What is Biotinidase Deficiency

Biotinidase deficiency is a rare, inherited metabolic disorder where the body cannot recycle biotin, an essential vitamin, leading to a deficiency that affects the nervous system and skin. When detected early through newborn screening, biotinidase deficiency is highly treatable with daily oral biotin supplementation, which can prevent or reverse most symptoms.

What causes Biotinidase deficiency?

Biotinidase deficiency occurs due to mutations in the BTD gene, which provides instructions for producing the enzyme biotinidase. This enzyme is responsible for recycling biotin from proteins in the diet. Without enough functional enzyme, the body cannot release free biotin, leading to a systemic shortage that impairs the function of several critical carboxylase enzymes. This metabolic disruption impacts the brain, skin, and immune system.

How common is Biotinidase deficiency?

The incidence of biotinidase deficiency is estimated to be approximately 1 in 60,000 newborns worldwide when considering both profound and partial forms. Because it is included in newborn screening programs in many countries, including the United States, most cases are identified shortly after birth before symptoms develop.

What are the primary symptoms and classifications?

The severity of biotinidase deficiency is typically classified based on the level of residual enzyme activity:

• Profound Biotinidase Deficiency: Less than 10% of normal enzyme activity; if untreated, this can cause seizures, hypotonia (low muscle tone), hearing loss, vision problems, and skin rashes.


• Partial Biotinidase Deficiency: 10% to 30% of normal enzyme activity; symptoms may be milder and often appear only during periods of physical stress, such as infections.

Is Biotinidase deficiency inherited?

Yes, biotinidase deficiency is an autosomal recessive condition. This means an affected individual must inherit one non-working copy of the BTD gene from each parent. Parents of an affected child are typically asymptomatic carriers.

Next steps

• Consult a metabolic specialist or geneticist to confirm diagnosis and determine the level of enzyme activity.


• Join our community at DiseaseMaps.org to connect with the 14 members who have shared their experiences with biotinidase deficiency.


• Ensure adherence to prescribed biotin supplementation as directed by your clinical team.

Medical disclaimer: This information is for educational purposes only and should not replace professional medical advice, diagnosis, or treatment.

References

• NIH Genetic and Rare Diseases Information Center (GARD): Biotinidase deficiency.


• Orphanet: Biotinidase deficiency (ORPHA:125).


• OMIM (Online Mendelian Inheritance in Man): #253260 Biotinidase Deficiency.


• National Organization for Rare Disorders (NORD): Biotinidase Deficiency.