Biotinidase Deficiency

Gene : BTD

What is biotinidase deficiency?

Biotinidase deficiency is an inherited metabolic disorder in which the body cannot process the vitamin biotin due to a deficiency in the enzyme biotinidase. Children affected with biotinidase deficiency can experience seizures, poor muscle tone, difficulty with movement and balance, developmental delay, vision problems, hearing loss, and skin abnormalities. There are two forms of biotinidase deficiency; a profound form with severe symptoms and a partial form with milder symptoms. Both forms of biotinidase deficiency can be successfully treated with lifelong treatment of supplemental biotin pills. Daily biotin medication prevents symptoms from appearing and often can reverse some damage caused by the disease. However, developmental delay, vision and hearing loss, if present, are irreversible. Biotinidase deficiency is caused by pathogenic variants in the BTD gene.

How is biotinidase deficiency inherited?

Biotinidase deficiency is inherited in an autosomal recessive manner. This type of inheritance requires the presence of two copies of a pathogenic variant in the gene for a person to have the genetic disease. Both parents must be carriers of a pathogenic variant in the gene in order to be at risk to have an affected child. The child must inherit a pathogenic variant from each carrier parent in order to be affected. There is a 1 in 4 chance that a baby will inherit two mutated copies of the gene and be affected when both parents are carriers.

What does it mean to be a carrier?

There are no signs or symptoms associated with being a carrier for biotinidase deficiency. However, the risk to have a child affected with biotinidase deficiency is increased. Testing of reproductive partners is recommended for carriers of biotinidase deficiency.

How common is biotinidase deficiency?

Biotinidase deficiency affects all ethnicities, and overall about 1 in 60,000 newborns will be diagnosed with either profound or partial biotinidase deficiency. Profound biotinidase deficiency is estimated to occur in 1 in 137,000 newborns while partial biotinidase deficiency will affect 1 in 110,000 newborns.

Family References and Resources
Clinician References
What is Analyzed?
  • Full gene sequencing
Affected Systems





Carrier Rates
Detection Rate
Carrier Frequency
General Population > 99% 1 in 120

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