An autosomal recessive disorder called biotinidase deficiency is brought on by mutations in the biotinidase gene. The age of onset and clinical phenotype vary according to the level of biotinidase activity that is still present. One in 61000 people have both a profound and partial biotinidase deficiency. In the general population the carrier frequency is 1 in 120. The diagnosis of biotinidase deficiency is made with this assay. Additionally it is helpful for subsequent testing for a few organic acidurias.