What Is Biotinidase Deficiency? Biotinidase deficiency is a highly treatable inherited disease in which the body cannot process biotin (vitamin B7), due to a deficiency in an enzyme called biotinidase. Biotinidase deficiency is caused by mutations in the BTD gene. Profound Biotinidase Deficiency Individuals who have less than 10% of the normal amount of the enzyme biotinidase are said to have profound biotinidase deficiency. Without treatment, their symptoms tend to be significant. Individuals with biotinidase deficiency can experience seizures, poor muscle tone, difficulty with movement and balance, vision loss, hearing loss, skin rashes, breathing problems, hair loss, fungal infections, and intellectual and/or developmental delays. These symptoms often begin after the first few weeks or months of life and can be life-threatening if untreated. Partial Biotinidase Deficiency Individuals who have between 10% and 30% of the normal amounts of biotinidase have a milder form of the disease known as partial biotinidase deficiency. They may experience less-severe symptoms, or they may not show any symptoms until they become ill or stressed. How Common Is Biotinidase Deficiency? The incidence of profound biotinidase deficiency is approximately 1 in 137,000 births. The prevalence of partial biotinidase deficiency is approximately 1 in 110,000 people. Since partial biotinidase deficiency can be mild, it is possible that the true prevalence is more common. How Is Biotinidase Deficiency Treated? Biotinidase deficiency is treated with a biotin pill taken daily by mouth. A physician can determine the proper dosage and adjust that dosage over time if necessary. This treatment is lifelong and highly effective. Both people with profound biotinidase deficiency and partial biotinidase deficiency should take biotin supplements. It is important to start biotin supplementation as soon as possible. Treatment with biotin supplements can help improve some symptoms of biotinidase deficiency. If there is delayed treatment, symptoms such as vision loss, hearing loss, and developmental delay are not reversible. For people who have vision or hearing loss, vision aids or hearing aids may be helpful. Learning specialists can help patients with intellectual delay learn as effectively as possible. What Is the Prognosis for a Person with Biotinidase Deficiency? With early detection and treatment, a person with biotinidase deficiency can live a completely normal life. If left untreated, the disease can cause life-threatening complications. When the disease is not detected early, patients may experience permanent damage to their hearing, vision, and intellectual ability. In cases where the disease is entirely unrecognized, it can be life-threatening. Other names forbiotinidase deficiency BTD deficiency Juvenile-onset multiple carboxylase deficiency Late-onset multiple carboxylase deficiency Multiple carboxylase deficiency References Küry et al., 2012, Eur J Hum Genet, 20(5), PMID: 22378278 Norrgard et al., 1999, Pediatr Res, 46(1):20-7, PMID: 10400129 OMIM: Online Mendelian Inheritance In Man, OMIM [253260], 2016, https://www.omim.org/entry/253260 Weber et al., 2004, Dev Med Child Neurol, 46(7):481-4, PMID: 15230462 Wolf, 2012, Genet Med, 14(6):565-75, PMID: 22241090 Wolf, 2016, https://www.ncbi.nlm.nih.gov/books/NBK1322/