Atypical Presentation of Aromatic L-Amino Acid Decarboxylase Deficiency with Developmental Epileptic Encephalopathy

Aromatic L-amino acid decarboxylase (AADC) deficiency is an autosomal recessive metabolic disorder resulting from disease-causing pathogenic variants of the dopa decarboxylase (DDC) gene. The neurological features of AADC deficiency include early-onset hypotonia, oculogyric crises, ptosis, dystonia, hypokinesia, impaired development, and autonomic dysfunction. We report a patient with genetically confirmed AADC deficiency presenting with developmental epileptic encephalopathy (DEE). We report a boy with severe intractable epileptic spasms and DEE. The patient was evaluated for cognitive and neurologic impairment. Exome sequencing revealed a homozygous mutation (NM_000790.4:c.121C>A; p.Leu41Met) in the DDCgene. This case expands the clinical spectrum of AADC deficiency and strengthens the association between dopa decarboxylase deficiency and epilepsy. Additional studies are warranted to clarify the mechanisms linking dopa decarboxylase dysfunction to DEE.