Biotinidase Deficiency: The late onset form of MULTIPLE CARBOXYLASE DEFICIENCY (deficiency of the activities of biotin-dependent enzymes propionyl-CoA carboxylase, methylcrotonyl-CoA carboxylase, and PYRUVATE CARBOXYLASE) due to a defect or deficiency in biotinidase which is essential for recycling BIOTIN.Biotinidase: An enzyme which catalyzes the release of BIOTIN from biocytin. In human, defects in the enzyme are the cause of the organic acidemia MULTIPLE CARBOXYLASE DEFICIENCY or BIOTINIDASE DEFICIENCY.Multiple Carboxylase Deficiency: A deficiency in the activities of biotin-dependent enzymes (propionyl-CoA carboxylase, methylcrotonyl-CoA carboxylase, and PYRUVATE CARBOXYLASE) due to one of two defects in BIOTIN metabolism. The neonatal form is due to HOLOCARBOXYLASE SYNTHETASE DEFICIENCY. The late-onset form is due to BIOTINIDASE DEFICIENCY.AmidohydrolasesBiotin: A water-soluble, enzyme co-factor present in minute amounts in every living cell. It occurs mainly bound to proteins or polypeptides and is abundant in liver, kidney, pancreas, yeast, and milk.