Urocanase deficiency is an ultrarare inborn error of histidine metabolism transmitted in an autosomal recessive manner and caused by mutations in the UROC1 gene. The defect of the enzyme causes urocanic aciduria, since the urocanase catalyzes the conversion of urocanic acid to imidazolnepropionic acid, and is associated with varying degrees of intellectual disability, but also with normal phenotypes.
To date only two cases have been reported with mutations in UROC1. A 19 year-old female who suffered from intellectual disability, urocanic aciduria and intermittent ataxia (Espinós et al., 2009). In this case, enzymatic assays and in silico studies were performed which provided findings supporting that both changes (c.209T>C and c.1348C>T) would alter the proper activity of the enzyme.
Recently, two developmentally normal siblings who carried the mutations c.356C>G and c.907G>C and presented with urocanic aciduria and urocanic academia have been reported (Glinton et al., 2019). Metabolomic profiling revealed that both patients showed perturbations in the histidine metabolism in urine and in plasma.