Mutations in the urocanase gene UROC1 are associated with urocanicaciduria. Urocanase is an enzyme in the histidine pathway encoded by the UROC1 gene. This report describes the first putative mutations, p.L70P and p.R450C, in the coding region of the UROC1 gene in a girl with urocanicaciduria presenting with mental retardation and intermittent ataxia. Computed (in silico) predictions, protein