Biotinidase deficiency

Biotinidase deficiency is an inherited disorder in which the body is not able to process the vitamin biotin properly. Biotin, sometimes called vitamin H, is an important water-soluble vitamin that aids in the metabolism of fats, carbohydrates and proteins. Biotin Deficiency can result in behavioral disorders, lack of coordination, learning disabilities and seizure. Doses of synthetic Biotin can alleviate and sometimes totally arrest such symptoms.

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Epidemiology

Approximately 1 in 60,000 newborns are affected by profound (less than 10 percent of normal enzyme activity) or partial (10-30 percent of normal enzyme activity) biotinidase deficiency.

Genetics

Mutations in the BTD gene cause biotinidase deficiency. Biotinidase is the enzyme that is made by the BTD gene. Many mutations that cause the enzyme to be nonfunctional or to be made at extremely low levels have been identified. Biotin is a vitamin that is chemically bound to proteins. (Most vitamins are only loosely associated with proteins.) Without biotinidase activity, the vitamin biotin cannot be separated from foods and therefore cannot be used by the body. Another function of the biotinidase enzyme is to recycle biotin from enzymes that are important in metabolism (processing of substances in cells). When biotin is lacking, specific enzymes called carboxylases cannot process proteins, fats, or carbohydrates. Individuals lacking biotinidase activity can still have normal carboxylases if they ingest small amounts of biotin.

This condition is inherited in an autosomal recessive pattern, which means two copies of the gene in each cell must be altered for a person to be affected by the disorder. Most often, the parents of a child with an autosomal recessive disorder are not affected but are carriers of one copy of the altered gene.

See also

• Biotin deficiency

References

• Dobrowolski SF, Angeletti J, Banas RA, Naylor EW (2003). "Real time PCR assays to detect common mutations in the biotinidase gene and application of mutational analysis to newborn screening for biotinidase deficiency". Mol Genet Metab 78 (2): 100-7. PMID 12618081
• McMahon RJ (2002). "Biotin in metabolism and molecular biology". Annu Rev Nutr 22: 221-39. PMID 12055344
• Neto EC, Schulte J, Rubim R, Lewis E, DeMari J, Castilhos C, Brites A, Giugliani R, Jensen KP, Wolf B (2004). "Newborn screening for biotinidase deficiency in Brazil: biochemical and molecular characterizations". Braz J Med Biol Res 37 (3): 295-9. PMID 15060693
• Weber P, Scholl S, Baumgartner ER (2004). "Outcome in patients with profound biotinidase deficiency: relevance of newborn screening". Dev Med Child Neurol 46 (7): 481-4. PMID 15230462
• Wolf B (2003). "Biotinidase Deficiency: New Directions and Practical Concerns". Curr Treat Options Neurol 5 (4): 321-328. PMID 12791199

This article incorporates public domain text from the Genetics Home Reference, a service of the U.S. National Library of Medicine