-hAADC - An Expansion (NTUH-AADC-011)
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      This clinical trial expansion is to offer patients, who are not enrolled
      into the Phase I/II trial, a chance of treatment, to provide the
      experience in this gene therapy, and to increase the dose slightly.
    explanation: The registry summary states the expansion and dose-escalation rationale.
- name: NCT04903288
  phase: PHASE_II
  status: ACTIVE_NOT_RECRUITING
  description: >-
    Phase 2 open-label trial assessing pharmacodynamics and safety of
    eladocagene exuparvovec administered with an MR-compatible ventricular
    cannula in pediatric AADC deficiency, with extension follow-up for motor
    development, AADC-specific symptoms, and long-term safety and efficacy.
  target_phenotypes:
  - preferred_term: Motor delay
    term:
      id: HP:0001270
      label: Motor delay
  - preferred_term: Decreased CSF homovanillic acid concentration
    term:
      id: HP:0003785
      label: Decreased CSF homovanillic acid concentration
  evidence:
  - reference: clinicaltrials:NCT04903288
    reference_title: "An Open-Label Trial to Address the Safety of the SmartFlow MR-Compatible Ventricular Cannula for Administering Eladocagene Exuparvovec to Pediatric Subjects"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The primary objectives of the trial phase are to assess the pharmacodynamics (PD) of eladocagene exuparvovec treatment by evaluation of homovanillic acid (HVA) levels"
    explanation: ClinicalTrials.gov identifies pharmacodynamic assessment of eladocagene exuparvovec in AADC deficiency.
  - reference: clinicaltrials:NCT04903288
    reference_title: "An Open-Label Trial to Address the Safety of the SmartFlow MR-Compatible Ventricular Cannula for Administering Eladocagene Exuparvovec to Pediatric Subjects"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The extension phase is designed to capture additional clinical information for eladocagene exuparvovec through study evaluations, changes in motor development, AADC-specific symptoms, and other PD measures."
    explanation: Trial follow-up includes motor development, AADC-specific symptoms, and pharmacodynamic measures.
  - reference: PMID:41724580
    reference_title: "Pharmacodynamics, Efficacy, and Safety of Intraputaminal Eladocagene Exuparvovec Administered to Pediatric Patients With Aromatic L-Amino Acid Decarboxylase Deficiency Using an MR-Compatible Cannula: 48 Weeks of Follow-Up."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Study GT-002 (NCT04903288) is a phase 2, multicenter, open-label trial
      assessing the pharmacodynamics, safety, and efficacy of eladocagene
      exuparvovec administered to the putamen bilaterally in pediatric patients
      with AADC deficiency using a magnetic resonance (MR)-compatible cannula.
    explanation: The 2026 publication confirms the trial identity, phase, design, intervention, population, and delivery system.
animal_models:
- species: Mus musculus
  genotype: Homozygous Ddc p.S250F knock-in
  category: Mild hypomorphic knock-in model
  genes:
  - preferred_term: Ddc
    term:
      id: MGI:94872
      label: Ddc
  description: >-
    Homozygous S250F mice retain minute AADC activity and are viable. They show
    marked serotonin depletion with behavioral and autonomic abnormalities, but
    only modest brain dopamine reduction and no loss or morphologic abnormality
    of dopaminergic neurons. The model therefore represents disease with mild
    residual enzyme activity rather than the severe human phenotype.
  associated_phenotypes:
  - Markedly reduced brain serotonin
  - Modestly reduced brain dopamine
  - Behavioral abnormality
  - Autonomic dysfunction
  evidence:
  - reference: PMID:28973165
    reference_title: A pathogenic S250F missense mutation results in a mouse model of mild aromatic l-amino acid decarboxylase (AADC) deficiency.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Although the low enzymatic activity of the protein resulted in only
      modestly reduced concentrations of brain dopamine, serotonin levels were
      markedly diminished, and this perturbed behavior as well as autonomic
      function in mutant mice.
    explanation: The knock-in study directly reports the biochemical and organismal phenotypes.
experimental_models:
- name: DDC-knockout SH-SY5Y cell model
  experimental_model_type: CELL_LINE
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  cell_source: CRISPR-Cas9 DDC-knockout SH-SY5Y neuroblastoma cells
  description: >-
    A human neuroblastoma DDC-knockout system models AADC protein and activity
    loss, low HVA, and high 3-O-methyldopa. Re-expression of R347Q and L353P was
    used for structural and functional variant analysis; tumor-cell context
    limits inference about developing human monoaminergic circuits.
  conditions:
  - Parental SH-SY5Y cells
  - CRISPR-Cas9 DDC-knockout SH-SY5Y cells
  - DDC-knockout cells transfected with R347Q or L353P AADC
  modeled_mechanisms:
  - target: DDC Enzymatic Deficiency
    description: DDC knockout directly models loss of AADC protein and catalytic activity.
    evidence:
    - reference: PMID:40318155
      reference_title: "The CRISPR-Cas9 knockout DDC SH-SY5Y in vitro model for AADC deficiency provides insight into the pathogenicity of R347Q and L353P variants: a cross-sectional structural and functional analysis."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        This model showed a deficiency in AADC protein and activity, with an
        altered dopamine metabolites profile (low homovanillic acid and high
        3-O-methyldopa)
      explanation: The cell model directly reproduces the primary enzyme defect and diagnostic metabolite direction.
  evidence:
  - reference: PMID:40318155
    reference_title: "The CRISPR-Cas9 knockout DDC SH-SY5Y in vitro model for AADC deficiency provides insight into the pathogenicity of R347Q and L353P variants: a cross-sectional structural and functional analysis."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Overall, the DDC-KO model recapitulates some key features of AADC
      deficiency, is useful to study the molecular basis of the disease, and
      represents an ideal system for small molecule screening regarding
      specific enzyme defects
