Mild form of aromatic L-amino acid decarboxylase deficiency

Aromatic L-amino acid decarboxylase (AADC) deficiency (Online Mendelian Inheritance in Man #608643) is a rare autosomal recessive neurometabolic disorder caused by pathogenic variants in the DDC gene, leading to impaired enzyme activity. Affected individuals typically develop symptoms in early infancy, including truncal hypotonia, global developmental delay and oculogyric crises, and the condition is generally associated with a severe clinical course and poor prognosis. We report a patient with a mild and atypical phenotype of AADC deficiency complicated by sensorineural hearing loss and oculocutaneous albinism. The clinical course and response to treatment are described. This unusual presentation raises the possibility of coexisting conditions contributing to the phenotype. This case highlights the clinical variability of AADC deficiency and underscores the importance of comprehensive genetic and biochemical investigations to achieve an accurate diagnosis and inform personalised management.