Aromatic l-amino acid decarboxylase (AADC) catalyzes
the conversion of levodopa to dopamine and 5-hydroxytryptophan to
serotonin; defects result in dopamine, norepinephrine, epinephrine,
and serotonin deficiencies. First described in 1990, this rare autosomal
recessive disorder is characterized by global developmental delay,
extrapyramidal symptoms, hypotonia, and severe autonomic dysfunction.12,13 Most
patients present in the first 6 months of life, with approximately 50% demonstrating
symptoms in the neonatal period.14 Neonatal presentation
is characterized by failure to thrive, with poor suck, swallowing
dysfunction, hypothermia, lethargy, ptosis, and hypotension. Due
to presentation with bradykinesia and athetosis, dystonic cerebral palsy
is a common initial diagnosis.13,14 Dystonia, tremor,
hypokinesia, and oculogyric crises compose the movement disorder.
Truncal hypotonia and hypokinesia can be profound, although deep
tendon reflexes are preserved. Limb hypertonia and emotional lability
are common, and variable degrees of cognitive impairment are observed.