    explanation: The authors define the model's supported use while limiting the claim to some disease features.
discussions:
- discussion_id: aadc_residual_activity_mouse_model_mismatch
  kind: HUMAN_MODEL_MISMATCH
  status: OPEN
  prompt: >-
    Which model can reproduce the near-absent AADC activity and profound motor
    phenotype of severe human disease while remaining viable for longitudinal
    mechanistic and treatment studies?
  rationale: >-
    The available S250F knock-in mouse retains enough activity for substantial
    dopamine production, has only modest dopamine depletion, and lacks
    dopaminergic-cell pathology. It is informative for mild residual-activity
    disease but cannot establish mechanisms or treatment thresholds for the
    severe phenotype that dominates clinical cohorts.
  attaches_to:
  - pathophysiology#DDC Enzymatic Deficiency
  - pathophysiology#Motor Circuit Dysfunction
  evidence:
  - reference: PMID:28973165
    reference_title: A pathogenic S250F missense mutation results in a mouse model of mild aromatic l-amino acid decarboxylase (AADC) deficiency.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      We conclude that even minute levels of active AADC are sufficient to
      allow for substantial amounts of dopamine to be produced in model mice
      harboring the S250F mutation. Such mutants represent a novel, mild model
      of human AADC deficiency.
    explanation: The model authors explicitly identify residual dopamine production and mild fidelity.
  proposed_experiments:
  - experiment_id: aadc_human_neuron_allelic_series
    name: Isogenic human monoaminergic-neuron DDC allelic series
    description: >-
      Compare DDC null, severe splice, ligand-binding-site, S250F, and corrected
      isogenic human iPSC-derived dopaminergic and serotonergic neurons for AADC
      activity, monoamine flux, maturation, electrophysiology, and rescue by
      gene addition or variant-directed substrate therapy.
- discussion_id: aadc_gene_therapy_long_term_comparative_gap
  kind: KNOWLEDGE_GAP
  status: OPEN
  prompt: >-
    How durable and broadly generalizable are gene-therapy benefits, and how do
    putaminal and midbrain targets compare in long-term efficacy and safety?
  rationale: >-
    Published follow-up supports benefit beyond five years in a small,
    uncontrolled treated cohort, but comparative target-site data, rare adverse
    events, and outcomes across severity, age, and genotype remain uncertain.
    Structured independent follow-up is therefore essential after regulatory
    authorization.
  attaches_to:
  - treatments#Eladocagene exuparvovec gene therapy
  - clinical_trials#NCT04903288
  evidence:
  - reference: PMID:37402126
    reference_title: "Gene therapy for aromatic L-amino acid decarboxylase deficiency: Requirements for safe application and knowledge-generating follow-up."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Due to lack of data on long-term outcomes and the comparative efficacy of
      alternative stereotactic procedures and brain target sites, a structured
      follow-up plan and systematic documentation of outcomes in a suitable,
      industry-independent registry study are necessary.
    explanation: The international expert statement directly defines the unresolved evidence needs.
  - reference: PMID:42389831
    reference_title: "Gene Therapy for Amino Acid Decarboxylase Deficiency: Clinical and Imaging Outcomes in a French Cohort."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Six patients received bilateral intraputaminal rAAV2-hAADC infusion.
    explanation: The newest cohort adds independent follow-up but remains too small and single-target to close the comparative evidence gap.
- discussion_id: aadc_natural_history_ascertainment_gap
  kind: KNOWLEDGE_GAP
  status: OPEN
  prompt: >-
    What are unbiased age-specific phenotype frequencies, developmental
    trajectories, and survival estimates across genotypes and ancestry groups?
  rationale: >-
    The largest clinical synthesis combines heterogeneous reports susceptible
    to reporting bias, while the international natural-history cohort is
    retrospective and age-skewed. Current percentages are useful descriptive
    estimates, not population-based risks or causal genotype-phenotype rules.
  attaches_to:
  - progression#Persistent motor and developmental disability
  - progression#Survival and prognosis
  evidence:
  - reference: PMID:36268467
    reference_title: "Clinical Features in Aromatic L-Amino Acid Decarboxylase (AADC) Deficiency: A Systematic Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Although reporting bias cannot be excluded, there is still a need for
      comprehensive clinical descriptions of symptoms at onset and during
      follow-up.
    explanation: The systematic review explicitly identifies reporting bias and incomplete longitudinal description.
notes: >-
  AADC deficiency is distinct from disorders of dopamine synthesis upstream of
  DDC because both catecholamine and serotonin pathways are affected. Classical
  symptomatic pharmacotherapy remains variable in effect, while intraputaminal
  eladocagene exuparvovec is the disease-directed gene-addition therapy with
  documented regulatory approval.
datasets:
- accession: geo:GSE153990
  title: An iPSC-derived midbrain dopaminergic neuronal model of aromatic amino acid decarboxylase (AADC) deficiency gives insight into neurodevelopmental disease features
  description: Aromatic L-amino acid decarboxylase (AADC) deficiency is a complex inherited neurological disorder of monoamine synthesis which results in dopamine and serotonin deficiency. Affected patients have severe cognitive and motor delay, recurrent oculogyric crises, a complex movement disorder and high risk of premature mortality. Standard pharmacological treatment provides limited clinical benefit. Promising gene therapy approaches are emerging, though may not be either suitable or easily accessible for all patients.
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  data_type: BULK_RNA_SEQ
  sample_count: 9
  publication: PMID:33734312
  notes: Identified by GEO DataSets index search for Aromatic L-amino acid decarboxylase deficiency (scripts/discover_datasets.py); accession and metadata verified against NCBI E-utilities on 2026-08-01. Title, sample count, and organism are GEO's own values.
📚

