ABSTRACT
Aromatic L-amino acid decarboxylase deficiency was identified as an autosomal recessively inherited disorder of biogenic amine metabolism, which resulted in combined generalized deficiency of serotonin, and all catecholamines. Reduced catecholamine production puts patients at risk for apnea and/or sudden cardiac arrest, especially when the patient is exposed to stressful situations including hospitalization for diagnostic procedures or surgery. Dopamine is synthesized in the substantia nigra, ventral tegmentum, and hypothalamus. Its deficiency affects voluntary movements, cognitive function, and emotion, but also hormonal functions. Dopamine deficiency results in progressive extrapyramidal movement disorders, especially hypokinesia, parkinsonism–dystonia and chorea. Deficiency of tyrosine hydroxylase results in isolated dopamine/catecholamine deficiency. Tyrosine hydroxylase catalyzes the rate-limiting step in the formation of the catecholamines, dopamine, norepinephrine, and epinephrine. The dopamine transporter actively retrieves dopamine from the synaptic cleft and is the principal regulator of dopaminergic neurotransmission.
