A late-onset form of multiple carboxylase deficiency, an inborn error of biotin metabolism that, if untreated, is characterized by seizures, breathing difficulties, hypotonia, skin rash, alopecia, hearing loss and delayed development. The disease is Monarch Disease Ontology identifier MONDO_0009665 (biotinidase deficiency). Also known as: BTD deficiency, deficiency of biotinidase, juvenile-onset multiple carboxylase deficiency, late-onset multiple carboxylase deficiency.