Biotinidase deficiency

Overview

What is biotinidase deficiency?

Biotinidase deficiency is a genetic, treatable, metabolic condition that is caused by the levels of an enzyme called biotinidase being too low or absent in an affected individual. Having less biotinidase enzyme activity than needed causes the body to not be able to use the vitamin biotin (sometimes referred to as vitamin H) appropriately by the body. Biotin is used by the body to assist in the break down of proteins, fats and carbohydrates from the food we eat to make them usable by the body. When biotinidase enzyme activity is too low, there is not enough biotin available in the body for proper metabolism of the food we eat.

Biotinidase deficiency is classified as partial or profound, based on how much biotinidase enzyme activity is present in the body. Individuals with untreated biotinidase deficiency may develop problems such as hypotonia (low muscle tone), eczema (skin rash), alopecia (hair loss), seizures, developmental delay, breathing problems, ataxia (balance, coordination and movement problem), candidiasis (a type of fungal infection), lactic aciduria (presence of high levels of lactic acid in the urine), hyperammonemia (higher than normal levels of ammonia in the blood), hearing loss, conjunctivitis (pink eye), lethargy (drowsiness or low energy), coma (period of unconsciousness), vomiting, diarrhea, hepatomegaly (enlarged liver), splenomegaly (enlarged spleen), speech problems and developmental delay.

Treatment of biotinidase deficiency is lifelong daily oral supplementation with free biotin. Many symptoms of untreated biotinidase deficiency are expected to improve with initiation of treatment, and since most newborns are screened for biotinidase deficiency as part of newborn screening programs, treatment is often started prior to the initiation of symptoms. Individuals with biotinidase deficiency who are appropriately treated prior to symptoms developing can be expected to remain asymptomatic.

Biotinidase deficiency is inherited in an autosomal recessive manner, and unaffected family members of affected individuals can be tested to determine their carrier status/reproductive risks for biotinidase deficiency.

SOURCE: Emory University - Department of Human Genetics in collaboration with ThinkGenetic • https://www.thinkgenetic.com/diseases/biotinidase-deficiency/overview/44573 • DATE UPDATED: 2016-10-21

References

Genetics Home Reference - Biotinidase Deficiency - https://ghr.nlm.nih.gov/condition/biotinidase-deficiency

Genereviews - Biotinidase Deficiency - https://www.ncbi.nlm.nih.gov/books/NBK1322/

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