Biotinidase deficiency is a rare, inherited condition in which the body cannot recycle biotin, a B vitamin needed to process fats, proteins, and carbohydrates. It is included on newborn screening because it is easy to detect and, when treated early, its effects are almost entirely preventable.
What causes biotinidase deficiency
The condition is caused by variants in the BTD gene, which provides instructions for the biotinidase enzyme. Without enough working enzyme, the body cannot free up biotin from food or reuse its own supply, so a deficiency develops over time. It is inherited in an autosomal recessive pattern, meaning a child inherits one variant from each parent. Profound biotinidase deficiency affects roughly 1 in 60,000 newborns.
How newborn screening detects it
Newborn screening measures biotinidase enzyme activity in the same few drops of blood collected from the heel prick in the first days of life. A low result prompts confirmatory testing to determine whether the deficiency is profound or partial. Because the screen is reliable and treatment is simple, most affected children are identified before any symptoms appear.
How biotinidase deficiency is treated
Treatment is straightforward and highly effective: lifelong daily biotin supplementation taken by mouth. Children who start early and stay on it typically develop normally. Without treatment, the condition can lead to seizures, weak muscle tone, hearing and vision loss, skin rashes, and hair loss, which is why early detection matters.
How genetic screening fits in
State newborn screening does an excellent job of catching biotinidase deficiency. Genetic screening looks at the same picture from the DNA level and, in a single test, can also assess the genes tied to more than 1,000 other clinically actionable childhood conditions, many of which are not on any state panel. Fore Genomics offers an at-home cheek-swab screen, sequenced in CLIA-certified and CAP-accredited labs, with results supported by board-certified genetic counselors. See what we screen for or start screening.
Frequently asked questions
Is biotinidase deficiency on every state's panel?
Yes. It is a core condition on the federal Recommended Uniform Screening Panel and is screened for in all U.S. states.
Is the treatment really just a vitamin?
Essentially, yes. Daily oral biotin at the right dose prevents the complications of the condition, and it is continued for life.
Is it inherited?
Yes. Biotinidase deficiency is autosomal recessive, so a child inherits a BTD variant from each parent. Parents are usually unaffected carriers.
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Medically reviewed by Fore's Clinical Team. This article is for general educational purposes and is not medical advice. Sources: HRSA Newborn Screening; National Organization for Rare Disorders (NORD).