Answers to questions families often have about caring for their child with biotinidase deficiency

Biotinidase deficiency is a genetic disorder caused by the lack of an enzyme that processes biotin, an important cofactor in the processing of fats, carbohydrates, and protein. Newborns are especially sensitive to biotinidase deficiency, and can have irreversible vision and hearing loss and seizures, although symptoms of biotinidase deficiency may also first occur in older children.

Symptoms may develop as early as the first week of life through childhood. Initial symptoms may include seizures, hypotonia, hyperventilation, laryngeal stridor or apnea, eczema, hair loss, inflammation of the eyes, yeast infections, and ataxia.

Most children with biotinidase deficiency are diagnosed by newborn screening tests. Quantitative biotinidase levels can also be tested if there are concerns in older children.

With treatment, prognosis is excellent. In children who aren't treated, prognosis will depend on the severity of the enzyme deficiency, with children with less than 10% of normal biotin levels having the worst prognosis.

Biotinidase deficiency is an autosomal recessive condition. Most likely, a child born with biotinidase will have no other known family members with the condition. Future babies with the same mother and father have a 1 in 4 chance of also inheriting the gene mutation responsible for biotinidase deficiency.

Treatment is biotin supplementation depending on the level of existing biotinidase activity.

With treatment, impact is minimum.

Biotin is a vitamin, whereas biotinidase is an enzyme that allows our body to extract biotin from foods. Biotin is important for reactions necessary to store glucose and fatty acids and to break down branch-chain amino acids. Both the amount of biotin and the activity of biotinidase can be measured in the blood.

All of the biotin available in foods is bound and not available to individuals who can not cleave it from its bound form due to the deficiency of biotinidase. Although some vegetables may contain some free biotin, it is not enough to provide adequate supplementation. The biotin in vitamin preparations is not bound (free). [Wolf: 2010]