References & Deep Research

References

25
ORPHA:35708
Aromatic L-amino acid decarboxylase deficiency
1 finding
Orphanet defines AADC deficiency as a rare severe genetic neurometabolic disorder caused by impaired catecholamine and serotonin synthesis.
"A rare, severe, genetic neurometabolic disorder associated with clinical manifestations related to impaired synthesis of dopamine, noradrenaline, adrenaline and serotonin."
PMID:28100251
Consensus guideline for the diagnosis and treatment of aromatic l-amino acid decarboxylase (AADC) deficiency.
1 finding
The international consensus guideline supports autosomal recessive inheritance, early onset, key motor/autonomic symptoms, laboratory diagnosis, imaging/EEG considerations, and medical management.
"In the face of limited definitive evidence, we constructed practical recommendations on clinical diagnosis, laboratory diagnosis, imaging and electroencephalograpy, medical treatments and non-medical treatments."
PMID:19172410
Aromatic L-amino acid decarboxylase deficiency: clinical features, drug therapy and follow-up.
1 finding
A German clinical cohort supports the combined serotonin/dopamine/ catecholamine deficiency, core neurologic and extraneurologic features, characteristic CSF profile, plasma enzyme confirmation, and symptomatic drug treatment classes.
"AADC deficiency is a disorder of biogenic amine metabolism resulting in generalized combined deficiency of serotonin, dopamine and catecholamines."
PMID:36268467
Clinical Features in Aromatic L-Amino Acid Decarboxylase (AADC) Deficiency: A Systematic Review.
1 finding
A systematic review of 261 molecularly or biochemically diagnosed patients supports DDC causation, early onset, frequent hypotonia, developmental delay, oculogyric crises, hypokinesia, ptosis, dysautonomia, gastrointestinal symptoms, sleep disorders, and behavioral disorders.
"By analysing 261 patients from 41 papers with molecular and/or biochemical diagnosis of AADC deficiency for which individuality could be determined with certainty, we found symptom onset to occur in the first 6 months of life in 93% of cases."
PMID:30689738
Gene therapy improves motor and mental function of aromatic l-amino acid decarboxylase deficiency.
1 finding
An open-label phase 1/2 intraputaminal AAV-DDC study supports restored putaminal dopamine synthesis and improved motor, oculogyric, dystonic, cognitive, and verbal function after gene therapy.
"The restoration of dopamine synthesis in the putamen via gene transfer provides transformative medical benefit across all patient ages, genotypes, and disease severities included in this study."
PMID:1357595
Aromatic L-amino acid decarboxylase deficiency: clinical features, diagnosis, and treatment of a new inborn error of neurotransmitter amine synthesis.
1 finding
The original case report documents severe hypotonia, oculogyric crises, absent/reduced AADC activity, reduced biogenic amines, elevated precursors, and partial response to bromocriptine/tranylcypromine-based therapy.
"Activity of aromatic L-amino acid decarboxylase was virtually absent in a liver biopsy sample and greatly reduced in plasma."
PMID:32409695
The genetic and clinical characteristics of aromatic L-amino acid decarboxylase deficiency in mainland China.
1 finding
A 23-patient mainland China cohort supports DDC variants, early onset, hypotonia, oculogyric crises, autonomic symptoms, and frequent partial improvement with pyridoxine, dopamine agonist, and MAO inhibitor regimens.
"Eighteen patients (78.3%) got various degree of improvement after using pyridoxine monotherapy or different combination of pyridoxine, dopamine agonists, and monoamine oxidase (MAO) inhibitors."
DOI:10.1001/jama.2024.28666
Eladocagene Exuparvovec for Aromatic L-Amino Acid Decarboxylase Deficiency
1 finding
JAMA Insights reports FDA approval of Kebilidi, eladocagene exuparvovec, for AADC deficiency in adult and pediatric patients.
