Defective BTD causes biotidinase deficiency

BTD deficiency is an autosomal recessive disorder in which the body is unable to recycle and reuse biotin (Btn). This results in a secondary Btn deficiency that leads to juvenile-onset multiple carboxylase deficiency (MIM:253260). Patients present with neurological and cutaneous symptoms, including seizures, hypotonia, skin rash, and alopecia, usually between the second and fifth months of life. Children with profound BTD deficiency are treated with pharmacological doses of biotin (5-20 mg daily). Neonatal screening for BTD deficiency is performed in most states of the United States and many other countries.

Summary from Reactome (R-HSA-3371598), read 2026-09-23.