Diagnosis of Aromatic L-Amino Acid Decarboxylase (AADC) Deficiency via Epilepsy Gene Panel Screening in a Patient with Atypical Presentation

Abstract

We describe an atypical presentation of a girl with aromatic L-amino acid decarboxylase (AADC) deficiency identified via a genetic testing program for children with epilepsy. At 21 months of age, she presented with poor head control, diffuse hypotonia, poor fixation, developmental delay, and dysphagia. She was lost to follow-up, then presented back at 3 years of age with staring spells and brief episodes of upward eye deviation. The diagnosis of unprovoked epilepsy allowed her to be included in a genetic testing program, which identified two heterozygous variants in the dopa decarboxylase (DCC) gene. Based on the genetic testing, plasma AADC enzyme activity and plasma 3-O-methyldopa results, a diagnosis of AADC deficiency was made when she was 4 years and 2 months of age. This case report shows that AADC deficiency can be the underlying diagnosis in patients with suspected epilepsy.