Aromatic L-amino acid decarboxylase deficiency（AADCD）is a rare autosomal recessive neuro-metabolic disorder caused by homozygous or compound heterozygous mutations in the DDC gene. AADC is a decarboxylase responsible for the formation of the neurotransmitters dopamine and serotonin by L-DOPA (levodopa) and 5-HTP (5-hydroxytryptophan), respectively. The absence of AADC affects the synthesis of key neurotransmitters that control the sympathetic nervous system, mood, cognition, and motor coordination.

Clinical manifestations include severe developmental delay, hypotonia, dyskinesia (periocular crisis, dystonia, hypokinesia) and autonomic symptoms;

No treatment is currently available. The dopamine agonist or MAO inhibitor class may slightly improve symptoms in a small proportion of patients.