"This JAMA Insights discusses the US Food and Drug Administration approval of Kebilidi, eladocagene exuparvovec, for the treatment of aromatic L-amino acid decarboxylase deficiency in adult and pediatric patients."
clinicaltrials:NCT04903288
An Open-Label Trial to Address the Safety of the SmartFlow MR-Compatible Ventricular Cannula for Administering Eladocagene Exuparvovec to Pediatric Subjects
1 finding
ClinicalTrials.gov documents an active-not-recruiting phase 2 trial of eladocagene exuparvovec in pediatric AADC deficiency.
"The primary objectives of the trial phase are to assess the pharmacodynamics (PD) of eladocagene exuparvovec treatment by evaluation of homovanillic acid (HVA) levels and to assess the safety of the SmartFlow magnetic resonance compatible ventricular cannula."
PMID:37824694
Aromatic L-Amino Acid Decarboxylase Deficiency.
1 finding
GeneReviews provides the current clinical baseline for presentation, diagnosis, management, surveillance, and genetic counseling.
"The diagnosis of AADC deficiency is established in a proband who has the following core diagnostic testing results: biallelic pathogenic variants in DDC identified by molecular genetic testing OR cerebrospinal fluid (CSF) or plasma neurotransmitter profile consistent with AADC deficiency AND..."
PMID:12891654
Aromatic L-amino acid decarboxylase deficiency: overview of clinical features and outcomes.
1 finding
An 11-patient series documents the characteristic early movement disorder and broad but generally poor functional outcomes.
"Functional clinical outcomes as a group remain poor, in spite of a variety of attempted treatment interventions, with marked impairment in motor abilities as well as in speech and communication; however, outcome was quite variable from patient to patient and covered a broad spectrum of..."
PMID:32369189
AADC deficiency from infancy to adulthood: Symptoms and developmental outcome in an international cohort of 63 patients.
1 finding
A 63-person international cohort defines early presentation, motor severity, developmental outcomes, treatment response, and mortality.
"The majority of subjects (70%) had profound motor impairment characterized by absent head control and minimal voluntary movement, while 17% had mild motor impairment and were able to walk independently."
PMID:34763085
Long-term efficacy and safety of eladocagene exuparvovec in patients with AADC deficiency.
1 finding
Follow-up of 26 treated patients supports sustained motor and cognitive benefit beyond five years while identifying transient postoperative dyskinesia and procedure-related complications.
"Rapid improvements in motor and cognitive function occurred within 12 months after gene therapy and were sustained during follow-up for >5 years."
PMID:38302374
Newborn screening for aromatic l-amino acid decarboxylase deficiency - Strategies, results, and implication for prevalence calculations.
1 finding
A prospective German pilot supports dried-blood-spot 3-O-methyldopa screening and supplies a population-specific birth-prevalence estimate.
"The proposed screening strategy with 3-OMD detection in DBS is feasible and effective to identify individuals with AADCD."
PMID:37635029
Streamlined determination of 3-O-methyldopa in dried blood spots: Prospective screening for aromatic l-amino-acid decarboxylase deficiency.
1 finding
Prospective Taiwanese screening found six molecularly confirmed newborns among 157,371 screened.
"Among them, six newborns were confirmed to carry two pathogenic DDC variants, indicating an incidence of AADC deficiency of ~1:26,000 (95% confidence interval: 1 in 12,021 to 1 in 57,228)."
PMID:37348148
Prevalence of DDC genotypes in patients with aromatic L-amino acid decarboxylase (AADC) deficiency and in silico prediction of structural protein changes.
1 finding
The largest assembled genotype dataset identifies the East Asian c.714+4A>T founder allele as the most common reported DDC variant.
"The splice variant c.714+4A>T, with a founder effect in Taiwan and China, was the most common variant (allele frequency = 32.4%), and c.[714+4A>T];[714+4A>T] was the most common genotype (genotype frequency = 21.3%)."
