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Biotinidase deficiency is an inherited disorder in which the body is unable to reuse and recycle the vitamin biotin. This disorder is classified as a multiple carboxylase deficiency, a group of disorders characterized by impaired activity of certain enzymes that depend on biotin.
The signs and symptoms of biotinidase deficiency typically appear within the first few months of life, but the age of onset varies. Children with profound biotinidase deficiency, the more severe form of the condition, often have seizures, weak muscle tone (hypotonia), breathing problems, and delayed development. If left untreated, the disorder can lead to hearing loss, eye abnormalities and loss of vision, problems with movement and balance (ataxia), skin rashes, hair loss (alopecia), and a fungal infection called candidiasis. Immediate treatment and lifelong management with biotin supplements can prevent many of these complications.
Partial biotinidase deficiency is a milder form of this condition. Affected children experience hypotonia, skin rashes, and hair loss, but these problems may appear only during illness, infection, or other times of stress.
Profound or partial biotinidase deficiency occurs in approximately 1 in 60,000 newborns
Mutations in the BTD gene cause biotinidase deficiency.
The BTD gene provides instructions for making an enzyme called biotinidase. This enzyme helps the body reuse biotin, a B vitamin found in foods such as liver, egg yolks, and milk. Biotinidase removes biotin that is bound to proteins in food, leaving the vitamin in its free (unbound) state. The body needs free biotin to break down fats, proteins, and carbohydrates effectively. Biotinidase also recycles biotin within the body.
Mutations in the BTD gene reduce or eliminate the activity of biotinidase. Profound biotinidase deficiency results when the activity of biotinidase is reduced to less than 10 percent of normal. Partial biotinidase deficiency occurs when biotinidase activity is reduced to between 10 percent and 30 percent of normal. Without enough of this enzyme, biotin cannot be separated from proteins or recycled normally. As a result, the body is less able to process important nutrients. These defects underlie the potentially serious medical problems associated with biotinidase deficiency.
Changes in this gene are associated with biotinidase deficiency.
This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.
These resources address the diagnosis or management of biotinidase deficiency and may include treatment providers.
You might also find information on the diagnosis or management of biotinidase deficiency in Educational resources (http://www.ghr.nlm.nih.gov/condition/biotinidase-deficiency/show/Educational+resources) and Patient support (http://www.ghr.nlm.nih.gov/condition/biotinidase-deficiency/show/Patient+support).
General information about the diagnosis (http://ghr.nlm.nih.gov/handbook/consult/diagnosis) and management (http://ghr.nlm.nih.gov/handbook/consult/treatment) of genetic conditions is available in the Handbook. Read more about genetic testing (http://ghr.nlm.nih.gov/handbook/testing), particularly the difference between clinical tests and research tests (http://ghr.nlm.nih.gov/handbook/testing/researchtesting).
To locate a healthcare provider, see How can I find a genetics professional in my area? (http://ghr.nlm.nih.gov/handbook/consult/findingprofessional) in the Handbook.
You may find the following resources about biotinidase deficiency helpful. These materials are written for the general public.
You may also be interested in these resources, which are designed for healthcare professionals and researchers.
For more information about naming genetic conditions, see the Genetics Home Reference Condition Naming Guidelines (http://ghr.nlm.nih.gov/ConditionNameGuide) and How are genetic conditions and genes named? (http://ghr.nlm.nih.gov/handbook/mutationsanddisorders/naming) in the Handbook.
Ask the Genetic and Rare Diseases Information Center (http://rarediseases.info.nih.gov/GARD/).
alopecia ; ataxia ; autosomal ; autosomal recessive ; biotin ; candidiasis ; carboxylase ; cell ; deficiency ; egg ; enzyme ; gene ; hypotonia ; infection ; muscle tone ; newborn screening ; recessive ; screening ; stress
You may find definitions for these and many other terms in the Genetics Home Reference Glossary (http://www.ghr.nlm.nih.gov/glossary).
The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? (http://ghr.nlm.nih.gov/handbook/consult/findingprofessional) in the Handbook.