The urocanase deficiency is caused by mutations in the UROC1 gene, which are transmitted in an autosomal recessive manner (a person needs to carry two UROC1 mutations to be affected). To date, four mutations have been described in two different families: c.209T>C (p.L70P) and c.1348C>T (p.R450C); and c.356C>G (p.P11R) and c.907G>C (p.A303P).
Urocanase deficiency is an inborn error of histidine metabolism. Therefore, a defective urocanase would cause the accumulation of acid urocanic that would be excreted in the urine, leading to urocanic aciduria (accumulation of acid urocanic in urine).
The diagnostic testing consists of the analysis if the 21 codified exons of the UROC1 gene that produce the protein urocanase.