Biotinidase deficiency is an autosomal recessive metabolic disorder in which biotin is not released from proteins in the diet during digestion or from normal protein turnover in the cell. This situation results in biotin deficiency. Biotin is an important water-soluble nutrient that aids in the metabolism of fats, carbohydrates, and proteins. Biotin deficiency can result in behavioral disorders, lack of coordination, learning disabilities and seizures. Biotin supplementation can alleviate and sometimes totally stop such symptoms. Signs and symptoms
Signs and symptoms of a biotinidase deficiency can appear several days after birth. These include seizures, hypotonia and muscle/limb weakness, ataxia, paresis, hearing loss, optic atrophy, skin rashes (including seborrheic dermatitis and psoriasis), and alopecia. If left untreated, the disorder can rapidly lead to coma and death.Biotinidase deficiency can also appear later in life. This is referred to as "late-onset" biotinidase deficiency. The symptoms are similar, but perhaps more mild, because if an individual survives the neonatal period they likely have some residual activity of biotin-related enzymes. Studies have noted individuals who were asymptomatic until adolescence or early adulthood. One study pointed out that untreated individuals may not show symptoms until age 21. Furthermore, in rare cases, even individuals with profound deficiencies of biotinidase can be asymptomatic.Symptom severity is predictably correlated with the severity of the enzyme defect. Profound biotinidase deficiency refers to situations where enzyme activity is 10% or less. Individuals with partial biotinidase deficiency may have enzyme activity of 10-30%.Functionally, there is no significant difference between dietary biotin deficiency and genetic loss of biotin-related enzyme activity.
"Newborn screening for biotinidase deficiency in Brazil: biochemical and molecular characterizations". Brazilian Journal of Medical and Biological Research. 37 (3): 295–9. doi:10.1590/S0100-879X2004000300001. PMID 15060693. Weber, Peter; Scholl, Sabine; Baumgartner, E Regula (2007). "Outcome in patients with profound biotinidase deficiency: relevance of newborn screening". Developmental Medicine & Child Neurology. 46 (7): 481–4. doi:10.1111/j.1469-8749.2004.tb00509.x. PMID 15230462. Wolf, Barry (2003). "Biotinidase deficiency: New directions and practical concerns". Current Treatment Options in Neurology. 5 (4): 321–8. doi:10.1007/s11940-003-0038-4. PMID 12791199. S2CID 25158348. External links
OMIM entries on Biotinidasa deficiency

 This article incorporates public domain material from Genetics Home Reference. United States National Library of Medicine.