Editing Biotin (section)

===Deficiency as a result of metabolic disorders===
[[Biotinidase deficiency]] is a deficiency of the enzyme that recycles biotin, due to an inherited genetic mutation.<ref name=ods/> Biotinidase catalyzes the cleavage of biotin from biocytin and biotinyl-peptides (the proteolytic degradation products of each holocarboxylase) and thereby recycles biotin.<ref name="DRItext" /> It is also important in freeing biotin from dietary protein-bound biotin.<ref name=Wolf1985/> Neonatal screening for biotinidase deficiency started in the United States in 1984,<ref name=Canda2020 /> which as of 2017 was reported as required in more than 30 countries.<ref name=Strovel2017/>

Profound biotinidase deficiency, defined as less than 10% of normal serum enzyme activity, which has been reported as 7.1 nmol/min/mL, has an incidence of 1 in 40,000 to 1 in 60,000, but with rates as high as 1 in 10,000 in countries with high incidence of consanguineous marriages (second cousin or closer). Partial biotinidase deficiency is defined as 10% to 30% of normal serum activity.<ref name=Canda2020>{{cite journal |vauthors=Canda E, Kalkan Uçar S, Çoker M |title=Biotinidase Deficiency: Prevalence, Impact And Management Strategies |journal=Pediatric Health Med Ther |volume=11 |issue= |pages=127–33 |date=2020 |pmid=32440248 |doi=10.2147/PHMT.S198656  |doi-broken-date=November 1, 2024  |doi-access=free|pmc=7211084 |url=}}</ref> Incidence data stems from government-mandated newborn screening.<ref name="Strovel2017">{{cite journal|last=Glynis|first=Ablon|date=November 2012|title=A Double-blind, Placebo-controlled Study Evaluating the Efficacy of an Oral Supplement in Women with Self-perceived Thinning Hair|journal=The Journal of Clinical and Aesthetic Dermatology|volume=5|issue=11|pages=28–34|pmid=23198010|pmc=3509882}}</ref> For profound deficiency, treatment is oral dosing with 5 to 20&nbsp;mg per day. Seizures are reported as resolving in hours to days, with other symptoms resolving within weeks.<ref name=Canda2020/> Treatment of partial biotinidase deficiency is also recommended even though some untreated people never manifest symptoms.<ref name=Canda2020 /> Lifelong treatment with supplemental biotin is recommended for both profound and partial biotinidase deficiency.<ref name=ods/>

Inherited metabolic disorders characterized by deficient activities of biotin-dependent carboxylases are termed [[multiple carboxylase deficiency]]. These include deficiencies in the enzymes [[holocarboxylase synthetase]].<ref name=ods/> [[Holocarboxylase synthetase deficiency]] prevents the body's cells from using biotin effectively and thus interferes with multiple carboxylase reactions.<ref name=Wolf1985>{{cite journal | vauthors = Wolf B, Grier RE, Secor McVoy JR, Heard GS | s2cid = 11554577 | title = Biotinidase deficiency: a novel vitamin recycling defect | journal = Journal of Inherited Metabolic Disease | volume = 8 | issue = Suppl 1 | pages = 53–8 | year = 1985 | pmid = 3930841 | doi = 10.1007/BF01800660 }}</ref> There can also be a genetic defect affecting the sodium-dependent multivitamin transporter protein.<ref name=Zempleni2008/>

Biochemical and clinical manifestations of any of these metabolic disorders can include [[Metabolic acidosis|ketolactic acidosis]], [[organic aciduria]], [[hyperammonemia]], rash, [[hypotonia]], [[seizure]]s, [[Intellectual disability|developmental delay]], [[alopecia]] and [[coma]].<ref name=PKIN2020Biotin />