Master's in Genetic Counseling (MGC)

Biotinidase Deficiency

Biotinidase deficiency is an autosomal recessive disorder affecting the recycling of biotin, an essential cofactor for four different enzymes. As a result, there is an impairment of the activity of those enzymes.

Clinical Features:

The clinical symptoms of biotinidase deficiency are variable with respect to age of onset, frequency, and severity. Affected infants appear normal at birth with signs and symptoms becoming evident after the first few weeks or months of life. These symptoms may include seizures, skin rash, hypotonia, ataxia, hair loss, optic nerve atrophy, hearing loss, developmental delay, and potentially life-threatening metabolic acidosis. Individuals with partial deficiency may also be at risk for developing some of these symptoms. (OMIM)

Laboratory Tests:

Screening for biotinidase deficiency is performed by measuring biotinidase enzyme activity. A serum analysis is required for diagnostic confirmation.

Treatment:

Treatment for biotinidase deficiency consists of daily oral biotin supplements. If initiated early in life, signs and symptoms may be prevented. If neurologic damage has already occurred, it is not reversible, but treatment with biotin will prevent further damage. For specific treatment guidelines, please consult with a genetic/metabolic specialist.

Screening Practice Considerations:

Detection of biotinidase deficiency does not depend on timing or type of feeding. It should be detected on the first specimen unless the infant has been transfused. It is desirable to obtain a specimen before a transfusion occurs. The enzyme is prone to heat damage if delayed in the mail or exposed to high temperatures. Prompt testing is required even if a false positive result is suspected.

Click on a state below for state specific follow-up procedures.

• Delaware
• Maryland
• Virginia