DDC

Chr 7AR

dopa decarboxylase

Also known as: AADC

The encoded protein catalyzes the decarboxylation of L-DOPA to dopamine and L-5-hydroxytryptophan to serotonin, serving as a critical enzyme in neurotransmitter biosynthesis. Mutations cause aromatic L-amino acid decarboxylase deficiency, an autosomal recessive disorder resulting in combined serotonin and catecholamine deficiency that typically presents in infancy with severe neurological symptoms. The gene shows very low constraint against loss-of-function variants (pLI near zero), consistent with the recessive inheritance pattern where heterozygous carriers are unaffected.

GeneReviewsOMIMResearchSummary from RefSeq, OMIM, UniProt
LOFmechanismARLOEUF 0.921 OMIM phenotype
Clinical SummaryDDC
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Gene-Disease Validity (ClinGen)
aromatic L-amino acid decarboxylase deficiency · ARDefinitive

Definitive — sufficient evidence for diagnostic panels

Population Constraint (gnomAD)
Low constraint (pLI 0.00) — loss-of-function variants are relatively tolerated in the population.
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Clinical Trials
12 active or recruiting trials — potential therapeutic options may be available
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GeneReview available — DDC
Authoritative clinical overview · Recommended first read
Open GeneReview ↗

Population Genetics & Constraint

gnomAD v4 — loss-of-function & missense intolerance

Tolerant — LoF & missense variants common in population
LoF Constraint
0.92LOEUF
pLI 0.000
Z-score 1.90
OE 0.60 (0.410.92)
Tolerant

Typical tolerance to LoF variation

Missense Constraint
0.41Z-score
OE missense 0.93 (0.841.03)
258 obs / 277.2 exp
Tolerant

Mild missense constraint

Observed / Expected Ratios
LoF OE0.60 (0.410.92)
00.351.4
Missense OE0.93 (0.841.03)
00.61.4
Synonymous OE1.09
01.21.6
LoF obs/exp: 16 / 26.5Missense obs/exp: 258 / 277.2Syn Z: -0.72
Curated Mechanism (G2P)Gene2Phenotype (DDG2P) ↗
definitiveDDC-related aromatic L-amino acid decarboxylase deficiencyLOFAR

Predictions shown for reference only — model trained on dominant genes, not applicable to AR conditions.

DN
0.78top 25%
GOF
0.7029th %ile
LOF
0.2483th %ile

The Badonyi & Marsh prediction model was trained exclusively on dominant disease genes. Predictions are not reliable for genes with autosomal recessive inheritance and are shown at reduced opacity for reference only.

Predictions from Badonyi M, Marsh JA. PLoS ONE. 2024;19(8):e0307312.

ClinVar Variant Classifications

0 submitted variants in ClinVar

Protein Context — Lollipop Plot

DDC · protein map & ClinVar variants

Showing all ClinVar variants across the protein. Search a specific variant to highlight its position.

3D Protein StructureAlphaFold

Clinical Trials

Active and recruiting trials from ClinicalTrials.gov

Breast AdenocarcinomaHormone Receptor PositiveStage IA Breast Cancer AJCC v7

Hormone Therapy With or Without Combination Chemotherapy in Treating Women Who Have Undergone Surgery for Node-Negative Breast Cancer (The TAILORx Trial)

ACTIVE NOT RECRUITING
NCT00310180Phase PHASE3National Cancer Institute (NCI)Started 2006-04-07
AnastrozoleExemestaneLaboratory Biomarker Analysis
Colorectal Neuroendocrine Tumor G1Gastric Neuroendocrine Tumor G1Neuroendocrine Neoplasm

Octreotide Acetate and Recombinant Interferon Alfa-2b or Bevacizumab in Treating Patients With Metastatic or Locally Advanced, High-Risk Neuroendocrine Tumor

ACTIVE NOT RECRUITING
NCT00569127Phase PHASE3National Cancer Institute (NCI)Started 2007-12-01
BevacizumabLaboratory Biomarker AnalysisOctreotide Acetate
Breast Carcinoma In SituInvasive Breast CarcinomaStage I Breast Cancer AJCC v7

