Saba Vakili - Department of Medical Genetics, Faculty of Medicine, Mashhad University of Medical Science, Mashhad, Iran.
Mohammadreza Emami - Department of Pediatric Endocrinology and Metabolism, Imam Reza Hospital, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.
Moein Mobini - Department of Pediatric Endocrinology and Metabolism, Imam Reza Hospital, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.
Rahim Vakili - Department of Pediatric Endocrinology and Metabolism, Imam Reza Hospital, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.

Hereditary tyrosinemia type III (OMIM ۲۷۶۷۱۰) is a rare inborn error of tyrosine metabolism caused by the deficiency of ۴-hydroxyphenylpyruvate dioxygenase (HPD). This metabolic statement is transmitted in an autosomal recessive trait and hitherto about ۱۸ cases presenting with this disease have been reported in the literature. Because of the low prevalence of the disease, the clinical phenotype remains variable and unclear, but the main symptoms are mostly related to the high concentrations of tyrosine and phenolic metabolites, namely mental retardation, ataxia, and seizures. We described the clinical, biochemical, and molecular characteristics of an Iranian female patient with tyrosinemia type III and her ۷-year follow-up plan. A novel variant of HPD (۶۰۹۶۹۵) mutation (c.۷۵۹+۱ G>A) was identified in a homozygous pattern. Despite not being compliant with the recommended diet, the patient continued to have normal neuropsychiatric development in the follow-up, which questions the efficacy of a low-tyrosine diet.

Child, HPD gene, Tyrosinemia type III, Tyrosine metabolism