DDC Gene: DOPA Decarboxylase – Function, Mutations, and Disease Associations

The DDC gene encodes DOPA decarboxylase (also known as aromatic L-amino acid decarboxylase, AADC), a pyridoxal phosphate-dependent enzyme that catalyzes the decarboxylation of L-DOPA to dopamine and L-5-hydroxytryptophan to serotonin. It is essential for the biosynthesis of catecholamines and indoleamines, playing a critical role in neurotransmission and neuroendocrine function.

Tissue Expression

Cell Line Expression

Hotspot Mutations

Mutation functional classification

• KEGG hsa00350: Tyrosine metabolism

• KEGG hsa00360: Phenylalanine metabolism

• KEGG hsa00380: Tryptophan metabolism

• KEGG hsa04728: Dopaminergic synapse

• Reactome R-HSA-209776: Dopamine synthesis

• Reactome R-HSA-209905: Serotonin synthesis

DOPA decarboxylase (DDC) is a homodimeric enzyme that requires pyridoxal phosphate as a cofactor. It catalyzes the decarboxylation of L-DOPA to dopamine and L-5-hydroxytryptophan to serotonin, two critical neurotransmitters. The protein is expressed primarily in the brain (especially basal ganglia), adrenal medulla, kidney, and liver. Mutations in DDC cause aromatic L-amino acid decarboxylase deficiency (AADCD), a rare autosomal recessive disorder characterized by severe neurological symptoms including hypotonia, oculogyric crises, and developmental delay. DDC is also a therapeutic target in Parkinson disease, where L-DOPA is administered to increase dopamine levels.