Testing MK-3475 (Pembrolizumab) as Adjuvant Therapy for Triple Receptor-Negative Breast Cancer

ACTIVE NOT RECRUITING
NCT02954874Phase PHASE3National Cancer Institute (NCI)Started 2017-01-18
Biospecimen CollectionLaboratory Biomarker AnalysisPatient Observation
Parkinson DiseaseImpulse Control Disorder

Efficacy of a Prediction Model-based Algorithm to PREVENT Drug-induced Impulse Control Disorders in Parkinson's Disease

NOT YET RECRUITING
NCT07505394Phase NAAssistance Publique - Hôpitaux de ParisStarted 2026-06-01
Algorithm-guided groupStandard of Care (SoC) group
Cardiomyopathy

Natural History Study in Pediatric Patients With MYBPC3 Mutation-associated Cardiomyopathy

RECRUITING
NCT05112237Tenaya TherapeuticsStarted 2021-11-01
Ductal Breast Carcinoma In Situ

MRI and Gene Expression in Diagnosing Patients With Ductal Breast Cancer In Situ

ACTIVE NOT RECRUITING
NCT02352883Phase NAECOG-ACRIN Cancer Research GroupStarted 2015-03-25
Magnetic Resonance ImagingTherapeutic Conventional SurgeryTherapeutic Surgical Procedure
Stage IB Lung Non-Small Cell Carcinoma AJCC v7Stage II Lung Non-Small Cell Cancer AJCC v7Stage IIA Lung Cancer AJCC v8

Genetic Testing in Screening Patients With Stage IB-IIIA Non-small Cell Lung Cancer That Has Been or Will Be Removed by Surgery (The ALCHEMIST Screening Trial)

ACTIVE NOT RECRUITING
NCT02194738Phase NANational Cancer Institute (NCI)Started 2014-09-26
Biospecimen CollectionCarboplatinCisplatin
Breast Cancer

S1207 Hormone Therapy With or Without Everolimus in Treating Patients With Breast Cancer

ACTIVE NOT RECRUITING
NCT01674140Phase PHASE3SWOG Cancer Research NetworkStarted 2013-09-12
anastrozoleeverolimusexemestane
Recurrent Diffuse Large B-Cell Lymphoma Activated B-Cell TypeRefractory Diffuse Large B-Cell Lymphoma Activated B-Cell Type

Ibrutinib Before and After Stem Cell Transplant in Treating Patients With Relapsed or Refractory Diffuse Large B-cell Lymphoma

ACTIVE NOT RECRUITING
NCT02443077Phase PHASE3National Cancer Institute (NCI)Started 2016-10-12
Autologous Bone Marrow TransplantationAutologous Hematopoietic Stem Cell TransplantationCarmustine
HIV-1-infection

DORAvirine Versus DOlutegravir Based Antiretroviral Regimens in Treatment-naïve People Living With HIV-1 Infection

RECRUITING
NCT06203132Phase PHASE3ANRS, Emerging Infectious DiseasesStarted 2025-01-27
Doravirine + tenofovir DF + lamivudineDolutegravir + tenofovir DF + lamivudine or emtricitabine
Lung Non-Squamous Non-Small Cell CarcinomaStage IB Lung Non-Small Cell Carcinoma AJCC v7Stage II Lung Non-Small Cell Cancer AJCC v7

Erlotinib Hydrochloride in Treating Patients With Stage IB-IIIA Non-small Cell Lung Cancer That Has Been Completely Removed by Surgery (An ALCHEMIST Treatment Trial)

ACTIVE NOT RECRUITING
NCT02193282Phase PHASE3National Cancer Institute (NCI)Started 2015-02-11
Clinical ObservationErlotinib HydrochlorideLaboratory Biomarker Analysis
Previously Treated Non-Small Cell Lung Cancer

Lung-MAP: A Master Screening Protocol for Previously-Treated Non-Small Cell Lung Cancer

RECRUITING
NCT03851445Phase PHASE2, PHASE3SWOG Cancer Research NetworkStarted 2019-02-06
Screening Platform
Clinical Literature
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