Supplementary Material for: DIFFERENT CLINIC DIFFERENT DIAGNOSIS: TYROSINEMIA TYPE 3

Introduction Tyrosinemia type III is an extremely rare autosomal recessive metabolic disorder resulting from biallelic pathogenic mutations in the HPD gene. To date, only a limited number of cases have been reported worldwide, and the full spectrum of clinical manifestations remains incompletely understood. While neurodevelopmental abnormalities are the most commonly described features, ocular involvement has rarely been documented. Case Presentation Here, we present a 9-month-old girl who exhibited strikingly atypical ocular symptoms characterized by persistent severe photophobia and allergic conjunctivitis at initial presentation. This combination of findings has been reported only sporadically in the literature. Biochemical and genetic investigations confirmed the diagnosis by identifying two novel heterozygous variants in the HPD gene. Implementation of a phenylalanine- and tyrosine-restricted diet led to a marked reduction in plasma tyrosine concentrations and improvement in clinical symptoms. Conclusion This case underscores the diagnostic importance of considering inherited metabolic disorders in infants presenting with severe photosensitivity and conjunctival irritation, even in the absence of other systemic features. Furthermore, it highlights the need for long-term follow-up to monitor potential neurological and ocular complications associated with persistently elevated tyrosine levels.