PMID:28973165
A pathogenic S250F missense mutation results in a mouse model of mild aromatic l-amino acid decarboxylase (AADC) deficiency.
1 finding
The homozygous S250F knock-in mouse is a viable, mild model with residual enzyme activity, marked serotonin loss, and behavioral and autonomic abnormalities.
"Such mutants represent a novel, mild model of human AADC deficiency."
PMID:40318155
The CRISPR-Cas9 knockout DDC SH-SY5Y in vitro model for AADC deficiency provides insight into the pathogenicity of R347Q and L353P variants: a cross-sectional structural and functional analysis.
1 finding
A DDC-knockout human neuroblastoma model reproduces enzyme loss and the low-HVA/high-3-OMD biochemical signature and supports variant testing.
"This model showed a deficiency in AADC protein and activity, with an altered dopamine metabolites profile (low homovanillic acid and high 3-O-methyldopa)."
PMID:37402126
Gene therapy for aromatic L-amino acid decarboxylase deficiency: Requirements for safe application and knowledge-generating follow-up.
1 finding
International experts identify unresolved long-term and comparative effectiveness questions after intracerebral AAV2 gene therapy.
"Due to lack of data on long-term outcomes and the comparative efficacy of alternative stereotactic procedures and brain target sites, a structured follow-up plan and systematic documentation of outcomes in a suitable, industry-independent registry study are necessary."
PMID:41724580
Pharmacodynamics, Efficacy, and Safety of Intraputaminal Eladocagene Exuparvovec Administered to Pediatric Patients With Aromatic L-Amino Acid Decarboxylase Deficiency Using an MR-Compatible Cannula: 48 Weeks of Follow-Up.
1 finding
The 2026 phase 2 report from NCT04903288 documents increased CSF HVA, acquired motor milestones, and no deaths or withdrawals through 48 weeks.
"At baseline (n = 13), all patients showed severe motor developmental delay; at week 48 (n = 12), nine achieved full head control, four could sit unassisted, two could stand with support, and two could walk independently to a toy."
PMID:42389831
Gene Therapy for Amino Acid Decarboxylase Deficiency: Clinical and Imaging Outcomes in a French Cohort.
1 finding
A July 2026 six-patient French cohort relates clinical recovery to dopamine-production dynamics rather than exhaustive putaminal coverage.
"Clinical recovery did not correlate with the putaminal coverage volume, indicating a biological threshold effect."
PMID:36103022
Eladocagene Exuparvovec: First Approval.
1 finding
The European authorization is restricted to patients aged at least 18 months with severe, clinically and molecularly confirmed disease.
"Eladocagene exuparvovec was approved in July 2022 in the EU for the treatment of patients aged 18 months and older with a clinical, molecular, and genetically confirmed diagnosis of AADC deficiency with a severe phenotype (i.e. patients who cannot sit, stand or walk)."
clinicaltrials:NCT01395641
A Phase I/II Clinical Trial for Treatment of Aromatic L-amino Acid Decarboxylase (AADC) Deficiency Using AAV2-hAADC
1 finding
The completed phase 1/2 study evaluated AAV2-hAADC safety and efficacy.
"This Phase I/II trial is to prove the efficacy and safety of AAV2-hAADC to treat patients with AADC deficiency."
clinicaltrials:NCT02926066
A Clinical Trial for Treatment of Aromatic L-amino Acid Decarboxylase (AADC) Deficiency Using AAV2-hAADC - An Expansion (NTUH-AADC-011)
1 finding
The completed phase 2 expansion increased experience and evaluated a modestly higher dose.
"This clinical trial expansion is to offer patients, who are not enrolled into the Phase I/II trial, a chance of treatment, to provide the experience in this gene therapy, and to increase the dose slightly."
CGGV:assertion_1dea33e3-7cf6-47f9-aa52-2525b439031a-2022-02-25T170000.000Z
DDC / aromatic L-amino acid decarboxylase deficiency (Definitive)
No top-level findings curated for this source.

