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Reviewed December 2014
What is biotinidase deficiency?
Biotinidase deficiency is an inherited disorder in which the body is unable to recycle the vitamin biotin. If this condition is not recognized and treated, its signs and symptoms typically appear within the first few months of life, although it can also become apparent later in childhood.
Profound biotinidase deficiency, the more severe form of the condition, can cause seizures, weak muscle tone (hypotonia), breathing problems, hearing and vision loss, problems with movement and balance (ataxia), skin rashes, hair loss (alopecia), and a fungal infection called candidiasis. Affected children also have delayed development. Lifelong treatment can prevent these complications from occurring or improve them if they have already developed.
Partial biotinidase deficiency is a milder form of this condition. Without treatment, affected children may experience hypotonia, skin rashes, and hair loss, but these problems may appear only during illness, infection, or other times of stress.
How common is biotinidase deficiency?
Profound or partial biotinidase deficiency occurs in approximately 1 in 60,000 newborns
What genes are related to biotinidase deficiency?
Mutations in the BTD gene cause biotinidase deficiency. The BTD gene provides instructions for making an enzyme called biotinidase. This enzyme recycles 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. Free biotin is needed by enzymes called biotin-dependent carboxylases to break down fats, proteins, and carbohydrates. Because several of these enzymes are impaired in biotinidase deficiency, the condition is considered a form of multiple carboxylase deficiency.
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 recycled. The resulting shortage of free biotin impairs the activity of biotin-dependent carboxylases, leading to a buildup of potentially toxic compounds in the body. If the condition is not treated promptly, this buildup damages various cells and tissues, causing the signs and symptoms described above.
Read more about the BTD gene.
How do people inherit biotinidase deficiency?
This condition is inherited in an autosomal recessive pattern, which means both copies of the BTD gene in each cell have mutations. The parents of an individual with biotinidase deficiency each carry one copy of the mutated gene, but they typically do not have any health problems associated with the condition.
Where can I find information about diagnosis or management of biotinidase deficiency?
These resources address the diagnosis or management of biotinidase deficiency and may include treatment providers.
General information about the diagnosis and management of genetic conditions is available in the Handbook. Read more about genetic testing, particularly the difference between clinical tests and research tests.
To locate a healthcare provider, see How can I find a genetics professional in my area? in the Handbook.
Where can I find additional information about biotinidase deficiency?
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.
What other names do people use for biotinidase deficiency?
What if I still have specific questions about biotinidase deficiency?
Where can I find general information about genetic conditions?
The Handbook provides basic information about genetics in clear language.
These links provide additional genetics resources that may be useful.
What glossary definitions help with understanding biotinidase deficiency?
alopecia ; ataxia ; autosomal ; autosomal recessive ; biotin ; candidiasis ; carboxylase ; cell ; deficiency ; egg ; enzyme ; gene ; hydrolase ; hypotonia ; infection ; inherited ; muscle tone ; newborn screening ; recessive ; screening ; stress ; toxic ; transferase
You may find definitions for these and many other terms in the Genetics Home Reference Glossary.
See also Understanding Medical Terminology.
References (6 links)
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? in the Handbook.