caused by the inability to reuse biotin molecules that are needed for cell growth, production of fatty acids and the metabolism of fats and amino acids. If left untreated, the symptoms can lead to later problems such as comas or death. Unless treatment is administered on a regular basis, symptoms can return at any point during the lifespan. Diagnosis Biotinidase deficiency can be found by genetic testing. This is often done at birth as part of newborn screening in several states throughout the United States. Results are found through testing a small amount of blood gathered through a heel prick of the infant. As not all states require that this test be done, it is often skipped in those where such testing is not required. Biotinidase deficiency can also be found by sequencing the BTD gene, particularly in those with a family history or known familial gene mutation. Treatment Treatment is possible but unless continued daily, problems may arise. Currently, this is done through supplementation of 5–10 mg of oral biotin a day. If symptoms have begun to show, standard treatments can take care of them, such as hearing aids for poor hearing. Epidemiology Based on the results of worldwide screening of biotinidase deficiency in 1991, the incidence of the disorder is: 5 in 137,401 for profound biotinidase deficiency One in 109,921 for partial biotinidase deficiency One in 61,067 for the combined incidence of profound and partial biotinidase deficiency Carrier frequency in the general population is approximately one in 120. See also Biotin Biotin deficiency Multiple carboxylase deficiency Holocarboxylase synthetase deficiency 3-Methylcrotonyl-CoA carboxylase deficiency References Further reading External links OMIM entries on Biotinidasa deficiency Autosomal recessive disorders Vitamin, coenzyme, and cofactor metabolism disorders Rare diseases