Deep Research

1
Aromatic L-amino acid decarboxylase deficiency research fallback ▸

Aromatic L-amino acid decarboxylase deficiency research fallback

Provider attempts

  • Falcon deep-research: attempted with a 75 second timeout on 2026-05-06 and terminated without producing an artifact.
  • OpenAI deep-research: attempted with a 75 second timeout on 2026-05-06 and terminated without producing an artifact.
  • Perplexity deep-research: skipped after the bounded Falcon/OpenAI attempts; curation proceeded from generated Orphanet, PubMed, DOI, and ClinicalTrials.gov caches.

Literature scope used for curation

This fallback curation is based on generated reference caches for ORPHA:35708, the international consensus guideline (PMID:28100251), clinical cohort evidence (PMID:19172410, PMID:32409695), the original biochemical case report (PMID:1357595), a systematic review of 261 patients (PMID:36268467), the intraputaminal AAV-DDC gene-therapy study (PMID:30689738), the JAMA Insights FDA approval summary for eladocagene exuparvovec (DOI:10.1001/jama.2024.28666), and the ClinicalTrials.gov cache for NCT04903288.

Curation synthesis

AADC deficiency is a DDC-related autosomal recessive neurometabolic disorder. Loss of aromatic L-amino acid decarboxylase activity reduces dopamine, serotonin, norepinephrine, and epinephrine synthesis, producing early hypotonia, global developmental delay, oculogyric crises, dystonia, autonomic symptoms, and the characteristic CSF pattern of low homovanillic acid and 5-hydroxyindoleacetic acid with elevated 3-ortho-methyldopa. The YAML uses ORPHA:35708 for structured phenotype frequencies and PubMed/ClinicalTrials.gov caches for clinical mechanisms, diagnostic evidence, and treatment support.

Key references

  • ORPHA:35708
  • PMID:28100251
  • PMID:19172410
  • PMID:36268467
  • PMID:30689738
  • PMID:1357595
  • PMID:32409695
  • DOI:10.1001/jama.2024.28666
  • clinicaltrials:NCT04903288